imsm: bad block management (phase1)

[thirdparty/mdadm.git] / super-intel.c

/*
 * mdadm - Intel(R) Matrix Storage Manager Support
 *
 * Copyright (C) 2002-2007 Intel Corporation
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope 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.,
 * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
 */

#include "mdadm.h"
#include "mdmon.h"
#include <values.h>
#include <scsi/sg.h>
#include <ctype.h>

/* MPB == Metadata Parameter Block */
#define MPB_SIGNATURE "Intel Raid ISM Cfg Sig. "
#define MPB_SIG_LEN (strlen(MPB_SIGNATURE))
#define MPB_VERSION_RAID0 "1.0.00"
#define MPB_VERSION_RAID1 "1.1.00"
#define MPB_VERSION_RAID5 "1.2.02"
#define MAX_SIGNATURE_LENGTH  32
#define MAX_RAID_SERIAL_LEN   16
#define MPB_SECTOR_CNT 418
#define IMSM_RESERVED_SECTORS 4096

/* Disk configuration info. */
#define IMSM_MAX_DEVICES 255
struct imsm_disk {
        __u8 serial[MAX_RAID_SERIAL_LEN];/* 0xD8 - 0xE7 ascii serial number */
        __u32 total_blocks;              /* 0xE8 - 0xEB total blocks */
        __u32 scsi_id;                   /* 0xEC - 0xEF scsi ID */
        __u32 status;                    /* 0xF0 - 0xF3 */
#define SPARE_DISK      0x01  /* Spare */
#define CONFIGURED_DISK 0x02  /* Member of some RaidDev */
#define FAILED_DISK     0x04  /* Permanent failure */
#define USABLE_DISK     0x08  /* Fully usable unless FAILED_DISK is set */

#define IMSM_DISK_FILLERS       5
        __u32 filler[IMSM_DISK_FILLERS]; /* 0xF4 - 0x107 MPB_DISK_FILLERS for future expansion */
};

/* RAID map configuration infos. */
struct imsm_map {
        __u32 pba_of_lba0;      /* start address of partition */
        __u32 blocks_per_member;/* blocks per member */
        __u32 num_data_stripes; /* number of data stripes */
        __u16 blocks_per_strip;
        __u8  map_state;        /* Normal, Uninitialized, Degraded, Failed */
#define IMSM_T_STATE_NORMAL 0
#define IMSM_T_STATE_UNINITIALIZED 1
#define IMSM_T_STATE_DEGRADED 2 /* FIXME: is this correct? */
#define IMSM_T_STATE_FAILED 3 /* FIXME: is this correct? */
        __u8  raid_level;
#define IMSM_T_RAID0 0
#define IMSM_T_RAID1 1
#define IMSM_T_RAID5 5          /* since metadata version 1.2.02 ? */
        __u8  num_members;      /* number of member disks */
        __u8  reserved[3];
        __u32 filler[7];        /* expansion area */
        __u32 disk_ord_tbl[1];  /* disk_ord_tbl[num_members],
                                   top byte special */
} __attribute__ ((packed));

struct imsm_vol {
        __u32 reserved[2];
        __u8  migr_state;       /* Normal or Migrating */
        __u8  migr_type;        /* Initializing, Rebuilding, ... */
        __u8  dirty;
        __u8  fill[1];
        __u32 filler[5];
        struct imsm_map map[1];
        /* here comes another one if migr_state */
} __attribute__ ((packed));

struct imsm_dev {
        __u8    volume[MAX_RAID_SERIAL_LEN];
        __u32 size_low;
        __u32 size_high;
        __u32 status;   /* Persistent RaidDev status */
        __u32 reserved_blocks; /* Reserved blocks at beginning of volume */
#define IMSM_DEV_FILLERS 12
        __u32 filler[IMSM_DEV_FILLERS];
        struct imsm_vol vol;
} __attribute__ ((packed));

struct imsm_super {
        __u8 sig[MAX_SIGNATURE_LENGTH]; /* 0x00 - 0x1F */
        __u32 check_sum;                /* 0x20 - 0x23 MPB Checksum */
        __u32 mpb_size;                 /* 0x24 - 0x27 Size of MPB */
        __u32 family_num;               /* 0x28 - 0x2B Checksum from first time this config was written */
        __u32 generation_num;           /* 0x2C - 0x2F Incremented each time this array's MPB is written */
        __u32 error_log_size;           /* 0x30 - 0x33 in bytes */
        __u32 attributes;               /* 0x34 - 0x37 */
        __u8 num_disks;                 /* 0x38 Number of configured disks */
        __u8 num_raid_devs;             /* 0x39 Number of configured volumes */
        __u8 error_log_pos;             /* 0x3A  */
        __u8 fill[1];                   /* 0x3B */
        __u32 cache_size;               /* 0x3c - 0x40 in mb */
        __u32 orig_family_num;          /* 0x40 - 0x43 original family num */
        __u32 pwr_cycle_count;          /* 0x44 - 0x47 simulated power cycle count for array */
        __u32 bbm_log_size;             /* 0x48 - 0x4B - size of bad Block Mgmt Log in bytes */
#define IMSM_FILLERS 35
        __u32 filler[IMSM_FILLERS];     /* 0x4C - 0xD7 RAID_MPB_FILLERS */
        struct imsm_disk disk[1];       /* 0xD8 diskTbl[numDisks] */
        /* here comes imsm_dev[num_raid_devs] */
        /* here comes BBM logs */
} __attribute__ ((packed));

#define BBM_LOG_MAX_ENTRIES 254

struct bbm_log_entry {
        __u64 defective_block_start;
#define UNREADABLE 0xFFFFFFFF
        __u32 spare_block_offset;
        __u16 remapped_marked_count;
        __u16 disk_ordinal;
} __attribute__ ((__packed__));

struct bbm_log {
        __u32 signature; /* 0xABADB10C */
        __u32 entry_count;
        __u32 reserved_spare_block_count; /* 0 */
        __u32 reserved; /* 0xFFFF */
        __u64 first_spare_lba;
        struct bbm_log_entry mapped_block_entries[BBM_LOG_MAX_ENTRIES];
} __attribute__ ((__packed__));


#ifndef MDASSEMBLE
static char *map_state_str[] = { "normal", "uninitialized", "degraded", "failed" };
#endif

static unsigned int sector_count(__u32 bytes)
{
        return ((bytes + (512-1)) & (~(512-1))) / 512;
}

static unsigned int mpb_sectors(struct imsm_super *mpb)
{
        return sector_count(__le32_to_cpu(mpb->mpb_size));
}

/* internal representation of IMSM metadata */
struct intel_super {
        union {
                void *buf; /* O_DIRECT buffer for reading/writing metadata */
                struct imsm_super *anchor; /* immovable parameters */
        };
        size_t len; /* size of the 'buf' allocation */
        int updates_pending; /* count of pending updates for mdmon */
        int creating_imsm; /* flag to indicate container creation */
        int current_vol; /* index of raid device undergoing creation */
        #define IMSM_MAX_DISKS 6
        struct imsm_disk *disk_tbl[IMSM_MAX_DISKS];
        #define IMSM_MAX_RAID_DEVS 2
        struct imsm_dev *dev_tbl[IMSM_MAX_RAID_DEVS];
        struct dl {
                struct dl *next;
                int index;
                __u8 serial[MAX_RAID_SERIAL_LEN];
                int major, minor;
                char *devname;
                int fd;
        } *disks;
    struct bbm_log *bbm_log;
};

struct extent {
        unsigned long long start, size;
};

/* definition of messages passed to imsm_process_update */
enum imsm_update_type {
        update_activate_spare,
        update_create_array,
};

struct imsm_update_activate_spare {
        enum imsm_update_type type;
        int disk_idx;
        int slot;
        int array;
        struct imsm_update_activate_spare *next;
};

struct imsm_update_create_array {
        enum imsm_update_type type;
        struct imsm_dev dev;
        int dev_idx;
};

static int imsm_env_devname_as_serial(void)
{
        char *val = getenv("IMSM_DEVNAME_AS_SERIAL");

        if (val && atoi(val) == 1)
                return 1;

        return 0;
}


static struct supertype *match_metadata_desc_imsm(char *arg)
{
        struct supertype *st;

        if (strcmp(arg, "imsm") != 0 &&
            strcmp(arg, "default") != 0
                )
                return NULL;

        st = malloc(sizeof(*st));
        memset(st, 0, sizeof(*st));
        st->ss = &super_imsm;
        st->max_devs = IMSM_MAX_DEVICES;
        st->minor_version = 0;
        st->sb = NULL;
        return st;
}

static __u8 *get_imsm_version(struct imsm_super *mpb)
{
        return &mpb->sig[MPB_SIG_LEN];
}

/* retrieve a disk directly from the anchor when the anchor is known to be
 * up-to-date, currently only at load time
 */
static struct imsm_disk *__get_imsm_disk(struct imsm_super *mpb, __u8 index)
{
        if (index >= mpb->num_disks)
                return NULL;
        return &mpb->disk[index];
}

static struct imsm_disk *get_imsm_disk(struct intel_super *super, __u8 index)
{
        if (index >= super->anchor->num_disks)
                return NULL;
        return super->disk_tbl[index];
}

/* generate a checksum directly from the anchor when the anchor is known to be
 * up-to-date, currently only at load or write_super after coalescing
 */
static __u32 __gen_imsm_checksum(struct imsm_super *mpb)
{
        __u32 end = mpb->mpb_size / sizeof(end);
        __u32 *p = (__u32 *) mpb;
        __u32 sum = 0;

        while (end--)
                sum += __le32_to_cpu(*p++);

        return sum - __le32_to_cpu(mpb->check_sum);
}

static size_t sizeof_imsm_dev(struct imsm_dev *dev)
{
        size_t size = sizeof(*dev);

        /* each map has disk_ord_tbl[num_members - 1] additional space */
        size += sizeof(__u32) * (dev->vol.map[0].num_members - 1);

        /* migrating means an additional map */
        if (dev->vol.migr_state) {
                size += sizeof(struct imsm_map);
                size += sizeof(__u32) * (dev->vol.map[1].num_members - 1);
        }

        return size;
}

static struct imsm_dev *__get_imsm_dev(struct imsm_super *mpb, __u8 index)
{
        int offset;
        int i;
        void *_mpb = mpb;

        if (index >= mpb->num_raid_devs)
                return NULL;

        /* devices start after all disks */
        offset = ((void *) &mpb->disk[mpb->num_disks]) - _mpb;

        for (i = 0; i <= index; i++)
                if (i == index)
                        return _mpb + offset;
                else
                        offset += sizeof_imsm_dev(_mpb + offset);

        return NULL;
}

static struct imsm_dev *get_imsm_dev(struct intel_super *super, __u8 index)
{
        if (index >= super->anchor->num_raid_devs)
                return NULL;
        return super->dev_tbl[index];
}

static __u32 get_imsm_disk_idx(struct imsm_map *map, int slot)
{
        __u32 *ord_tbl = &map->disk_ord_tbl[slot];

        /* top byte is 'special' */
        return __le32_to_cpu(*ord_tbl & ~(0xff << 24));
}

static int get_imsm_raid_level(struct imsm_map *map)
{
        if (map->raid_level == 1) {
                if (map->num_members == 2)
                        return 1;
                else
                        return 10;
        }

        return map->raid_level;
}

static int cmp_extent(const void *av, const void *bv)
{
        const struct extent *a = av;
        const struct extent *b = bv;
        if (a->start < b->start)
                return -1;
        if (a->start > b->start)
                return 1;
        return 0;
}

static struct extent *get_extents(struct intel_super *super, struct dl *dl)
{
        /* find a list of used extents on the given physical device */
        struct imsm_disk *disk;
        struct extent *rv, *e;
        int i, j;
        int memberships = 0;

        disk = get_imsm_disk(super, dl->index);
        if (!disk)
                return NULL;

        for (i = 0; i < super->anchor->num_raid_devs; i++) {
                struct imsm_dev *dev = get_imsm_dev(super, i);
                struct imsm_map *map = dev->vol.map;

                for (j = 0; j < map->num_members; j++) {
                        __u32 index = get_imsm_disk_idx(map, j);

                        if (index == dl->index)
                                memberships++;
                }
        }
        rv = malloc(sizeof(struct extent) * (memberships + 1));
        if (!rv)
                return NULL;
        e = rv;

        for (i = 0; i < super->anchor->num_raid_devs; i++) {
                struct imsm_dev *dev = get_imsm_dev(super, i);
                struct imsm_map *map = dev->vol.map;

                for (j = 0; j < map->num_members; j++) {
                        __u32 index = get_imsm_disk_idx(map, j);

                        if (index == dl->index) {
                                e->start = __le32_to_cpu(map->pba_of_lba0);
                                e->size = __le32_to_cpu(map->blocks_per_member);
                                e++;
                        }
                }
        }
        qsort(rv, memberships, sizeof(*rv), cmp_extent);

        e->start = __le32_to_cpu(disk->total_blocks) -
                   (MPB_SECTOR_CNT + IMSM_RESERVED_SECTORS);
        e->size = 0;
        return rv;
}

#ifndef MDASSEMBLE
static void print_imsm_dev(struct imsm_dev *dev, int index)
{
        __u64 sz;
        int slot;
        struct imsm_map *map = dev->vol.map;

        printf("\n");
        printf("[%s]:\n", dev->volume);
        printf("     RAID Level : %d\n", get_imsm_raid_level(map));
        printf("        Members : %d\n", map->num_members);
        for (slot = 0; slot < map->num_members; slot++)
                if (index == get_imsm_disk_idx(map, slot))
                        break;
        if (slot < map->num_members)
                printf("      This Slot : %d\n", slot);
        else
                printf("      This Slot : ?\n");
        sz = __le32_to_cpu(dev->size_high);
        sz <<= 32;
        sz += __le32_to_cpu(dev->size_low);
        printf("     Array Size : %llu%s\n", (unsigned long long)sz,
               human_size(sz * 512));
        sz = __le32_to_cpu(map->blocks_per_member);
        printf("   Per Dev Size : %llu%s\n", (unsigned long long)sz,
               human_size(sz * 512));
        printf("  Sector Offset : %u\n",
                __le32_to_cpu(map->pba_of_lba0));
        printf("    Num Stripes : %u\n",
                __le32_to_cpu(map->num_data_stripes));
        printf("     Chunk Size : %u KiB\n",
                __le16_to_cpu(map->blocks_per_strip) / 2);
        printf("       Reserved : %d\n", __le32_to_cpu(dev->reserved_blocks));
        printf("  Migrate State : %s\n", dev->vol.migr_state ? "migrating" : "idle");
        printf("    Dirty State : %s\n", dev->vol.dirty ? "dirty" : "clean");
        printf("      Map State : %s\n", map_state_str[map->map_state]);
}

static void print_imsm_disk(struct imsm_super *mpb, int index)
{
        struct imsm_disk *disk = __get_imsm_disk(mpb, index);
        char str[MAX_RAID_SERIAL_LEN];
        __u32 s;
        __u64 sz;

        if (index < 0)
                return;

        printf("\n");
        snprintf(str, MAX_RAID_SERIAL_LEN, "%s", disk->serial);
        printf("  Disk%02d Serial : %s\n", index, str);
        s = __le32_to_cpu(disk->status);
        printf("          State :%s%s%s%s\n", s&SPARE_DISK ? " spare" : "",
                                              s&CONFIGURED_DISK ? " active" : "",
                                              s&FAILED_DISK ? " failed" : "",
                                              s&USABLE_DISK ? " usable" : "");
        printf("             Id : %08x\n", __le32_to_cpu(disk->scsi_id));
        sz = __le32_to_cpu(disk->total_blocks) -
             (MPB_SECTOR_CNT + IMSM_RESERVED_SECTORS * mpb->num_raid_devs);
        printf("    Usable Size : %llu%s\n", (unsigned long long)sz,
               human_size(sz * 512));
}

static void examine_super_imsm(struct supertype *st, char *homehost)
{
        struct intel_super *super = st->sb;
        struct imsm_super *mpb = super->anchor;
        char str[MAX_SIGNATURE_LENGTH];
        int i;
        __u32 sum;

        snprintf(str, MPB_SIG_LEN, "%s", mpb->sig);
        printf("          Magic : %s\n", str);
        snprintf(str, strlen(MPB_VERSION_RAID0), "%s", get_imsm_version(mpb));
        printf("        Version : %s\n", get_imsm_version(mpb));
        printf("         Family : %08x\n", __le32_to_cpu(mpb->family_num));
        printf("     Generation : %08x\n", __le32_to_cpu(mpb->generation_num));
        sum = __le32_to_cpu(mpb->check_sum);
        printf("       Checksum : %08x %s\n", sum,
                __gen_imsm_checksum(mpb) == sum ? "correct" : "incorrect");
        printf("    MPB Sectors : %d\n", mpb_sectors(mpb));
        printf("          Disks : %d\n", mpb->num_disks);
        printf("   RAID Devices : %d\n", mpb->num_raid_devs);
        print_imsm_disk(mpb, super->disks->index);
        if (super->bbm_log) {
                struct bbm_log *log = super->bbm_log;

                printf("\n");
                printf("Bad Block Management Log:\n");
                printf("       Log Size : %d\n", __le32_to_cpu(mpb->bbm_log_size));
                printf("      Signature : %x\n", __le32_to_cpu(log->signature));
                printf("    Entry Count : %d\n", __le32_to_cpu(log->entry_count));
                printf("   Spare Blocks : %d\n",  __le32_to_cpu(log->reserved_spare_block_count));
                printf("    First Spare : %llx\n", __le64_to_cpu(log->first_spare_lba));
        }
        for (i = 0; i < mpb->num_raid_devs; i++)
                print_imsm_dev(__get_imsm_dev(mpb, i), super->disks->index);
        for (i = 0; i < mpb->num_disks; i++) {
                if (i == super->disks->index)
                        continue;
                print_imsm_disk(mpb, i);
        }
}

static void brief_examine_super_imsm(struct supertype *st)
{
        struct intel_super *super = st->sb;

        printf("ARRAY /dev/imsm family=%08x metadata=external:imsm\n",
                __le32_to_cpu(super->anchor->family_num));
}

static void detail_super_imsm(struct supertype *st, char *homehost)
{
        printf("%s\n", __FUNCTION__);
}

static void brief_detail_super_imsm(struct supertype *st)
{
        printf("%s\n", __FUNCTION__);
}
#endif

static int match_home_imsm(struct supertype *st, char *homehost)
{
        printf("%s\n", __FUNCTION__);

        return 0;
}

static void uuid_from_super_imsm(struct supertype *st, int uuid[4])
{
        printf("%s\n", __FUNCTION__);
}

#if 0
static void
get_imsm_numerical_version(struct imsm_super *mpb, int *m, int *p)
{
        __u8 *v = get_imsm_version(mpb);
        __u8 *end = mpb->sig + MAX_SIGNATURE_LENGTH;
        char major[] = { 0, 0, 0 };
        char minor[] = { 0 ,0, 0 };
        char patch[] = { 0, 0, 0 };
        char *ver_parse[] = { major, minor, patch };
        int i, j;

        i = j = 0;
        while (*v != '\0' && v < end) {
                if (*v != '.' && j < 2)
                        ver_parse[i][j++] = *v;
                else {
                        i++;
                        j = 0;
                }
                v++;
        }

        *m = strtol(minor, NULL, 0);
        *p = strtol(patch, NULL, 0);
}
#endif

static int imsm_level_to_layout(int level)
{
        switch (level) {
        case 0:
        case 1:
                return 0;
        case 5:
        case 6:
                return ALGORITHM_LEFT_ASYMMETRIC;
        case 10:
                return 0x102; //FIXME is this correct?
        }
        return -1;
}

static void getinfo_super_imsm_volume(struct supertype *st, struct mdinfo *info)
{
        struct intel_super *super = st->sb;
        struct imsm_dev *dev = get_imsm_dev(super, super->current_vol);
        struct imsm_map *map = &dev->vol.map[0];

        info->container_member    = super->current_vol;
        info->array.raid_disks    = map->num_members;
        info->array.level         = get_imsm_raid_level(map);
        info->array.layout        = imsm_level_to_layout(info->array.level);
        info->array.md_minor      = -1;
        info->array.ctime         = 0;
        info->array.utime         = 0;
        info->array.chunk_size    = __le16_to_cpu(map->blocks_per_strip * 512);

        info->data_offset         = __le32_to_cpu(map->pba_of_lba0);
        info->component_size      = __le32_to_cpu(map->blocks_per_member);

        info->disk.major = 0;
        info->disk.minor = 0;

        sprintf(info->text_version, "/%s/%d",
                devnum2devname(st->container_dev),
                info->container_member);
}


static void getinfo_super_imsm(struct supertype *st, struct mdinfo *info)
{
        struct intel_super *super = st->sb;
        struct imsm_disk *disk;
        __u32 s;

        if (super->current_vol >= 0) {
                getinfo_super_imsm_volume(st, info);
                return;
        }
        info->array.raid_disks    = super->anchor->num_disks;
        info->array.level         = LEVEL_CONTAINER;
        info->array.layout        = 0;
        info->array.md_minor      = -1;
        info->array.ctime         = 0; /* N/A for imsm */ 
        info->array.utime         = 0;
        info->array.chunk_size    = 0;

        info->disk.major = 0;
        info->disk.minor = 0;
        info->disk.raid_disk = -1;
        info->reshape_active = 0;
        strcpy(info->text_version, "imsm");
        info->disk.number = -1;
        info->disk.state = 0;

        if (super->disks) {
                disk = get_imsm_disk(super, super->disks->index);
                if (!disk) {
                        info->disk.number = -1;
                        info->disk.raid_disk = -1;
                        return;
                }
                info->disk.number = super->disks->index;
                info->disk.raid_disk = super->disks->index;
                info->data_offset = __le32_to_cpu(disk->total_blocks) -
                                    (MPB_SECTOR_CNT + IMSM_RESERVED_SECTORS);
                info->component_size = MPB_SECTOR_CNT + IMSM_RESERVED_SECTORS;
                s = __le32_to_cpu(disk->status);
                info->disk.state  = s & CONFIGURED_DISK ? (1 << MD_DISK_ACTIVE) : 0;
                info->disk.state |= s & FAILED_DISK ? (1 << MD_DISK_FAULTY) : 0;
                info->disk.state |= s & USABLE_DISK ? (1 << MD_DISK_SYNC) : 0;
        }
}

static int update_super_imsm(struct supertype *st, struct mdinfo *info,
                             char *update, char *devname, int verbose,
                             int uuid_set, char *homehost)
{
        /* FIXME */

        /* For 'assemble' and 'force' we need to return non-zero if any
         * change was made.  For others, the return value is ignored.
         * Update options are:
         *  force-one : This device looks a bit old but needs to be included,
         *        update age info appropriately.
         *  assemble: clear any 'faulty' flag to allow this device to
         *              be assembled.
         *  force-array: Array is degraded but being forced, mark it clean
         *         if that will be needed to assemble it.
         *
         *  newdev:  not used ????
         *  grow:  Array has gained a new device - this is currently for
         *              linear only
         *  resync: mark as dirty so a resync will happen.
         *  name:  update the name - preserving the homehost
         *
         * Following are not relevant for this imsm:
         *  sparc2.2 : update from old dodgey metadata
         *  super-minor: change the preferred_minor number
         *  summaries:  update redundant counters.
         *  uuid:  Change the uuid of the array to match watch is given
         *  homehost:  update the recorded homehost
         *  _reshape_progress: record new reshape_progress position.
         */
        int rv = 0;
        //struct intel_super *super = st->sb;
        //struct imsm_super *mpb = super->mpb;

        if (strcmp(update, "grow") == 0) {
        }
        if (strcmp(update, "resync") == 0) {
                /* dev->vol.dirty = 1; */
        }

        /* IMSM has no concept of UUID or homehost */

        return rv;
}

static size_t disks_to_mpb_size(int disks)
{
        size_t size;

        size = sizeof(struct imsm_super);
        size += (disks - 1) * sizeof(struct imsm_disk);
        size += 2 * sizeof(struct imsm_dev);
        /* up to 2 maps per raid device (-2 for imsm_maps in imsm_dev */
        size += (4 - 2) * sizeof(struct imsm_map);
        /* 4 possible disk_ord_tbl's */
        size += 4 * (disks - 1) * sizeof(__u32);

        return size;
}

static __u64 avail_size_imsm(struct supertype *st, __u64 devsize)
{
        if (devsize < (MPB_SECTOR_CNT + IMSM_RESERVED_SECTORS))
                return 0;

        return devsize - (MPB_SECTOR_CNT + IMSM_RESERVED_SECTORS);
}

static int compare_super_imsm(struct supertype *st, struct supertype *tst)
{
        /*
         * return:
         *  0 same, or first was empty, and second was copied
         *  1 second had wrong number
         *  2 wrong uuid
         *  3 wrong other info
         */
        struct intel_super *first = st->sb;
        struct intel_super *sec = tst->sb;

        if (!first) {
                st->sb = tst->sb;
                tst->sb = NULL;
                return 0;
        }

        if (memcmp(first->anchor->sig, sec->anchor->sig, MAX_SIGNATURE_LENGTH) != 0)
                return 3;
        if (first->anchor->family_num != sec->anchor->family_num)
                return 3;
        if (first->anchor->mpb_size != sec->anchor->mpb_size)
                return 3;
        if (first->anchor->check_sum != sec->anchor->check_sum)
                return 3;

        return 0;
}

static void fd2devname(int fd, char *name)
{
        struct stat st;
        char path[256];
        char dname[100];
        char *nm;
        int rv;

        name[0] = '\0';
        if (fstat(fd, &st) != 0)
                return;
        sprintf(path, "/sys/dev/block/%d:%d",
                major(st.st_rdev), minor(st.st_rdev));

        rv = readlink(path, dname, sizeof(dname));
        if (rv <= 0)
                return;
        
        dname[rv] = '\0';
        nm = strrchr(dname, '/');
        nm++;
        snprintf(name, MAX_RAID_SERIAL_LEN, "/dev/%s", nm);
}


extern int scsi_get_serial(int fd, void *buf, size_t buf_len);

static int imsm_read_serial(int fd, char *devname,
                            __u8 serial[MAX_RAID_SERIAL_LEN])
{
        unsigned char scsi_serial[255];
        int rv;
        int rsp_len;
        int i, cnt;

        memset(scsi_serial, 0, sizeof(scsi_serial));

        if (imsm_env_devname_as_serial()) {
                char name[MAX_RAID_SERIAL_LEN];
                
                fd2devname(fd, name);
                strcpy((char *) serial, name);
                return 0;
        }

        rv = scsi_get_serial(fd, scsi_serial, sizeof(scsi_serial));

        if (rv != 0) {
                if (devname)
                        fprintf(stderr,
                                Name ": Failed to retrieve serial for %s\n",
                                devname);
                return rv;
        }

        rsp_len = scsi_serial[3];
        for (i = 0, cnt = 0; i < rsp_len; i++) {
                if (!isspace(scsi_serial[4 + i]))
                        serial[cnt++] = scsi_serial[4 + i];
                if (cnt == MAX_RAID_SERIAL_LEN)
                        break;
        }

        serial[MAX_RAID_SERIAL_LEN - 1] = '\0';

        return 0;
}

static int
load_imsm_disk(int fd, struct intel_super *super, char *devname, int keep_fd)
{
        struct dl *dl;
        struct stat stb;
        struct imsm_disk *disk;
        int rv;
        int i;

        dl = malloc(sizeof(*dl));
        disk = malloc(sizeof(*disk));
        if (!dl || !disk) {
                if (devname)
                        fprintf(stderr,
                                Name ": failed to allocate disk buffer for %s\n",
                                devname);
                if (disk)
                        free(disk);
                if (dl)
                        free(dl);
                return 2;
        }
        memset(dl, 0, sizeof(*dl));
        memset(disk, 0, sizeof(*disk));

        fstat(fd, &stb);
        dl->major = major(stb.st_rdev);
        dl->minor = minor(stb.st_rdev);
        dl->next = super->disks;
        dl->fd = keep_fd ? fd : -1;
        dl->devname = devname ? strdup(devname) : NULL;
        dl->index = -1;
        super->disks = dl;
        rv = imsm_read_serial(fd, devname, dl->serial);

        if (rv != 0)
                return 2;

        /* look up this disk's index */
        for (i = 0; i < super->anchor->num_disks; i++) {
                struct imsm_disk *disk_iter;

                disk_iter = __get_imsm_disk(super->anchor, i);

                if (memcmp(disk_iter->serial, dl->serial,
                           MAX_RAID_SERIAL_LEN) == 0) {
                        *disk = *disk_iter;
                        super->disk_tbl[i] = disk;
                        dl->index = i;
                        break;
                }
        }

        if (i == super->anchor->num_disks) {
                if (devname)
                        fprintf(stderr,
                                Name ": failed to match serial \'%s\' for %s\n",
                                dl->serial, devname);
                free(disk);
                return 0;
        }

        return 0;
}

static void imsm_copy_dev(struct imsm_dev *dest, struct imsm_dev *src)
{
        int i;

        *dest = *src;

        for (i = 0; i < src->vol.map[0].num_members; i++)
                dest->vol.map[0].disk_ord_tbl[i] = src->vol.map[0].disk_ord_tbl[i];

        if (!src->vol.migr_state)
                return;

        dest->vol.map[1] = src->vol.map[1];
        for (i = 0; i < src->vol.map[1].num_members; i++)
                dest->vol.map[1].disk_ord_tbl[i] = src->vol.map[1].disk_ord_tbl[i];
}

static int parse_raid_devices(struct intel_super *super)
{
        int i;
        struct imsm_dev *dev_new;
        size_t len;

        for (i = 0; i < super->anchor->num_raid_devs; i++) {
                struct imsm_dev *dev_iter = __get_imsm_dev(super->anchor, i);

                len = sizeof_imsm_dev(dev_iter);
                dev_new = malloc(len);
                if (!dev_new)
                        return 1;
                imsm_copy_dev(dev_new, dev_iter);
                super->dev_tbl[i] = dev_new;
        }

        return 0;
}

/* retrieve a pointer to the bbm log which starts after all raid devices */
struct bbm_log *__get_imsm_bbm_log(struct imsm_super *mpb)
{
        void *ptr = NULL;

        if (__le32_to_cpu(mpb->bbm_log_size)) {
                ptr = mpb;
                ptr += mpb->mpb_size - __le32_to_cpu(mpb->bbm_log_size);
        } 

        return ptr;
}

static void __free_imsm(struct intel_super *super);

/* load_imsm_mpb - read matrix metadata
 * allocates super->mpb to be freed by free_super
 */
static int load_imsm_mpb(int fd, struct intel_super *super, char *devname)
{
        unsigned long long dsize;
        unsigned long long sectors;
        struct stat;
        struct imsm_super *anchor;
        __u32 check_sum;
        int rc;

        get_dev_size(fd, NULL, &dsize);

        if (lseek64(fd, dsize - (512 * 2), SEEK_SET) < 0) {
                if (devname)
                        fprintf(stderr,
                                Name ": Cannot seek to anchor block on %s: %s\n",
                                devname, strerror(errno));
                return 1;
        }

        if (posix_memalign((void**)&anchor, 512, 512) != 0) {
                if (devname)
                        fprintf(stderr,
                                Name ": Failed to allocate imsm anchor buffer"
                                " on %s\n", devname);
                return 1;
        }
        if (read(fd, anchor, 512) != 512) {
                if (devname)
                        fprintf(stderr,
                                Name ": Cannot read anchor block on %s: %s\n",
                                devname, strerror(errno));
                free(anchor);
                return 1;
        }

        if (strncmp((char *) anchor->sig, MPB_SIGNATURE, MPB_SIG_LEN) != 0) {
                if (devname)
                        fprintf(stderr,
                                Name ": no IMSM anchor on %s\n", devname);
                free(anchor);
                return 2;
        }

        __free_imsm(super);
        super->len = __le32_to_cpu(anchor->mpb_size);
        super->len = ROUND_UP(anchor->mpb_size, 512);
        if (posix_memalign(&super->buf, 512, super->len) != 0) {
                if (devname)
                        fprintf(stderr,
                                Name ": unable to allocate %zu byte mpb buffer\n",
                                super->len);
                free(anchor);
                return 2;
        }
        memcpy(super->buf, anchor, 512);

        sectors = mpb_sectors(anchor) - 1;
        free(anchor);
        if (!sectors) {
                rc = load_imsm_disk(fd, super, devname, 0);
                if (rc == 0)
                        rc = parse_raid_devices(super);
                return rc;
        }

        /* read the extended mpb */
        if (lseek64(fd, dsize - (512 * (2 + sectors)), SEEK_SET) < 0) {
                if (devname)
                        fprintf(stderr,
                                Name ": Cannot seek to extended mpb on %s: %s\n",
                                devname, strerror(errno));
                return 1;
        }

        if (read(fd, super->buf + 512, super->len - 512) != super->len - 512) {
                if (devname)
                        fprintf(stderr,
                                Name ": Cannot read extended mpb on %s: %s\n",
                                devname, strerror(errno));
                return 2;
        }

        check_sum = __gen_imsm_checksum(super->anchor);
        if (check_sum != __le32_to_cpu(super->anchor->check_sum)) {
                if (devname)
                        fprintf(stderr,
                                Name ": IMSM checksum %x != %x on %s\n",
                                check_sum, __le32_to_cpu(super->anchor->check_sum),
                                devname);
                return 2;
        }

        /* FIXME the BBM log is disk specific so we cannot use this global
         * buffer for all disks.  Ok for now since we only look at the global
         * bbm_log_size parameter to gate assembly
         */
        super->bbm_log = __get_imsm_bbm_log(super->anchor);

        rc = load_imsm_disk(fd, super, devname, 0);
        if (rc == 0)
                rc = parse_raid_devices(super);
        return rc;
}

static void free_imsm_disks(struct intel_super *super)
{
        int i;

        while (super->disks) {
                struct dl *d = super->disks;

                super->disks = d->next;
                if (d->fd >= 0)
                        close(d->fd);
                if (d->devname)
                        free(d->devname);
                free(d);
        }
        for (i = 0; i < IMSM_MAX_DISKS; i++)
                if (super->disk_tbl[i]) {
                        free(super->disk_tbl[i]);
                        super->disk_tbl[i] = NULL;
                }
}

/* free all the pieces hanging off of a super pointer */
static void __free_imsm(struct intel_super *super)
{
        int i;

        if (super->buf) {
                free(super->buf);
                super->buf = NULL;
        }
        free_imsm_disks(super);
        for (i = 0; i < IMSM_MAX_RAID_DEVS; i++)
                if (super->dev_tbl[i]) {
                        free(super->dev_tbl[i]);
                        super->dev_tbl[i] = NULL;
                }
}

static void free_imsm(struct intel_super *super)
{
        __free_imsm(super);
        free(super);
}

static void free_super_imsm(struct supertype *st)
{
        struct intel_super *super = st->sb;

        if (!super)
                return;

        free_imsm(super);
        st->sb = NULL;
}

static struct intel_super *alloc_super(int creating_imsm)
{
        struct intel_super *super = malloc(sizeof(*super));

        if (super) {
                memset(super, 0, sizeof(*super));
                super->creating_imsm = creating_imsm;
                super->current_vol = -1;
        }

        return super;
}

#ifndef MDASSEMBLE
static int load_super_imsm_all(struct supertype *st, int fd, void **sbp,
                               char *devname, int keep_fd)
{
        struct mdinfo *sra;
        struct intel_super *super;
        struct mdinfo *sd, *best = NULL;
        __u32 bestgen = 0;
        __u32 gen;
        char nm[20];
        int dfd;
        int rv;

        /* check if this disk is a member of an active array */
        sra = sysfs_read(fd, 0, GET_LEVEL|GET_VERSION|GET_DEVS|GET_STATE);
        if (!sra)
                return 1;

        if (sra->array.major_version != -1 ||
            sra->array.minor_version != -2 ||
            strcmp(sra->text_version, "imsm") != 0)
                return 1;

        super = alloc_super(0);
        if (!super)
                return 1;

        /* find the most up to date disk in this array */
        for (sd = sra->devs; sd; sd = sd->next) {
                sprintf(nm, "%d:%d", sd->disk.major, sd->disk.minor);
                dfd = dev_open(nm, keep_fd ? O_RDWR : O_RDONLY);
                if (!dfd) {
                        free_imsm(super);
                        return 2;
                }
                rv = load_imsm_mpb(dfd, super, NULL);
                if (!keep_fd)
                        close(dfd);
                if (rv == 0) {
                        gen = __le32_to_cpu(super->anchor->generation_num);
                        if (!best || gen > bestgen) {
                                bestgen = gen;
                                best = sd;
                        }
                } else {
                        free_imsm(super);
                        return 2;
                }
        }

        if (!best) {
                free_imsm(super);
                return 1;
        }

        /* load the most up to date anchor */
        sprintf(nm, "%d:%d", best->disk.major, best->disk.minor);
        dfd = dev_open(nm, O_RDONLY);
        if (!dfd) {
                free_imsm(super);
                return 1;
        }
        rv = load_imsm_mpb(dfd, super, NULL);
        close(dfd);
        if (rv != 0) {
                free_imsm(super);
                return 2;
        }

        /* reset the disk list */
        free_imsm_disks(super);

        /* populate disk list */
        for (sd = sra->devs ; sd ; sd = sd->next) {
                sprintf(nm, "%d:%d", sd->disk.major, sd->disk.minor);
                dfd = dev_open(nm, keep_fd? O_RDWR : O_RDONLY);
                if (!dfd) {
                        free_imsm(super);
                        return 2;
                }
                load_imsm_disk(dfd, super, NULL, keep_fd);
                if (!keep_fd)
                        close(dfd);
        }

        if (st->subarray[0]) {
                if (atoi(st->subarray) <= super->anchor->num_raid_devs)
                        super->current_vol = atoi(st->subarray);
                else
                        return 1;
        }

        *sbp = super;
        if (st->ss == NULL) {
                st->ss = &super_imsm;
                st->minor_version = 0;
                st->max_devs = IMSM_MAX_DEVICES;
                st->container_dev = fd2devnum(fd);
        }

        return 0;
}
#endif

static int load_super_imsm(struct supertype *st, int fd, char *devname)
{
        struct intel_super *super;
        int rv;

#ifndef MDASSEMBLE
        if (load_super_imsm_all(st, fd, &st->sb, devname, 1) == 0)
                return 0;
#endif
        if (st->subarray[0])
                return 1; /* FIXME */

        super = alloc_super(0);
        if (!super) {
                fprintf(stderr,
                        Name ": malloc of %zu failed.\n",
                        sizeof(*super));
                return 1;
        }

        rv = load_imsm_mpb(fd, super, devname);

        if (rv) {
                if (devname)
                        fprintf(stderr,
                                Name ": Failed to load all information "
                                "sections on %s\n", devname);
                free_imsm(super);
                return rv;
        }

        st->sb = super;
        if (st->ss == NULL) {
                st->ss = &super_imsm;
                st->minor_version = 0;
                st->max_devs = IMSM_MAX_DEVICES;
        }

        return 0;
}

static __u16 info_to_blocks_per_strip(mdu_array_info_t *info)
{
        if (info->level == 1)
                return 128;
        return info->chunk_size >> 9;
}

static __u32 info_to_num_data_stripes(mdu_array_info_t *info)
{
        __u32 num_stripes;

        num_stripes = (info->size * 2) / info_to_blocks_per_strip(info);
        if (info->level == 1)
                num_stripes /= 2;

        return num_stripes;
}

static __u32 info_to_blocks_per_member(mdu_array_info_t *info)
{
        return (info->size * 2) & ~(info_to_blocks_per_strip(info) - 1);
}

static int init_super_imsm_volume(struct supertype *st, mdu_array_info_t *info,
                                  unsigned long long size, char *name,
                                  char *homehost, int *uuid)
{
        /* We are creating a volume inside a pre-existing container.
         * so st->sb is already set.
         */
        struct intel_super *super = st->sb;
        struct imsm_super *mpb = super->anchor;
        struct imsm_dev *dev;
        struct imsm_vol *vol;
        struct imsm_map *map;
        int idx = mpb->num_raid_devs;
        int i;
        unsigned long long array_blocks;
        __u32 offset = 0;
        size_t size_old, size_new;

        if (mpb->num_raid_devs >= 2) {
                fprintf(stderr, Name": This imsm-container already has the "
                        "maximum of 2 volumes\n");
                return 0;
        }

        /* ensure the mpb is large enough for the new data */
        size_old = __le32_to_cpu(mpb->mpb_size);
        size_new = disks_to_mpb_size(info->nr_disks);
        if (size_new > size_old) {
                void *mpb_new;
                size_t size_round = ROUND_UP(size_new, 512);

                if (posix_memalign(&mpb_new, 512, size_round) != 0) {
                        fprintf(stderr, Name": could not allocate new mpb\n");
                        return 0;
                }
                memcpy(mpb_new, mpb, size_old);
                free(mpb);
                mpb = mpb_new;
                super->anchor = mpb_new;
                mpb->mpb_size = __cpu_to_le32(size_new);
                memset(mpb_new + size_old, 0, size_round - size_old);
        }
        super->current_vol = idx;
        sprintf(st->subarray, "%d", idx);
        dev = malloc(sizeof(*dev) + sizeof(__u32) * (info->raid_disks - 1));
        if (!dev) {
                fprintf(stderr, Name": could not allocate raid device\n");
                return 0;
        }
        strncpy((char *) dev->volume, name, MAX_RAID_SERIAL_LEN);
        array_blocks = calc_array_size(info->level, info->raid_disks,
                                       info->layout, info->chunk_size,
                                       info->size*2);
        dev->size_low = __cpu_to_le32((__u32) array_blocks);
        dev->size_high = __cpu_to_le32((__u32) (array_blocks >> 32));
        dev->status = __cpu_to_le32(0);
        dev->reserved_blocks = __cpu_to_le32(0);
        vol = &dev->vol;
        vol->migr_state = 0;
        vol->migr_type = 0;
        vol->dirty = 0;
        for (i = 0; i < idx; i++) {
                struct imsm_dev *prev = get_imsm_dev(super, i);
                struct imsm_map *pmap = &prev->vol.map[0];

                offset += __le32_to_cpu(pmap->blocks_per_member);
                offset += IMSM_RESERVED_SECTORS;
        }
        map = &vol->map[0];
        map->pba_of_lba0 = __cpu_to_le32(offset);
        map->blocks_per_member = __cpu_to_le32(info_to_blocks_per_member(info));
        map->blocks_per_strip = __cpu_to_le16(info_to_blocks_per_strip(info));
        map->num_data_stripes = __cpu_to_le32(info_to_num_data_stripes(info));
        map->map_state = info->level ? IMSM_T_STATE_UNINITIALIZED :
                                       IMSM_T_STATE_NORMAL;

        if (info->level == 1 && info->raid_disks > 2) {
                fprintf(stderr, Name": imsm does not support more than 2 disks"
                                "in a raid1 volume\n");
                return 0;
        }
        if (info->level == 10)
                map->raid_level = 1;
        else
                map->raid_level = info->level;

        map->num_members = info->raid_disks;
        for (i = 0; i < map->num_members; i++) {
                /* initialized in add_to_super */
                map->disk_ord_tbl[i] = __cpu_to_le32(0);
        }
        mpb->num_raid_devs++;
        super->dev_tbl[super->current_vol] = dev;

        return 1;
}

static int init_super_imsm(struct supertype *st, mdu_array_info_t *info,
                           unsigned long long size, char *name,
                           char *homehost, int *uuid)
{
        /* This is primarily called by Create when creating a new array.
         * We will then get add_to_super called for each component, and then
         * write_init_super called to write it out to each device.
         * For IMSM, Create can create on fresh devices or on a pre-existing
         * array.
         * To create on a pre-existing array a different method will be called.
         * This one is just for fresh drives.
         */
        struct intel_super *super;
        struct imsm_super *mpb;
        size_t mpb_size;

        if (!info) {
                st->sb = NULL;
                return 0;
        }
        if (st->sb)
                return init_super_imsm_volume(st, info, size, name, homehost,
                                              uuid);

        super = alloc_super(1);
        if (!super)
                return 0;
        mpb_size = disks_to_mpb_size(info->nr_disks);
        if (posix_memalign(&super->buf, 512, mpb_size) != 0) {
                free(super);
                return 0;
        }
        mpb = super->buf;
        memset(mpb, 0, mpb_size); 

        memcpy(mpb->sig, MPB_SIGNATURE, strlen(MPB_SIGNATURE));
        memcpy(mpb->sig + strlen(MPB_SIGNATURE), MPB_VERSION_RAID5,
               strlen(MPB_VERSION_RAID5)); 
        mpb->mpb_size = mpb_size;

        st->sb = super;
        return 1;
}

static void add_to_super_imsm_volume(struct supertype *st, mdu_disk_info_t *dk,
                                     int fd, char *devname)
{
        struct intel_super *super = st->sb;
        struct dl *dl;
        struct imsm_dev *dev;
        struct imsm_map *map;
        struct imsm_disk *disk;
        __u32 status;

        dev = get_imsm_dev(super, super->current_vol);
        map = &dev->vol.map[0];

        for (dl = super->disks; dl ; dl = dl->next)
                if (dl->major == dk->major &&
                    dl->minor == dk->minor)
                        break;
        if (!dl || ! (dk->state & (1<<MD_DISK_SYNC)))
                return;

        map->disk_ord_tbl[dk->number] = __cpu_to_le32(dl->index);

        disk = get_imsm_disk(super, dl->index);
        status = CONFIGURED_DISK | USABLE_DISK;
        disk->status = __cpu_to_le32(status);
}

static void add_to_super_imsm(struct supertype *st, mdu_disk_info_t *dk,
                              int fd, char *devname)
{
        struct intel_super *super = st->sb;
        struct imsm_super *mpb = super->anchor;
        struct imsm_disk *disk;
        struct dl *dd;
        unsigned long long size;
        __u32 status, id;
        int rv;
        struct stat stb;

        if (super->current_vol >= 0) {
                add_to_super_imsm_volume(st, dk, fd, devname);
                return;
        }

        fstat(fd, &stb);
        dd = malloc(sizeof(*dd));
        disk = malloc(sizeof(*disk));
        if (!dd || !disk) {
                fprintf(stderr,
                        Name ": malloc failed %s:%d.\n", __func__, __LINE__);
                if (!dd)
                        free(dd);
                if (!disk)
                        free(disk);
                abort();
        }
        memset(dd, 0, sizeof(*dd));
        memset(disk, 0, sizeof(*disk));
        dd->major = major(stb.st_rdev);
        dd->minor = minor(stb.st_rdev);
        dd->index = dk->number;
        dd->devname = devname ? strdup(devname) : NULL;
        dd->next = super->disks;
        dd->fd = fd;
        rv = imsm_read_serial(fd, devname, dd->serial);
        if (rv) {
                fprintf(stderr,
                        Name ": failed to retrieve scsi serial, aborting\n");
                free(dd);
                free(disk);
                abort();
        }

        if (mpb->num_disks <= dk->number)
                mpb->num_disks = dk->number + 1;

        get_dev_size(fd, NULL, &size);
        size /= 512;
        status = USABLE_DISK | SPARE_DISK;
        strcpy((char *) disk->serial, (char *) dd->serial);
        disk->total_blocks = __cpu_to_le32(size);
        disk->status = __cpu_to_le32(status);
        if (sysfs_disk_to_scsi_id(fd, &id) == 0)
                disk->scsi_id = __cpu_to_le32(id);
        else
                disk->scsi_id = __cpu_to_le32(0);
        super->disk_tbl[dd->index] = disk;

        /* update the family number if we are creating a container */
        if (super->creating_imsm) {
                disk = __get_imsm_disk(mpb, dd->index);
                *disk = *super->disk_tbl[dd->index]; /* copy in new disk */
                mpb->family_num = __cpu_to_le32(__gen_imsm_checksum(mpb));
        }
        
        super->disks = dd;
}

static int store_imsm_mpb(int fd, struct intel_super *super);

static int write_super_imsm(struct intel_super *super, int doclose)
{
        struct imsm_super *mpb = super->anchor;
        struct dl *d;
        __u32 generation;
        __u32 sum;
        int i;

        /* 'generation' is incremented everytime the metadata is written */
        generation = __le32_to_cpu(mpb->generation_num);
        generation++;
        mpb->generation_num = __cpu_to_le32(generation);

        for (i = 0; i < mpb->num_disks; i++)
                mpb->disk[i] = *super->disk_tbl[i];
        for (i = 0; i < mpb->num_raid_devs; i++) {
                struct imsm_dev *dev = __get_imsm_dev(mpb, i);

                imsm_copy_dev(dev, super->dev_tbl[i]);
        }

        /* recalculate checksum */
        sum = __gen_imsm_checksum(mpb);
        mpb->check_sum = __cpu_to_le32(sum);

        for (d = super->disks; d ; d = d->next) {
                if (store_imsm_mpb(d->fd, super)) {
                        fprintf(stderr, "%s: failed for device %d:%d %s\n",
                                __func__, d->major, d->minor, strerror(errno));
                        return 0;
                }
                if (doclose) {
                        close(d->fd);
                        d->fd = -1;
                }
        }

        return 1;
}

static int write_init_super_imsm(struct supertype *st)
{
        if (st->update_tail) {
                /* queue the recently created array as a metadata update */
                size_t len;
                struct imsm_update_create_array *u;
                struct intel_super *super = st->sb;
                struct imsm_dev *dev;
                struct dl *d;

                if (super->current_vol < 0 ||
                    !(dev = get_imsm_dev(super, super->current_vol))) {
                        fprintf(stderr, "%s: could not determine sub-array\n",
                                __func__);
                        return 1;
                }


                len = sizeof(*u) - sizeof(*dev) + sizeof_imsm_dev(dev);
                u = malloc(len);
                if (!u) {
                        fprintf(stderr, "%s: failed to allocate update buffer\n",
                                __func__);
                        return 1;
                }

                u->type = update_create_array;
                u->dev_idx = super->current_vol;
                imsm_copy_dev(&u->dev, dev);
                append_metadata_update(st, u, len);

                for (d = super->disks; d ; d = d->next) {
                        close(d->fd);
                        d->fd = -1;
                }

                return 0;
        } else
                return write_super_imsm(st->sb, 1);
}

static int store_zero_imsm(struct supertype *st, int fd)
{
        unsigned long long dsize;
        void *buf;

        get_dev_size(fd, NULL, &dsize);

        /* first block is stored on second to last sector of the disk */
        if (lseek64(fd, dsize - (512 * 2), SEEK_SET) < 0)
                return 1;

        if (posix_memalign(&buf, 512, 512) != 0)
                return 1;

        memset(buf, 0, 512);
        if (write(fd, buf, 512) != 512)
                return 1;
        return 0;
}

static int validate_geometry_imsm_container(struct supertype *st, int level,
                                            int layout, int raiddisks, int chunk,
                                            unsigned long long size, char *dev,
                                            unsigned long long *freesize,
                                            int verbose)
{
        int fd;
        unsigned long long ldsize;

        if (level != LEVEL_CONTAINER)
                return 0;
        if (!dev)
                return 1;

        fd = open(dev, O_RDONLY|O_EXCL, 0);
        if (fd < 0) {
                if (verbose)
                        fprintf(stderr, Name ": imsm: Cannot open %s: %s\n",
                                dev, strerror(errno));
                return 0;
        }
        if (!get_dev_size(fd, dev, &ldsize)) {
                close(fd);
                return 0;
        }
        close(fd);

        *freesize = avail_size_imsm(st, ldsize >> 9);

        return 1;
}

/* validate_geometry_imsm_volume - lifted from validate_geometry_ddf_bvd 
 * FIX ME add ahci details
 */
static int validate_geometry_imsm_volume(struct supertype *st, int level,
                                         int layout, int raiddisks, int chunk,
                                         unsigned long long size, char *dev,
                                         unsigned long long *freesize,
                                         int verbose)
{
        struct stat stb;
        struct intel_super *super = st->sb;
        struct dl *dl;
        unsigned long long pos = 0;
        unsigned long long maxsize;
        struct extent *e;
        int i;

        if (level == LEVEL_CONTAINER)
                return 0;

        if (level == 1 && raiddisks > 2) {
                if (verbose)
                        fprintf(stderr, Name ": imsm does not support more "
                                "than 2 in a raid1 configuration\n");
                return 0;
        }

        /* We must have the container info already read in. */
        if (!super)
                return 0;

        if (!dev) {
                /* General test:  make sure there is space for
                 * 'raiddisks' device extents of size 'size' at a given
                 * offset
                 */
                unsigned long long minsize = size*2 /* convert to blocks */;
                unsigned long long start_offset = ~0ULL;
                int dcnt = 0;
                if (minsize == 0)
                        minsize = MPB_SECTOR_CNT + IMSM_RESERVED_SECTORS;
                for (dl = super->disks; dl ; dl = dl->next) {
                        int found = 0;

                        pos = 0;
                        i = 0;
                        e = get_extents(super, dl);
                        if (!e) continue;
                        do {
                                unsigned long long esize;
                                esize = e[i].start - pos;
                                if (esize >= minsize)
                                        found = 1;
                                if (found && start_offset == ~0ULL) {
                                        start_offset = pos;
                                        break;
                                } else if (found && pos != start_offset) {
                                        found = 0;
                                        break;
                                }
                                pos = e[i].start + e[i].size;
                                i++;
                        } while (e[i-1].size);
                        if (found)
                                dcnt++;
                        free(e);
                }
                if (dcnt < raiddisks) {
                        if (verbose)
                                fprintf(stderr, Name ": imsm: Not enough "
                                        "devices with space for this array "
                                        "(%d < %d)\n",
                                        dcnt, raiddisks);
                        return 0;
                }
                return 1;
        }
        /* This device must be a member of the set */
        if (stat(dev, &stb) < 0)
                return 0;
        if ((S_IFMT & stb.st_mode) != S_IFBLK)
                return 0;
        for (dl = super->disks ; dl ; dl = dl->next) {
                if (dl->major == major(stb.st_rdev) &&
                    dl->minor == minor(stb.st_rdev))
                        break;
        }
        if (!dl) {
                if (verbose)
                        fprintf(stderr, Name ": %s is not in the "
                                "same imsm set\n", dev);
                return 0;
        }
        e = get_extents(super, dl);
        maxsize = 0;
        i = 0;
        if (e) do {
                unsigned long long esize;
                esize = e[i].start - pos;
                if (esize >= maxsize)
                        maxsize = esize;
                pos = e[i].start + e[i].size;
                i++;
        } while (e[i-1].size);
        *freesize = maxsize;

        return 1;
}

int imsm_bbm_log_size(struct imsm_super *mpb)
{
        return __le32_to_cpu(mpb->bbm_log_size);
}

static int validate_geometry_imsm(struct supertype *st, int level, int layout,
                                  int raiddisks, int chunk, unsigned long long size,
                                  char *dev, unsigned long long *freesize,
                                  int verbose)
{
        int fd, cfd;
        struct mdinfo *sra;

        /* if given unused devices create a container 
         * if given given devices in a container create a member volume
         */
        if (level == LEVEL_CONTAINER) {
                /* Must be a fresh device to add to a container */
                return validate_geometry_imsm_container(st, level, layout,
                                                        raiddisks, chunk, size,
                                                        dev, freesize,
                                                        verbose);
        }
        
        if (st->sb) {
                /* creating in a given container */
                return validate_geometry_imsm_volume(st, level, layout,
                                                     raiddisks, chunk, size,
                                                     dev, freesize, verbose);
        }

        /* limit creation to the following levels */
        if (!dev)
                switch (level) {
                case 0:
                case 1:
                case 10:
                case 5:
                        break;
                default:
                        return 1;
                }

        /* This device needs to be a device in an 'imsm' container */
        fd = open(dev, O_RDONLY|O_EXCL, 0);
        if (fd >= 0) {
                if (verbose)
                        fprintf(stderr,
                                Name ": Cannot create this array on device %s\n",
                                dev);
                close(fd);
                return 0;
        }
        if (errno != EBUSY || (fd = open(dev, O_RDONLY, 0)) < 0) {
                if (verbose)
                        fprintf(stderr, Name ": Cannot open %s: %s\n",
                                dev, strerror(errno));
                return 0;
        }
        /* Well, it is in use by someone, maybe an 'imsm' container. */
        cfd = open_container(fd);
        if (cfd < 0) {
                close(fd);
                if (verbose)
                        fprintf(stderr, Name ": Cannot use %s: It is busy\n",
                                dev);
                return 0;
        }
        sra = sysfs_read(cfd, 0, GET_VERSION);
        close(fd);
        if (sra && sra->array.major_version == -1 &&
            strcmp(sra->text_version, "imsm") == 0) {
                /* This is a member of a imsm container.  Load the container
                 * and try to create a volume
                 */
                struct intel_super *super;

                if (load_super_imsm_all(st, cfd, (void **) &super, NULL, 1) == 0) {
                        st->sb = super;
                        st->container_dev = fd2devnum(cfd);
                        close(cfd);
                        return validate_geometry_imsm_volume(st, level, layout,
                                                             raiddisks, chunk,
                                                             size, dev,
                                                             freesize, verbose);
                }
                close(cfd);
        } else /* may belong to another container */
                return 0;

        return 1;
}

static struct mdinfo *container_content_imsm(struct supertype *st)
{
        /* Given a container loaded by load_super_imsm_all,
         * extract information about all the arrays into
         * an mdinfo tree.
         *
         * For each imsm_dev create an mdinfo, fill it in,
         *  then look for matching devices in super->disks
         *  and create appropriate device mdinfo.
         */
        struct intel_super *super = st->sb;
        struct imsm_super *mpb = super->anchor;
        struct mdinfo *rest = NULL;
        int i;

        /* do not assemble arrays that might have bad blocks */
        if (imsm_bbm_log_size(super->anchor)) {
                fprintf(stderr, Name ": BBM log found in metadata. "
                                "Cannot activate array(s).\n");
                return NULL;
        }

        for (i = 0; i < mpb->num_raid_devs; i++) {
                struct imsm_dev *dev = get_imsm_dev(super, i);
                struct imsm_vol *vol = &dev->vol;
                struct imsm_map *map = vol->map;
                struct mdinfo *this;
                int slot;

                this = malloc(sizeof(*this));
                memset(this, 0, sizeof(*this));
                this->next = rest;
                rest = this;

                this->array.level = get_imsm_raid_level(map);
                this->array.raid_disks = map->num_members;
                this->array.layout = imsm_level_to_layout(this->array.level);
                this->array.md_minor = -1;
                this->array.ctime = 0;
                this->array.utime = 0;
                this->array.chunk_size = __le16_to_cpu(map->blocks_per_strip) << 9;
                this->array.state = !vol->dirty;
                this->container_member = i;
                if (map->map_state == IMSM_T_STATE_UNINITIALIZED || dev->vol.dirty)
                        this->resync_start = 0;
                else
                        this->resync_start = ~0ULL;

                strncpy(this->name, (char *) dev->volume, MAX_RAID_SERIAL_LEN);
                this->name[MAX_RAID_SERIAL_LEN] = 0;

                sprintf(this->text_version, "/%s/%d",
                        devnum2devname(st->container_dev),
                        this->container_member);

                memset(this->uuid, 0, sizeof(this->uuid));

                this->component_size = __le32_to_cpu(map->blocks_per_member);

                for (slot = 0 ; slot <  map->num_members; slot++) {
                        struct imsm_disk *disk;
                        struct mdinfo *info_d;
                        struct dl *d;
                        int idx;
                        __u32 s;

                        idx = __le32_to_cpu(map->disk_ord_tbl[slot] & ~(0xff << 24));
                        for (d = super->disks; d ; d = d->next)
                                if (d->index == idx)
                                        break;

                        if (d == NULL)
                                break; /* shouldn't this be continue ?? */

                        info_d = malloc(sizeof(*info_d));
                        if (!info_d)
                                break; /* ditto ?? */
                        memset(info_d, 0, sizeof(*info_d));
                        info_d->next = this->devs;
                        this->devs = info_d;

                        disk = get_imsm_disk(super, idx);
                        s = __le32_to_cpu(disk->status);

                        info_d->disk.number = d->index;
                        info_d->disk.major = d->major;
                        info_d->disk.minor = d->minor;
                        info_d->disk.raid_disk = slot;
                        info_d->disk.state  = s & CONFIGURED_DISK ? (1 << MD_DISK_ACTIVE) : 0;
                        info_d->disk.state |= s & FAILED_DISK ? (1 << MD_DISK_FAULTY) : 0;
                        info_d->disk.state |= s & USABLE_DISK ? (1 << MD_DISK_SYNC) : 0;

                        this->array.working_disks++;

                        info_d->events = __le32_to_cpu(mpb->generation_num);
                        info_d->data_offset = __le32_to_cpu(map->pba_of_lba0);
                        info_d->component_size = __le32_to_cpu(map->blocks_per_member);
                        if (d->devname)
                                strcpy(info_d->name, d->devname);
                }
        }

        return rest;
}


static int imsm_open_new(struct supertype *c, struct active_array *a,
                         char *inst)
{
        struct intel_super *super = c->sb;
        struct imsm_super *mpb = super->anchor;
        
        if (atoi(inst) >= mpb->num_raid_devs) {
                fprintf(stderr, "%s: subarry index %d, out of range\n",
                        __func__, atoi(inst));
                return -ENODEV;
        }

        dprintf("imsm: open_new %s\n", inst);
        a->info.container_member = atoi(inst);
        return 0;
}

static __u8 imsm_check_degraded(struct intel_super *super, int n, int failed)
{
        struct imsm_dev *dev = get_imsm_dev(super, n);
        struct imsm_map *map = dev->vol.map;

        if (!failed)
                return map->map_state;

        switch (get_imsm_raid_level(map)) {
        case 0:
                return IMSM_T_STATE_FAILED;
                break;
        case 1:
                if (failed < map->num_members)
                        return IMSM_T_STATE_DEGRADED;
                else
                        return IMSM_T_STATE_FAILED;
                break;
        case 10:
        {
                /**
                 * check to see if any mirrors have failed,
                 * otherwise we are degraded
                 */
                int device_per_mirror = 2; /* FIXME is this always the case?
                                            * and are they always adjacent?
                                            */
                int failed = 0;
                int i;

                for (i = 0; i < map->num_members; i++) {
                        int idx = get_imsm_disk_idx(map, i);
                        struct imsm_disk *disk = get_imsm_disk(super, idx);

                        if (__le32_to_cpu(disk->status) & FAILED_DISK)
                                failed++;

                        if (failed >= device_per_mirror)
                                return IMSM_T_STATE_FAILED;

                        /* reset 'failed' for next mirror set */
                        if (!((i + 1) % device_per_mirror))
                                failed = 0;
                }

                return IMSM_T_STATE_DEGRADED;
        }
        case 5:
                if (failed < 2)
                        return IMSM_T_STATE_DEGRADED;
                else
                        return IMSM_T_STATE_FAILED;
                break;
        default:
                break;
        }

        return map->map_state;
}

static int imsm_count_failed(struct intel_super *super, struct imsm_map *map)
{
        int i;
        int failed = 0;
        struct imsm_disk *disk;

        for (i = 0; i < map->num_members; i++) {
                int idx = get_imsm_disk_idx(map, i);

                disk = get_imsm_disk(super, idx);
                if (__le32_to_cpu(disk->status) & FAILED_DISK)
                        failed++;
        }

        return failed;
}

static void imsm_set_array_state(struct active_array *a, int consistent)
{
        int inst = a->info.container_member;
        struct intel_super *super = a->container->sb;
        struct imsm_dev *dev = get_imsm_dev(super, inst);
        struct imsm_map *map = &dev->vol.map[0];
        int dirty = !consistent;
        int failed;
        __u8 map_state;

        if (a->resync_start == ~0ULL) {
                failed = imsm_count_failed(super, map);
                map_state = imsm_check_degraded(super, inst, failed);
                /* complete recovery or initial resync */
                if (!failed)
                        map_state = IMSM_T_STATE_NORMAL;
                if (map->map_state != map_state) {
                        dprintf("imsm: map_state %d: %d\n",
                                inst, map_state);
                        map->map_state = map_state;
                        super->updates_pending++;
                }

                /* complete resync */
                if (!dirty && dev->vol.dirty) {
                        dprintf("imsm: mark 'clean'\n");
                        dev->vol.dirty = 0;
                        super->updates_pending++;

                }
        }

        /* mark dirty */
        if (dirty && !dev->vol.dirty) {
                dprintf("imsm: mark 'dirty' (%llu)\n", a->resync_start);
                dev->vol.dirty = 1;
                super->updates_pending++;
        }
}

static void imsm_set_disk(struct active_array *a, int n, int state)
{
        int inst = a->info.container_member;
        struct intel_super *super = a->container->sb;
        struct imsm_dev *dev = get_imsm_dev(super, inst);
        struct imsm_map *map = dev->vol.map;
        struct imsm_disk *disk;
        __u32 status;
        int failed = 0;
        int new_failure = 0;

        if (n > map->num_members)
                fprintf(stderr, "imsm: set_disk %d out of range 0..%d\n",
                        n, map->num_members - 1);

        if (n < 0)
                return;

        dprintf("imsm: set_disk %d:%x\n", n, state);

        disk = get_imsm_disk(super, get_imsm_disk_idx(map, n));

        /* check for new failures */
        status = __le32_to_cpu(disk->status);
        if ((state & DS_FAULTY) && !(status & FAILED_DISK)) {
                status |= FAILED_DISK;
                disk->status = __cpu_to_le32(status);
                new_failure = 1;
                super->updates_pending++;
        }

        /* the number of failures have changed, count up 'failed' to determine
         * degraded / failed status
         */
        if (new_failure && map->map_state != IMSM_T_STATE_FAILED)
                failed = imsm_count_failed(super, map);

        /* determine map_state based on failed or in_sync count */
        if (failed)
                map->map_state = imsm_check_degraded(super, inst, failed);
        else if (map->map_state == IMSM_T_STATE_DEGRADED) {
                struct mdinfo *d;
                int working = 0;

                for (d = a->info.devs ; d ; d = d->next)
                        if (d->curr_state & DS_INSYNC)
                                working++;

                if (working == a->info.array.raid_disks) {
                        map->map_state = IMSM_T_STATE_NORMAL;
                        super->updates_pending++;
                }
        }
}

static int store_imsm_mpb(int fd, struct intel_super *super)
{
        struct imsm_super *mpb = super->anchor;
        __u32 mpb_size = __le32_to_cpu(mpb->mpb_size);
        unsigned long long dsize;
        unsigned long long sectors;

        get_dev_size(fd, NULL, &dsize);

        if (mpb_size > 512) {
                /* -1 to account for anchor */
                sectors = mpb_sectors(mpb) - 1;

                /* write the extended mpb to the sectors preceeding the anchor */
                if (lseek64(fd, dsize - (512 * (2 + sectors)), SEEK_SET) < 0)
                        return 1;

                if (write(fd, super->buf + 512, 512 * sectors) != 512 * sectors)
                        return 1;
        }

        /* first block is stored on second to last sector of the disk */
        if (lseek64(fd, dsize - (512 * 2), SEEK_SET) < 0)
                return 1;

        if (write(fd, super->buf, 512) != 512)
                return 1;

        return 0;
}

static void imsm_sync_metadata(struct supertype *container)
{
        struct intel_super *super = container->sb;

        if (!super->updates_pending)
                return;

        write_super_imsm(super, 0);

        super->updates_pending = 0;
}

static struct mdinfo *imsm_activate_spare(struct active_array *a,
                                          struct metadata_update **updates)
{
        /**
         * Take a device that is marked spare in the metadata and use it to
         * replace a failed/vacant slot in an array.  There may be a case where
         * a device is failed in one array but active in a second.
         * imsm_process_update catches this case and does not clear the SPARE_DISK
         * flag, allowing the second array to start using the device on failure.
         * SPARE_DISK is cleared when all arrays are using a device.
         *
         * FIXME: is this a valid use of SPARE_DISK?
         */

        struct intel_super *super = a->container->sb;
        int inst = a->info.container_member;
        struct imsm_dev *dev = get_imsm_dev(super, inst);
        struct imsm_map *map = dev->vol.map;
        int failed = a->info.array.raid_disks;
        struct mdinfo *rv = NULL;
        struct mdinfo *d;
        struct mdinfo *di;
        struct metadata_update *mu;
        struct dl *dl;
        struct imsm_update_activate_spare *u;
        int num_spares = 0;
        int i;

        for (d = a->info.devs ; d ; d = d->next) {
                if ((d->curr_state & DS_FAULTY) &&
                        d->state_fd >= 0)
                        /* wait for Removal to happen */
                        return NULL;
                if (d->state_fd >= 0)
                        failed--;
        }

        dprintf("imsm: activate spare: inst=%d failed=%d (%d) level=%d\n",
                inst, failed, a->info.array.raid_disks, a->info.array.level);
        if (imsm_check_degraded(super, inst, failed) != IMSM_T_STATE_DEGRADED)
                return NULL;

        /* For each slot, if it is not working, find a spare */
        dl = super->disks;
        for (i = 0; i < a->info.array.raid_disks; i++) {
                for (d = a->info.devs ; d ; d = d->next)
                        if (d->disk.raid_disk == i)
                                break;
                dprintf("found %d: %p %x\n", i, d, d?d->curr_state:0);
                if (d && (d->state_fd >= 0))
                        continue;

                /* OK, this device needs recovery.  Find a spare */
                for ( ; dl ; dl = dl->next) {
                        unsigned long long esize;
                        unsigned long long pos;
                        struct mdinfo *d2;
                        struct extent *ex;
                        struct imsm_disk *disk;
                        int j;
                        int found;
                        __u32 array_start;

                        /* If in this array, skip */
                        for (d2 = a->info.devs ; d2 ; d2 = d2->next)
                                if (d2->disk.major == dl->major &&
                                    d2->disk.minor == dl->minor) {
                                        dprintf("%x:%x already in array\n", dl->major, dl->minor);
                                        break;
                                }
                        if (d2)
                                continue;

                        /* is this unused device marked as a spare? */
                        disk = get_imsm_disk(super, dl->index);
                        if (!(__le32_to_cpu(disk->status) & SPARE_DISK))
                                continue;

                        /* We are allowed to use this device - is there space?
                         * We need a->info.component_size sectors */
                        ex = get_extents(super, dl);
                        if (!ex) {
                                dprintf("cannot get extents\n");
                                continue;
                        }
                        found = 0;
                        j = 0;
                        pos = 0;
                        array_start = __le32_to_cpu(map->pba_of_lba0);

                        do {
                                /* check that we can start at pba_of_lba0 with
                                 * a->info.component_size of space
                                 */
                                esize = ex[j].start - pos;
                                if (array_start >= pos &&
                                    array_start + a->info.component_size < ex[j].start) {
                                        found = 1;
                                        break;
                                }
                                pos = ex[j].start + ex[j].size;
                                j++;
                                    
                        } while (ex[j-1].size);

                        free(ex);
                        if (!found) {
                                dprintf("%x:%x does not have %llu at %d\n",
                                        dl->major, dl->minor,
                                        a->info.component_size,
                                        __le32_to_cpu(map->pba_of_lba0));
                                /* No room */
                                continue;
                        }

                        /* found a usable disk with enough space */
                        di = malloc(sizeof(*di));
                        memset(di, 0, sizeof(*di));
                        di->disk.number = dl->index;
                        di->disk.raid_disk = i;
                        di->disk.major = dl->major;
                        di->disk.minor = dl->minor;
                        di->disk.state = 0;
                        di->data_offset = array_start;
                        di->component_size = a->info.component_size;
                        di->container_member = inst;
                        di->next = rv;
                        rv = di;
                        num_spares++;
                        dprintf("%x:%x to be %d at %llu\n", dl->major, dl->minor,
                                i, pos);

                        break;
                }
        }

        if (!rv)
                /* No spares found */
                return rv;
        /* Now 'rv' has a list of devices to return.
         * Create a metadata_update record to update the
         * disk_ord_tbl for the array
         */
        mu = malloc(sizeof(*mu));
        mu->buf = malloc(sizeof(struct imsm_update_activate_spare) * num_spares);
        mu->space = NULL;
        mu->len = sizeof(struct imsm_update_activate_spare) * num_spares;
        mu->next = *updates;
        u = (struct imsm_update_activate_spare *) mu->buf;

        for (di = rv ; di ; di = di->next) {
                u->type = update_activate_spare;
                u->disk_idx = di->disk.number; 
                u->slot = di->disk.raid_disk;
                u->array = inst;
                u->next = u + 1;
                u++;
        }
        (u-1)->next = NULL;
        *updates = mu;

        return rv;
}

static int weight(unsigned int field)
{
        int weight;

        for (weight = 0; field; weight++)
                field &= field - 1;

        return weight;
}

static int disks_overlap(struct imsm_map *m1, struct imsm_map *m2)
{
        int i;
        int j;
        int idx;

        for (i = 0; i < m1->num_members; i++) {
                idx = get_imsm_disk_idx(m1, i);
                for (j = 0; j < m2->num_members; j++)
                        if (idx == get_imsm_disk_idx(m2, j))
                                return 1;
        }

        return 0;
}

static void imsm_process_update(struct supertype *st,
                                struct metadata_update *update)
{
        /**
         * crack open the metadata_update envelope to find the update record
         * update can be one of:
         *      update_activate_spare - a spare device has replaced a failed
         *      device in an array, update the disk_ord_tbl.  If this disk is
         *      present in all member arrays then also clear the SPARE_DISK
         *      flag
         */
        struct intel_super *super = st->sb;
        struct imsm_super *mpb = super->anchor;
        enum imsm_update_type type = *(enum imsm_update_type *) update->buf;

        switch (type) {
        case update_activate_spare: {
                struct imsm_update_activate_spare *u = (void *) update->buf; 
                struct imsm_dev *dev = get_imsm_dev(super, u->array);
                struct imsm_map *map = &dev->vol.map[0];
                struct active_array *a;
                struct imsm_disk *disk;
                __u32 status;
                struct dl *dl;
                struct mdinfo *d;
                unsigned int members;
                unsigned int found;
                int victim;
                int i;

                for (dl = super->disks; dl; dl = dl->next)
                        if (dl->index == u->disk_idx)
                                break;

                if (!dl) {
                        fprintf(stderr, "error: imsm_activate_spare passed "
                                "an unknown disk_idx: %d\n", u->disk_idx);
                        return;
                }

                super->updates_pending++;

                victim = get_imsm_disk_idx(map, u->slot);
                map->disk_ord_tbl[u->slot] = __cpu_to_le32(u->disk_idx);
                disk = get_imsm_disk(super, u->disk_idx);
                status = __le32_to_cpu(disk->status);
                status |= CONFIGURED_DISK;
                disk->status = __cpu_to_le32(status);

                /* map unique/live arrays using the spare */
                members = 0;
                found = 0;
                for (a = st->arrays; a; a = a->next) {
                        int inst = a->info.container_member;

                        dev = get_imsm_dev(super, inst);
                        map = &dev->vol.map[0];
                        if (map->raid_level > 0)
                                members |= 1 << inst;
                        for (d = a->info.devs; d; d = d->next)
                                if (d->disk.major == dl->major &&
                                    d->disk.minor == dl->minor)
                                        found |= 1 << inst;
                }

                /* until all arrays that can absorb this disk have absorbed
                 * this disk it can still be considered a spare
                 */
                if (weight(found) >= weight(members)) {
                        status = __le32_to_cpu(disk->status);
                        status &= ~SPARE_DISK;
                        disk->status = __cpu_to_le32(status);
                }

                /* count arrays using the victim in the metadata */
                found = 0;
                for (a = st->arrays; a ; a = a->next) {
                        dev = get_imsm_dev(super, a->info.container_member);
                        map = &dev->vol.map[0];
                        for (i = 0; i < map->num_members; i++)
                                if (victim == get_imsm_disk_idx(map, i))
                                        found++;
                }

                /* clear some flags if the victim is no longer being
                 * utilized anywhere
                 */
                disk = get_imsm_disk(super, victim);
                if (!found) {
                        status = __le32_to_cpu(disk->status);
                        status &= ~(CONFIGURED_DISK | USABLE_DISK);
                        disk->status = __cpu_to_le32(status);
                }
                break;
        }
        case update_create_array: {
                /* someone wants to create a new array, we need to be aware of
                 * a few races/collisions:
                 * 1/ 'Create' called by two separate instances of mdadm
                 * 2/ 'Create' versus 'activate_spare': mdadm has chosen
                 *     devices that have since been assimilated via
                 *     activate_spare.
                 * In the event this update can not be carried out mdadm will
                 * (FIX ME) notice that its update did not take hold.
                 */
                struct imsm_update_create_array *u = (void *) update->buf;
                struct imsm_dev *dev;
                struct imsm_map *map, *new_map;
                unsigned long long start, end;
                unsigned long long new_start, new_end;
                int i;
                int overlap = 0;

                /* handle racing creates: first come first serve */
                if (u->dev_idx < mpb->num_raid_devs) {
                        dprintf("%s: subarray %d already defined\n",
                                __func__, u->dev_idx);
                        return;
                }

                /* check update is next in sequence */
                if (u->dev_idx != mpb->num_raid_devs) {
                        dprintf("%s: can not create arrays out of sequence\n",
                                __func__);
                        return;
                }

                new_map = &u->dev.vol.map[0];
                new_start = __le32_to_cpu(new_map->pba_of_lba0);
                new_end = new_start + __le32_to_cpu(new_map->blocks_per_member);

                /* handle activate_spare versus create race:
                 * check to make sure that overlapping arrays do not include
                 * overalpping disks
                 */
                for (i = 0; i < mpb->num_raid_devs; i++) {
                        dev = get_imsm_dev(super, i);
                        map = &dev->vol.map[0];
                        start = __le32_to_cpu(map->pba_of_lba0);
                        end = start + __le32_to_cpu(map->blocks_per_member);
                        if ((new_start >= start && new_start <= end) ||
                            (start >= new_start && start <= new_end))
                                overlap = 1;
                        if (overlap && disks_overlap(map, new_map)) {
                                dprintf("%s: arrays overlap\n", __func__);
                                return;
                        }
                }
                /* check num_members sanity */
                if (new_map->num_members > mpb->num_disks) {
                        dprintf("%s: num_disks out of range\n", __func__);
                        return;
                }

                /* check that prepare update was successful */
                if (!update->space) {
                        dprintf("%s: prepare update failed\n", __func__);
                        return;
                }

                super->updates_pending++;
                dev = update->space;
                update->space = NULL;
                imsm_copy_dev(dev, &u->dev);
                super->dev_tbl[u->dev_idx] = dev;
                mpb->num_raid_devs++;

                /* fix up flags, if arrays overlap then the drives can not be
                 * spares
                 */
                for (i = 0; i < map->num_members; i++) {
                        struct imsm_disk *disk;
                        __u32 status;

                        disk = get_imsm_disk(super, get_imsm_disk_idx(map, i));
                        status = __le32_to_cpu(disk->status);
                        status |= CONFIGURED_DISK;
                        if (overlap)
                                status &= ~SPARE_DISK;
                        disk->status = __cpu_to_le32(status);
                }
                break;
        }
        }
}

static void imsm_prepare_update(struct supertype *st,
                                struct metadata_update *update)
{
        /**
         * Allocate space to hold new disk entries, raid-device entries or a
         * new mpb if necessary.  We currently maintain an mpb large enough to
         * hold 2 subarrays for the given number of disks.  This may not be
         * sufficient when reshaping.
         *
         * FIX ME handle the reshape case.
         *
         * The monitor will be able to safely change super->mpb by arranging
         * for it to be freed in check_update_queue().  I.e. the monitor thread
         * will start using the new pointer and the manager can continue to use
         * the old value until check_update_queue() runs.
         */
        enum imsm_update_type type = *(enum imsm_update_type *) update->buf;

        switch (type) {
        case update_create_array: {
                struct imsm_update_create_array *u = (void *) update->buf;
                size_t len = sizeof_imsm_dev(&u->dev);

                update->space = malloc(len);
                break;
        default:
                break;
        }
        }

        return;
}

struct superswitch super_imsm = {
#ifndef MDASSEMBLE
        .examine_super  = examine_super_imsm,
        .brief_examine_super = brief_examine_super_imsm,
        .detail_super   = detail_super_imsm,
        .brief_detail_super = brief_detail_super_imsm,
        .write_init_super = write_init_super_imsm,
#endif
        .match_home     = match_home_imsm,
        .uuid_from_super= uuid_from_super_imsm,
        .getinfo_super  = getinfo_super_imsm,
        .update_super   = update_super_imsm,

        .avail_size     = avail_size_imsm,

        .compare_super  = compare_super_imsm,

        .load_super     = load_super_imsm,
        .init_super     = init_super_imsm,
        .add_to_super   = add_to_super_imsm,
        .store_super    = store_zero_imsm,
        .free_super     = free_super_imsm,
        .match_metadata_desc = match_metadata_desc_imsm,
        .container_content = container_content_imsm,

        .validate_geometry = validate_geometry_imsm,
        .external       = 1,

/* for mdmon */
        .open_new       = imsm_open_new,
        .load_super     = load_super_imsm,
        .set_array_state= imsm_set_array_state,
        .set_disk       = imsm_set_disk,
        .sync_metadata  = imsm_sync_metadata,
        .activate_spare = imsm_activate_spare,
        .process_update = imsm_process_update,
        .prepare_update = imsm_prepare_update,
};