mdadm/Grow: Fix use after close bug by closing after fork

[thirdparty/mdadm.git] / Grow.c

/*
 * mdadm - manage Linux "md" devices aka RAID arrays.
 *
 * Copyright (C) 2001-2013 Neil Brown <neilb@suse.de>
 *
 *
 *    This program is free software; you can redistribute it and/or modify
 *    it under the terms of the GNU General Public License as published by
 *    the Free Software Foundation; either version 2 of the License, or
 *    (at your option) any later version.
 *
 *    This program is distributed in the hope that it will be useful,
 *    but WITHOUT ANY WARRANTY; without even the implied warranty of
 *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *    GNU General Public License for more details.
 *
 *    You should have received a copy of the GNU General Public License
 *    along with this program; if not, write to the Free Software
 *    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 *    Author: Neil Brown
 *    Email: <neilb@suse.de>
 */
#include        "mdadm.h"
#include        "dlink.h"
#include        <sys/mman.h>
#include        <stddef.h>
#include        <stdint.h>
#include        <sys/wait.h>

#if ! defined(__BIG_ENDIAN) && ! defined(__LITTLE_ENDIAN)
#error no endian defined
#endif
#include        "md_u.h"
#include        "md_p.h"

int restore_backup(struct supertype *st,
                   struct mdinfo *content,
                   int working_disks,
                   int next_spare,
                   char **backup_filep,
                   int verbose)
{
        int i;
        int *fdlist;
        struct mdinfo *dev;
        int err;
        int disk_count = next_spare + working_disks;
        char *backup_file = *backup_filep;

        dprintf("Called restore_backup()\n");
        fdlist = xmalloc(sizeof(int) * disk_count);

        enable_fds(next_spare);
        for (i = 0; i < next_spare; i++)
                fdlist[i] = -1;
        for (dev = content->devs; dev; dev = dev->next) {
                char buf[22];
                int fd;

                sprintf(buf, "%d:%d", dev->disk.major, dev->disk.minor);
                fd = dev_open(buf, O_RDWR);

                if (dev->disk.raid_disk >= 0)
                        fdlist[dev->disk.raid_disk] = fd;
                else
                        fdlist[next_spare++] = fd;
        }

        if (!backup_file) {
                backup_file = locate_backup(content->sys_name);
                *backup_filep = backup_file;
        }

        if (st->ss->external && st->ss->recover_backup)
                err = st->ss->recover_backup(st, content);
        else
                err = Grow_restart(st, content, fdlist, next_spare,
                                   backup_file, verbose > 0);

        while (next_spare > 0) {
                next_spare--;
                if (fdlist[next_spare] >= 0)
                        close(fdlist[next_spare]);
        }
        free(fdlist);
        if (err) {
                pr_err("Failed to restore critical section for reshape - sorry.\n");
                if (!backup_file)
                        pr_err("Possibly you need to specify a --backup-file\n");
                return 1;
        }

        dprintf("restore_backup() returns status OK.\n");
        return 0;
}

int Grow_Add_device(char *devname, int fd, char *newdev)
{
        /* Add a device to an active array.
         * Currently, just extend a linear array.
         * This requires writing a new superblock on the
         * new device, calling the kernel to add the device,
         * and if that succeeds, update the superblock on
         * all other devices.
         * This means that we need to *find* all other devices.
         */
        struct mdinfo info;

        dev_t rdev;
        int nfd, fd2;
        int d, nd;
        struct supertype *st = NULL;
        char *subarray = NULL;

        if (md_get_array_info(fd, &info.array) < 0) {
                pr_err("cannot get array info for %s\n", devname);
                return 1;
        }

        if (info.array.level != -1) {
                pr_err("can only add devices to linear arrays\n");
                return 1;
        }

        st = super_by_fd(fd, &subarray);
        if (!st) {
                pr_err("cannot handle arrays with superblock version %d\n",
                       info.array.major_version);
                return 1;
        }

        if (subarray) {
                pr_err("Cannot grow linear sub-arrays yet\n");
                free(subarray);
                free(st);
                return 1;
        }

        nfd = open(newdev, O_RDWR|O_EXCL|O_DIRECT);
        if (nfd < 0) {
                pr_err("cannot open %s\n", newdev);
                free(st);
                return 1;
        }
        if (!fstat_is_blkdev(nfd, newdev, &rdev)) {
                close(nfd);
                free(st);
                return 1;
        }
        /* now check out all the devices and make sure we can read the
         * superblock */
        for (d=0 ; d < info.array.raid_disks ; d++) {
                mdu_disk_info_t disk;
                char *dv;

                st->ss->free_super(st);

                disk.number = d;
                if (md_get_disk_info(fd, &disk) < 0) {
                        pr_err("cannot get device detail for device %d\n", d);
                        close(nfd);
                        free(st);
                        return 1;
                }
                dv = map_dev(disk.major, disk.minor, 1);
                if (!dv) {
                        pr_err("cannot find device file for device %d\n", d);
                        close(nfd);
                        free(st);
                        return 1;
                }
                fd2 = dev_open(dv, O_RDWR);
                if (fd2 < 0) {
                        pr_err("cannot open device file %s\n", dv);
                        close(nfd);
                        free(st);
                        return 1;
                }

                if (st->ss->load_super(st, fd2, NULL)) {
                        pr_err("cannot find super block on %s\n", dv);
                        close(nfd);
                        close(fd2);
                        free(st);
                        return 1;
                }
                close(fd2);
        }
        /* Ok, looks good. Lets update the superblock and write it out to
         * newdev.
         */

        info.disk.number = d;
        info.disk.major = major(rdev);
        info.disk.minor = minor(rdev);
        info.disk.raid_disk = d;
        info.disk.state = (1 << MD_DISK_SYNC) | (1 << MD_DISK_ACTIVE);
        if (st->ss->update_super(st, &info, "linear-grow-new", newdev,
                                 0, 0, NULL) != 0) {
                pr_err("Preparing new metadata failed on %s\n", newdev);
                close(nfd);
                return 1;
        }

        if (st->ss->store_super(st, nfd)) {
                pr_err("Cannot store new superblock on %s\n", newdev);
                close(nfd);
                return 1;
        }
        close(nfd);

        if (ioctl(fd, ADD_NEW_DISK, &info.disk) != 0) {
                pr_err("Cannot add new disk to this array\n");
                return 1;
        }
        /* Well, that seems to have worked.
         * Now go through and update all superblocks
         */

        if (md_get_array_info(fd, &info.array) < 0) {
                pr_err("cannot get array info for %s\n", devname);
                return 1;
        }

        nd = d;
        for (d=0 ; d < info.array.raid_disks ; d++) {
                mdu_disk_info_t disk;
                char *dv;

                disk.number = d;
                if (md_get_disk_info(fd, &disk) < 0) {
                        pr_err("cannot get device detail for device %d\n", d);
                        return 1;
                }
                dv = map_dev(disk.major, disk.minor, 1);
                if (!dv) {
                        pr_err("cannot find device file for device %d\n", d);
                        return 1;
                }
                fd2 = dev_open(dv, O_RDWR);
                if (fd2 < 0) {
                        pr_err("cannot open device file %s\n", dv);
                        return 1;
                }
                if (st->ss->load_super(st, fd2, NULL)) {
                        pr_err("cannot find super block on %s\n", dv);
                        close(fd);
                        close(fd2);
                        return 1;
                }
                info.array.raid_disks = nd+1;
                info.array.nr_disks = nd+1;
                info.array.active_disks = nd+1;
                info.array.working_disks = nd+1;

                if (st->ss->update_super(st, &info, "linear-grow-update", dv,
                                     0, 0, NULL) != 0) {
                        pr_err("Updating metadata failed on %s\n", dv);
                        close(fd2);
                        return 1;
                }

                if (st->ss->store_super(st, fd2)) {
                        pr_err("Cannot store new superblock on %s\n", dv);
                        close(fd2);
                        return 1;
                }
                close(fd2);
        }

        return 0;
}

int Grow_addbitmap(char *devname, int fd, struct context *c, struct shape *s)
{
        /*
         * First check that array doesn't have a bitmap
         * Then create the bitmap
         * Then add it
         *
         * For internal bitmaps, we need to check the version,
         * find all the active devices, and write the bitmap block
         * to all devices
         */
        mdu_bitmap_file_t bmf;
        mdu_array_info_t array;
        struct supertype *st;
        char *subarray = NULL;
        int major = BITMAP_MAJOR_HI;
        unsigned long long bitmapsize, array_size;
        struct mdinfo *mdi;

        /*
         * We only ever get called if s->bitmap_file is != NULL, so this check
         * is just here to quiet down static code checkers.
         */
        if (!s->bitmap_file)
                return 1;

        if (strcmp(s->bitmap_file, "clustered") == 0)
                major = BITMAP_MAJOR_CLUSTERED;

        if (ioctl(fd, GET_BITMAP_FILE, &bmf) != 0) {
                if (errno == ENOMEM)
                        pr_err("Memory allocation failure.\n");
                else
                        pr_err("bitmaps not supported by this kernel.\n");
                return 1;
        }
        if (bmf.pathname[0]) {
                if (strcmp(s->bitmap_file,"none") == 0) {
                        if (ioctl(fd, SET_BITMAP_FILE, -1) != 0) {
                                pr_err("failed to remove bitmap %s\n",
                                        bmf.pathname);
                                return 1;
                        }
                        return 0;
                }
                pr_err("%s already has a bitmap (%s)\n", devname, bmf.pathname);
                return 1;
        }
        if (md_get_array_info(fd, &array) != 0) {
                pr_err("cannot get array status for %s\n", devname);
                return 1;
        }
        if (array.state & (1 << MD_SB_BITMAP_PRESENT)) {
                if (strcmp(s->bitmap_file, "none")==0) {
                        array.state &= ~(1 << MD_SB_BITMAP_PRESENT);
                        if (md_set_array_info(fd, &array) != 0) {
                                if (array.state & (1 << MD_SB_CLUSTERED))
                                        pr_err("failed to remove clustered bitmap.\n");
                                else
                                        pr_err("failed to remove internal bitmap.\n");
                                return 1;
                        }
                        return 0;
                }
                pr_err("bitmap already present on %s\n", devname);
                return 1;
        }

        if (strcmp(s->bitmap_file, "none") == 0) {
                pr_err("no bitmap found on %s\n", devname);
                return 1;
        }
        if (array.level <= 0) {
                pr_err("Bitmaps not meaningful with level %s\n",
                        map_num(pers, array.level)?:"of this array");
                return 1;
        }
        bitmapsize = array.size;
        bitmapsize <<= 1;
        if (get_dev_size(fd, NULL, &array_size) &&
            array_size > (0x7fffffffULL << 9)) {
                /* Array is big enough that we cannot trust array.size
                 * try other approaches
                 */
                bitmapsize = get_component_size(fd);
        }
        if (bitmapsize == 0) {
                pr_err("Cannot reliably determine size of array to create bitmap - sorry.\n");
                return 1;
        }

        if (array.level == 10) {
                int ncopies;

                ncopies = (array.layout & 255) * ((array.layout >> 8) & 255);
                bitmapsize = bitmapsize * array.raid_disks / ncopies;

                if (strcmp(s->bitmap_file, "clustered") == 0 &&
                    !is_near_layout_10(array.layout)) {
                        pr_err("only near layout is supported with clustered raid10\n");
                        return 1;
                }
        }

        st = super_by_fd(fd, &subarray);
        if (!st) {
                pr_err("Cannot understand version %d.%d\n",
                        array.major_version, array.minor_version);
                return 1;
        }
        if (subarray) {
                pr_err("Cannot add bitmaps to sub-arrays yet\n");
                free(subarray);
                free(st);
                return 1;
        }

        mdi = sysfs_read(fd, NULL, GET_CONSISTENCY_POLICY);
        if (mdi) {
                if (mdi->consistency_policy == CONSISTENCY_POLICY_PPL) {
                        pr_err("Cannot add bitmap to array with PPL\n");
                        free(mdi);
                        free(st);
                        return 1;
                }
                free(mdi);
        }

        if (strcmp(s->bitmap_file, "internal") == 0 ||
            strcmp(s->bitmap_file, "clustered") == 0) {
                int rv;
                int d;
                int offset_setable = 0;
                if (st->ss->add_internal_bitmap == NULL) {
                        pr_err("Internal bitmaps not supported with %s metadata\n", st->ss->name);
                        return 1;
                }
                st->nodes = c->nodes;
                st->cluster_name = c->homecluster;
                mdi = sysfs_read(fd, NULL, GET_BITMAP_LOCATION);
                if (mdi)
                        offset_setable = 1;
                for (d = 0; d < st->max_devs; d++) {
                        mdu_disk_info_t disk;
                        char *dv;
                        int fd2;

                        disk.number = d;
                        if (md_get_disk_info(fd, &disk) < 0)
                                continue;
                        if (disk.major == 0 && disk.minor == 0)
                                continue;
                        if ((disk.state & (1 << MD_DISK_SYNC)) == 0)
                                continue;
                        dv = map_dev(disk.major, disk.minor, 1);
                        if (!dv)
                                continue;
                        if (((disk.state & (1 << MD_DISK_WRITEMOSTLY)) == 0) &&
                           (strcmp(s->bitmap_file, "clustered") == 0)) {
                                pr_err("%s disks marked write-mostly are not supported with clustered bitmap\n",devname);
                                return 1;
                        }
                        fd2 = dev_open(dv, O_RDWR);
                        if (fd2 < 0)
                                continue;
                        rv = st->ss->load_super(st, fd2, NULL);
                        if (!rv) {
                                rv = st->ss->add_internal_bitmap(
                                        st, &s->bitmap_chunk, c->delay,
                                        s->write_behind, bitmapsize,
                                        offset_setable, major);
                                if (!rv) {
                                        st->ss->write_bitmap(st, fd2,
                                                             NodeNumUpdate);
                                } else {
                                        pr_err("failed to create internal bitmap - chunksize problem.\n");
                                }
                        } else {
                                pr_err("failed to load super-block.\n");
                        }
                        close(fd2);
                        if (rv)
                                return 1;
                }
                if (offset_setable) {
                        st->ss->getinfo_super(st, mdi, NULL);
                        if (sysfs_init(mdi, fd, NULL)) {
                                pr_err("failed to initialize sysfs.\n");
                                free(mdi);
                        }
                        rv = sysfs_set_num_signed(mdi, NULL, "bitmap/location",
                                                  mdi->bitmap_offset);
                        free(mdi);
                } else {
                        if (strcmp(s->bitmap_file, "clustered") == 0)
                                array.state |= (1 << MD_SB_CLUSTERED);
                        array.state |= (1 << MD_SB_BITMAP_PRESENT);
                        rv = md_set_array_info(fd, &array);
                }
                if (rv < 0) {
                        if (errno == EBUSY)
                                pr_err("Cannot add bitmap while array is resyncing or reshaping etc.\n");
                        pr_err("failed to set internal bitmap.\n");
                        return 1;
                }
        } else {
                int uuid[4];
                int bitmap_fd;
                int d;
                int max_devs = st->max_devs;

                /* try to load a superblock */
                for (d = 0; d < max_devs; d++) {
                        mdu_disk_info_t disk;
                        char *dv;
                        int fd2;
                        disk.number = d;
                        if (md_get_disk_info(fd, &disk) < 0)
                                continue;
                        if ((disk.major==0 && disk.minor == 0) ||
                            (disk.state & (1 << MD_DISK_REMOVED)))
                                continue;
                        dv = map_dev(disk.major, disk.minor, 1);
                        if (!dv)
                                continue;
                        fd2 = dev_open(dv, O_RDONLY);
                        if (fd2 >= 0) {
                                if (st->ss->load_super(st, fd2, NULL) == 0) {
                                        close(fd2);
                                        st->ss->uuid_from_super(st, uuid);
                                        break;
                                }
                                close(fd2);
                        }
                }
                if (d == max_devs) {
                        pr_err("cannot find UUID for array!\n");
                        return 1;
                }
                if (CreateBitmap(s->bitmap_file, c->force, (char*)uuid,
                                 s->bitmap_chunk, c->delay, s->write_behind,
                                 bitmapsize, major)) {
                        return 1;
                }
                bitmap_fd = open(s->bitmap_file, O_RDWR);
                if (bitmap_fd < 0) {
                        pr_err("weird: %s cannot be opened\n", s->bitmap_file);
                        return 1;
                }
                if (ioctl(fd, SET_BITMAP_FILE, bitmap_fd) < 0) {
                        int err = errno;
                        if (errno == EBUSY)
                                pr_err("Cannot add bitmap while array is resyncing or reshaping etc.\n");
                        pr_err("Cannot set bitmap file for %s: %s\n",
                                devname, strerror(err));
                        return 1;
                }
        }

        return 0;
}

int Grow_consistency_policy(char *devname, int fd, struct context *c, struct shape *s)
{
        struct supertype *st;
        struct mdinfo *sra;
        struct mdinfo *sd;
        char *subarray = NULL;
        int ret = 0;
        char container_dev[PATH_MAX];
        char buf[20];

        if (s->consistency_policy != CONSISTENCY_POLICY_RESYNC &&
            s->consistency_policy != CONSISTENCY_POLICY_PPL) {
                pr_err("Operation not supported for consistency policy %s\n",
                       map_num_s(consistency_policies, s->consistency_policy));
                return 1;
        }

        st = super_by_fd(fd, &subarray);
        if (!st)
                return 1;

        sra = sysfs_read(fd, NULL, GET_CONSISTENCY_POLICY|GET_LEVEL|
                                   GET_DEVS|GET_STATE);
        if (!sra) {
                ret = 1;
                goto free_st;
        }

        if (s->consistency_policy == CONSISTENCY_POLICY_PPL &&
            !st->ss->write_init_ppl) {
                pr_err("%s metadata does not support PPL\n", st->ss->name);
                ret = 1;
                goto free_info;
        }

        if (sra->array.level != 5) {
                pr_err("Operation not supported for array level %d\n",
                                sra->array.level);
                ret = 1;
                goto free_info;
        }

        if (sra->consistency_policy == (unsigned)s->consistency_policy) {
                pr_err("Consistency policy is already %s\n",
                       map_num_s(consistency_policies, s->consistency_policy));
                ret = 1;
                goto free_info;
        } else if (sra->consistency_policy != CONSISTENCY_POLICY_RESYNC &&
                   sra->consistency_policy != CONSISTENCY_POLICY_PPL) {
                pr_err("Current consistency policy is %s, cannot change to %s\n",
                       map_num_s(consistency_policies, sra->consistency_policy),
                       map_num_s(consistency_policies, s->consistency_policy));
                ret = 1;
                goto free_info;
        }

        if (s->consistency_policy == CONSISTENCY_POLICY_PPL) {
                if (sysfs_get_str(sra, NULL, "sync_action", buf, 20) <= 0) {
                        ret = 1;
                        goto free_info;
                } else if (strcmp(buf, "reshape\n") == 0) {
                        pr_err("PPL cannot be enabled when reshape is in progress\n");
                        ret = 1;
                        goto free_info;
                }
        }

        if (subarray) {
                char *update;

                if (s->consistency_policy == CONSISTENCY_POLICY_PPL)
                        update = "ppl";
                else
                        update = "no-ppl";

                sprintf(container_dev, "/dev/%s", st->container_devnm);

                ret = Update_subarray(container_dev, subarray, update, NULL,
                                      c->verbose);
                if (ret)
                        goto free_info;
        }

        if (s->consistency_policy == CONSISTENCY_POLICY_PPL) {
                struct mdinfo info;

                if (subarray) {
                        struct mdinfo *mdi;
                        int cfd;

                        cfd = open(container_dev, O_RDWR|O_EXCL);
                        if (cfd < 0) {
                                pr_err("Failed to open %s\n", container_dev);
                                ret = 1;
                                goto free_info;
                        }

                        ret = st->ss->load_container(st, cfd, st->container_devnm);
                        close(cfd);

                        if (ret) {
                                pr_err("Cannot read superblock for %s\n",
                                       container_dev);
                                goto free_info;
                        }

                        mdi = st->ss->container_content(st, subarray);
                        info = *mdi;
                        free(mdi);
                }

                for (sd = sra->devs; sd; sd = sd->next) {
                        int dfd;
                        char *devpath;

                        devpath = map_dev(sd->disk.major, sd->disk.minor, 0);
                        dfd = dev_open(devpath, O_RDWR);
                        if (dfd < 0) {
                                pr_err("Failed to open %s\n", devpath);
                                ret = 1;
                                goto free_info;
                        }

                        if (!subarray) {
                                ret = st->ss->load_super(st, dfd, NULL);
                                if (ret) {
                                        pr_err("Failed to load super-block.\n");
                                        close(dfd);
                                        goto free_info;
                                }

                                ret = st->ss->update_super(st, sra, "ppl",
                                                           devname,
                                                           c->verbose, 0, NULL);
                                if (ret) {
                                        close(dfd);
                                        st->ss->free_super(st);
                                        goto free_info;
                                }
                                st->ss->getinfo_super(st, &info, NULL);
                        }

                        ret |= sysfs_set_num(sra, sd, "ppl_sector",
                                             info.ppl_sector);
                        ret |= sysfs_set_num(sra, sd, "ppl_size",
                                             info.ppl_size);

                        if (ret) {
                                pr_err("Failed to set PPL attributes for %s\n",
                                       sd->sys_name);
                                close(dfd);
                                st->ss->free_super(st);
                                goto free_info;
                        }

                        ret = st->ss->write_init_ppl(st, &info, dfd);
                        if (ret)
                                pr_err("Failed to write PPL\n");

                        close(dfd);

                        if (!subarray)
                                st->ss->free_super(st);

                        if (ret)
                                goto free_info;
                }
        }

        ret = sysfs_set_str(sra, NULL, "consistency_policy",
                            map_num_s(consistency_policies,
                                         s->consistency_policy));
        if (ret)
                pr_err("Failed to change array consistency policy\n");

free_info:
        sysfs_free(sra);
free_st:
        free(st);
        free(subarray);

        return ret;
}

/*
 * When reshaping an array we might need to backup some data.
 * This is written to all spares with a 'super_block' describing it.
 * The superblock goes 4K from the end of the used space on the
 * device.
 * It if written after the backup is complete.
 * It has the following structure.
 */

static struct mdp_backup_super {
        char    magic[16];  /* md_backup_data-1 or -2 */
        __u8    set_uuid[16];
        __u64   mtime;
        /* start/sizes in 512byte sectors */
        __u64   devstart;       /* address on backup device/file of data */
        __u64   arraystart;
        __u64   length;
        __u32   sb_csum;        /* csum of preceeding bytes. */
        __u32   pad1;
        __u64   devstart2;      /* offset in to data of second section */
        __u64   arraystart2;
        __u64   length2;
        __u32   sb_csum2;       /* csum of preceeding bytes. */
        __u8 pad[512-68-32];
} __attribute__((aligned(512))) bsb, bsb2;

static __u32 bsb_csum(char *buf, int len)
{
        int i;
        int csum = 0;
        for (i = 0; i < len; i++)
                csum = (csum<<3) + buf[0];
        return __cpu_to_le32(csum);
}

static int check_idle(struct supertype *st)
{
        /* Check that all member arrays for this container, or the
         * container of this array, are idle
         */
        char *container = (st->container_devnm[0]
                           ? st->container_devnm : st->devnm);
        struct mdstat_ent *ent, *e;
        int is_idle = 1;

        ent = mdstat_read(0, 0);
        for (e = ent ; e; e = e->next) {
                if (!is_container_member(e, container))
                        continue;
                /* frozen array is not idle*/
                if (e->percent >= 0 || e->metadata_version[9] == '-') {
                        is_idle = 0;
                        break;
                }
        }
        free_mdstat(ent);
        return is_idle;
}

static int freeze_container(struct supertype *st)
{
        char *container = (st->container_devnm[0]
                           ? st->container_devnm : st->devnm);

        if (!check_idle(st))
                return -1;

        if (block_monitor(container, 1)) {
                pr_err("failed to freeze container\n");
                return -2;
        }

        return 1;
}

static void unfreeze_container(struct supertype *st)
{
        char *container = (st->container_devnm[0]
                           ? st->container_devnm : st->devnm);

        unblock_monitor(container, 1);
}

static int freeze(struct supertype *st)
{
        /* Try to freeze resync/rebuild on this array/container.
         * Return -1 if the array is busy,
         * return -2 container cannot be frozen,
         * return 0 if this kernel doesn't support 'frozen'
         * return 1 if it worked.
         */
        if (st->ss->external)
                return freeze_container(st);
        else {
                struct mdinfo *sra = sysfs_read(-1, st->devnm, GET_VERSION);
                int err;
                char buf[20];

                if (!sra)
                        return -1;
                /* Need to clear any 'read-auto' status */
                if (sysfs_get_str(sra, NULL, "array_state", buf, 20) > 0 &&
                    strncmp(buf, "read-auto", 9) == 0)
                        sysfs_set_str(sra, NULL, "array_state", "clean");

                err = sysfs_freeze_array(sra);
                sysfs_free(sra);
                return err;
        }
}

static void unfreeze(struct supertype *st)
{
        if (st->ss->external)
                return unfreeze_container(st);
        else {
                struct mdinfo *sra = sysfs_read(-1, st->devnm, GET_VERSION);
                char buf[20];

                if (sra &&
                    sysfs_get_str(sra, NULL, "sync_action", buf, 20) > 0 &&
                    strcmp(buf, "frozen\n") == 0)
                        sysfs_set_str(sra, NULL, "sync_action", "idle");
                sysfs_free(sra);
        }
}

static void wait_reshape(struct mdinfo *sra)
{
        int fd = sysfs_get_fd(sra, NULL, "sync_action");
        char action[20];

        if (fd < 0)
                return;

        while (sysfs_fd_get_str(fd, action, 20) > 0 &&
               strncmp(action, "reshape", 7) == 0)
                sysfs_wait(fd, NULL);
        close(fd);
}

static int reshape_super(struct supertype *st, unsigned long long size,
                         int level, int layout, int chunksize, int raid_disks,
                         int delta_disks, char *backup_file, char *dev,
                         int direction, int verbose)
{
        /* nothing extra to check in the native case */
        if (!st->ss->external)
                return 0;
        if (!st->ss->reshape_super || !st->ss->manage_reshape) {
                pr_err("%s metadata does not support reshape\n",
                        st->ss->name);
                return 1;
        }

        return st->ss->reshape_super(st, size, level, layout, chunksize,
                                     raid_disks, delta_disks, backup_file, dev,
                                     direction, verbose);
}

static void sync_metadata(struct supertype *st)
{
        if (st->ss->external) {
                if (st->update_tail) {
                        flush_metadata_updates(st);
                        st->update_tail = &st->updates;
                } else
                        st->ss->sync_metadata(st);
        }
}

static int subarray_set_num(char *container, struct mdinfo *sra, char *name, int n)
{
        /* when dealing with external metadata subarrays we need to be
         * prepared to handle EAGAIN.  The kernel may need to wait for
         * mdmon to mark the array active so the kernel can handle
         * allocations/writeback when preparing the reshape action
         * (md_allow_write()).  We temporarily disable safe_mode_delay
         * to close a race with the array_state going clean before the
         * next write to raid_disks / stripe_cache_size
         */
        char safe[50];
        int rc;

        /* only 'raid_disks' and 'stripe_cache_size' trigger md_allow_write */
        if (!container ||
            (strcmp(name, "raid_disks") != 0 &&
             strcmp(name, "stripe_cache_size") != 0))
                return sysfs_set_num(sra, NULL, name, n);

        rc = sysfs_get_str(sra, NULL, "safe_mode_delay", safe, sizeof(safe));
        if (rc <= 0)
                return -1;
        sysfs_set_num(sra, NULL, "safe_mode_delay", 0);
        rc = sysfs_set_num(sra, NULL, name, n);
        if (rc < 0 && errno == EAGAIN) {
                ping_monitor(container);
                /* if we get EAGAIN here then the monitor is not active
                 * so stop trying
                 */
                rc = sysfs_set_num(sra, NULL, name, n);
        }
        sysfs_set_str(sra, NULL, "safe_mode_delay", safe);
        return rc;
}

int start_reshape(struct mdinfo *sra, int already_running,
                  int before_data_disks, int data_disks, struct supertype *st)
{
        int err;
        unsigned long long sync_max_to_set;

        sysfs_set_num(sra, NULL, "suspend_lo", 0x7FFFFFFFFFFFFFFFULL);
        err = sysfs_set_num(sra, NULL, "suspend_hi", sra->reshape_progress);
        err = err ?: sysfs_set_num(sra, NULL, "suspend_lo",
                                   sra->reshape_progress);
        if (before_data_disks <= data_disks)
                sync_max_to_set = sra->reshape_progress / data_disks;
        else
                sync_max_to_set = (sra->component_size * data_disks
                                   - sra->reshape_progress) / data_disks;

        if (!already_running)
                sysfs_set_num(sra, NULL, "sync_min", sync_max_to_set);

        if (st->ss->external)
                err = err ?: sysfs_set_num(sra, NULL, "sync_max", sync_max_to_set);
        else
                err = err ?: sysfs_set_str(sra, NULL, "sync_max", "max");

        if (!already_running && err == 0) {
                int cnt = 5;
                do {
                        err = sysfs_set_str(sra, NULL, "sync_action",
                                            "reshape");
                        if (err)
                                sleep(1);
                } while (err && errno == EBUSY && cnt-- > 0);
        }
        return err;
}

void abort_reshape(struct mdinfo *sra)
{
        sysfs_set_str(sra, NULL, "sync_action", "idle");
        /*
         * Prior to kernel commit: 23ddff3792f6 ("md: allow suspend_lo and
         * suspend_hi to decrease as well as increase.")
         * you could only increase suspend_{lo,hi} unless the region they
         * covered was empty.  So to reset to 0, you need to push suspend_lo
         * up past suspend_hi first.  So to maximize the chance of mdadm
         * working on all kernels, we want to keep doing that.
         */
        sysfs_set_num(sra, NULL, "suspend_lo", 0x7FFFFFFFFFFFFFFFULL);
        sysfs_set_num(sra, NULL, "suspend_hi", 0);
        sysfs_set_num(sra, NULL, "suspend_lo", 0);
        sysfs_set_num(sra, NULL, "sync_min", 0);
        // It isn't safe to reset sync_max as we aren't monitoring.
        // Array really should be stopped at this point.
}

int remove_disks_for_takeover(struct supertype *st,
                              struct mdinfo *sra,
                              int layout)
{
        int nr_of_copies;
        struct mdinfo *remaining;
        int slot;

        if (st->ss->external) {
                int rv = 0;
                struct mdinfo *arrays = st->ss->container_content(st, NULL);
                /*
                 * containter_content returns list of arrays in container
                 * If arrays->next is not NULL it means that there are
                 * 2 arrays in container and operation should be blocked
                 */
                if (arrays) {
                        if (arrays->next)
                                rv = 1;
                        sysfs_free(arrays);
                        if (rv) {
                                pr_err("Error. Cannot perform operation on %s- for this operation "
                                       "it MUST be single array in container\n", st->devnm);
                                return rv;
                        }
                }
        }

        if (sra->array.level == 10)
                nr_of_copies = layout & 0xff;
        else if (sra->array.level == 1)
                nr_of_copies = sra->array.raid_disks;
        else
                return 1;

        remaining = sra->devs;
        sra->devs = NULL;
        /* for each 'copy', select one device and remove from the list. */
        for (slot = 0; slot < sra->array.raid_disks; slot += nr_of_copies) {
                struct mdinfo **diskp;
                int found = 0;

                /* Find a working device to keep */
                for (diskp =  &remaining; *diskp ; diskp = &(*diskp)->next) {
                        struct mdinfo *disk = *diskp;

                        if (disk->disk.raid_disk < slot)
                                continue;
                        if (disk->disk.raid_disk >= slot + nr_of_copies)
                                continue;
                        if (disk->disk.state & (1<<MD_DISK_REMOVED))
                                continue;
                        if (disk->disk.state & (1<<MD_DISK_FAULTY))
                                continue;
                        if (!(disk->disk.state & (1<<MD_DISK_SYNC)))
                                continue;

                        /* We have found a good disk to use! */
                        *diskp = disk->next;
                        disk->next = sra->devs;
                        sra->devs = disk;
                        found = 1;
                        break;
                }
                if (!found)
                        break;
        }

        if (slot < sra->array.raid_disks) {
                /* didn't find all slots */
                struct mdinfo **e;
                e = &remaining;
                while (*e)
                        e = &(*e)->next;
                *e = sra->devs;
                sra->devs = remaining;
                return 1;
        }

        /* Remove all 'remaining' devices from the array */
        while (remaining) {
                struct mdinfo *sd = remaining;
                remaining = sd->next;

                sysfs_set_str(sra, sd, "state", "faulty");
                sysfs_set_str(sra, sd, "slot", "none");
                /* for external metadata disks should be removed in mdmon */
                if (!st->ss->external)
                        sysfs_set_str(sra, sd, "state", "remove");
                sd->disk.state |= (1<<MD_DISK_REMOVED);
                sd->disk.state &= ~(1<<MD_DISK_SYNC);
                sd->next = sra->devs;
                sra->devs = sd;
        }
        return 0;
}

void reshape_free_fdlist(int *fdlist,
                         unsigned long long *offsets,
                         int size)
{
        int i;

        for (i = 0; i < size; i++)
                if (fdlist[i] >= 0)
                        close(fdlist[i]);

        free(fdlist);
        free(offsets);
}

int reshape_prepare_fdlist(char *devname,
                           struct mdinfo *sra,
                           int raid_disks,
                           int nrdisks,
                           unsigned long blocks,
                           char *backup_file,
                           int *fdlist,
                           unsigned long long *offsets)
{
        int d = 0;
        struct mdinfo *sd;

        enable_fds(nrdisks);
        for (d = 0; d <= nrdisks; d++)
                fdlist[d] = -1;
        d = raid_disks;
        for (sd = sra->devs; sd; sd = sd->next) {
                if (sd->disk.state & (1<<MD_DISK_FAULTY))
                        continue;
                if (sd->disk.state & (1<<MD_DISK_SYNC) &&
                    sd->disk.raid_disk < raid_disks) {
                        char *dn = map_dev(sd->disk.major, sd->disk.minor, 1);
                        fdlist[sd->disk.raid_disk] = dev_open(dn, O_RDONLY);
                        offsets[sd->disk.raid_disk] = sd->data_offset*512;
                        if (fdlist[sd->disk.raid_disk] < 0) {
                                pr_err("%s: cannot open component %s\n",
                                       devname, dn ? dn : "-unknown-");
                                d = -1;
                                goto release;
                        }
                } else if (backup_file == NULL) {
                        /* spare */
                        char *dn = map_dev(sd->disk.major, sd->disk.minor, 1);
                                fdlist[d] = dev_open(dn, O_RDWR);
                                offsets[d] = (sd->data_offset + sra->component_size - blocks - 8)*512;
                                if (fdlist[d] < 0) {
                                        pr_err("%s: cannot open component %s\n",
                                                devname, dn ? dn : "-unknown-");
                                        d = -1;
                                        goto release;
                                }
                                d++;
                        }
                }
release:
        return d;
}

int reshape_open_backup_file(char *backup_file,
                             int fd,
                             char *devname,
                             long blocks,
                             int *fdlist,
                             unsigned long long *offsets,
                             char *sys_name,
                             int restart)
{
        /* Return 1 on success, 0 on any form of failure */
        /* need to check backup file is large enough */
        char buf[512];
        struct stat stb;
        unsigned int dev;
        int i;

        *fdlist = open(backup_file, O_RDWR|O_CREAT|(restart ? O_TRUNC : O_EXCL),
                       S_IRUSR | S_IWUSR);
        *offsets = 8 * 512;
        if (*fdlist < 0) {
                pr_err("%s: cannot create backup file %s: %s\n",
                        devname, backup_file, strerror(errno));
                return 0;
        }
        /* Guard against backup file being on array device.
         * If array is partitioned or if LVM etc is in the
         * way this will not notice, but it is better than
         * nothing.
         */
        fstat(*fdlist, &stb);
        dev = stb.st_dev;
        fstat(fd, &stb);
        if (stb.st_rdev == dev) {
                pr_err("backup file must NOT be on the array being reshaped.\n");
                close(*fdlist);
                return 0;
        }

        memset(buf, 0, 512);
        for (i=0; i < blocks + 8 ; i++) {
                if (write(*fdlist, buf, 512) != 512) {
                        pr_err("%s: cannot create backup file %s: %s\n",
                                devname, backup_file, strerror(errno));
                        return 0;
                }
        }
        if (fsync(*fdlist) != 0) {
                pr_err("%s: cannot create backup file %s: %s\n",
                        devname, backup_file, strerror(errno));
                return 0;
        }

        if (!restart && strncmp(backup_file, MAP_DIR, strlen(MAP_DIR)) != 0) {
                char *bu = make_backup(sys_name);
                if (symlink(backup_file, bu))
                        pr_err("Recording backup file in " MAP_DIR " failed: %s\n",
                               strerror(errno));
                free(bu);
        }

        return 1;
}

unsigned long compute_backup_blocks(int nchunk, int ochunk,
                                    unsigned int ndata, unsigned int odata)
{
        unsigned long a, b, blocks;
        /* So how much do we need to backup.
         * We need an amount of data which is both a whole number of
         * old stripes and a whole number of new stripes.
         * So LCM for (chunksize*datadisks).
         */
        a = (ochunk/512) * odata;
        b = (nchunk/512) * ndata;
        /* Find GCD */
        a = GCD(a, b);
        /* LCM == product / GCD */
        blocks = (unsigned long)(ochunk/512) * (unsigned long)(nchunk/512) *
                odata * ndata / a;

        return blocks;
}

char *analyse_change(char *devname, struct mdinfo *info, struct reshape *re)
{
        /* Based on the current array state in info->array and
         * the changes in info->new_* etc, determine:
         *  - whether the change is possible
         *  - Intermediate level/raid_disks/layout
         *  - whether a restriping reshape is needed
         *  - number of sectors in minimum change unit.  This
         *    will cover a whole number of stripes in 'before' and
         *    'after'.
         *
         * Return message if the change should be rejected
         *        NULL if the change can be achieved
         *
         * This can be called as part of starting a reshape, or
         * when assembling an array that is undergoing reshape.
         */
        int near, far, offset, copies;
        int new_disks;
        int old_chunk, new_chunk;
        /* delta_parity records change in number of devices
         * caused by level change
         */
        int delta_parity = 0;

        memset(re, 0, sizeof(*re));

        /* If a new level not explicitly given, we assume no-change */
        if (info->new_level == UnSet)
                info->new_level = info->array.level;

        if (info->new_chunk)
                switch (info->new_level) {
                case 0:
                case 4:
                case 5:
                case 6:
                case 10:
                        /* chunk size is meaningful, must divide component_size
                         * evenly
                         */
                        if (info->component_size % (info->new_chunk/512)) {
                                unsigned long long shrink = info->component_size;
                                shrink &= ~(unsigned long long)(info->new_chunk/512-1);
                                pr_err("New chunk size (%dK) does not evenly divide device size (%lluk)\n",
                                       info->new_chunk/1024, info->component_size/2);
                                pr_err("After shrinking any filesystem, \"mdadm --grow %s --size %llu\"\n",
                                       devname, shrink/2);
                                pr_err("will shrink the array so the given chunk size would work.\n");
                                return "";
                        }
                        break;
                default:
                        return "chunk size not meaningful for this level";
                }
        else
                info->new_chunk = info->array.chunk_size;

        switch (info->array.level) {
        default:
                return "No reshape is possibly for this RAID level";
        case LEVEL_LINEAR:
                if (info->delta_disks != UnSet)
                        return "Only --add is supported for LINEAR, setting --raid-disks is not needed";
                else
                        return "Only --add is supported for LINEAR, other --grow options are not meaningful";
        case 1:
                /* RAID1 can convert to RAID1 with different disks, or
                 * raid5 with 2 disks, or
                 * raid0 with 1 disk
                 */
                if (info->new_level > 1 && (info->component_size & 7))
                        return "Cannot convert RAID1 of this size - reduce size to multiple of 4K first.";
                if (info->new_level == 0) {
                        if (info->delta_disks != UnSet &&
                            info->delta_disks != 0)
                                return "Cannot change number of disks with RAID1->RAID0 conversion";
                        re->level = 0;
                        re->before.data_disks = 1;
                        re->after.data_disks = 1;
                        return NULL;
                }
                if (info->new_level == 1) {
                        if (info->delta_disks == UnSet)
                                /* Don't know what to do */
                                return "no change requested for Growing RAID1";
                        re->level = 1;
                        return NULL;
                }
                if (info->array.raid_disks != 2 && info->new_level == 5)
                        return "Can only convert a 2-device array to RAID5";
                if (info->array.raid_disks == 2 && info->new_level == 5) {
                        re->level = 5;
                        re->before.data_disks = 1;
                        if (info->delta_disks != UnSet &&
                            info->delta_disks != 0)
                                re->after.data_disks = 1 + info->delta_disks;
                        else
                                re->after.data_disks = 1;
                        if (re->after.data_disks < 1)
                                return "Number of disks too small for RAID5";

                        re->before.layout = ALGORITHM_LEFT_SYMMETRIC;
                        info->array.chunk_size = 65536;
                        break;
                }
                /* Could do some multi-stage conversions, but leave that to
                 * later.
                 */
                return "Impossibly level change request for RAID1";

        case 10:
                /* RAID10 can be converted from near mode to
                 * RAID0 by removing some devices.
                 * It can also be reshaped if the kernel supports
                 * new_data_offset.
                 */
                switch (info->new_level) {
                case 0:
                        if ((info->array.layout & ~0xff) != 0x100)
                                return "Cannot Grow RAID10 with far/offset layout";
                        /*
                         * number of devices must be multiple of
                         * number of copies
                         */
                        if (info->array.raid_disks %
                            (info->array.layout & 0xff))
                                return "RAID10 layout too complex for Grow operation";

                        new_disks = (info->array.raid_disks /
                                     (info->array.layout & 0xff));
                        if (info->delta_disks == UnSet)
                                info->delta_disks = (new_disks
                                                     - info->array.raid_disks);

                        if (info->delta_disks !=
                            new_disks - info->array.raid_disks)
                                return "New number of raid-devices impossible for RAID10";
                        if (info->new_chunk &&
                            info->new_chunk != info->array.chunk_size)
                                return "Cannot change chunk-size with RAID10 Grow";

                        /* looks good */
                        re->level = 0;
                        re->before.data_disks = new_disks;
                        re->after.data_disks = re->before.data_disks;
                        return NULL;

                case 10:
                        near = info->array.layout & 0xff;
                        far = (info->array.layout >> 8) & 0xff;
                        offset = info->array.layout & 0x10000;
                        if (far > 1 && !offset)
                                return "Cannot reshape RAID10 in far-mode";
                        copies = near * far;

                        old_chunk = info->array.chunk_size * far;

                        if (info->new_layout == UnSet)
                                info->new_layout = info->array.layout;
                        else {
                                near = info->new_layout & 0xff;
                                far = (info->new_layout >> 8) & 0xff;
                                offset = info->new_layout & 0x10000;
                                if (far > 1 && !offset)
                                        return "Cannot reshape RAID10 to far-mode";
                                if (near * far != copies)
                                        return "Cannot change number of copies when reshaping RAID10";
                        }
                        if (info->delta_disks == UnSet)
                                info->delta_disks = 0;
                        new_disks = (info->array.raid_disks +
                                     info->delta_disks);

                        new_chunk = info->new_chunk * far;

                        re->level = 10;
                        re->before.layout = info->array.layout;
                        re->before.data_disks = info->array.raid_disks;
                        re->after.layout = info->new_layout;
                        re->after.data_disks = new_disks;
                        /* For RAID10 we don't do backup but do allow reshape,
                         * so set backup_blocks to INVALID_SECTORS rather than
                         * zero.
                         * And there is no need to synchronise stripes on both
                         * 'old' and  'new'.  So the important
                         * number is the minimum data_offset difference
                         * which is the larger of (offset copies * chunk).
                         */
                        re->backup_blocks = INVALID_SECTORS;
                        re->min_offset_change = max(old_chunk, new_chunk) / 512;
                        if (new_disks < re->before.data_disks &&
                            info->space_after < re->min_offset_change)
                                /* Reduce component size by one chunk */
                                re->new_size = (info->component_size -
                                                re->min_offset_change);
                        else
                                re->new_size = info->component_size;
                        re->new_size = re->new_size * new_disks / copies;
                        return NULL;

                default:
                        return "RAID10 can only be changed to RAID0";
                }
        case 0:
                /* RAID0 can be converted to RAID10, or to RAID456 */
                if (info->new_level == 10) {
                        if (info->new_layout == UnSet &&
                            info->delta_disks == UnSet) {
                                /* Assume near=2 layout */
                                info->new_layout = 0x102;
                                info->delta_disks = info->array.raid_disks;
                        }
                        if (info->new_layout == UnSet) {
                                int copies = 1 + (info->delta_disks
                                                  / info->array.raid_disks);
                                if (info->array.raid_disks * (copies-1) !=
                                    info->delta_disks)
                                        return "Impossible number of devices for RAID0->RAID10";
                                info->new_layout = 0x100 + copies;
                        }
                        if (info->delta_disks == UnSet) {
                                int copies = info->new_layout & 0xff;
                                if (info->new_layout != 0x100 + copies)
                                        return "New layout impossible for RAID0->RAID10";;
                                info->delta_disks = (copies - 1) *
                                        info->array.raid_disks;
                        }
                        if (info->new_chunk &&
                            info->new_chunk != info->array.chunk_size)
                                return "Cannot change chunk-size with RAID0->RAID10";
                        /* looks good */
                        re->level = 10;
                        re->before.data_disks = (info->array.raid_disks +
                                                 info->delta_disks);
                        re->after.data_disks = re->before.data_disks;
                        re->before.layout = info->new_layout;
                        return NULL;
                }

                /* RAID0 can also covert to RAID0/4/5/6 by first converting to
                 * a raid4 style layout of the final level.
                 */
                switch (info->new_level) {
                case 4:
                        delta_parity = 1;
                case 0:
                        re->level = 4;
                        re->before.layout = 0;
                        break;
                case 5:
                        delta_parity = 1;
                        re->level = 5;
                        re->before.layout = ALGORITHM_PARITY_N;
                        if (info->new_layout == UnSet)
                                info->new_layout = map_name(r5layout, "default");
                        break;
                case 6:
                        delta_parity = 2;
                        re->level = 6;
                        re->before.layout = ALGORITHM_PARITY_N;
                        if (info->new_layout == UnSet)
                                info->new_layout = map_name(r6layout, "default");
                        break;
                default:
                        return "Impossible level change requested";
                }
                re->before.data_disks = info->array.raid_disks;
                /* determining 'after' layout happens outside this 'switch' */
                break;

        case 4:
                info->array.layout = ALGORITHM_PARITY_N;
        case 5:
                switch (info->new_level) {
                case 0:
                        delta_parity = -1;
                case 4:
                        re->level = info->array.level;
                        re->before.data_disks = info->array.raid_disks - 1;
                        re->before.layout = info->array.layout;
                        break;
                case 5:
                        re->level = 5;
                        re->before.data_disks = info->array.raid_disks - 1;
                        re->before.layout = info->array.layout;
                        break;
                case 6:
                        delta_parity = 1;
                        re->level = 6;
                        re->before.data_disks = info->array.raid_disks - 1;
                        switch (info->array.layout) {
                        case ALGORITHM_LEFT_ASYMMETRIC:
                                re->before.layout = ALGORITHM_LEFT_ASYMMETRIC_6;
                                break;
                        case ALGORITHM_RIGHT_ASYMMETRIC:
                                re->before.layout = ALGORITHM_RIGHT_ASYMMETRIC_6;
                                break;
                        case ALGORITHM_LEFT_SYMMETRIC:
                                re->before.layout = ALGORITHM_LEFT_SYMMETRIC_6;
                                break;
                        case ALGORITHM_RIGHT_SYMMETRIC:
                                re->before.layout = ALGORITHM_RIGHT_SYMMETRIC_6;
                                break;
                        case ALGORITHM_PARITY_0:
                                re->before.layout = ALGORITHM_PARITY_0_6;
                                break;
                        case ALGORITHM_PARITY_N:
                                re->before.layout = ALGORITHM_PARITY_N_6;
                                break;
                        default:
                                return "Cannot convert an array with this layout";
                        }
                        break;
                case 1:
                        if (info->array.raid_disks != 2)
                                return "Can only convert a 2-device array to RAID1";
                        if (info->delta_disks != UnSet &&
                            info->delta_disks != 0)
                                return "Cannot set raid_disk when converting RAID5->RAID1";
                        re->level = 1;
                        info->new_chunk = 0;
                        return NULL;
                default:
                        return "Impossible level change requested";
                }
                break;
        case 6:
                switch (info->new_level) {
                case 4:
                case 5:
                        delta_parity = -1;
                case 6:
                        re->level = 6;
                        re->before.data_disks = info->array.raid_disks - 2;
                        re->before.layout = info->array.layout;
                        break;
                default:
                        return "Impossible level change requested";
                }
                break;
        }

        /* If we reached here then it looks like a re-stripe is
         * happening.  We have determined the intermediate level
         * and initial raid_disks/layout and stored these in 're'.
         *
         * We need to deduce the final layout that can be atomically
         * converted to the end state.
         */
        switch (info->new_level) {
        case 0:
                /* We can only get to RAID0 from RAID4 or RAID5
                 * with appropriate layout and one extra device
                 */
                if (re->level != 4 && re->level != 5)
                        return "Cannot covert to RAID0 from this level";

                switch (re->level) {
                case 4:
                        re->before.layout = 0;
                        re->after.layout = 0;
                        break;
                case 5:
                        re->after.layout = ALGORITHM_PARITY_N;
                        break;
                }
                break;

        case 4:
                /* We can only get to RAID4 from RAID5 */
                if (re->level != 4 && re->level != 5)
                        return "Cannot convert to RAID4 from this level";

                switch (re->level) {
                case 4:
                        re->after.layout = 0;
                        break;
                case 5:
                        re->after.layout = ALGORITHM_PARITY_N;
                        break;
                }
                break;

        case 5:
                /* We get to RAID5 from RAID5 or RAID6 */
                if (re->level != 5 && re->level != 6)
                        return "Cannot convert to RAID5 from this level";

                switch (re->level) {
                case 5:
                        if (info->new_layout == UnSet)
                                re->after.layout = re->before.layout;
                        else
                                re->after.layout = info->new_layout;
                        break;
                case 6:
                        if (info->new_layout == UnSet)
                                info->new_layout = re->before.layout;

                        /* after.layout needs to be raid6 version of new_layout */
                        if (info->new_layout == ALGORITHM_PARITY_N)
                                re->after.layout = ALGORITHM_PARITY_N;
                        else {
                                char layout[40];
                                char *ls = map_num(r5layout, info->new_layout);
                                int l;
                                if (ls) {
                                        /* Current RAID6 layout has a RAID5
                                         * equivalent - good
                                         */
                                        strcat(strcpy(layout, ls), "-6");
                                        l = map_name(r6layout, layout);
                                        if (l == UnSet)
                                                return "Cannot find RAID6 layout to convert to";
                                } else {
                                        /* Current RAID6 has no equivalent.
                                         * If it is already a '-6' layout we
                                         * can leave it unchanged, else we must
                                         * fail
                                         */
                                        ls = map_num(r6layout,
                                                     info->new_layout);
                                        if (!ls ||
                                            strcmp(ls+strlen(ls)-2, "-6") != 0)
                                                return "Please specify new layout";
                                        l = info->new_layout;
                                }
                                re->after.layout = l;
                        }
                }
                break;

        case 6:
                /* We must already be at level 6 */
                if (re->level != 6)
                        return "Impossible level change";
                if (info->new_layout == UnSet)
                        re->after.layout = info->array.layout;
                else
                        re->after.layout = info->new_layout;
                break;
        default:
                return "Impossible level change requested";
        }
        if (info->delta_disks == UnSet)
                info->delta_disks = delta_parity;

        re->after.data_disks =
                (re->before.data_disks + info->delta_disks - delta_parity);

        switch (re->level) {
        case 6:
                re->parity = 2;
                break;
        case 4:
        case 5:
                re->parity = 1;
                break;
        default:
                re->parity = 0;
                break;
        }
        /* So we have a restripe operation, we need to calculate the number
         * of blocks per reshape operation.
         */
        re->new_size = info->component_size * re->before.data_disks;
        if (info->new_chunk == 0)
                info->new_chunk = info->array.chunk_size;
        if (re->after.data_disks == re->before.data_disks &&
            re->after.layout == re->before.layout &&
            info->new_chunk == info->array.chunk_size) {
                /* Nothing to change, can change level immediately. */
                re->level = info->new_level;
                re->backup_blocks = 0;
                return NULL;
        }
        if (re->after.data_disks == 1 && re->before.data_disks == 1) {
                /* chunk and layout changes make no difference */
                re->level = info->new_level;
                re->backup_blocks = 0;
                return NULL;
        }

        if (re->after.data_disks == re->before.data_disks &&
            get_linux_version() < 2006032)
                return "in-place reshape is not safe before 2.6.32 - sorry.";

        if (re->after.data_disks < re->before.data_disks &&
            get_linux_version() < 2006030)
                return "reshape to fewer devices is not supported before 2.6.30 - sorry.";

        re->backup_blocks = compute_backup_blocks(
                info->new_chunk, info->array.chunk_size,
                re->after.data_disks, re->before.data_disks);
        re->min_offset_change = re->backup_blocks / re->before.data_disks;

        re->new_size = info->component_size * re->after.data_disks;
        return NULL;
}

static int set_array_size(struct supertype *st, struct mdinfo *sra,
                          char *text_version)
{
        struct mdinfo *info;
        char *subarray;
        int ret_val = -1;

        if ((st == NULL) || (sra == NULL))
                return ret_val;

        if (text_version == NULL)
                text_version = sra->text_version;
        subarray = strchr(text_version + 1, '/')+1;
        info = st->ss->container_content(st, subarray);
        if (info) {
                unsigned long long current_size = 0;
                unsigned long long new_size = info->custom_array_size/2;

                if (sysfs_get_ll(sra, NULL, "array_size", &current_size) == 0 &&
                    new_size > current_size) {
                        if (sysfs_set_num(sra, NULL, "array_size", new_size)
                                        < 0)
                                dprintf("Error: Cannot set array size");
                        else {
                                ret_val = 0;
                                dprintf("Array size changed");
                        }
                        dprintf_cont(" from %llu to %llu.\n",
                                     current_size, new_size);
                }
                sysfs_free(info);
        } else
                dprintf("Error: set_array_size(): info pointer in NULL\n");

        return ret_val;
}

static int reshape_array(char *container, int fd, char *devname,
                         struct supertype *st, struct mdinfo *info,
                         int force, struct mddev_dev *devlist,
                         unsigned long long data_offset,
                         char *backup_file, int verbose, int forked,
                         int restart, int freeze_reshape);
static int reshape_container(char *container, char *devname,
                             int mdfd,
                             struct supertype *st,
                             struct mdinfo *info,
                             int force,
                             char *backup_file, int verbose,
                             int forked, int restart, int freeze_reshape);

int Grow_reshape(char *devname, int fd,
                 struct mddev_dev *devlist,
                 unsigned long long data_offset,
                 struct context *c, struct shape *s)
{
        /* Make some changes in the shape of an array.
         * The kernel must support the change.
         *
         * There are three different changes.  Each can trigger
         * a resync or recovery so we freeze that until we have
         * requested everything (if kernel supports freezing - 2.6.30).
         * The steps are:
         *  - change size (i.e. component_size)
         *  - change level
         *  - change layout/chunksize/ndisks
         *
         * The last can require a reshape.  It is different on different
         * levels so we need to check the level before actioning it.
         * Some times the level change needs to be requested after the
         * reshape (e.g. raid6->raid5, raid5->raid0)
         *
         */
        struct mdu_array_info_s array;
        int rv = 0;
        struct supertype *st;
        char *subarray = NULL;

        int frozen;
        int changed = 0;
        char *container = NULL;
        int cfd = -1;

        struct mddev_dev *dv;
        int added_disks;

        struct mdinfo info;
        struct mdinfo *sra;

        if (md_get_array_info(fd, &array) < 0) {
                pr_err("%s is not an active md array - aborting\n",
                        devname);
                return 1;
        }
        if (s->level != UnSet && s->chunk) {
                pr_err("Cannot change array level in the same operation as changing chunk size.\n");
                return 1;
        }

        if (data_offset != INVALID_SECTORS && array.level != 10 &&
            (array.level < 4 || array.level > 6)) {
                pr_err("--grow --data-offset not yet supported\n");
                return 1;
        }

        if (s->size > 0 &&
            (s->chunk || s->level!= UnSet || s->layout_str || s->raiddisks)) {
                pr_err("cannot change component size at the same time as other changes.\n"
                        "   Change size first, then check data is intact before making other changes.\n");
                return 1;
        }

        if (s->raiddisks && s->raiddisks < array.raid_disks &&
            array.level > 1 && get_linux_version() < 2006032 &&
            !check_env("MDADM_FORCE_FEWER")) {
                pr_err("reducing the number of devices is not safe before Linux 2.6.32\n"
                        "       Please use a newer kernel\n");
                return 1;
        }

        if (array.level > 1 && s->size > 1 &&
            (unsigned long long) (array.chunk_size / 1024) > s->size) {
                pr_err("component size must be larger than chunk size.\n");
                return 1;
        }

        st = super_by_fd(fd, &subarray);
        if (!st) {
                pr_err("Unable to determine metadata format for %s\n", devname);
                return 1;
        }
        if (s->raiddisks > st->max_devs) {
                pr_err("Cannot increase raid-disks on this array beyond %d\n", st->max_devs);
                return 1;
        }
        if (s->level == 0 && (array.state & (1 << MD_SB_BITMAP_PRESENT)) &&
                !(array.state & (1 << MD_SB_CLUSTERED)) && !st->ss->external) {
                array.state &= ~(1 << MD_SB_BITMAP_PRESENT);
                if (md_set_array_info(fd, &array) != 0) {
                        pr_err("failed to remove internal bitmap.\n");
                        return 1;
                }
        }

        /* in the external case we need to check that the requested reshape is
         * supported, and perform an initial check that the container holds the
         * pre-requisite spare devices (mdmon owns final validation)
         */
        if (st->ss->external) {
                int retval;

                if (subarray) {
                        container = st->container_devnm;
                        cfd = open_dev_excl(st->container_devnm);
                } else {
                        container = st->devnm;
                        close(fd);
                        cfd = open_dev_excl(st->devnm);
                        fd = cfd;
                }
                if (cfd < 0) {
                        pr_err("Unable to open container for %s\n", devname);
                        free(subarray);
                        return 1;
                }

                retval = st->ss->load_container(st, cfd, NULL);

                if (retval) {
                        pr_err("Cannot read superblock for %s\n", devname);
                        close(cfd);
                        free(subarray);
                        return 1;
                }

                if (s->raiddisks && subarray) {
                        pr_err("--raid-devices operation can be performed on a container only\n");
                        close(cfd);
                        free(subarray);
                        return 1;
                }

                /* check if operation is supported for metadata handler */
                if (st->ss->container_content) {
                        struct mdinfo *cc = NULL;
                        struct mdinfo *content = NULL;

                        cc = st->ss->container_content(st, subarray);
                        for (content = cc; content ; content = content->next) {
                                int allow_reshape = 1;

                                /* check if reshape is allowed based on metadata
                                 * indications stored in content.array.status
                                 */
                                if (content->array.state &
                                    (1 << MD_SB_BLOCK_VOLUME))
                                        allow_reshape = 0;
                                if (content->array.state &
                                    (1 << MD_SB_BLOCK_CONTAINER_RESHAPE))
                                        allow_reshape = 0;
                                if (!allow_reshape) {
                                        pr_err("cannot reshape arrays in container with unsupported metadata: %s(%s)\n",
                                               devname, container);
                                        sysfs_free(cc);
                                        free(subarray);
                                        return 1;
                                }
                                if (content->consistency_policy ==
                                    CONSISTENCY_POLICY_PPL) {
                                        pr_err("Operation not supported when ppl consistency policy is enabled\n");
                                        sysfs_free(cc);
                                        free(subarray);
                                        return 1;
                                }
                                if (content->consistency_policy ==
                                    CONSISTENCY_POLICY_BITMAP) {
                                        pr_err("Operation not supported when write-intent bitmap is enabled\n");
                                        sysfs_free(cc);
                                        free(subarray);
                                        return 1;
                                }
                        }
                        sysfs_free(cc);
                }
                if (mdmon_running(container))
                        st->update_tail = &st->updates;
        }

        added_disks = 0;
        for (dv = devlist; dv; dv = dv->next)
                added_disks++;
        if (s->raiddisks > array.raid_disks &&
            array.spare_disks + added_disks <
            (s->raiddisks - array.raid_disks) &&
            !c->force) {
                pr_err("Need %d spare%s to avoid degraded array, and only have %d.\n"
                       "       Use --force to over-ride this check.\n",
                       s->raiddisks - array.raid_disks,
                       s->raiddisks - array.raid_disks == 1 ? "" : "s",
                       array.spare_disks + added_disks);
                return 1;
        }

        sra = sysfs_read(fd, NULL, GET_LEVEL | GET_DISKS | GET_DEVS |
                         GET_STATE | GET_VERSION);
        if (sra) {
                if (st->ss->external && subarray == NULL) {
                        array.level = LEVEL_CONTAINER;
                        sra->array.level = LEVEL_CONTAINER;
                }
        } else {
                pr_err("failed to read sysfs parameters for %s\n",
                        devname);
                return 1;
        }
        frozen = freeze(st);
        if (frozen < -1) {
                /* freeze() already spewed the reason */
                sysfs_free(sra);
                return 1;
        } else if (frozen < 0) {
                pr_err("%s is performing resync/recovery and cannot be reshaped\n", devname);
                sysfs_free(sra);
                return 1;
        }

        /* ========= set size =============== */
        if (s->size > 0 &&
            (s->size == MAX_SIZE || s->size != (unsigned)array.size)) {
                unsigned long long orig_size = get_component_size(fd)/2;
                unsigned long long min_csize;
                struct mdinfo *mdi;
                int raid0_takeover = 0;

                if (orig_size == 0)
                        orig_size = (unsigned) array.size;

                if (orig_size == 0) {
                        pr_err("Cannot set device size in this type of array.\n");
                        rv = 1;
                        goto release;
                }

                if (array.level == 0) {
                        pr_err("Component size change is not supported for RAID0\n");
                        rv = 1;
                        goto release;
                }

                if (reshape_super(st, s->size, UnSet, UnSet, 0, 0, UnSet, NULL,
                                  devname, APPLY_METADATA_CHANGES,
                                  c->verbose > 0)) {
                        rv = 1;
                        goto release;
                }
                sync_metadata(st);
                if (st->ss->external) {
                        /* metadata can have size limitation
                         * update size value according to metadata information
                         */
                        struct mdinfo *sizeinfo =
                                st->ss->container_content(st, subarray);
                        if (sizeinfo) {
                                unsigned long long new_size =
                                        sizeinfo->custom_array_size/2;
                                int data_disks = get_data_disks(
                                                sizeinfo->array.level,
                                                sizeinfo->array.layout,
                                                sizeinfo->array.raid_disks);
                                new_size /= data_disks;
                                dprintf("Metadata size correction from %llu to %llu (%llu)\n",
                                        orig_size, new_size,
                                        new_size * data_disks);
                                s->size = new_size;
                                sysfs_free(sizeinfo);
                        }
                }

                /* Update the size of each member device in case
                 * they have been resized.  This will never reduce
                 * below the current used-size.  The "size" attribute
                 * understands '0' to mean 'max'.
                 */
                min_csize = 0;
                for (mdi = sra->devs; mdi; mdi = mdi->next) {
                        sysfs_set_num(sra, mdi, "size",
                                      s->size == MAX_SIZE ? 0 : s->size);
                        if (array.not_persistent == 0 &&
                            array.major_version == 0 &&
                            get_linux_version() < 3001000) {
                                /* Dangerous to allow size to exceed 2TB */
                                unsigned long long csize;
                                if (sysfs_get_ll(sra, mdi, "size",
                                                 &csize) == 0) {
                                        if (csize >= 2ULL*1024*1024*1024)
                                                csize = 2ULL*1024*1024*1024;
                                        if ((min_csize == 0 ||
                                             (min_csize > csize)))
                                                min_csize = csize;
                                }
                        }
                }
                if (min_csize && s->size > min_csize) {
                        pr_err("Cannot safely make this array use more than 2TB per device on this kernel.\n");
                        rv = 1;
                        goto size_change_error;
                }
                if (min_csize && s->size == MAX_SIZE) {
                        /* Don't let the kernel choose a size - it will get
                         * it wrong
                         */
                        pr_err("Limited v0.90 array to 2TB per device\n");
                        s->size = min_csize;
                }
                if (st->ss->external) {
                        if (sra->array.level == 0) {
                                rv = sysfs_set_str(sra, NULL, "level", "raid5");
                                if (!rv) {
                                        raid0_takeover = 1;
                                        /* get array parameters after takeover
                                         * to change one parameter at time only
                                         */
                                        rv = md_get_array_info(fd, &array);
                                }
                        }
                        /* make sure mdmon is
                         * aware of the new level */
                        if (!mdmon_running(st->container_devnm))
                                start_mdmon(st->container_devnm);
                        ping_monitor(container);
                        if (mdmon_running(st->container_devnm) &&
                                        st->update_tail == NULL)
                                st->update_tail = &st->updates;
                }

                if (s->size == MAX_SIZE)
                        s->size = 0;
                array.size = s->size;
                if (s->size & ~INT32_MAX) {
                        /* got truncated to 32bit, write to
                         * component_size instead
                         */
                        if (sra)
                                rv = sysfs_set_num(sra, NULL,
                                                   "component_size", s->size);
                        else
                                rv = -1;
                } else {
                        rv = md_set_array_info(fd, &array);

                        /* manage array size when it is managed externally
                         */
                        if ((rv == 0) && st->ss->external)
                                rv = set_array_size(st, sra, sra->text_version);
                }

                if (raid0_takeover) {
                        /* do not recync non-existing parity,
                         * we will drop it anyway
                         */
                        sysfs_set_str(sra, NULL, "sync_action", "frozen");
                        /* go back to raid0, drop parity disk
                         */
                        sysfs_set_str(sra, NULL, "level", "raid0");
                        md_get_array_info(fd, &array);
                }

size_change_error:
                if (rv != 0) {
                        int err = errno;

                        /* restore metadata */
                        if (reshape_super(st, orig_size, UnSet, UnSet, 0, 0,
                                          UnSet, NULL, devname,
                                          ROLLBACK_METADATA_CHANGES,
                                          c->verbose) == 0)
                                sync_metadata(st);
                        pr_err("Cannot set device size for %s: %s\n",
                                devname, strerror(err));
                        if (err == EBUSY &&
                            (array.state & (1<<MD_SB_BITMAP_PRESENT)))
                                cont_err("Bitmap must be removed before size can be changed\n");
                        rv = 1;
                        goto release;
                }
                if (s->assume_clean) {
                        /* This will fail on kernels older than 3.0 unless
                         * a backport has been arranged.
                         */
                        if (sra == NULL ||
                            sysfs_set_str(sra, NULL, "resync_start",
                                          "none") < 0)
                                pr_err("--assume-clean not supported with --grow on this kernel\n");
                }
                md_get_array_info(fd, &array);
                s->size = get_component_size(fd)/2;
                if (s->size == 0)
                        s->size = array.size;
                if (c->verbose >= 0) {
                        if (s->size == orig_size)
                                pr_err("component size of %s unchanged at %lluK\n",
                                        devname, s->size);
                        else
                                pr_err("component size of %s has been set to %lluK\n",
                                        devname, s->size);
                }
                changed = 1;
        } else if (array.level != LEVEL_CONTAINER) {
                s->size = get_component_size(fd)/2;
                if (s->size == 0)
                        s->size = array.size;
        }

        /* See if there is anything else to do */
        if ((s->level == UnSet || s->level == array.level) &&
            (s->layout_str == NULL) &&
            (s->chunk == 0 || s->chunk == array.chunk_size) &&
            data_offset == INVALID_SECTORS &&
            (s->raiddisks == 0 || s->raiddisks == array.raid_disks)) {
                /* Nothing more to do */
                if (!changed && c->verbose >= 0)
                        pr_err("%s: no change requested\n", devname);
                goto release;
        }

        /* ========= check for Raid10/Raid1 -> Raid0 conversion ===============
         * current implementation assumes that following conditions must be met:
         * - RAID10:
         *      - far_copies == 1
         *      - near_copies == 2
         */
        if ((s->level == 0 && array.level == 10 && sra &&
             array.layout == ((1 << 8) + 2) && !(array.raid_disks & 1)) ||
            (s->level == 0 && array.level == 1 && sra)) {
                int err;

                err = remove_disks_for_takeover(st, sra, array.layout);
                if (err) {
                        dprintf("Array cannot be reshaped\n");
                        if (cfd > -1)
                                close(cfd);
                        rv = 1;
                        goto release;
                }
                /* Make sure mdmon has seen the device removal
                 * and updated metadata before we continue with
                 * level change
                 */
                if (container)
                        ping_monitor(container);
        }

        memset(&info, 0, sizeof(info));
        info.array = array;
        if (sysfs_init(&info, fd, NULL)) {
                pr_err("failed to initialize sysfs.\n");
                rv = 1;
                goto release;
        }
        strcpy(info.text_version, sra->text_version);
        info.component_size = s->size*2;
        info.new_level = s->level;
        info.new_chunk = s->chunk * 1024;
        if (info.array.level == LEVEL_CONTAINER) {
                info.delta_disks = UnSet;
                info.array.raid_disks = s->raiddisks;
        } else if (s->raiddisks)
                info.delta_disks = s->raiddisks - info.array.raid_disks;
        else
                info.delta_disks = UnSet;
        if (s->layout_str == NULL) {
                info.new_layout = UnSet;
                if (info.array.level == 6 &&
                    (info.new_level == 6 || info.new_level == UnSet) &&
                    info.array.layout >= 16) {
                        pr_err("%s has a non-standard layout.  If you wish to preserve this\n", devname);
                        cont_err("during the reshape, please specify --layout=preserve\n");
                        cont_err("If you want to change it, specify a layout or use --layout=normalise\n");
                        rv = 1;
                        goto release;
                }
        } else if (strcmp(s->layout_str, "normalise") == 0 ||
                   strcmp(s->layout_str, "normalize") == 0) {
                /* If we have a -6 RAID6 layout, remove the '-6'. */
                info.new_layout = UnSet;
                if (info.array.level == 6 && info.new_level == UnSet) {
                        char l[40], *h;
                        strcpy(l, map_num_s(r6layout, info.array.layout));
                        h = strrchr(l, '-');
                        if (h && strcmp(h, "-6") == 0) {
                                *h = 0;
                                info.new_layout = map_name(r6layout, l);
                        }
                } else {
                        pr_err("%s is only meaningful when reshaping a RAID6 array.\n", s->layout_str);
                        rv = 1;
                        goto release;
                }
        } else if (strcmp(s->layout_str, "preserve") == 0) {
                /* This means that a non-standard RAID6 layout
                 * is OK.
                 * In particular:
                 * - When reshape a RAID6 (e.g. adding a device)
                 *   which is in a non-standard layout, it is OK
                 *   to preserve that layout.
                 * - When converting a RAID5 to RAID6, leave it in
                 *   the XXX-6 layout, don't re-layout.
                 */
                if (info.array.level == 6 && info.new_level == UnSet)
                        info.new_layout = info.array.layout;
                else if (info.array.level == 5 && info.new_level == 6) {
                        char l[40];
                        strcpy(l, map_num_s(r5layout, info.array.layout));
                        strcat(l, "-6");
                        info.new_layout = map_name(r6layout, l);
                } else {
                        pr_err("%s in only meaningful when reshaping to RAID6\n", s->layout_str);
                        rv = 1;
                        goto release;
                }
        } else {
                int l = info.new_level;
                if (l == UnSet)
                        l = info.array.level;
                switch (l) {
                case 5:
                        info.new_layout = map_name(r5layout, s->layout_str);
                        break;
                case 6:
                        info.new_layout = map_name(r6layout, s->layout_str);
                        break;
                case 10:
                        info.new_layout = parse_layout_10(s->layout_str);
                        break;
                case LEVEL_FAULTY:
                        info.new_layout = parse_layout_faulty(s->layout_str);
                        break;
                default:
                        pr_err("layout not meaningful with this level\n");
                        rv = 1;
                        goto release;
                }
                if (info.new_layout == UnSet) {
                        pr_err("layout %s not understood for this level\n",
                                s->layout_str);
                        rv = 1;
                        goto release;
                }
        }

        if (array.level == LEVEL_FAULTY) {
                if (s->level != UnSet && s->level != array.level) {
                        pr_err("cannot change level of Faulty device\n");
                        rv =1 ;
                }
                if (s->chunk) {
                        pr_err("cannot set chunksize of Faulty device\n");
                        rv =1 ;
                }
                if (s->raiddisks && s->raiddisks != 1) {
                        pr_err("cannot set raid_disks of Faulty device\n");
                        rv =1 ;
                }
                if (s->layout_str) {
                        if (md_get_array_info(fd, &array) != 0) {
                                dprintf("Cannot get array information.\n");
                                goto release;
                        }
                        array.layout = info.new_layout;
                        if (md_set_array_info(fd, &array) != 0) {
                                pr_err("failed to set new layout\n");
                                rv = 1;
                        } else if (c->verbose >= 0)
                                printf("layout for %s set to %d\n",
                                       devname, array.layout);
                }
        } else if (array.level == LEVEL_CONTAINER) {
                /* This change is to be applied to every array in the
                 * container.  This is only needed when the metadata imposes
                 * restraints of the various arrays in the container.
                 * Currently we only know that IMSM requires all arrays
                 * to have the same number of devices so changing the
                 * number of devices (On-Line Capacity Expansion) must be
                 * performed at the level of the container
                 */
                close_fd(&fd);
                rv = reshape_container(container, devname, -1, st, &info,
                                       c->force, c->backup_file, c->verbose,
                                       0, 0, 0);
                frozen = 0;
        } else {
                /* get spare devices from external metadata
                 */
                if (st->ss->external) {
                        struct mdinfo *info2;

                        info2 = st->ss->container_content(st, subarray);
                        if (info2) {
                                info.array.spare_disks =
                                        info2->array.spare_disks;
                                sysfs_free(info2);
                        }
                }

                /* Impose these changes on a single array.  First
                 * check that the metadata is OK with the change. */

                if (reshape_super(st, 0, info.new_level,
                                  info.new_layout, info.new_chunk,
                                  info.array.raid_disks, info.delta_disks,
                                  c->backup_file, devname,
                                  APPLY_METADATA_CHANGES, c->verbose)) {
                        rv = 1;
                        goto release;
                }
                sync_metadata(st);
                rv = reshape_array(container, fd, devname, st, &info, c->force,
                                   devlist, data_offset, c->backup_file,
                                   c->verbose, 0, 0, 0);
                frozen = 0;
        }
release:
        sysfs_free(sra);
        if (frozen > 0)
                unfreeze(st);
        return rv;
}

/* verify_reshape_position()
 *      Function checks if reshape position in metadata is not farther
 *      than position in md.
 * Return value:
 *       0 : not valid sysfs entry
 *              it can be caused by not started reshape, it should be started
 *              by reshape array or raid0 array is before takeover
 *      -1 :    error, reshape position is obviously wrong
 *       1 :    success, reshape progress correct or updated
*/
static int verify_reshape_position(struct mdinfo *info, int level)
{
        int ret_val = 0;
        char buf[40];
        int rv;

        /* read sync_max, failure can mean raid0 array */
        rv = sysfs_get_str(info, NULL, "sync_max", buf, 40);

        if (rv > 0) {
                char *ep;
                unsigned long long position = strtoull(buf, &ep, 0);

                dprintf("Read sync_max sysfs entry is: %s\n", buf);
                if (!(ep == buf || (*ep != 0 && *ep != '\n' && *ep != ' '))) {
                        position *= get_data_disks(level,
                                                   info->new_layout,
                                                   info->array.raid_disks);
                        if (info->reshape_progress < position) {
                                dprintf("Corrected reshape progress (%llu) to md position (%llu)\n",
                                        info->reshape_progress, position);
                                info->reshape_progress = position;
                                ret_val = 1;
                        } else if (info->reshape_progress > position) {
                                pr_err("Fatal error: array reshape was not properly frozen (expected reshape position is %llu, but reshape progress is %llu.\n",
                                       position, info->reshape_progress);
                                ret_val = -1;
                        } else {
                                dprintf("Reshape position in md and metadata are the same;");
                                ret_val = 1;
                        }
                }
        } else if (rv == 0) {
                /* for valid sysfs entry, 0-length content
                 * should be indicated as error
                 */
                ret_val = -1;
        }

        return ret_val;
}

static unsigned long long choose_offset(unsigned long long lo,
                                        unsigned long long hi,
                                        unsigned long long min,
                                        unsigned long long max)
{
        /* Choose a new offset between hi and lo.
         * It must be between min and max, but
         * we would prefer something near the middle of hi/lo, and also
         * prefer to be aligned to a big power of 2.
         *
         * So we start with the middle, then for each bit,
         * starting at '1' and increasing, if it is set, we either
         * add it or subtract it if possible, preferring the option
         * which is furthest from the boundary.
         *
         * We stop once we get a 1MB alignment. As units are in sectors,
         * 1MB = 2*1024 sectors.
         */
        unsigned long long choice = (lo + hi) / 2;
        unsigned long long bit = 1;

        for (bit = 1; bit < 2*1024; bit = bit << 1) {
                unsigned long long bigger, smaller;
                if (! (bit & choice))
                        continue;
                bigger = choice + bit;
                smaller = choice - bit;
                if (bigger > max && smaller < min)
                        break;
                if (bigger > max)
                        choice = smaller;
                else if (smaller < min)
                        choice = bigger;
                else if (hi - bigger > smaller - lo)
                        choice = bigger;
                else
                        choice = smaller;
        }
        return choice;
}

static int set_new_data_offset(struct mdinfo *sra, struct supertype *st,
                               char *devname, int delta_disks,
                               unsigned long long data_offset,
                               unsigned long long min,
                               int can_fallback)
{
        struct mdinfo *sd;
        int dir = 0;
        int err = 0;
        unsigned long long before, after;

        /* Need to find min space before and after so same is used
         * on all devices
         */
        before = UINT64_MAX;
        after = UINT64_MAX;
        for (sd = sra->devs; sd; sd = sd->next) {
                char *dn;
                int dfd;
                int rv;
                struct supertype *st2;
                struct mdinfo info2;

                if (sd->disk.state & (1<<MD_DISK_FAULTY))
                        continue;
                dn = map_dev(sd->disk.major, sd->disk.minor, 0);
                dfd = dev_open(dn, O_RDONLY);
                if (dfd < 0) {
                        pr_err("%s: cannot open component %s\n",
                                devname, dn ? dn : "-unknown-");
                        goto release;
                }
                st2 = dup_super(st);
                rv = st2->ss->load_super(st2,dfd, NULL);
                close(dfd);
                if (rv) {
                        free(st2);
                        pr_err("%s: cannot get superblock from %s\n",
                                devname, dn);
                        goto release;
                }
                st2->ss->getinfo_super(st2, &info2, NULL);
                st2->ss->free_super(st2);
                free(st2);
                if (info2.space_before == 0 &&
                    info2.space_after == 0) {
                        /* Metadata doesn't support data_offset changes */
                        if (!can_fallback)
                                pr_err("%s: Metadata version doesn't support data_offset changes\n",
                                       devname);
                        goto fallback;
                }
                if (before > info2.space_before)
                        before = info2.space_before;
                if (after > info2.space_after)
                        after = info2.space_after;

                if (data_offset != INVALID_SECTORS) {
                        if (dir == 0) {
                                if (info2.data_offset == data_offset) {
                                        pr_err("%s: already has that data_offset\n",
                                               dn);
                                        goto release;
                                }
                                if (data_offset < info2.data_offset)
                                        dir = -1;
                                else
                                        dir = 1;
                        } else if ((data_offset <= info2.data_offset &&
                                    dir == 1) ||
                                   (data_offset >= info2.data_offset &&
                                    dir == -1)) {
                                pr_err("%s: differing data offsets on devices make this --data-offset setting impossible\n",
                                        dn);
                                goto release;
                        }
                }
        }
        if (before == UINT64_MAX)
                /* impossible really, there must be no devices */
                return 1;

        for (sd = sra->devs; sd; sd = sd->next) {
                char *dn = map_dev(sd->disk.major, sd->disk.minor, 0);
                unsigned long long new_data_offset;

                if (sd->disk.state & (1<<MD_DISK_FAULTY))
                        continue;
                if (delta_disks < 0) {
                        /* Don't need any space as array is shrinking
                         * just move data_offset up by min
                         */
                        if (data_offset == INVALID_SECTORS)
                                new_data_offset = sd->data_offset + min;
                        else {
                                if (data_offset < sd->data_offset + min) {
                                        pr_err("--data-offset too small for %s\n",
                                                dn);
                                        goto release;
                                }
                                new_data_offset = data_offset;
                        }
                } else if (delta_disks > 0) {
                        /* need space before */
                        if (before < min) {
                                if (can_fallback)
                                        goto fallback;
                                pr_err("Insufficient head-space for reshape on %s\n",
                                        dn);
                                goto release;
                        }
                        if (data_offset == INVALID_SECTORS)
                                new_data_offset = sd->data_offset - min;
                        else {
                                if (data_offset > sd->data_offset - min) {
                                        pr_err("--data-offset too large for %s\n",
                                                dn);
                                        goto release;
                                }
                                new_data_offset = data_offset;
                        }
                } else {
                        if (dir == 0) {
                                /* can move up or down.  If 'data_offset'
                                 * was set we would have already decided,
                                 * so just choose direction with most space.
                                 */
                                if (before > after)
                                        dir = -1;
                                else
                                        dir = 1;
                        }
                        sysfs_set_str(sra, NULL, "reshape_direction",
                                      dir == 1 ? "backwards" : "forwards");
                        if (dir > 0) {
                                /* Increase data offset */
                                if (after < min) {
                                        if (can_fallback)
                                                goto fallback;
                                        pr_err("Insufficient tail-space for reshape on %s\n",
                                                dn);
                                        goto release;
                                }
                                if (data_offset != INVALID_SECTORS &&
                                    data_offset < sd->data_offset + min) {
                                        pr_err("--data-offset too small on %s\n",
                                                dn);
                                        goto release;
                                }
                                if (data_offset != INVALID_SECTORS)
                                        new_data_offset = data_offset;
                                else
                                        new_data_offset = choose_offset(sd->data_offset,
                                                                        sd->data_offset + after,
                                                                        sd->data_offset + min,
                                                                        sd->data_offset + after);
                        } else {
                                /* Decrease data offset */
                                if (before < min) {
                                        if (can_fallback)
                                                goto fallback;
                                        pr_err("insufficient head-room on %s\n",
                                                dn);
                                        goto release;
                                }
                                if (data_offset != INVALID_SECTORS &&
                                    data_offset > sd->data_offset - min) {
                                        pr_err("--data-offset too large on %s\n",
                                                dn);
                                        goto release;
                                }
                                if (data_offset != INVALID_SECTORS)
                                        new_data_offset = data_offset;
                                else
                                        new_data_offset = choose_offset(sd->data_offset - before,
                                                                        sd->data_offset,
                                                                        sd->data_offset - before,
                                                                        sd->data_offset - min);
                        }
                }
                err = sysfs_set_num(sra, sd, "new_offset", new_data_offset);
                if (err < 0 && errno == E2BIG) {
                        /* try again after increasing data size to max */
                        err = sysfs_set_num(sra, sd, "size", 0);
                        if (err < 0 && errno == EINVAL &&
                            !(sd->disk.state & (1<<MD_DISK_SYNC))) {
                                /* some kernels have a bug where you cannot
                                 * use '0' on spare devices. */
                                sysfs_set_num(sra, sd, "size",
                                              (sra->component_size + after)/2);
                        }
                        err = sysfs_set_num(sra, sd, "new_offset",
                                            new_data_offset);
                }
                if (err < 0) {
                        if (errno == E2BIG && data_offset != INVALID_SECTORS) {
                                pr_err("data-offset is too big for %s\n", dn);
                                goto release;
                        }
                        if (sd == sra->devs &&
                            (errno == ENOENT || errno == E2BIG))
                                /* Early kernel, no 'new_offset' file,
                                 * or kernel doesn't like us.
                                 * For RAID5/6 this is not fatal
                                 */
                                return 1;
                        pr_err("Cannot set new_offset for %s\n", dn);
                        break;
                }
        }
        return err;
release:
        return -1;
fallback:
        /* Just use a backup file */
        return 1;
}

static int raid10_reshape(char *container, int fd, char *devname,
                          struct supertype *st, struct mdinfo *info,
                          struct reshape *reshape,
                          unsigned long long data_offset,
                          int force, int verbose)
{
        /* Changing raid_disks, layout, chunksize or possibly
         * just data_offset for a RAID10.
         * We must always change data_offset.  We change by at least
         * ->min_offset_change which is the largest of the old and new
         * chunk sizes.
         * If raid_disks is increasing, then data_offset must decrease
         * by at least this copy size.
         * If raid_disks is unchanged, data_offset must increase or
         * decrease by at least min_offset_change but preferably by much more.
         * We choose half of the available space.
         * If raid_disks is decreasing, data_offset must increase by
         * at least min_offset_change.  To allow of this, component_size
         * must be decreased by the same amount.
         *
         * So we calculate the required minimum and direction, possibly
         * reduce the component_size, then iterate through the devices
         * and set the new_data_offset.
         * If that all works, we set chunk_size, layout, raid_disks, and start
         * 'reshape'
         */
        struct mdinfo *sra;
        unsigned long long min;
        int err = 0;

        sra = sysfs_read(fd, NULL,
                         GET_COMPONENT|GET_DEVS|GET_OFFSET|GET_STATE|GET_CHUNK
                );
        if (!sra) {
                pr_err("%s: Cannot get array details from sysfs\n", devname);
                goto release;
        }
        min = reshape->min_offset_change;

        if (info->delta_disks)
                sysfs_set_str(sra, NULL, "reshape_direction",
                              info->delta_disks < 0 ? "backwards" : "forwards");
        if (info->delta_disks < 0 && info->space_after < min) {
                int rv = sysfs_set_num(sra, NULL, "component_size",
                                       (sra->component_size - min)/2);
                if (rv) {
                        pr_err("cannot reduce component size\n");
                        goto release;
                }
        }
        err = set_new_data_offset(sra, st, devname, info->delta_disks,
                                  data_offset, min, 0);
        if (err == 1) {
                pr_err("Cannot set new_data_offset: RAID10 reshape not\n");
                cont_err("supported on this kernel\n");
                err = -1;
        }
        if (err < 0)
                goto release;

        if (!err && sysfs_set_num(sra, NULL, "chunk_size", info->new_chunk) < 0)
                err = errno;
        if (!err && sysfs_set_num(sra, NULL, "layout",
                                  reshape->after.layout) < 0)
                err = errno;
        if (!err &&
            sysfs_set_num(sra, NULL, "raid_disks",
                          info->array.raid_disks + info->delta_disks) < 0)
                err = errno;
        if (!err && sysfs_set_str(sra, NULL, "sync_action", "reshape") < 0)
                err = errno;
        if (err) {
                pr_err("Cannot set array shape for %s\n",
                       devname);
                if (err == EBUSY &&
                    (info->array.state & (1<<MD_SB_BITMAP_PRESENT)))
                        cont_err("       Bitmap must be removed before shape can be changed\n");
                goto release;
        }
        sysfs_free(sra);
        return 0;
release:
        sysfs_free(sra);
        return 1;
}

static void get_space_after(int fd, struct supertype *st, struct mdinfo *info)
{
        struct mdinfo *sra, *sd;
        /* Initialisation to silence compiler warning */
        unsigned long long min_space_before = 0, min_space_after = 0;
        int first = 1;

        sra = sysfs_read(fd, NULL, GET_DEVS);
        if (!sra)
                return;
        for (sd = sra->devs; sd; sd = sd->next) {
                char *dn;
                int dfd;
                struct supertype *st2;
                struct mdinfo info2;

                if (sd->disk.state & (1<<MD_DISK_FAULTY))
                        continue;
                dn = map_dev(sd->disk.major, sd->disk.minor, 0);
                dfd = dev_open(dn, O_RDONLY);
                if (dfd < 0)
                        break;
                st2 = dup_super(st);
                if (st2->ss->load_super(st2,dfd, NULL)) {
                        close(dfd);
                        free(st2);
                        break;
                }
                close(dfd);
                st2->ss->getinfo_super(st2, &info2, NULL);
                st2->ss->free_super(st2);
                free(st2);
                if (first ||
                    min_space_before > info2.space_before)
                        min_space_before = info2.space_before;
                if (first ||
                    min_space_after > info2.space_after)
                        min_space_after = info2.space_after;
                first = 0;
        }
        if (sd == NULL && !first) {
                info->space_after = min_space_after;
                info->space_before = min_space_before;
        }
        sysfs_free(sra);
}

static void update_cache_size(char *container, struct mdinfo *sra,
                              struct mdinfo *info,
                              int disks, unsigned long long blocks)
{
        /* Check that the internal stripe cache is
         * large enough, or it won't work.
         * It must hold at least 4 stripes of the larger
         * chunk size
         */
        unsigned long cache;
        cache = max(info->array.chunk_size, info->new_chunk);
        cache *= 4; /* 4 stripes minimum */
        cache /= 512; /* convert to sectors */
        /* make sure there is room for 'blocks' with a bit to spare */
        if (cache < 16 + blocks / disks)
                cache = 16 + blocks / disks;
        cache /= (4096/512); /* Convert from sectors to pages */

        if (sra->cache_size < cache)
                subarray_set_num(container, sra, "stripe_cache_size",
                                 cache+1);
}

static int impose_reshape(struct mdinfo *sra,
                          struct mdinfo *info,
                          struct supertype *st,
                          int fd,
                          int restart,
                          char *devname, char *container,
                          struct reshape *reshape)
{
        struct mdu_array_info_s array;

        sra->new_chunk = info->new_chunk;

        if (restart) {
                /* for external metadata checkpoint saved by mdmon can be lost
                 * or missed /due to e.g. crash/. Check if md is not during
                 * restart farther than metadata points to.
                 * If so, this means metadata information is obsolete.
                 */
                if (st->ss->external)
                        verify_reshape_position(info, reshape->level);
                sra->reshape_progress = info->reshape_progress;
        } else {
                sra->reshape_progress = 0;
                if (reshape->after.data_disks < reshape->before.data_disks)
                        /* start from the end of the new array */
                        sra->reshape_progress = (sra->component_size
                                                 * reshape->after.data_disks);
        }

        md_get_array_info(fd, &array);
        if (info->array.chunk_size == info->new_chunk &&
            reshape->before.layout == reshape->after.layout &&
            st->ss->external == 0) {
                /* use SET_ARRAY_INFO but only if reshape hasn't started */
                array.raid_disks = reshape->after.data_disks + reshape->parity;
                if (!restart && md_set_array_info(fd, &array) != 0) {
                        int err = errno;

                        pr_err("Cannot set device shape for %s: %s\n",
                               devname, strerror(errno));

                        if (err == EBUSY &&
                            (array.state & (1<<MD_SB_BITMAP_PRESENT)))
                                cont_err("Bitmap must be removed before shape can be changed\n");

                        goto release;
                }
        } else if (!restart) {
                /* set them all just in case some old 'new_*' value
                 * persists from some earlier problem.
                 */
                int err = 0;
                if (sysfs_set_num(sra, NULL, "chunk_size", info->new_chunk) < 0)
                        err = errno;
                if (!err && sysfs_set_num(sra, NULL, "layout",
                                          reshape->after.layout) < 0)
                        err = errno;
                if (!err && subarray_set_num(container, sra, "raid_disks",
                                             reshape->after.data_disks +
                                             reshape->parity) < 0)
                        err = errno;
                if (err) {
                        pr_err("Cannot set device shape for %s\n", devname);

                        if (err == EBUSY &&
                            (array.state & (1<<MD_SB_BITMAP_PRESENT)))
                                cont_err("Bitmap must be removed before shape can be changed\n");
                        goto release;
                }
        }
        return 0;
release:
        return -1;
}

static int impose_level(int fd, int level, char *devname, int verbose)
{
        char *c;
        struct mdu_array_info_s array;
        struct mdinfo info;

        if (sysfs_init(&info, fd, NULL)) {
                pr_err("failed to initialize sysfs.\n");
                return  1;
        }

        md_get_array_info(fd, &array);
        if (level == 0 && is_level456(array.level)) {
                /* To convert to RAID0 we need to fail and
                 * remove any non-data devices. */
                int found = 0;
                int d;
                int data_disks = array.raid_disks - 1;
                if (array.level == 6)
                        data_disks -= 1;
                if (array.level == 5 && array.layout != ALGORITHM_PARITY_N)
                        return -1;
                if (array.level == 6 && array.layout != ALGORITHM_PARITY_N_6)
                        return -1;
                sysfs_set_str(&info, NULL,"sync_action", "idle");
                /* First remove any spares so no recovery starts */
                for (d = 0, found = 0;
                     d < MAX_DISKS && found < array.nr_disks; d++) {
                        mdu_disk_info_t disk;
                        disk.number = d;
                        if (md_get_disk_info(fd, &disk) < 0)
                                continue;
                        if (disk.major == 0 && disk.minor == 0)
                                continue;
                        found++;
                        if ((disk.state & (1 << MD_DISK_ACTIVE)) &&
                            disk.raid_disk < data_disks)
                                /* keep this */
                                continue;
                        ioctl(fd, HOT_REMOVE_DISK,
                              makedev(disk.major, disk.minor));
                }
                /* Now fail anything left */
                md_get_array_info(fd, &array);
                for (d = 0, found = 0;
                     d < MAX_DISKS && found < array.nr_disks; d++) {
                        mdu_disk_info_t disk;
                        disk.number = d;
                        if (md_get_disk_info(fd, &disk) < 0)
                                continue;
                        if (disk.major == 0 && disk.minor == 0)
                                continue;
                        found++;
                        if ((disk.state & (1 << MD_DISK_ACTIVE)) &&
                            disk.raid_disk < data_disks)
                                /* keep this */
                                continue;
                        ioctl(fd, SET_DISK_FAULTY,
                              makedev(disk.major, disk.minor));
                        hot_remove_disk(fd, makedev(disk.major, disk.minor), 1);
                }
        }
        c = map_num(pers, level);
        if (c) {
                int err = sysfs_set_str(&info, NULL, "level", c);
                if (err) {
                        err = errno;
                        pr_err("%s: could not set level to %s\n",
                                devname, c);
                        if (err == EBUSY &&
                            (array.state & (1<<MD_SB_BITMAP_PRESENT)))
                                cont_err("Bitmap must be removed before level can be changed\n");
                        return err;
                }
                if (verbose >= 0)
                        pr_err("level of %s changed to %s\n", devname, c);
        }
        return 0;
}

int sigterm = 0;
static void catch_term(int sig)
{
        sigterm = 1;
}

static int reshape_array(char *container, int fd, char *devname,
                         struct supertype *st, struct mdinfo *info,
                         int force, struct mddev_dev *devlist,
                         unsigned long long data_offset,
                         char *backup_file, int verbose, int forked,
                         int restart, int freeze_reshape)
{
        struct reshape reshape;
        int spares_needed;
        char *msg;
        int orig_level = UnSet;
        int odisks;
        int delayed;

        struct mdu_array_info_s array;
        char *c;

        struct mddev_dev *dv;
        int added_disks;

        int *fdlist = NULL;
        unsigned long long *offsets = NULL;
        int d;
        int nrdisks;
        int err;
        unsigned long blocks;
        unsigned long long array_size;
        int done;
        struct mdinfo *sra = NULL;
        char buf[20];

        /* when reshaping a RAID0, the component_size might be zero.
         * So try to fix that up.
         */
        if (md_get_array_info(fd, &array) != 0) {
                dprintf("Cannot get array information.\n");
                goto release;
        }
        if (array.level == 0 && info->component_size == 0) {
                get_dev_size(fd, NULL, &array_size);
                info->component_size = array_size / array.raid_disks;
        }

        if (array.level == 10)
                /* Need space_after info */
                get_space_after(fd, st, info);

        if (info->reshape_active) {
                int new_level = info->new_level;
                info->new_level = UnSet;
                if (info->delta_disks > 0)
                        info->array.raid_disks -= info->delta_disks;
                msg = analyse_change(devname, info, &reshape);
                info->new_level = new_level;
                if (info->delta_disks > 0)
                        info->array.raid_disks += info->delta_disks;
                if (!restart)
                        /* Make sure the array isn't read-only */
                        ioctl(fd, RESTART_ARRAY_RW, 0);
        } else
                msg = analyse_change(devname, info, &reshape);
        if (msg) {
                /* if msg == "", error has already been printed */
                if (msg[0])
                        pr_err("%s\n", msg);
                goto release;
        }
        if (restart && (reshape.level != info->array.level ||
                        reshape.before.layout != info->array.layout ||
                        reshape.before.data_disks + reshape.parity !=
                        info->array.raid_disks - max(0, info->delta_disks))) {
                pr_err("reshape info is not in native format - cannot continue.\n");
                goto release;
        }

        if (st->ss->external && restart && (info->reshape_progress == 0) &&
            !((sysfs_get_str(info, NULL, "sync_action",
                             buf, sizeof(buf)) > 0) &&
              (strncmp(buf, "reshape", 7) == 0))) {
                /* When reshape is restarted from '0', very begin of array
                 * it is possible that for external metadata reshape and array
                 * configuration doesn't happen.
                 * Check if md has the same opinion, and reshape is restarted
                 * from 0. If so, this is regular reshape start after reshape
                 * switch in metadata to next array only.
                 */
                if ((verify_reshape_position(info, reshape.level) >= 0) &&
                    (info->reshape_progress == 0))
                        restart = 0;
        }
        if (restart) {
                /*
                 * reshape already started. just skip to monitoring
                 * the reshape
                 */
                if (reshape.backup_blocks == 0)
                        return 0;
                if (restart & RESHAPE_NO_BACKUP)
                        return 0;

                /* Need 'sra' down at 'started:' */
                sra = sysfs_read(fd, NULL,
                                 GET_COMPONENT|GET_DEVS|GET_OFFSET|GET_STATE|
                                 GET_CHUNK|GET_CACHE);
                if (!sra) {
                        pr_err("%s: Cannot get array details from sysfs\n",
                               devname);
                        goto release;
                }

                if (!backup_file)
                        backup_file = locate_backup(sra->sys_name);

                goto started;
        }
        /* The container is frozen but the array may not be.
         * So freeze the array so spares don't get put to the wrong use
         * FIXME there should probably be a cleaner separation between
         * freeze_array and freeze_container.
         */
        sysfs_freeze_array(info);
        /* Check we have enough spares to not be degraded */
        added_disks = 0;
        for (dv = devlist; dv ; dv=dv->next)
                added_disks++;
        spares_needed = max(reshape.before.data_disks,
                            reshape.after.data_disks) +
                reshape.parity - array.raid_disks;

        if (!force && info->new_level > 1 && info->array.level > 1 &&
            spares_needed > info->array.spare_disks + added_disks) {
                pr_err("Need %d spare%s to avoid degraded array, and only have %d.\n"
                       "       Use --force to over-ride this check.\n",
                       spares_needed,
                       spares_needed == 1 ? "" : "s",
                       info->array.spare_disks + added_disks);
                goto release;
        }
        /* Check we have enough spares to not fail */
        spares_needed = max(reshape.before.data_disks,
                            reshape.after.data_disks)
                - array.raid_disks;
        if ((info->new_level > 1 || info->new_level == 0) &&
            spares_needed > info->array.spare_disks +added_disks) {
                pr_err("Need %d spare%s to create working array, and only have %d.\n",
                       spares_needed, spares_needed == 1 ? "" : "s",
                       info->array.spare_disks + added_disks);
                goto release;
        }

        if (reshape.level != array.level) {
                int err = impose_level(fd, reshape.level, devname, verbose);
                if (err)
                        goto release;
                info->new_layout = UnSet; /* after level change,
                                           * layout is meaningless */
                orig_level = array.level;
                sysfs_freeze_array(info);

                if (reshape.level > 0 && st->ss->external) {
                        /* make sure mdmon is aware of the new level */
                        if (mdmon_running(container))
                                flush_mdmon(container);

                        if (!mdmon_running(container))
                                start_mdmon(container);
                        ping_monitor(container);
                        if (mdmon_running(container) && st->update_tail == NULL)
                                st->update_tail = &st->updates;
                }
        }
        /* ->reshape_super might have chosen some spares from the
         * container that it wants to be part of the new array.
         * We can collect them with ->container_content and give
         * them to the kernel.
         */
        if (st->ss->reshape_super && st->ss->container_content) {
                char *subarray = strchr(info->text_version+1, '/')+1;
                struct mdinfo *info2 =
                        st->ss->container_content(st, subarray);
                struct mdinfo *d;

                if (info2) {
                        if (sysfs_init(info2, fd, st->devnm)) {
                                pr_err("unable to initialize sysfs for %s\n",
                                       st->devnm);
                                free(info2);
                                goto release;
                        }
                        /* When increasing number of devices, we need to set
                         * new raid_disks before adding these, or they might
                         * be rejected.
                         */
                        if (reshape.backup_blocks &&
                            reshape.after.data_disks >
                            reshape.before.data_disks)
                                subarray_set_num(container, info2, "raid_disks",
                                                 reshape.after.data_disks +
                                                 reshape.parity);
                        for (d = info2->devs; d; d = d->next) {
                                if (d->disk.state == 0 &&
                                    d->disk.raid_disk >= 0) {
                                        /* This is a spare that wants to
                                         * be part of the array.
                                         */
                                        add_disk(fd, st, info2, d);
                                }
                        }
                        sysfs_free(info2);
                }
        }
        /* We might have been given some devices to add to the
         * array.  Now that the array has been changed to the right
         * level and frozen, we can safely add them.
         */
        if (devlist) {
                if (Manage_subdevs(devname, fd, devlist, verbose, 0, NULL, 0))
                        goto release;
        }

        if (reshape.backup_blocks == 0 && data_offset != INVALID_SECTORS)
                reshape.backup_blocks = reshape.before.data_disks * info->array.chunk_size/512;
        if (reshape.backup_blocks == 0) {
                /* No restriping needed, but we might need to impose
                 * some more changes: layout, raid_disks, chunk_size
                 */
                /* read current array info */
                if (md_get_array_info(fd, &array) != 0) {
                        dprintf("Cannot get array information.\n");
                        goto release;
                }
                /* compare current array info with new values and if
                 * it is different update them to new */
                if (info->new_layout != UnSet &&
                    info->new_layout != array.layout) {
                        array.layout = info->new_layout;
                        if (md_set_array_info(fd, &array) != 0) {
                                pr_err("failed to set new layout\n");
                                goto release;
                        } else if (verbose >= 0)
                                printf("layout for %s set to %d\n",
                                       devname, array.layout);
                }
                if (info->delta_disks != UnSet && info->delta_disks != 0 &&
                    array.raid_disks !=
                    (info->array.raid_disks + info->delta_disks)) {
                        array.raid_disks += info->delta_disks;
                        if (md_set_array_info(fd, &array) != 0) {
                                pr_err("failed to set raid disks\n");
                                goto release;
                        } else if (verbose >= 0) {
                                printf("raid_disks for %s set to %d\n",
                                       devname, array.raid_disks);
                        }
                }
                if (info->new_chunk != 0 &&
                    info->new_chunk != array.chunk_size) {
                        if (sysfs_set_num(info, NULL,
                                          "chunk_size", info->new_chunk) != 0) {
                                pr_err("failed to set chunk size\n");
                                goto release;
                        } else if (verbose >= 0)
                                printf("chunk size for %s set to %d\n",
                                       devname, info->new_chunk);
                }
                unfreeze(st);
                return 0;
        }

        /*
         * There are three possibilities.
         * 1/ The array will shrink.
         *    We need to ensure the reshape will pause before reaching
         *    the 'critical section'.  We also need to fork and wait for
         *    that to happen.  When it does we
         *       suspend/backup/complete/unfreeze
         *
         * 2/ The array will not change size.
         *    This requires that we keep a backup of a sliding window
         *    so that we can restore data after a crash.  So we need
         *    to fork and monitor progress.
         *    In future we will allow the data_offset to change, so
         *    a sliding backup becomes unnecessary.
         *
         * 3/ The array will grow. This is relatively easy.
         *    However the kernel's restripe routines will cheerfully
         *    overwrite some early data before it is safe.  So we
         *    need to make a backup of the early parts of the array
         *    and be ready to restore it if rebuild aborts very early.
         *    For externally managed metadata, we still need a forked
         *    child to monitor the reshape and suspend IO over the region
         *    that is being reshaped.
         *
         *    We backup data by writing it to one spare, or to a
         *    file which was given on command line.
         *
         * In each case, we first make sure that storage is available
         * for the required backup.
         * Then we:
         *   -  request the shape change.
         *   -  fork to handle backup etc.
         */
        /* Check that we can hold all the data */
        get_dev_size(fd, NULL, &array_size);
        if (reshape.new_size < (array_size/512)) {
                pr_err("this change will reduce the size of the array.\n"
                       "       use --grow --array-size first to truncate array.\n"
                       "       e.g. mdadm --grow %s --array-size %llu\n",
                       devname, reshape.new_size/2);
                goto release;
        }

        if (array.level == 10) {
                /* Reshaping RAID10 does not require any data backup by
                 * user-space.  Instead it requires that the data_offset
                 * is changed to avoid the need for backup.
                 * So this is handled very separately
                 */
                if (restart)
                        /* Nothing to do. */
                        return 0;
                return raid10_reshape(container, fd, devname, st, info,
                                      &reshape, data_offset, force, verbose);
        }
        sra = sysfs_read(fd, NULL,
                         GET_COMPONENT|GET_DEVS|GET_OFFSET|GET_STATE|GET_CHUNK|
                         GET_CACHE);
        if (!sra) {
                pr_err("%s: Cannot get array details from sysfs\n",
                        devname);
                goto release;
        }

        if (!backup_file)
                switch(set_new_data_offset(sra, st, devname,
                                           reshape.after.data_disks - reshape.before.data_disks,
                                           data_offset,
                                           reshape.min_offset_change, 1)) {
        case -1:
                goto release;
        case 0:
                /* Updated data_offset, so it's easy now */
                update_cache_size(container, sra, info,
                                  min(reshape.before.data_disks,
                                      reshape.after.data_disks),
                                  reshape.backup_blocks);

                /* Right, everything seems fine. Let's kick things off.
                 */
                sync_metadata(st);

                if (impose_reshape(sra, info, st, fd, restart,
                                   devname, container, &reshape) < 0)
                        goto release;
                if (sysfs_set_str(sra, NULL, "sync_action", "reshape") < 0) {
                        struct mdinfo *sd;
                        if (errno != EINVAL) {
                                pr_err("Failed to initiate reshape!\n");
                                goto release;
                        }
                        /* revert data_offset and try the old way */
                        for (sd = sra->devs; sd; sd = sd->next) {
                                sysfs_set_num(sra, sd, "new_offset",
                                              sd->data_offset);
                                sysfs_set_str(sra, NULL, "reshape_direction",
                                              "forwards");
                        }
                        break;
                }
                if (info->new_level == reshape.level)
                        return 0;
                /* need to adjust level when reshape completes */
                switch(fork()) {
                case -1: /* ignore error, but don't wait */
                        return 0;
                default: /* parent */
                        return 0;
                case 0:
                        manage_fork_fds(0);
                        map_fork();
                        break;
                }
                close(fd);
                wait_reshape(sra);
                fd = open_dev(sra->sys_name);
                if (fd >= 0)
                        impose_level(fd, info->new_level, devname, verbose);
                return 0;
        case 1: /* Couldn't set data_offset, try the old way */
                if (data_offset != INVALID_SECTORS) {
                        pr_err("Cannot update data_offset on this array\n");
                        goto release;
                }
                break;
        }

started:
        /* Decide how many blocks (sectors) for a reshape
         * unit.  The number we have so far is just a minimum
         */
        blocks = reshape.backup_blocks;
        if (reshape.before.data_disks ==
            reshape.after.data_disks) {
                /* Make 'blocks' bigger for better throughput, but
                 * not so big that we reject it below.
                 * Try for 16 megabytes
                 */
                while (blocks * 32 < sra->component_size && blocks < 16*1024*2)
                        blocks *= 2;
        } else
                pr_err("Need to backup %luK of critical section..\n", blocks/2);

        if (blocks >= sra->component_size/2) {
                pr_err("%s: Something wrong - reshape aborted\n", devname);
                goto release;
        }

        /* Now we need to open all these devices so we can read/write.
         */
        nrdisks = max(reshape.before.data_disks,
                      reshape.after.data_disks) + reshape.parity
                + sra->array.spare_disks;
        fdlist = xcalloc((1+nrdisks), sizeof(int));
        offsets = xcalloc((1+nrdisks), sizeof(offsets[0]));

        odisks = reshape.before.data_disks + reshape.parity;
        d = reshape_prepare_fdlist(devname, sra, odisks, nrdisks, blocks,
                                   backup_file, fdlist, offsets);
        if (d < odisks) {
                goto release;
        }
        if ((st->ss->manage_reshape == NULL) ||
            (st->ss->recover_backup == NULL)) {
                if (backup_file == NULL) {
                        if (reshape.after.data_disks <=
                            reshape.before.data_disks) {
                                pr_err("%s: Cannot grow - need backup-file\n",
                                       devname);
                                pr_err(" Please provide one with \"--backup=...\"\n");
                                goto release;
                        } else if (d == odisks) {
                                pr_err("%s: Cannot grow - need a spare or backup-file to backup critical section\n", devname);
                                goto release;
                        }
                } else {
                        if (!reshape_open_backup_file(backup_file, fd, devname,
                                                      (signed)blocks,
                                                      fdlist+d, offsets+d,
                                                      sra->sys_name, restart)) {
                                goto release;
                        }
                        d++;
                }
        }

        update_cache_size(container, sra, info,
                          min(reshape.before.data_disks,
                              reshape.after.data_disks), blocks);

        /* Right, everything seems fine. Let's kick things off.
         * If only changing raid_disks, use ioctl, else use
         * sysfs.
         */
        sync_metadata(st);

        if (impose_reshape(sra, info, st, fd, restart,
                           devname, container, &reshape) < 0)
                goto release;

        err = start_reshape(sra, restart, reshape.before.data_disks,
                            reshape.after.data_disks, st);
        if (err) {
                pr_err("Cannot %s reshape for %s\n",
                       restart ? "continue" : "start", devname);
                goto release;
        }
        if (restart)
                sysfs_set_str(sra, NULL, "array_state", "active");
        if (freeze_reshape) {
                free(fdlist);
                free(offsets);
                sysfs_free(sra);
                pr_err("Reshape has to be continued from location %llu when root filesystem has been mounted.\n",
                        sra->reshape_progress);
                return 1;
        }

        if (!forked)
                if (continue_via_systemd(container ?: sra->sys_name,
                                         GROW_SERVICE)) {
                        free(fdlist);
                        free(offsets);
                        sysfs_free(sra);
                        return 0;
                }

        /* Now we just need to kick off the reshape and watch, while
         * handling backups of the data...
         * This is all done by a forked background process.
         */
        switch(forked ? 0 : fork()) {
        case -1:
                pr_err("Cannot run child to monitor reshape: %s\n",
                        strerror(errno));
                abort_reshape(sra);
                goto release;
        default:
                free(fdlist);
                free(offsets);
                sysfs_free(sra);
                return 0;
        case 0:
                map_fork();
                break;
        }

        /* Close unused file descriptor in the forked process */
        close_fd(&fd);

        /* If another array on the same devices is busy, the
         * reshape will wait for them.  This would mean that
         * the first section that we suspend will stay suspended
         * for a long time.  So check on that possibility
         * by looking for "DELAYED" in /proc/mdstat, and if found,
         * wait a while
         */
        do {
                struct mdstat_ent *mds, *m;
                delayed = 0;
                mds = mdstat_read(1, 0);
                for (m = mds; m; m = m->next)
                        if (strcmp(m->devnm, sra->sys_name) == 0) {
                                if (m->resync && m->percent == RESYNC_DELAYED)
                                        delayed = 1;
                                if (m->resync == 0)
                                        /* Haven't started the reshape thread
                                         * yet, wait a bit
                                         */
                                        delayed = 2;
                                break;
                        }
                free_mdstat(mds);
                if (delayed == 1 && get_linux_version() < 3007000) {
                        pr_err("Reshape is delayed, but cannot wait carefully with this kernel.\n"
                               "       You might experience problems until other reshapes complete.\n");
                        delayed = 0;
                }
                if (delayed)
                        mdstat_wait(30 - (delayed-1) * 25);
        } while (delayed);
        mdstat_close();
        if (check_env("MDADM_GROW_VERIFY"))
                fd = open(devname, O_RDONLY | O_DIRECT);
        else
                fd = -1;
        mlockall(MCL_FUTURE);

        if (signal_s(SIGTERM, catch_term) == SIG_ERR)
                goto release;

        if (st->ss->external) {
                /* metadata handler takes it from here */
                done = st->ss->manage_reshape(
                        fd, sra, &reshape, st, blocks,
                        fdlist, offsets, d - odisks, fdlist + odisks,
                        offsets + odisks);
        } else
                done = child_monitor(
                        fd, sra, &reshape, st, blocks, fdlist, offsets,
                        d - odisks, fdlist + odisks, offsets + odisks);

        free(fdlist);
        free(offsets);

        if (backup_file && done) {
                char *bul;
                bul = make_backup(sra->sys_name);
                if (bul) {
                        char buf[1024];
                        int l = readlink(bul, buf, sizeof(buf) - 1);
                        if (l > 0) {
                                buf[l]=0;
                                unlink(buf);
                        }
                        unlink(bul);
                        free(bul);
                }
                unlink(backup_file);
        }
        if (!done) {
                abort_reshape(sra);
                goto out;
        }

        if (!st->ss->external &&
            !(reshape.before.data_disks != reshape.after.data_disks &&
              info->custom_array_size) && info->new_level == reshape.level &&
            !forked) {
                /* no need to wait for the reshape to finish as
                 * there is nothing more to do.
                 */
                sysfs_free(sra);
                exit(0);
        }
        wait_reshape(sra);

        if (st->ss->external) {
                /* Re-load the metadata as much could have changed */
                int cfd = open_dev(st->container_devnm);
                if (cfd >= 0) {
                        flush_mdmon(container);
                        st->ss->free_super(st);
                        st->ss->load_container(st, cfd, container);
                        close(cfd);
                }
        }

        /* set new array size if required customer_array_size is used
         * by this metadata.
         */
        if (reshape.before.data_disks != reshape.after.data_disks &&
            info->custom_array_size)
                set_array_size(st, info, info->text_version);

        if (info->new_level != reshape.level) {
                if (fd < 0)
                        fd = open(devname, O_RDONLY);
                impose_level(fd, info->new_level, devname, verbose);
                close(fd);
                if (info->new_level == 0)
                        st->update_tail = NULL;
        }
out:
        sysfs_free(sra);
        if (forked)
                return 0;
        unfreeze(st);
        exit(0);

release:
        free(fdlist);
        free(offsets);
        if (orig_level != UnSet && sra) {
                c = map_num(pers, orig_level);
                if (c && sysfs_set_str(sra, NULL, "level", c) == 0)
                        pr_err("aborting level change\n");
        }
        sysfs_free(sra);
        if (!forked)
                unfreeze(st);
        return 1;
}

/* mdfd handle is passed to be closed in child process (after fork).
 */
int reshape_container(char *container, char *devname,
                      int mdfd,
                      struct supertype *st,
                      struct mdinfo *info,
                      int force,
                      char *backup_file, int verbose,
                      int forked, int restart, int freeze_reshape)
{
        struct mdinfo *cc = NULL;
        int rv = restart;
        char last_devnm[32] = "";

        /* component_size is not meaningful for a container,
         * so pass '0' meaning 'no change'
         */
        if (!restart &&
            reshape_super(st, 0, info->new_level,
                          info->new_layout, info->new_chunk,
                          info->array.raid_disks, info->delta_disks,
                          backup_file, devname, APPLY_METADATA_CHANGES,
                          verbose)) {
                unfreeze(st);
                return 1;
        }

        sync_metadata(st);

        /* ping monitor to be sure that update is on disk
         */
        ping_monitor(container);

        if (!forked && !freeze_reshape)
                if (continue_via_systemd(container, GROW_SERVICE))
                        return 0;

        switch (forked ? 0 : fork()) {
        case -1: /* error */
                perror("Cannot fork to complete reshape\n");
                unfreeze(st);
                return 1;
        default: /* parent */
                if (!freeze_reshape)
                        printf("%s: multi-array reshape continues in background\n", Name);
                return 0;
        case 0: /* child */
                manage_fork_fds(0);
                map_fork();
                break;
        }

        /* close unused handle in child process
         */
        if (mdfd > -1)
                close(mdfd);

        while(1) {
                /* For each member array with reshape_active,
                 * we need to perform the reshape.
                 * We pick the first array that needs reshaping and
                 * reshape it.  reshape_array() will re-read the metadata
                 * so the next time through a different array should be
                 * ready for reshape.
                 * It is possible that the 'different' array will not
                 * be assembled yet.  In that case we simple exit.
                 * When it is assembled, the mdadm which assembles it
                 * will take over the reshape.
                 */
                struct mdinfo *content;
                int fd;
                struct mdstat_ent *mdstat;
                char *adev;
                dev_t devid;

                sysfs_free(cc);

                cc = st->ss->container_content(st, NULL);

                for (content = cc; content ; content = content->next) {
                        char *subarray;
                        if (!content->reshape_active)
                                continue;

                        subarray = strchr(content->text_version+1, '/')+1;
                        mdstat = mdstat_by_subdev(subarray, container);
                        if (!mdstat)
                                continue;
                        if (mdstat->active == 0) {
                                pr_err("Skipping inactive array %s.\n",
                                       mdstat->devnm);
                                free_mdstat(mdstat);
                                mdstat = NULL;
                                continue;
                        }
                        break;
                }
                if (!content)
                        break;

                devid = devnm2devid(mdstat->devnm);
                adev = map_dev(major(devid), minor(devid), 0);
                if (!adev)
                        adev = content->text_version;

                fd = open_dev(mdstat->devnm);
                if (fd < 0) {
                        pr_err("Device %s cannot be opened for reshape.\n",
                               adev);
                        break;
                }

                if (strcmp(last_devnm, mdstat->devnm) == 0) {
                        /* Do not allow for multiple reshape_array() calls for
                         * the same array.
                         * It can happen when reshape_array() returns without
                         * error, when reshape is not finished (wrong reshape
                         * starting/continuation conditions).  Mdmon doesn't
                         * switch to next array in container and reentry
                         * conditions for the same array occur.
                         * This is possibly interim until the behaviour of
                         * reshape_array is resolved().
                         */
                        printf("%s: Multiple reshape execution detected for device  %s.\n", Name, adev);
                        close(fd);
                        break;
                }
                strcpy(last_devnm, mdstat->devnm);

                if (sysfs_init(content, fd, mdstat->devnm)) {
                        pr_err("Unable to initialize sysfs for %s\n",
                               mdstat->devnm);
                        rv = 1;
                        break;
                }

                if (mdmon_running(container))
                        flush_mdmon(container);

                rv = reshape_array(container, fd, adev, st,
                                   content, force, NULL, INVALID_SECTORS,
                                   backup_file, verbose, 1, restart,
                                   freeze_reshape);
                close(fd);

                if (freeze_reshape) {
                        sysfs_free(cc);
                        exit(0);
                }

                restart = 0;
                if (rv)
                        break;

                if (mdmon_running(container))
                        flush_mdmon(container);
        }
        if (!rv)
                unfreeze(st);
        sysfs_free(cc);
        exit(0);
}

/*
 * We run a child process in the background which performs the following
 * steps:
 *   - wait for resync to reach a certain point
 *   - suspend io to the following section
 *   - backup that section
 *   - allow resync to proceed further
 *   - resume io
 *   - discard the backup.
 *
 * When are combined in slightly different ways in the three cases.
 * Grow:
 *   - suspend/backup/allow/wait/resume/discard
 * Shrink:
 *   - allow/wait/suspend/backup/allow/wait/resume/discard
 * same-size:
 *   - wait/resume/discard/suspend/backup/allow
 *
 * suspend/backup/allow always come together
 * wait/resume/discard do too.
 * For the same-size case we have two backups to improve flow.
 *
 */

int progress_reshape(struct mdinfo *info, struct reshape *reshape,
                     unsigned long long backup_point,
                     unsigned long long wait_point,
                     unsigned long long *suspend_point,
                     unsigned long long *reshape_completed, int *frozen)
{
        /* This function is called repeatedly by the reshape manager.
         * It determines how much progress can safely be made and allows
         * that progress.
         * - 'info' identifies the array and particularly records in
         *    ->reshape_progress the metadata's knowledge of progress
         *      This is a sector offset from the start of the array
         *      of the next array block to be relocated.  This number
         *      may increase from 0 or decrease from array_size, depending
         *      on the type of reshape that is happening.
         *    Note that in contrast, 'sync_completed' is a block count of the
         *    reshape so far.  It gives the distance between the start point
         *    (head or tail of device) and the next place that data will be
         *    written.  It always increases.
         * - 'reshape' is the structure created by analyse_change
         * - 'backup_point' shows how much the metadata manager has backed-up
         *   data.  For reshapes with increasing progress, it is the next address
         *   to be backed up, previous addresses have been backed-up.  For
         *   decreasing progress, it is the earliest address that has been
         *   backed up - later address are also backed up.
         *   So addresses between reshape_progress and backup_point are
         *   backed up providing those are in the 'correct' order.
         * - 'wait_point' is an array address.  When reshape_completed
         *   passes this point, progress_reshape should return.  It might
         *   return earlier if it determines that ->reshape_progress needs
         *   to be updated or further backup is needed.
         * - suspend_point is maintained by progress_reshape and the caller
         *   should not touch it except to initialise to zero.
         *   It is an array address and it only increases in 2.6.37 and earlier.
         *   This makes it difficult to handle reducing reshapes with
         *   external metadata.
         *   However:  it is similar to backup_point in that it records the
         *     other end of a suspended region from  reshape_progress.
         *     it is moved to extend the region that is safe to backup and/or
         *     reshape
         * - reshape_completed is read from sysfs and returned.  The caller
         *   should copy this into ->reshape_progress when it has reason to
         *   believe that the metadata knows this, and any backup outside this
         *   has been erased.
         *
         * Return value is:
         *   1 if more data from backup_point - but only as far as suspend_point,
         *     should be backed up
         *   0 if things are progressing smoothly
         *  -1 if the reshape is finished because it is all done,
         *  -2 if the reshape is finished due to an error.
         */

        int advancing = (reshape->after.data_disks
                         >= reshape->before.data_disks);
        unsigned long long need_backup; /* All data between start of array and
                                         * here will at some point need to
                                         * be backed up.
                                         */
        unsigned long long read_offset, write_offset;
        unsigned long long write_range;
        unsigned long long max_progress, target, completed;
        unsigned long long array_size = (info->component_size
                                         * reshape->before.data_disks);
        int fd;
        char buf[20];

        /* First, we unsuspend any region that is now known to be safe.
         * If suspend_point is on the 'wrong' side of reshape_progress, then
         * we don't have or need suspension at the moment.  This is true for
         * native metadata when we don't need to back-up.
         */
        if (advancing) {
                if (info->reshape_progress <= *suspend_point)
                        sysfs_set_num(info, NULL, "suspend_lo",
                                      info->reshape_progress);
        } else {
                /* Note: this won't work in 2.6.37 and before.
                 * Something somewhere should make sure we don't need it!
                 */
                if (info->reshape_progress >= *suspend_point)
                        sysfs_set_num(info, NULL, "suspend_hi",
                                      info->reshape_progress);
        }

        /* Now work out how far it is safe to progress.
         * If the read_offset for ->reshape_progress is less than
         * 'blocks' beyond the write_offset, we can only progress as far
         * as a backup.
         * Otherwise we can progress until the write_offset for the new location
         * reaches (within 'blocks' of) the read_offset at the current location.
         * However that region must be suspended unless we are using native
         * metadata.
         * If we need to suspend more, we limit it to 128M per device, which is
         * rather arbitrary and should be some time-based calculation.
         */
        read_offset = info->reshape_progress / reshape->before.data_disks;
        write_offset = info->reshape_progress / reshape->after.data_disks;
        write_range = info->new_chunk/512;
        if (reshape->before.data_disks == reshape->after.data_disks)
                need_backup = array_size;
        else
                need_backup = reshape->backup_blocks;
        if (advancing) {
                if (read_offset < write_offset + write_range)
                        max_progress = backup_point;
                else
                        max_progress =
                                read_offset * reshape->after.data_disks;
        } else {
                if (read_offset > write_offset - write_range)
                        /* Can only progress as far as has been backed up,
                         * which must be suspended */
                        max_progress = backup_point;
                else if (info->reshape_progress <= need_backup)
                        max_progress = backup_point;
                else {
                        if (info->array.major_version >= 0)
                                /* Can progress until backup is needed */
                                max_progress = need_backup;
                        else {
                                /* Can progress until metadata update is required */
                                max_progress =
                                        read_offset * reshape->after.data_disks;
                                /* but data must be suspended */
                                if (max_progress < *suspend_point)
                                        max_progress = *suspend_point;
                        }
                }
        }

        /* We know it is safe to progress to 'max_progress' providing
         * it is suspended or we are using native metadata.
         * Consider extending suspend_point 128M per device if it
         * is less than 64M per device beyond reshape_progress.
         * But always do a multiple of 'blocks'
         * FIXME this is too big - it takes to long to complete
         * this much.
         */
        target = 64*1024*2 * min(reshape->before.data_disks,
                                 reshape->after.data_disks);
        target /= reshape->backup_blocks;
        if (target < 2)
                target = 2;
        target *= reshape->backup_blocks;

        /* For externally managed metadata we always need to suspend IO to
         * the area being reshaped so we regularly push suspend_point forward.
         * For native metadata we only need the suspend if we are going to do
         * a backup.
         */
        if (advancing) {
                if ((need_backup > info->reshape_progress ||
                     info->array.major_version < 0) &&
                    *suspend_point < info->reshape_progress + target) {
                        if (need_backup < *suspend_point + 2 * target)
                                *suspend_point = need_backup;
                        else if (*suspend_point + 2 * target < array_size)
                                *suspend_point += 2 * target;
                        else
                                *suspend_point = array_size;
                        sysfs_set_num(info, NULL, "suspend_hi", *suspend_point);
                        if (max_progress > *suspend_point)
                                max_progress = *suspend_point;
                }
        } else {
                if (info->array.major_version >= 0) {
                        /* Only need to suspend when about to backup */
                        if (info->reshape_progress < need_backup * 2 &&
                            *suspend_point > 0) {
                                *suspend_point = 0;
                                sysfs_set_num(info, NULL, "suspend_lo", 0);
                                sysfs_set_num(info, NULL, "suspend_hi",
                                              need_backup);
                        }
                } else {
                        /* Need to suspend continually */
                        if (info->reshape_progress < *suspend_point)
                                *suspend_point = info->reshape_progress;
                        if (*suspend_point + target < info->reshape_progress)
                                /* No need to move suspend region yet */;
                        else {
                                if (*suspend_point >= 2 * target)
                                        *suspend_point -= 2 * target;
                                else
                                        *suspend_point = 0;
                                sysfs_set_num(info, NULL, "suspend_lo",
                                              *suspend_point);
                        }
                        if (max_progress < *suspend_point)
                                max_progress = *suspend_point;
                }
        }

        /* now set sync_max to allow that progress. sync_max, like
         * sync_completed is a count of sectors written per device, so
         * we find the difference between max_progress and the start point,
         * and divide that by after.data_disks to get a sync_max
         * number.
         * At the same time we convert wait_point to a similar number
         * for comparing against sync_completed.
         */
        /* scale down max_progress to per_disk */
        max_progress /= reshape->after.data_disks;
        /*
         * Round to chunk size as some kernels give an erroneously
         * high number
         */
        max_progress /= info->new_chunk/512;
        max_progress *= info->new_chunk/512;
        /* And round to old chunk size as the kernel wants that */
        max_progress /= info->array.chunk_size/512;
        max_progress *= info->array.chunk_size/512;
        /* Limit progress to the whole device */
        if (max_progress > info->component_size)
                max_progress = info->component_size;
        wait_point /= reshape->after.data_disks;
        if (!advancing) {
                /* switch from 'device offset' to 'processed block count' */
                max_progress = info->component_size - max_progress;
                wait_point = info->component_size - wait_point;
        }

        if (!*frozen)
                sysfs_set_num(info, NULL, "sync_max", max_progress);

        /* Now wait.  If we have already reached the point that we were
         * asked to wait to, don't wait at all, else wait for any change.
         * We need to select on 'sync_completed' as that is the place that
         * notifications happen, but we are really interested in
         * 'reshape_position'
         */
        fd = sysfs_get_fd(info, NULL, "sync_completed");
        if (fd < 0)
                goto check_progress;

        if (sysfs_fd_get_ll(fd, &completed) < 0)
                goto check_progress;

        while (completed < max_progress && completed < wait_point) {
                /* Check that sync_action is still 'reshape' to avoid
                 * waiting forever on a dead array
                 */
                char action[20];
                if (sysfs_get_str(info, NULL, "sync_action", action, 20) <= 0 ||
                    strncmp(action, "reshape", 7) != 0)
                        break;
                /* Some kernels reset 'sync_completed' to zero
                 * before setting 'sync_action' to 'idle'.
                 * So we need these extra tests.
                 */
                if (completed == 0 && advancing &&
                    strncmp(action, "idle", 4) == 0 &&
                    info->reshape_progress > 0)
                        break;
                if (completed == 0 && !advancing &&
                    strncmp(action, "idle", 4) == 0 &&
                    info->reshape_progress <
                    (info->component_size * reshape->after.data_disks))
                        break;
                sysfs_wait(fd, NULL);
                if (sysfs_fd_get_ll(fd, &completed) < 0)
                        goto check_progress;
        }
        /* Some kernels reset 'sync_completed' to zero,
         * we need to have real point we are in md.
         * So in that case, read 'reshape_position' from sysfs.
         */
        if (completed == 0) {
                unsigned long long reshapep;
                char action[20];
                if (sysfs_get_str(info, NULL, "sync_action", action, 20) > 0 &&
                    strncmp(action, "idle", 4) == 0 &&
                    sysfs_get_ll(info, NULL,
                                 "reshape_position", &reshapep) == 0)
                        *reshape_completed = reshapep;
        } else {
                /* some kernels can give an incorrectly high
                 * 'completed' number, so round down */
                completed /= (info->new_chunk/512);
                completed *= (info->new_chunk/512);
                /* Convert 'completed' back in to a 'progress' number */
                completed *= reshape->after.data_disks;
                if (!advancing)
                        completed = (info->component_size
                                     * reshape->after.data_disks
                                     - completed);
                *reshape_completed = completed;
        }

        close(fd);

        /* We return the need_backup flag.  Caller will decide
         * how much - a multiple of ->backup_blocks up to *suspend_point
         */
        if (advancing)
                return need_backup > info->reshape_progress;
        else
                return need_backup >= info->reshape_progress;

check_progress:
        /* if we couldn't read a number from sync_completed, then
         * either the reshape did complete, or it aborted.
         * We can tell which by checking for 'none' in reshape_position.
         * If it did abort, then it might immediately restart if it
         * it was just a device failure that leaves us degraded but
         * functioning.
         */
        if (sysfs_get_str(info, NULL, "reshape_position", buf,
                          sizeof(buf)) < 0 || strncmp(buf, "none", 4) != 0) {
                /* The abort might only be temporary.  Wait up to 10
                 * seconds for fd to contain a valid number again.
                 */
                int wait = 10000;
                int rv = -2;
                unsigned long long new_sync_max;
                while (fd >= 0 && rv < 0 && wait > 0) {
                        if (sysfs_wait(fd, &wait) != 1)
                                break;
                        switch (sysfs_fd_get_ll(fd, &completed)) {
                        case 0:
                                /* all good again */
                                rv = 1;
                                /* If "sync_max" is no longer max_progress
                                 * we need to freeze things
                                 */
                                sysfs_get_ll(info, NULL, "sync_max",
                                             &new_sync_max);
                                *frozen = (new_sync_max != max_progress);
                                break;
                        case -2: /* read error - abort */
                                wait = 0;
                                break;
                        }
                }
                if (fd >= 0)
                        close(fd);
                return rv; /* abort */
        } else {
                /* Maybe racing with array shutdown - check state */
                if (fd >= 0)
                        close(fd);
                if (sysfs_get_str(info, NULL, "array_state", buf,
                                  sizeof(buf)) < 0 ||
                    strncmp(buf, "inactive", 8) == 0 ||
                    strncmp(buf, "clear",5) == 0)
                        return -2; /* abort */
                return -1; /* complete */
        }
}

/* FIXME return status is never checked */
static int grow_backup(struct mdinfo *sra,
                unsigned long long offset, /* per device */
                unsigned long stripes, /* per device, in old chunks */
                int *sources, unsigned long long *offsets,
                int disks, int chunk, int level, int layout,
                int dests, int *destfd, unsigned long long *destoffsets,
                int part, int *degraded,
                char *buf)
{
        /* Backup 'blocks' sectors at 'offset' on each device of the array,
         * to storage 'destfd' (offset 'destoffsets'), after first
         * suspending IO.  Then allow resync to continue
         * over the suspended section.
         * Use part 'part' of the backup-super-block.
         */
        int odata = disks;
        int rv = 0;
        int i;
        unsigned long long ll;
        int new_degraded;
        //printf("offset %llu\n", offset);
        if (level >= 4)
                odata--;
        if (level == 6)
                odata--;

        /* Check that array hasn't become degraded, else we might backup the wrong data */
        if (sysfs_get_ll(sra, NULL, "degraded", &ll) < 0)
                return -1; /* FIXME this error is ignored */
        new_degraded = (int)ll;
        if (new_degraded != *degraded) {
                /* check each device to ensure it is still working */
                struct mdinfo *sd;
                for (sd = sra->devs ; sd ; sd = sd->next) {
                        if (sd->disk.state & (1<<MD_DISK_FAULTY))
                                continue;
                        if (sd->disk.state & (1<<MD_DISK_SYNC)) {
                                char sbuf[100];

                                if (sysfs_get_str(sra, sd, "state",
                                                  sbuf, sizeof(sbuf)) < 0 ||
                                    strstr(sbuf, "faulty") ||
                                    strstr(sbuf, "in_sync") == NULL) {
                                        /* this device is dead */
                                        sd->disk.state = (1<<MD_DISK_FAULTY);
                                        if (sd->disk.raid_disk >= 0 &&
                                            sources[sd->disk.raid_disk] >= 0) {
                                                close(sources[sd->disk.raid_disk]);
                                                sources[sd->disk.raid_disk] = -1;
                                        }
                                }
                        }
                }
                *degraded = new_degraded;
        }
        if (part) {
                bsb.arraystart2 = __cpu_to_le64(offset * odata);
                bsb.length2 = __cpu_to_le64(stripes * (chunk/512) * odata);
        } else {
                bsb.arraystart = __cpu_to_le64(offset * odata);
                bsb.length = __cpu_to_le64(stripes * (chunk/512) * odata);
        }
        if (part)
                bsb.magic[15] = '2';
        for (i = 0; i < dests; i++)
                if (part)
                        lseek64(destfd[i], destoffsets[i] +
                                __le64_to_cpu(bsb.devstart2)*512, 0);
                else
                        lseek64(destfd[i], destoffsets[i], 0);

        rv = save_stripes(sources, offsets, disks, chunk, level, layout,
                          dests, destfd, offset * 512 * odata,
                          stripes * chunk * odata, buf);

        if (rv)
                return rv;
        bsb.mtime = __cpu_to_le64(time(0));
        for (i = 0; i < dests; i++) {
                bsb.devstart = __cpu_to_le64(destoffsets[i]/512);

                bsb.sb_csum = bsb_csum((char*)&bsb,
                                       ((char*)&bsb.sb_csum)-((char*)&bsb));
                if (memcmp(bsb.magic, "md_backup_data-2", 16) == 0)
                        bsb.sb_csum2 = bsb_csum((char*)&bsb,
                                                ((char*)&bsb.sb_csum2)-((char*)&bsb));

                rv = -1;
                if ((unsigned long long)lseek64(destfd[i],
                                                destoffsets[i] - 4096, 0) !=
                    destoffsets[i] - 4096)
                        break;
                if (write(destfd[i], &bsb, 512) != 512)
                        break;
                if (destoffsets[i] > 4096) {
                        if ((unsigned long long)lseek64(destfd[i], destoffsets[i]+stripes*chunk*odata, 0) !=
                            destoffsets[i]+stripes*chunk*odata)
                                break;
                        if (write(destfd[i], &bsb, 512) != 512)
                                break;
                }
                fsync(destfd[i]);
                rv = 0;
        }

        return rv;
}

/* in 2.6.30, the value reported by sync_completed can be
 * less that it should be by one stripe.
 * This only happens when reshape hits sync_max and pauses.
 * So allow wait_backup to either extent sync_max further
 * than strictly necessary, or return before the
 * sync has got quite as far as we would really like.
 * This is what 'blocks2' is for.
 * The various caller give appropriate values so that
 * every works.
 */
/* FIXME return value is often ignored */
static int forget_backup(int dests, int *destfd,
                         unsigned long long *destoffsets,
                         int part)
{
        /*
         * Erase backup 'part' (which is 0 or 1)
         */
        int i;
        int rv;

        if (part) {
                bsb.arraystart2 = __cpu_to_le64(0);
                bsb.length2 = __cpu_to_le64(0);
        } else {
                bsb.arraystart = __cpu_to_le64(0);
                bsb.length = __cpu_to_le64(0);
        }
        bsb.mtime = __cpu_to_le64(time(0));
        rv = 0;
        for (i = 0; i < dests; i++) {
                bsb.devstart = __cpu_to_le64(destoffsets[i]/512);
                bsb.sb_csum = bsb_csum((char*)&bsb,
                                       ((char*)&bsb.sb_csum)-((char*)&bsb));
                if (memcmp(bsb.magic, "md_backup_data-2", 16) == 0)
                        bsb.sb_csum2 = bsb_csum((char*)&bsb,
                                                ((char*)&bsb.sb_csum2)-((char*)&bsb));
                if ((unsigned long long)lseek64(destfd[i], destoffsets[i]-4096, 0) !=
                    destoffsets[i]-4096)
                        rv = -1;
                if (rv == 0 && write(destfd[i], &bsb, 512) != 512)
                        rv = -1;
                fsync(destfd[i]);
        }
        return rv;
}

static void fail(char *msg)
{
        int rv;
        rv = (write(2, msg, strlen(msg)) != (int)strlen(msg));
        rv |= (write(2, "\n", 1) != 1);
        exit(rv ? 1 : 2);
}

static char *abuf, *bbuf;
static unsigned long long abuflen;
static void validate(int afd, int bfd, unsigned long long offset)
{
        /* check that the data in the backup against the array.
         * This is only used for regression testing and should not
         * be used while the array is active
         */
        if (afd < 0)
                return;
        lseek64(bfd, offset - 4096, 0);
        if (read(bfd, &bsb2, 512) != 512)
                fail("cannot read bsb");
        if (bsb2.sb_csum != bsb_csum((char*)&bsb2,
                                     ((char*)&bsb2.sb_csum)-((char*)&bsb2)))
                fail("first csum bad");
        if (memcmp(bsb2.magic, "md_backup_data", 14) != 0)
                fail("magic is bad");
        if (memcmp(bsb2.magic, "md_backup_data-2", 16) == 0 &&
            bsb2.sb_csum2 != bsb_csum((char*)&bsb2,
                                      ((char*)&bsb2.sb_csum2)-((char*)&bsb2)))
                fail("second csum bad");

        if (__le64_to_cpu(bsb2.devstart)*512 != offset)
                fail("devstart is wrong");

        if (bsb2.length) {
                unsigned long long len = __le64_to_cpu(bsb2.length)*512;

                if (abuflen < len) {
                        free(abuf);
                        free(bbuf);
                        abuflen = len;
                        if (posix_memalign((void**)&abuf, 4096, abuflen) ||
                            posix_memalign((void**)&bbuf, 4096, abuflen)) {
                                abuflen = 0;
                                /* just stop validating on mem-alloc failure */
                                return;
                        }
                }

                lseek64(bfd, offset, 0);
                if ((unsigned long long)read(bfd, bbuf, len) != len) {
                        //printf("len %llu\n", len);
                        fail("read first backup failed");
                }
                lseek64(afd, __le64_to_cpu(bsb2.arraystart)*512, 0);
                if ((unsigned long long)read(afd, abuf, len) != len)
                        fail("read first from array failed");
                if (memcmp(bbuf, abuf, len) != 0) {
#if 0
                        int i;
                        printf("offset=%llu len=%llu\n",
                               (unsigned long long)__le64_to_cpu(bsb2.arraystart)*512, len);
                        for (i=0; i<len; i++)
                                if (bbuf[i] != abuf[i]) {
                                        printf("first diff byte %d\n", i);
                                        break;
                                }
#endif
                        fail("data1 compare failed");
                }
        }
        if (bsb2.length2) {
                unsigned long long len = __le64_to_cpu(bsb2.length2)*512;

                if (abuflen < len) {
                        free(abuf);
                        free(bbuf);
                        abuflen = len;
                        abuf = xmalloc(abuflen);
                        bbuf = xmalloc(abuflen);
                }

                lseek64(bfd, offset+__le64_to_cpu(bsb2.devstart2)*512, 0);
                if ((unsigned long long)read(bfd, bbuf, len) != len)
                        fail("read second backup failed");
                lseek64(afd, __le64_to_cpu(bsb2.arraystart2)*512, 0);
                if ((unsigned long long)read(afd, abuf, len) != len)
                        fail("read second from array failed");
                if (memcmp(bbuf, abuf, len) != 0)
                        fail("data2 compare failed");
        }
}

int child_monitor(int afd, struct mdinfo *sra, struct reshape *reshape,
                  struct supertype *st, unsigned long blocks,
                  int *fds, unsigned long long *offsets,
                  int dests, int *destfd, unsigned long long *destoffsets)
{
        /* Monitor a reshape where backup is being performed using
         * 'native' mechanism - either to a backup file, or
         * to some space in a spare.
         */
        char *buf;
        int degraded = -1;
        unsigned long long speed;
        unsigned long long suspend_point, array_size;
        unsigned long long backup_point, wait_point;
        unsigned long long reshape_completed;
        int done = 0;
        int increasing = reshape->after.data_disks >=
                reshape->before.data_disks;
        int part = 0; /* The next part of the backup area to fill.  It
                       * may already be full, so we need to check */
        int level = reshape->level;
        int layout = reshape->before.layout;
        int data = reshape->before.data_disks;
        int disks = reshape->before.data_disks + reshape->parity;
        int chunk = sra->array.chunk_size;
        struct mdinfo *sd;
        unsigned long stripes;
        int uuid[4];
        int frozen = 0;

        /* set up the backup-super-block.  This requires the
         * uuid from the array.
         */
        /* Find a superblock */
        for (sd = sra->devs; sd; sd = sd->next) {
                char *dn;
                int devfd;
                int ok;
                if (sd->disk.state & (1<<MD_DISK_FAULTY))
                        continue;
                dn = map_dev(sd->disk.major, sd->disk.minor, 1);
                devfd = dev_open(dn, O_RDONLY);
                if (devfd < 0)
                        continue;
                ok = st->ss->load_super(st, devfd, NULL);
                close(devfd);
                if (ok == 0)
                        break;
        }
        if (!sd) {
                pr_err("Cannot find a superblock\n");
                return 0;
        }

        memset(&bsb, 0, 512);
        memcpy(bsb.magic, "md_backup_data-1", 16);
        st->ss->uuid_from_super(st, uuid);
        memcpy(bsb.set_uuid, uuid, 16);
        bsb.mtime = __cpu_to_le64(time(0));
        bsb.devstart2 = blocks;

        stripes = blocks / (sra->array.chunk_size/512) /
                reshape->before.data_disks;

        if (posix_memalign((void**)&buf, 4096, disks * chunk))
                /* Don't start the 'reshape' */
                return 0;
        if (reshape->before.data_disks == reshape->after.data_disks) {
                sysfs_get_ll(sra, NULL, "sync_speed_min", &speed);
                sysfs_set_num(sra, NULL, "sync_speed_min", 200000);
        }

        if (increasing) {
                array_size = sra->component_size * reshape->after.data_disks;
                backup_point = sra->reshape_progress;
                suspend_point = 0;
        } else {
                array_size = sra->component_size * reshape->before.data_disks;
                backup_point = reshape->backup_blocks;
                suspend_point = array_size;
        }

        while (!done) {
                int rv;

                /* Want to return as soon the oldest backup slot can
                 * be released as that allows us to start backing up
                 * some more, providing suspend_point has been
                 * advanced, which it should have.
                 */
                if (increasing) {
                        wait_point = array_size;
                        if (part == 0 && __le64_to_cpu(bsb.length) > 0)
                                wait_point = (__le64_to_cpu(bsb.arraystart) +
                                              __le64_to_cpu(bsb.length));
                        if (part == 1 && __le64_to_cpu(bsb.length2) > 0)
                                wait_point = (__le64_to_cpu(bsb.arraystart2) +
                                              __le64_to_cpu(bsb.length2));
                } else {
                        wait_point = 0;
                        if (part == 0 && __le64_to_cpu(bsb.length) > 0)
                                wait_point = __le64_to_cpu(bsb.arraystart);
                        if (part == 1 && __le64_to_cpu(bsb.length2) > 0)
                                wait_point = __le64_to_cpu(bsb.arraystart2);
                }

                reshape_completed = sra->reshape_progress;
                rv = progress_reshape(sra, reshape,
                                      backup_point, wait_point,
                                      &suspend_point, &reshape_completed,
                                      &frozen);
                /* external metadata would need to ping_monitor here */
                sra->reshape_progress = reshape_completed;

                /* Clear any backup region that is before 'here' */
                if (increasing) {
                        if (__le64_to_cpu(bsb.length) > 0 &&
                            reshape_completed >= (__le64_to_cpu(bsb.arraystart) +
                                                  __le64_to_cpu(bsb.length)))
                                forget_backup(dests, destfd,
                                              destoffsets, 0);
                        if (__le64_to_cpu(bsb.length2) > 0 &&
                            reshape_completed >= (__le64_to_cpu(bsb.arraystart2) +
                                                  __le64_to_cpu(bsb.length2)))
                                forget_backup(dests, destfd,
                                              destoffsets, 1);
                } else {
                        if (__le64_to_cpu(bsb.length) > 0 &&
                            reshape_completed <= (__le64_to_cpu(bsb.arraystart)))
                                forget_backup(dests, destfd,
                                              destoffsets, 0);
                        if (__le64_to_cpu(bsb.length2) > 0 &&
                            reshape_completed <= (__le64_to_cpu(bsb.arraystart2)))
                                forget_backup(dests, destfd,
                                              destoffsets, 1);
                }
                if (sigterm)
                        rv = -2;
                if (rv < 0) {
                        if (rv == -1)
                                done = 1;
                        break;
                }
                if (rv == 0 && increasing && !st->ss->external) {
                        /* No longer need to monitor this reshape */
                        sysfs_set_str(sra, NULL, "sync_max", "max");
                        done = 1;
                        break;
                }

                while (rv) {
                        unsigned long long offset;
                        unsigned long actual_stripes;
                        /* Need to backup some data.
                         * If 'part' is not used and the desired
                         * backup size is suspended, do a backup,
                         * then consider the next part.
                         */
                        /* Check that 'part' is unused */
                        if (part == 0 && __le64_to_cpu(bsb.length) != 0)
                                break;
                        if (part == 1 && __le64_to_cpu(bsb.length2) != 0)
                                break;

                        offset = backup_point / data;
                        actual_stripes = stripes;
                        if (increasing) {
                                if (offset + actual_stripes * (chunk/512) >
                                    sra->component_size)
                                        actual_stripes = ((sra->component_size - offset)
                                                          / (chunk/512));
                                if (offset + actual_stripes * (chunk/512) >
                                    suspend_point/data)
                                        break;
                        } else {
                                if (offset < actual_stripes * (chunk/512))
                                        actual_stripes = offset / (chunk/512);
                                offset -= actual_stripes * (chunk/512);
                                if (offset < suspend_point/data)
                                        break;
                        }
                        if (actual_stripes == 0)
                                break;
                        grow_backup(sra, offset, actual_stripes, fds, offsets,
                                    disks, chunk, level, layout, dests, destfd,
                                    destoffsets, part, &degraded, buf);
                        validate(afd, destfd[0], destoffsets[0]);
                        /* record where 'part' is up to */
                        part = !part;
                        if (increasing)
                                backup_point += actual_stripes * (chunk/512) * data;
                        else
                                backup_point -= actual_stripes * (chunk/512) * data;
                }
        }

        /* FIXME maybe call progress_reshape one more time instead */
        /* remove any remaining suspension */
        sysfs_set_num(sra, NULL, "suspend_lo", 0x7FFFFFFFFFFFFFFFULL);
        sysfs_set_num(sra, NULL, "suspend_hi", 0);
        sysfs_set_num(sra, NULL, "suspend_lo", 0);
        sysfs_set_num(sra, NULL, "sync_min", 0);

        if (reshape->before.data_disks == reshape->after.data_disks)
                sysfs_set_num(sra, NULL, "sync_speed_min", speed);
        free(buf);
        return done;
}

/*
 * If any spare contains md_back_data-1 which is recent wrt mtime,
 * write that data into the array and update the super blocks with
 * the new reshape_progress
 */
int Grow_restart(struct supertype *st, struct mdinfo *info, int *fdlist,
                 int cnt, char *backup_file, int verbose)
{
        int i, j;
        int old_disks;
        unsigned long long *offsets;
        unsigned long long  nstripe, ostripe;
        int ndata, odata;

        odata = info->array.raid_disks - info->delta_disks - 1;
        if (info->array.level == 6)
                odata--; /* number of data disks */
        ndata = info->array.raid_disks - 1;
        if (info->new_level == 6)
                ndata--;

        old_disks = info->array.raid_disks - info->delta_disks;

        if (info->delta_disks <= 0)
                /* Didn't grow, so the backup file must have
                 * been used
                 */
                old_disks = cnt;
        for (i=old_disks-(backup_file?1:0); i<cnt; i++) {
                struct mdinfo dinfo;
                int fd;
                int bsbsize;
                char *devname, namebuf[20];
                unsigned long long lo, hi;

                /* This was a spare and may have some saved data on it.
                 * Load the superblock, find and load the
                 * backup_super_block.
                 * If either fail, go on to next device.
                 * If the backup contains no new info, just return
                 * else restore data and update all superblocks
                 */
                if (i == old_disks-1) {
                        fd = open(backup_file, O_RDONLY);
                        if (fd<0) {
                                pr_err("backup file %s inaccessible: %s\n",
                                        backup_file, strerror(errno));
                                continue;
                        }
                        devname = backup_file;
                } else {
                        fd = fdlist[i];
                        if (fd < 0)
                                continue;
                        if (st->ss->load_super(st, fd, NULL))
                                continue;

                        st->ss->getinfo_super(st, &dinfo, NULL);
                        st->ss->free_super(st);

                        if (lseek64(fd,
                                    (dinfo.data_offset + dinfo.component_size - 8) <<9,
                                    0) < 0) {
                                pr_err("Cannot seek on device %d\n", i);
                                continue; /* Cannot seek */
                        }
                        sprintf(namebuf, "device-%d", i);
                        devname = namebuf;
                }
                if (read(fd, &bsb, sizeof(bsb)) != sizeof(bsb)) {
                        if (verbose)
                                pr_err("Cannot read from %s\n", devname);
                        continue; /* Cannot read */
                }
                if (memcmp(bsb.magic, "md_backup_data-1", 16) != 0 &&
                    memcmp(bsb.magic, "md_backup_data-2", 16) != 0) {
                        if (verbose)
                                pr_err("No backup metadata on %s\n", devname);
                        continue;
                }
                if (bsb.sb_csum != bsb_csum((char*)&bsb, ((char*)&bsb.sb_csum)-((char*)&bsb))) {
                        if (verbose)
                                pr_err("Bad backup-metadata checksum on %s\n",
                                       devname);
                        continue; /* bad checksum */
                }
                if (memcmp(bsb.magic, "md_backup_data-2", 16) == 0 &&
                    bsb.sb_csum2 != bsb_csum((char*)&bsb, ((char*)&bsb.sb_csum2)-((char*)&bsb))) {
                        if (verbose)
                                pr_err("Bad backup-metadata checksum2 on %s\n",
                                       devname);
                        continue; /* Bad second checksum */
                }
                if (memcmp(bsb.set_uuid,info->uuid, 16) != 0) {
                        if (verbose)
                                pr_err("Wrong uuid on backup-metadata on %s\n",
                                       devname);
                        continue; /* Wrong uuid */
                }

                /*
                 * array utime and backup-mtime should be updated at
                 * much the same time, but it seems that sometimes
                 * they aren't... So allow considerable flexability in
                 * matching, and allow this test to be overridden by
                 * an environment variable.
                 */
                if(time_after(info->array.utime, (unsigned int)__le64_to_cpu(bsb.mtime) + 2*60*60) ||
                   time_before(info->array.utime, (unsigned int)__le64_to_cpu(bsb.mtime) - 10*60)) {
                        if (check_env("MDADM_GROW_ALLOW_OLD")) {
                                pr_err("accepting backup with timestamp %lu for array with timestamp %lu\n",
                                        (unsigned long)__le64_to_cpu(bsb.mtime),
                                        (unsigned long)info->array.utime);
                        } else {
                                pr_err("too-old timestamp on backup-metadata on %s\n", devname);
                                pr_err("If you think it is should be safe, try 'export MDADM_GROW_ALLOW_OLD=1'\n");
                                continue; /* time stamp is too bad */
                        }
                }

                if (bsb.magic[15] == '1') {
                        if (bsb.length == 0)
                                continue;
                        if (info->delta_disks >= 0) {
                                /* reshape_progress is increasing */
                                if (__le64_to_cpu(bsb.arraystart)
                                    + __le64_to_cpu(bsb.length)
                                    < info->reshape_progress) {
                                nonew:
                                        if (verbose)
                                                pr_err("backup-metadata found on %s but is not needed\n", devname);
                                        continue; /* No new data here */
                                }
                        } else {
                                /* reshape_progress is decreasing */
                                if (__le64_to_cpu(bsb.arraystart) >=
                                    info->reshape_progress)
                                        goto nonew; /* No new data here */
                        }
                } else {
                        if (bsb.length == 0 && bsb.length2 == 0)
                                continue;
                        if (info->delta_disks >= 0) {
                                /* reshape_progress is increasing */
                                if ((__le64_to_cpu(bsb.arraystart)
                                     + __le64_to_cpu(bsb.length)
                                     < info->reshape_progress) &&
                                    (__le64_to_cpu(bsb.arraystart2)
                                     + __le64_to_cpu(bsb.length2)
                                     < info->reshape_progress))
                                        goto nonew; /* No new data here */
                        } else {
                                /* reshape_progress is decreasing */
                                if (__le64_to_cpu(bsb.arraystart) >=
                                    info->reshape_progress &&
                                    __le64_to_cpu(bsb.arraystart2) >=
                                    info->reshape_progress)
                                        goto nonew; /* No new data here */
                        }
                }
                if (lseek64(fd, __le64_to_cpu(bsb.devstart)*512, 0)< 0) {
                second_fail:
                        if (verbose)
                                pr_err("Failed to verify secondary backup-metadata block on %s\n",
                                       devname);
                        continue; /* Cannot seek */
                }
                /* There should be a duplicate backup superblock 4k before here */
                if (lseek64(fd, -4096, 1) < 0 ||
                    read(fd, &bsb2, sizeof(bsb2)) != sizeof(bsb2))
                        goto second_fail; /* Cannot find leading superblock */
                if (bsb.magic[15] == '1')
                        bsbsize = offsetof(struct mdp_backup_super, pad1);
                else
                        bsbsize = offsetof(struct mdp_backup_super, pad);
                if (memcmp(&bsb2, &bsb, bsbsize) != 0)
                        goto second_fail; /* Cannot find leading superblock */

                /* Now need the data offsets for all devices. */
                offsets = xmalloc(sizeof(*offsets)*info->array.raid_disks);
                for(j=0; j<info->array.raid_disks; j++) {
                        if (fdlist[j] < 0)
                                continue;
                        if (st->ss->load_super(st, fdlist[j], NULL))
                                /* FIXME should be this be an error */
                                continue;
                        st->ss->getinfo_super(st, &dinfo, NULL);
                        st->ss->free_super(st);
                        offsets[j] = dinfo.data_offset * 512;
                }
                printf("%s: restoring critical section\n", Name);

                if (restore_stripes(fdlist, offsets, info->array.raid_disks,
                                    info->new_chunk, info->new_level,
                                    info->new_layout, fd,
                                    __le64_to_cpu(bsb.devstart)*512,
                                    __le64_to_cpu(bsb.arraystart)*512,
                                    __le64_to_cpu(bsb.length)*512, NULL)) {
                        /* didn't succeed, so giveup */
                        if (verbose)
                                pr_err("Error restoring backup from %s\n",
                                        devname);
                        free(offsets);
                        return 1;
                }

                if (bsb.magic[15] == '2' &&
                    restore_stripes(fdlist, offsets, info->array.raid_disks,
                                    info->new_chunk, info->new_level,
                                    info->new_layout, fd,
                                    __le64_to_cpu(bsb.devstart)*512 +
                                    __le64_to_cpu(bsb.devstart2)*512,
                                    __le64_to_cpu(bsb.arraystart2)*512,
                                    __le64_to_cpu(bsb.length2)*512, NULL)) {
                        /* didn't succeed, so giveup */
                        if (verbose)
                                pr_err("Error restoring second backup from %s\n",
                                        devname);
                        free(offsets);
                        return 1;
                }

                free(offsets);

                /* Ok, so the data is restored. Let's update those superblocks. */

                lo = hi = 0;
                if (bsb.length) {
                        lo = __le64_to_cpu(bsb.arraystart);
                        hi = lo + __le64_to_cpu(bsb.length);
                }
                if (bsb.magic[15] == '2' && bsb.length2) {
                        unsigned long long lo1, hi1;
                        lo1 = __le64_to_cpu(bsb.arraystart2);
                        hi1 = lo1 + __le64_to_cpu(bsb.length2);
                        if (lo == hi) {
                                lo = lo1;
                                hi = hi1;
                        } else if (lo < lo1)
                                hi = hi1;
                        else
                                lo = lo1;
                }
                if (lo < hi && (info->reshape_progress < lo ||
                                info->reshape_progress > hi))
                        /* backup does not affect reshape_progress*/ ;
                else if (info->delta_disks >= 0) {
                        info->reshape_progress = __le64_to_cpu(bsb.arraystart) +
                                __le64_to_cpu(bsb.length);
                        if (bsb.magic[15] == '2') {
                                unsigned long long p2;

                                p2 = __le64_to_cpu(bsb.arraystart2) +
                                        __le64_to_cpu(bsb.length2);
                                if (p2 > info->reshape_progress)
                                        info->reshape_progress = p2;
                        }
                } else {
                        info->reshape_progress = __le64_to_cpu(bsb.arraystart);
                        if (bsb.magic[15] == '2') {
                                unsigned long long p2;

                                p2 = __le64_to_cpu(bsb.arraystart2);
                                if (p2 < info->reshape_progress)
                                        info->reshape_progress = p2;
                        }
                }
                for (j=0; j<info->array.raid_disks; j++) {
                        if (fdlist[j] < 0)
                                continue;
                        if (st->ss->load_super(st, fdlist[j], NULL))
                                continue;
                        st->ss->getinfo_super(st, &dinfo, NULL);
                        dinfo.reshape_progress = info->reshape_progress;
                        st->ss->update_super(st, &dinfo, "_reshape_progress",
                                             NULL,0, 0, NULL);
                        st->ss->store_super(st, fdlist[j]);
                        st->ss->free_super(st);
                }
                return 0;
        }
        /* Didn't find any backup data, try to see if any
         * was needed.
         */
        if (info->delta_disks < 0) {
                /* When shrinking, the critical section is at the end.
                 * So see if we are before the critical section.
                 */
                unsigned long long first_block;
                nstripe = ostripe = 0;
                first_block = 0;
                while (ostripe >= nstripe) {
                        ostripe += info->array.chunk_size / 512;
                        first_block = ostripe * odata;
                        nstripe = first_block / ndata / (info->new_chunk/512) *
                                (info->new_chunk/512);
                }

                if (info->reshape_progress >= first_block)
                        return 0;
        }
        if (info->delta_disks > 0) {
                /* See if we are beyond the critical section. */
                unsigned long long last_block;
                nstripe = ostripe = 0;
                last_block = 0;
                while (nstripe >= ostripe) {
                        nstripe += info->new_chunk / 512;
                        last_block = nstripe * ndata;
                        ostripe = last_block / odata / (info->array.chunk_size/512) *
                                (info->array.chunk_size/512);
                }

                if (info->reshape_progress >= last_block)
                        return 0;
        }
        /* needed to recover critical section! */
        if (verbose)
                pr_err("Failed to find backup of critical section\n");
        return 1;
}

int Grow_continue_command(char *devname, int fd,
                          char *backup_file, int verbose)
{
        int ret_val = 0;
        struct supertype *st = NULL;
        struct mdinfo *content = NULL;
        struct mdinfo array;
        char *subarray = NULL;
        struct mdinfo *cc = NULL;
        struct mdstat_ent *mdstat = NULL;
        int cfd = -1;
        int fd2;

        dprintf("Grow continue from command line called for %s\n", devname);

        st = super_by_fd(fd, &subarray);
        if (!st || !st->ss) {
                pr_err("Unable to determine metadata format for %s\n", devname);
                return 1;
        }
        dprintf("Grow continue is run for ");
        if (st->ss->external == 0) {
                int d;
                int cnt = 5;
                dprintf_cont("native array (%s)\n", devname);
                if (md_get_array_info(fd, &array.array) < 0) {
                        pr_err("%s is not an active md array - aborting\n",
                               devname);
                        ret_val = 1;
                        goto Grow_continue_command_exit;
                }
                content = &array;
                sysfs_init(content, fd, NULL);
                /* Need to load a superblock.
                 * FIXME we should really get what we need from
                 * sysfs
                 */
                do {
                        for (d = 0; d < MAX_DISKS; d++) {
                                mdu_disk_info_t disk;
                                char *dv;
                                int err;
                                disk.number = d;
                                if (md_get_disk_info(fd, &disk) < 0)
                                        continue;
                                if (disk.major == 0 && disk.minor == 0)
                                        continue;
                                if ((disk.state & (1 << MD_DISK_ACTIVE)) == 0)
                                        continue;
                                dv = map_dev(disk.major, disk.minor, 1);
                                if (!dv)
                                        continue;
                                fd2 = dev_open(dv, O_RDONLY);
                                if (fd2 < 0)
                                        continue;
                                err = st->ss->load_super(st, fd2, NULL);
                                close(fd2);
                                if (err)
                                        continue;
                                break;
                        }
                        if (d == MAX_DISKS) {
                                pr_err("Unable to load metadata for %s\n",
                                       devname);
                                ret_val = 1;
                                goto Grow_continue_command_exit;
                        }
                        st->ss->getinfo_super(st, content, NULL);
                        if (!content->reshape_active)
                                sleep(3);
                        else
                                break;
                } while (cnt-- > 0);
        } else {
                char *container;

                if (subarray) {
                        dprintf_cont("subarray (%s)\n", subarray);
                        container = st->container_devnm;
                        cfd = open_dev_excl(st->container_devnm);
                } else {
                        container = st->devnm;
                        close(fd);
                        cfd = open_dev_excl(st->devnm);
                        dprintf_cont("container (%s)\n", container);
                        fd = cfd;
                }
                if (cfd < 0) {
                        pr_err("Unable to open container for %s\n", devname);
                        ret_val = 1;
                        goto Grow_continue_command_exit;
                }

                /* find in container array under reshape
                 */
                ret_val = st->ss->load_container(st, cfd, NULL);
                if (ret_val) {
                        pr_err("Cannot read superblock for %s\n", devname);
                        ret_val = 1;
                        goto Grow_continue_command_exit;
                }

                cc = st->ss->container_content(st, subarray);
                for (content = cc; content ; content = content->next) {
                        char *array_name;
                        int allow_reshape = 1;

                        if (content->reshape_active == 0)
                                continue;
                        /* The decision about array or container wide
                         * reshape is taken in Grow_continue based
                         * content->reshape_active state, therefore we
                         * need to check_reshape based on
                         * reshape_active and subarray name
                         */
                        if (content->array.state & (1<<MD_SB_BLOCK_VOLUME))
                                allow_reshape = 0;
                        if (content->reshape_active == CONTAINER_RESHAPE &&
                            (content->array.state
                             & (1<<MD_SB_BLOCK_CONTAINER_RESHAPE)))
                                allow_reshape = 0;

                        if (!allow_reshape) {
                                pr_err("cannot continue reshape of an array in container with unsupported metadata: %s(%s)\n",
                                       devname, container);
                                ret_val = 1;
                                goto Grow_continue_command_exit;
                        }

                        array_name = strchr(content->text_version+1, '/')+1;
                        mdstat = mdstat_by_subdev(array_name, container);
                        if (!mdstat)
                                continue;
                        if (mdstat->active == 0) {
                                pr_err("Skipping inactive array %s.\n",
                                       mdstat->devnm);
                                free_mdstat(mdstat);
                                mdstat = NULL;
                                continue;
                        }
                        break;
                }
                if (!content) {
                        pr_err("Unable to determine reshaped array for %s\n", devname);
                        ret_val = 1;
                        goto Grow_continue_command_exit;
                }
                fd2 = open_dev(mdstat->devnm);
                if (fd2 < 0) {
                        pr_err("cannot open (%s)\n", mdstat->devnm);
                        ret_val = 1;
                        goto Grow_continue_command_exit;
                }

                if (sysfs_init(content, fd2, mdstat->devnm)) {
                        pr_err("Unable to initialize sysfs for %s, Grow cannot continue.\n",
                               mdstat->devnm);
                        ret_val = 1;
                        close(fd2);
                        goto Grow_continue_command_exit;
                }

                close(fd2);

                /* start mdmon in case it is not running
                 */
                if (!mdmon_running(container))
                        start_mdmon(container);
                ping_monitor(container);

                if (mdmon_running(container))
                        st->update_tail = &st->updates;
                else {
                        pr_err("No mdmon found. Grow cannot continue.\n");
                        ret_val = 1;
                        goto Grow_continue_command_exit;
                }
        }

        /* verify that array under reshape is started from
         * correct position
         */
        if (verify_reshape_position(content, content->array.level) < 0) {
                ret_val = 1;
                goto Grow_continue_command_exit;
        }

        /* continue reshape
         */
        ret_val = Grow_continue(fd, st, content, backup_file, 1, 0);

Grow_continue_command_exit:
        if (cfd > -1)
                close(cfd);
        st->ss->free_super(st);
        free_mdstat(mdstat);
        sysfs_free(cc);
        free(subarray);

        return ret_val;
}

int Grow_continue(int mdfd, struct supertype *st, struct mdinfo *info,
                  char *backup_file, int forked, int freeze_reshape)
{
        int ret_val = 2;

        if (!info->reshape_active)
                return ret_val;

        if (st->ss->external) {
                int cfd = open_dev(st->container_devnm);

                if (cfd < 0)
                        return 1;

                st->ss->load_container(st, cfd, st->container_devnm);
                close(cfd);
                ret_val = reshape_container(st->container_devnm, NULL, mdfd,
                                            st, info, 0, backup_file, 0,
                                            forked, 1 | info->reshape_active,
                                            freeze_reshape);
        } else
                ret_val = reshape_array(NULL, mdfd, "array", st, info, 1,
                                        NULL, INVALID_SECTORS, backup_file,
                                        0, forked, 1 | info->reshape_active,
                                        freeze_reshape);

        return ret_val;
}

char *make_backup(char *name)
{
        char *base = "backup_file-";
        int len;
        char *fname;

        len = strlen(MAP_DIR) + 1 + strlen(base) + strlen(name)+1;
        fname = xmalloc(len);
        sprintf(fname, "%s/%s%s", MAP_DIR, base, name);
        return fname;
}

char *locate_backup(char *name)
{
        char *fl = make_backup(name);
        struct stat stb;

        if (stat(fl, &stb) == 0 && S_ISREG(stb.st_mode))
                return fl;

        free(fl);
        return NULL;
}