Subject: Make wait_for and open_dev_excl faster

[thirdparty/mdadm.git] / util.c

/*
 * mdadm - manage Linux "md" devices aka RAID arrays.
 *
 * Copyright (C) 2001-2012 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        "md_p.h"
#include        <sys/socket.h>
#include        <sys/utsname.h>
#include        <sys/wait.h>
#include        <sys/un.h>
#include        <sys/resource.h>
#include        <ctype.h>
#include        <dirent.h>
#include        <signal.h>

/*
 * following taken from linux/blkpg.h because they aren't
 * anywhere else and it isn't safe to #include linux/ * stuff.
 */

#define BLKPG      _IO(0x12,105)

/* The argument structure */
struct blkpg_ioctl_arg {
        int op;
        int flags;
        int datalen;
        void *data;
};

/* The subfunctions (for the op field) */
#define BLKPG_ADD_PARTITION     1
#define BLKPG_DEL_PARTITION     2

/* Sizes of name fields. Unused at present. */
#define BLKPG_DEVNAMELTH        64
#define BLKPG_VOLNAMELTH        64

/* The data structure for ADD_PARTITION and DEL_PARTITION */
struct blkpg_partition {
        long long start;                /* starting offset in bytes */
        long long length;               /* length in bytes */
        int pno;                        /* partition number */
        char devname[BLKPG_DEVNAMELTH]; /* partition name, like sda5 or c0d1p2,
                                           to be used in kernel messages */
        char volname[BLKPG_VOLNAMELTH]; /* volume label */
};

#include "part.h"

/* Force a compilation error if condition is true */
#define BUILD_BUG_ON(condition) ((void)BUILD_BUG_ON_ZERO(condition))

/* Force a compilation error if condition is true, but also produce a
   result (of value 0 and type size_t), so the expression can be used
   e.g. in a structure initializer (or where-ever else comma expressions
   aren't permitted). */
#define BUILD_BUG_ON_ZERO(e) (sizeof(struct { int:-!!(e); }))

/*
 * Parse a 128 bit uuid in 4 integers
 * format is 32 hexx nibbles with options :.<space> separator
 * If not exactly 32 hex digits are found, return 0
 * else return 1
 */
int parse_uuid(char *str, int uuid[4])
{
        int hit = 0; /* number of Hex digIT */
        int i;
        char c;
        for (i = 0; i < 4; i++)
                uuid[i] = 0;

        while ((c = *str++) != 0) {
                int n;
                if (c >= '0' && c <= '9')
                        n = c-'0';
                else if (c >= 'a' && c <= 'f')
                        n = 10 + c - 'a';
                else if (c >= 'A' && c <= 'F')
                        n = 10 + c - 'A';
                else if (strchr(":. -", c))
                        continue;
                else return 0;

                if (hit<32) {
                        uuid[hit/8] <<= 4;
                        uuid[hit/8] += n;
                }
                hit++;
        }
        if (hit == 32)
                return 1;
        return 0;
}

/*
 * Get the md version number.
 * We use the RAID_VERSION ioctl if it is supported
 * If not, but we have a block device with major '9', we assume
 * 0.36.0
 *
 * Return version number as 24 but number - assume version parts
 * always < 255
 */

int md_get_version(int fd)
{
        struct stat stb;
        mdu_version_t vers;

        if (fstat(fd, &stb)<0)
                return -1;
        if ((S_IFMT&stb.st_mode) != S_IFBLK)
                return -1;

        if (ioctl(fd, RAID_VERSION, &vers) == 0)
                return  (vers.major*10000) + (vers.minor*100) + vers.patchlevel;
        if (errno == EACCES)
                return -1;
        if (major(stb.st_rdev) == MD_MAJOR)
                return (3600);
        return -1;
}

int get_linux_version()
{
        struct utsname name;
        char *cp;
        int a = 0, b = 0,c = 0;
        if (uname(&name) <0)
                return -1;

        cp = name.release;
        a = strtoul(cp, &cp, 10);
        if (*cp == '.')
                b = strtoul(cp+1, &cp, 10);
        if (*cp == '.')
                c = strtoul(cp+1, &cp, 10);

        return (a*1000000)+(b*1000)+c;
}

#ifndef MDASSEMBLE
int mdadm_version(char *version)
{
        int a, b, c;
        char *cp;

        if (!version)
                version = Version;

        cp = strchr(version, '-');
        if (!cp || *(cp+1) != ' ' || *(cp+2) != 'v')
                return -1;
        cp += 3;
        a = strtoul(cp, &cp, 10);
        if (*cp != '.')
                return -1;
        b = strtoul(cp+1, &cp, 10);
        if (*cp == '.')
                c = strtoul(cp+1, &cp, 10);
        else
                c = 0;
        if (*cp != ' ' && *cp != '-')
                return -1;
        return (a*1000000)+(b*1000)+c;
}

unsigned long long parse_size(char *size)
{
        /* parse 'size' which should be a number optionally
         * followed by 'K', 'M', or 'G'.
         * Without a suffix, K is assumed.
         * Number returned is in sectors (half-K)
         * INVALID_SECTORS returned on error.
         */
        char *c;
        long long s = strtoll(size, &c, 10);
        if (s > 0) {
                switch (*c) {
                case 'K':
                        c++;
                default:
                        s *= 2;
                        break;
                case 'M':
                        c++;
                        s *= 1024 * 2;
                        break;
                case 'G':
                        c++;
                        s *= 1024 * 1024 * 2;
                        break;
                case 's': /* sectors */
                        c++;
                        break;
                }
        } else
                s = INVALID_SECTORS;
        if (*c)
                s = INVALID_SECTORS;
        return s;
}

int parse_layout_10(char *layout)
{
        int copies, rv;
        char *cp;
        /* Parse the layout string for raid10 */
        /* 'f', 'o' or 'n' followed by a number <= raid_disks */
        if ((layout[0] !=  'n' && layout[0] != 'f' && layout[0] != 'o') ||
            (copies = strtoul(layout+1, &cp, 10)) < 1 ||
            copies > 200 ||
            *cp)
                return -1;
        if (layout[0] == 'n')
                rv = 256 + copies;
        else if (layout[0] == 'o')
                rv = 0x10000 + (copies<<8) + 1;
        else
                rv = 1 + (copies<<8);
        return rv;
}

int parse_layout_faulty(char *layout)
{
        /* Parse the layout string for 'faulty' */
        int ln = strcspn(layout, "0123456789");
        char *m = xstrdup(layout);
        int mode;
        m[ln] = 0;
        mode = map_name(faultylayout, m);
        if (mode == UnSet)
                return -1;

        return mode | (atoi(layout+ln)<< ModeShift);
}

long parse_num(char *num)
{
        /* Either return a valid number, or -1 */
        char *c;
        long rv = strtol(num, &c, 10);
        if (rv < 0 || *c || !num[0])
                return -1;
        else
                return rv;
}
#endif

void remove_partitions(int fd)
{
        /* remove partitions from this block devices.
         * This is used for components added to an array
         */
#ifdef BLKPG_DEL_PARTITION
        struct blkpg_ioctl_arg a;
        struct blkpg_partition p;

        a.op = BLKPG_DEL_PARTITION;
        a.data = (void*)&p;
        a.datalen = sizeof(p);
        a.flags = 0;
        memset(a.data, 0, a.datalen);
        for (p.pno = 0; p.pno < 16; p.pno++)
                ioctl(fd, BLKPG, &a);
#endif
}

int test_partition(int fd)
{
        /* Check if fd is a whole-disk or a partition.
         * BLKPG will return EINVAL on a partition, and BLKPG_DEL_PARTITION
         * will return ENXIO on an invalid partition number.
         */
        struct blkpg_ioctl_arg a;
        struct blkpg_partition p;
        a.op = BLKPG_DEL_PARTITION;
        a.data = (void*)&p;
        a.datalen = sizeof(p);
        a.flags = 0;
        memset(a.data, 0, a.datalen);
        p.pno = 1<<30;
        if (ioctl(fd, BLKPG, &a) == 0)
                /* Very unlikely, but not a partition */
                return 0;
        if (errno == ENXIO)
                /* not a partition */
                return 0;

        return 1;
}

int test_partition_from_id(dev_t id)
{
        char buf[20];
        int fd, rv;

        sprintf(buf, "%d:%d", major(id), minor(id));
        fd = dev_open(buf, O_RDONLY);
        if (fd < 0)
                return -1;
        rv = test_partition(fd);
        close(fd);
        return rv;
}

int enough(int level, int raid_disks, int layout, int clean, char *avail)
{
        int copies, first;
        int i;
        int avail_disks = 0;

        for (i = 0; i < raid_disks; i++)
                avail_disks += !!avail[i];

        switch (level) {
        case 10:
                /* This is the tricky one - we need to check
                 * which actual disks are present.
                 */
                copies = (layout&255)* ((layout>>8) & 255);
                first = 0;
                do {
                        /* there must be one of the 'copies' form 'first' */
                        int n = copies;
                        int cnt = 0;
                        int this = first;
                        while (n--) {
                                if (avail[this])
                                        cnt++;
                                this = (this+1) % raid_disks;
                        }
                        if (cnt == 0)
                                return 0;
                        first = (first+(layout&255)) % raid_disks;
                } while (first != 0);
                return 1;

        case LEVEL_MULTIPATH:
                return avail_disks>= 1;
        case LEVEL_LINEAR:
        case 0:
                return avail_disks == raid_disks;
        case 1:
                return avail_disks >= 1;
        case 4:
        case 5:
                if (clean)
                        return avail_disks >= raid_disks-1;
                else
                        return avail_disks >= raid_disks;
        case 6:
                if (clean)
                        return avail_disks >= raid_disks-2;
                else
                        return avail_disks >= raid_disks;
        default:
                return 0;
        }
}

int enough_fd(int fd)
{
        struct mdu_array_info_s array;
        struct mdu_disk_info_s disk;
        int avail_disks = 0;
        int i, rv;
        char *avail;

        if (ioctl(fd, GET_ARRAY_INFO, &array) != 0 ||
            array.raid_disks <= 0)
                return 0;
        avail = xcalloc(array.raid_disks, 1);
        for (i = 0; i < MAX_DISKS && array.nr_disks > 0; i++) {
                disk.number = i;
                if (ioctl(fd, GET_DISK_INFO, &disk) != 0)
                        continue;
                if (disk.major == 0 && disk.minor == 0)
                        continue;
                array.nr_disks--;

                if (! (disk.state & (1<<MD_DISK_SYNC)))
                        continue;
                if (disk.raid_disk < 0 || disk.raid_disk >= array.raid_disks)
                        continue;
                avail_disks++;
                avail[disk.raid_disk] = 1;
        }
        /* This is used on an active array, so assume it is clean */
        rv = enough(array.level, array.raid_disks, array.layout,
                    1, avail);
        free(avail);
        return rv;
}

const int uuid_zero[4] = { 0, 0, 0, 0 };

int same_uuid(int a[4], int b[4], int swapuuid)
{
        if (swapuuid) {
                /* parse uuids are hostendian.
                 * uuid's from some superblocks are big-ending
                 * if there is a difference, we need to swap..
                 */
                unsigned char *ac = (unsigned char *)a;
                unsigned char *bc = (unsigned char *)b;
                int i;
                for (i = 0; i < 16; i += 4) {
                        if (ac[i+0] != bc[i+3] ||
                            ac[i+1] != bc[i+2] ||
                            ac[i+2] != bc[i+1] ||
                            ac[i+3] != bc[i+0])
                                return 0;
                }
                return 1;
        } else {
                if (a[0]==b[0] &&
                    a[1]==b[1] &&
                    a[2]==b[2] &&
                    a[3]==b[3])
                        return 1;
                return 0;
        }
}

void copy_uuid(void *a, int b[4], int swapuuid)
{
        if (swapuuid) {
                /* parse uuids are hostendian.
                 * uuid's from some superblocks are big-ending
                 * if there is a difference, we need to swap..
                 */
                unsigned char *ac = (unsigned char *)a;
                unsigned char *bc = (unsigned char *)b;
                int i;
                for (i = 0; i < 16; i += 4) {
                        ac[i+0] = bc[i+3];
                        ac[i+1] = bc[i+2];
                        ac[i+2] = bc[i+1];
                        ac[i+3] = bc[i+0];
                }
        } else
                memcpy(a, b, 16);
}

char *__fname_from_uuid(int id[4], int swap, char *buf, char sep)
{
        int i, j;
        char uuid[16];
        char *c = buf;
        strcpy(c, "UUID-");
        c += strlen(c);
        copy_uuid(uuid, id, swap);
        for (i = 0; i < 4; i++) {
                if (i)
                        *c++ = sep;
                for (j = 3; j >= 0; j--) {
                        sprintf(c,"%02x", (unsigned char) uuid[j+4*i]);
                        c+= 2;
                }
        }
        return buf;

}

char *fname_from_uuid(struct supertype *st, struct mdinfo *info, char *buf, char sep)
{
        // dirty hack to work around an issue with super1 superblocks...
        // super1 superblocks need swapuuid set in order for assembly to
        // work, but can't have it set if we want this printout to match
        // all the other uuid printouts in super1.c, so we force swapuuid
        // to 1 to make our printout match the rest of super1
        return __fname_from_uuid(info->uuid, (st->ss == &super1) ? 1 : st->ss->swapuuid, buf, sep);
}

#ifndef MDASSEMBLE
int check_ext2(int fd, char *name)
{
        /*
         * Check for an ext2fs file system.
         * Superblock is always 1K at 1K offset
         *
         * s_magic is le16 at 56 == 0xEF53
         * report mtime - le32 at 44
         * blocks - le32 at 4
         * logblksize - le32 at 24
         */
        unsigned char sb[1024];
        time_t mtime;
        int size, bsize;
        if (lseek(fd, 1024,0)!= 1024)
                return 0;
        if (read(fd, sb, 1024)!= 1024)
                return 0;
        if (sb[56] != 0x53 || sb[57] != 0xef)
                return 0;

        mtime = sb[44]|(sb[45]|(sb[46]|sb[47]<<8)<<8)<<8;
        bsize = sb[24]|(sb[25]|(sb[26]|sb[27]<<8)<<8)<<8;
        size = sb[4]|(sb[5]|(sb[6]|sb[7]<<8)<<8)<<8;
        pr_err("%s appears to contain an ext2fs file system\n",
                name);
        cont_err("size=%dK  mtime=%s",
                size*(1<<bsize), ctime(&mtime));
        return 1;
}

int check_reiser(int fd, char *name)
{
        /*
         * superblock is at 64K
         * size is 1024;
         * Magic string "ReIsErFs" or "ReIsEr2Fs" at 52
         *
         */
        unsigned char sb[1024];
        unsigned long size;
        if (lseek(fd, 64*1024, 0) != 64*1024)
                return 0;
        if (read(fd, sb, 1024) != 1024)
                return 0;
        if (strncmp((char*)sb+52, "ReIsErFs",8) != 0 &&
            strncmp((char*)sb+52, "ReIsEr2Fs",9) != 0)
                return 0;
        pr_err("%s appears to contain a reiserfs file system\n",name);
        size = sb[0]|(sb[1]|(sb[2]|sb[3]<<8)<<8)<<8;
        cont_err("size = %luK\n", size*4);

        return 1;
}

int check_raid(int fd, char *name)
{
        struct mdinfo info;
        time_t crtime;
        char *level;
        struct supertype *st = guess_super(fd);

        if (!st)
                return 0;
        st->ss->load_super(st, fd, name);
        /* Looks like a raid array .. */
        pr_err("%s appears to be part of a raid array:\n",
                name);
        st->ss->getinfo_super(st, &info, NULL);
        st->ss->free_super(st);
        crtime = info.array.ctime;
        level = map_num(pers, info.array.level);
        if (!level) level = "-unknown-";
        cont_err("level=%s devices=%d ctime=%s",
                 level, info.array.raid_disks, ctime(&crtime));
        return 1;
}

int ask(char *mesg)
{
        char *add = "";
        int i;
        for (i = 0; i < 5; i++) {
                char buf[100];
                fprintf(stderr, "%s%s", mesg, add);
                fflush(stderr);
                if (fgets(buf, 100, stdin)==NULL)
                        return 0;
                if (buf[0]=='y' || buf[0]=='Y')
                        return 1;
                if (buf[0]=='n' || buf[0]=='N')
                        return 0;
                add = "(y/n) ";
        }
        pr_err("assuming 'no'\n");
        return 0;
}
#endif /* MDASSEMBLE */

int is_standard(char *dev, int *nump)
{
        /* tests if dev is a "standard" md dev name.
         * i.e if the last component is "/dNN" or "/mdNN",
         * where NN is a string of digits
         * Returns 1 if a partitionable standard,
         *   -1 if non-partitonable,
         *   0 if not a standard name.
         */
        char *d = strrchr(dev, '/');
        int type = 0;
        int num;
        if (!d)
                return 0;
        if (strncmp(d, "/d",2) == 0)
                d += 2, type = 1; /* /dev/md/dN{pM} */
        else if (strncmp(d, "/md_d", 5) == 0)
                d += 5, type = 1; /* /dev/md_dN{pM} */
        else if (strncmp(d, "/md", 3) == 0)
                d += 3, type = -1; /* /dev/mdN */
        else if (d-dev > 3 && strncmp(d-2, "md/", 3) == 0)
                d += 1, type = -1; /* /dev/md/N */
        else
                return 0;
        if (!*d)
                return 0;
        num = atoi(d);
        while (isdigit(*d))
                d++;
        if (*d)
                return 0;
        if (nump) *nump = num;

        return type;
}

unsigned long calc_csum(void *super, int bytes)
{
        unsigned long long newcsum = 0;
        int i;
        unsigned int csum;
        unsigned int *superc = (unsigned int*) super;

        for(i = 0; i < bytes/4; i++)
                newcsum += superc[i];
        csum = (newcsum& 0xffffffff) + (newcsum>>32);
#ifdef __alpha__
/* The in-kernel checksum calculation is always 16bit on
 * the alpha, though it is 32 bit on i386...
 * I wonder what it is elsewhere... (it uses an API in
 * a way that it shouldn't).
 */
        csum = (csum & 0xffff) + (csum >> 16);
        csum = (csum & 0xffff) + (csum >> 16);
#endif
        return csum;
}

#ifndef MDASSEMBLE
char *human_size(long long bytes)
{
        static char buf[30];

        /* We convert bytes to either centi-M{ega,ibi}bytes or
         * centi-G{igi,ibi}bytes, with appropriate rounding,
         * and then print 1/100th of those as a decimal.
         * We allow upto 2048Megabytes before converting to
         * gigabytes, as that shows more precision and isn't
         * too large a number.
         * Terabytes are not yet handled.
         */

        if (bytes < 5000*1024)
                buf[0] = 0;
        else if (bytes < 2*1024LL*1024LL*1024LL) {
                long cMiB = (bytes / ( (1LL<<20) / 200LL ) +1) /2;
                long cMB  = (bytes / ( 1000000LL / 200LL ) +1) /2;
                snprintf(buf, sizeof(buf), " (%ld.%02ld MiB %ld.%02ld MB)",
                        cMiB/100 , cMiB % 100,
                        cMB/100, cMB % 100);
        } else {
                long cGiB = (bytes / ( (1LL<<30) / 200LL ) +1) /2;
                long cGB  = (bytes / (1000000000LL/200LL ) +1) /2;
                snprintf(buf, sizeof(buf), " (%ld.%02ld GiB %ld.%02ld GB)",
                        cGiB/100 , cGiB % 100,
                        cGB/100, cGB % 100);
        }
        return buf;
}

char *human_size_brief(long long bytes, int prefix)
{
        static char buf[30];

        /* We convert bytes to either centi-M{ega,ibi}bytes or
         * centi-G{igi,ibi}bytes, with appropriate rounding,
         * and then print 1/100th of those as a decimal.
         * We allow upto 2048Megabytes before converting to
         * gigabytes, as that shows more precision and isn't
         * too large a number.
         * Terabytes are not yet handled.
         *
         * If prefix == IEC, we mean prefixes like kibi,mebi,gibi etc.
         * If prefix == JEDEC, we mean prefixes like kilo,mega,giga etc.
         */

        if (bytes < 5000*1024)
                buf[0] = 0;
        else if (prefix == IEC) {
                if (bytes < 2*1024LL*1024LL*1024LL) {
                        long cMiB = (bytes / ( (1LL<<20) / 200LL ) +1) /2;
                        snprintf(buf, sizeof(buf), "%ld.%02ldMiB",
                                cMiB/100 , cMiB % 100);
                } else {
                        long cGiB = (bytes / ( (1LL<<30) / 200LL ) +1) /2;
                        snprintf(buf, sizeof(buf), "%ld.%02ldGiB",
                                        cGiB/100 , cGiB % 100);
                }
        }
        else if (prefix == JEDEC) {
                if (bytes < 2*1024LL*1024LL*1024LL) {
                        long cMB  = (bytes / ( 1000000LL / 200LL ) +1) /2;
                        snprintf(buf, sizeof(buf), "%ld.%02ldMB",
                                        cMB/100, cMB % 100);
                } else {
                        long cGB  = (bytes / (1000000000LL/200LL ) +1) /2;
                        snprintf(buf, sizeof(buf), "%ld.%02ldGB",
                                        cGB/100 , cGB % 100);
                }
        }
        else
                buf[0] = 0;

        return buf;
}

void print_r10_layout(int layout)
{
        int near = layout & 255;
        int far = (layout >> 8) & 255;
        int offset = (layout&0x10000);
        char *sep = "";

        if (near != 1) {
                printf("%s near=%d", sep, near);
                sep = ",";
        }
        if (far != 1)
                printf("%s %s=%d", sep, offset?"offset":"far", far);
        if (near*far == 1)
                printf("NO REDUNDANCY");
}
#endif

unsigned long long calc_array_size(int level, int raid_disks, int layout,
                                   int chunksize, unsigned long long devsize)
{
        if (level == 1)
                return devsize;
        devsize &= ~(unsigned long long)((chunksize>>9)-1);
        return get_data_disks(level, layout, raid_disks) * devsize;
}

int get_data_disks(int level, int layout, int raid_disks)
{
        int data_disks = 0;
        switch (level) {
        case 0: data_disks = raid_disks;
                break;
        case 1: data_disks = 1;
                break;
        case 4:
        case 5: data_disks = raid_disks - 1;
                break;
        case 6: data_disks = raid_disks - 2;
                break;
        case 10: data_disks = raid_disks / (layout & 255) / ((layout>>8)&255);
                break;
        }

        return data_disks;
}

int devnm2devid(char *devnm)
{
        /* First look in /sys/block/$DEVNM/dev for %d:%d
         * If that fails, try parsing out a number
         */
        char path[100];
        char *ep;
        int fd;
        int mjr,mnr;

        sprintf(path, "/sys/block/%s/dev", devnm);
        fd = open(path, O_RDONLY);
        if (fd >= 0) {
                char buf[20];
                int n = read(fd, buf, sizeof(buf));
                close(fd);
                if (n > 0)
                        buf[n] = 0;
                if (n > 0 && sscanf(buf, "%d:%d\n", &mjr, &mnr) == 2)
                        return makedev(mjr, mnr);
        }
        if (strncmp(devnm, "md_d", 4) == 0 &&
            isdigit(devnm[4]) &&
            (mnr = strtoul(devnm+4, &ep, 10)) >= 0 &&
            ep > devnm && *ep == 0)
                return makedev(get_mdp_major(), mnr << MdpMinorShift);

        if (strncmp(devnm, "md", 2) == 0 &&
            isdigit(devnm[2]) &&
            (mnr = strtoul(devnm+2, &ep, 10)) >= 0 &&
            ep > devnm && *ep == 0)
                return makedev(MD_MAJOR, mnr);

        return 0;
}

#if !defined(MDASSEMBLE) || defined(MDASSEMBLE) && defined(MDASSEMBLE_AUTO)
char *get_md_name(char *devnm)
{
        /* find /dev/md%d or /dev/md/%d or make a device /dev/.tmp.md%d */
        /* if dev < 0, want /dev/md/d%d or find mdp in /proc/devices ... */

        static char devname[50];
        struct stat stb;
        dev_t rdev = devnm2devid(devnm);
        char *dn;

        if (rdev == 0)
                return 0;
        if (strncmp(devnm, "md_", 3) == 0) {
                snprintf(devname, sizeof(devname), "/dev/md/%s",
                        devnm + 3);
                if (stat(devname, &stb) == 0
                    && (S_IFMT&stb.st_mode) == S_IFBLK
                    && (stb.st_rdev == rdev))
                        return devname;
        }
        snprintf(devname, sizeof(devname), "/dev/%s", devnm);
        if (stat(devname, &stb) == 0
            && (S_IFMT&stb.st_mode) == S_IFBLK
            && (stb.st_rdev == rdev))
                return devname;

        snprintf(devname, sizeof(devname), "/dev/md/%s", devnm+2);
        if (stat(devname, &stb) == 0
            && (S_IFMT&stb.st_mode) == S_IFBLK
            && (stb.st_rdev == rdev))
                return devname;

        dn = map_dev(major(rdev), minor(rdev), 0);
        if (dn)
                return dn;
        snprintf(devname, sizeof(devname), "/dev/.tmp.%s", devnm);
        if (mknod(devname, S_IFBLK | 0600, rdev) == -1)
                if (errno != EEXIST)
                        return NULL;

        if (stat(devname, &stb) == 0
            && (S_IFMT&stb.st_mode) == S_IFBLK
            && (stb.st_rdev == rdev))
                return devname;
        unlink(devname);
        return NULL;
}

void put_md_name(char *name)
{
        if (strncmp(name, "/dev/.tmp.md", 12) == 0)
                unlink(name);
}

char *find_free_devnm(int use_partitions)
{
        static char devnm[32];
        int devnum;
        for (devnum = 127; devnum != 128;
             devnum = devnum ? devnum-1 : (1<<20)-1) {

                if (use_partitions)
                        sprintf(devnm, "md_d%d", devnum);
                else
                        sprintf(devnm, "md%d", devnum);
                if (mddev_busy(devnm))
                        continue;
                if (!conf_name_is_free(devnm))
                        continue;
                if (!use_udev()) {
                        /* make sure it is new to /dev too, at least as a
                         * non-standard */
                        int devid = devnm2devid(devnm);
                        if (devid) {
                                char *dn = map_dev(major(devid),
                                                   minor(devid), 0);
                                if (dn && ! is_standard(dn, NULL))
                                        continue;
                        }
                }
                break;
        }
        if (devnum == 128)
                return NULL;
        return devnm;
}
#endif /* !defined(MDASSEMBLE) || defined(MDASSEMBLE) && defined(MDASSEMBLE_AUTO) */

int dev_open(char *dev, int flags)
{
        /* like 'open', but if 'dev' matches %d:%d, create a temp
         * block device and open that
         */
        char *e;
        int fd = -1;
        char devname[32];
        int major;
        int minor;

        if (!dev) return -1;
        flags |= O_DIRECT;

        major = strtoul(dev, &e, 0);
        if (e > dev && *e == ':' && e[1] &&
            (minor = strtoul(e+1, &e, 0)) >= 0 &&
            *e == 0) {
                snprintf(devname, sizeof(devname), "/dev/.tmp.md.%d:%d:%d",
                         (int)getpid(), major, minor);
                if (mknod(devname, S_IFBLK|0600, makedev(major, minor)) == 0) {
                        fd = open(devname, flags);
                        unlink(devname);
                }
                if (fd < 0) {
                        /* Try /tmp as /dev appear to be read-only */
                        snprintf(devname, sizeof(devname), "/tmp/.tmp.md.%d:%d:%d",
                                 (int)getpid(), major, minor);
                        if (mknod(devname, S_IFBLK|0600, makedev(major, minor)) == 0) {
                                fd = open(devname, flags);
                                unlink(devname);
                        }
                }
        } else
                fd = open(dev, flags);
        return fd;
}

int open_dev_flags(char *devnm, int flags)
{
        int devid;
        char buf[20];

        devid = devnm2devid(devnm);
        sprintf(buf, "%d:%d", major(devid), minor(devid));
        return dev_open(buf, flags);
}

int open_dev(char *devnm)
{
        return open_dev_flags(devnm, O_RDONLY);
}

int open_dev_excl(char *devnm)
{
        char buf[20];
        int i;
        int flags = O_RDWR;
        int devid = devnm2devid(devnm);
        long delay = 1000;

        sprintf(buf, "%d:%d", major(devid), minor(devid));
        for (i = 0 ; i < 25 ; i++) {
                int fd = dev_open(buf, flags|O_EXCL);
                if (fd >= 0)
                        return fd;
                if (errno == EACCES && flags == O_RDWR) {
                        flags = O_RDONLY;
                        continue;
                }
                if (errno != EBUSY)
                        return fd;
                usleep(delay);
                if (delay < 200000)
                        delay *= 2;
        }
        return -1;
}

int same_dev(char *one, char *two)
{
        struct stat st1, st2;
        if (stat(one, &st1) != 0)
                return 0;
        if (stat(two, &st2) != 0)
                return 0;
        if ((st1.st_mode & S_IFMT) != S_IFBLK)
                return 0;
        if ((st2.st_mode & S_IFMT) != S_IFBLK)
                return 0;
        return st1.st_rdev == st2.st_rdev;
}

void wait_for(char *dev, int fd)
{
        int i;
        struct stat stb_want;
        long delay = 1000;

        if (fstat(fd, &stb_want) != 0 ||
            (stb_want.st_mode & S_IFMT) != S_IFBLK)
                return;

        for (i = 0 ; i < 25 ; i++) {
                struct stat stb;
                if (stat(dev, &stb) == 0 &&
                    (stb.st_mode & S_IFMT) == S_IFBLK &&
                    (stb.st_rdev == stb_want.st_rdev))
                        return;
                usleep(delay);
                if (delay < 200000)
                        delay *= 2;
        }
        if (i == 25)
                dprintf("%s: timeout waiting for %s\n", __func__, dev);
}

struct superswitch *superlist[] =
{
        &super0, &super1,
        &super_ddf, &super_imsm,
        &mbr, &gpt,
        NULL };

#if !defined(MDASSEMBLE) || defined(MDASSEMBLE) && defined(MDASSEMBLE_AUTO)

struct supertype *super_by_fd(int fd, char **subarrayp)
{
        mdu_array_info_t array;
        int vers;
        int minor;
        struct supertype *st = NULL;
        struct mdinfo *sra;
        char *verstr;
        char version[20];
        int i;
        char *subarray = NULL;
        char container[32] = "";

        sra = sysfs_read(fd, NULL, GET_VERSION);

        if (sra) {
                vers = sra->array.major_version;
                minor = sra->array.minor_version;
                verstr = sra->text_version;
        } else {
                if (ioctl(fd, GET_ARRAY_INFO, &array))
                        array.major_version = array.minor_version = 0;
                vers = array.major_version;
                minor = array.minor_version;
                verstr = "";
        }

        if (vers != -1) {
                sprintf(version, "%d.%d", vers, minor);
                verstr = version;
        }
        if (minor == -2 && is_subarray(verstr)) {
                char *dev = verstr+1;

                subarray = strchr(dev, '/');
                if (subarray) {
                        *subarray++ = '\0';
                        subarray = xstrdup(subarray);
                }
                strcpy(container, dev);
                if (sra)
                        sysfs_free(sra);
                sra = sysfs_read(-1, container, GET_VERSION);
                if (sra && sra->text_version[0])
                        verstr = sra->text_version;
                else
                        verstr = "-no-metadata-";
        }

        for (i = 0; st == NULL && superlist[i] ; i++)
                st = superlist[i]->match_metadata_desc(verstr);

        if (sra)
                sysfs_free(sra);
        if (st) {
                st->sb = NULL;
                if (subarrayp)
                        *subarrayp = subarray;
                strcpy(st->container_devnm, container);
                strcpy(st->devnm, fd2devnm(fd));
        } else
                free(subarray);

        return st;
}
#endif /* !defined(MDASSEMBLE) || defined(MDASSEMBLE) && defined(MDASSEMBLE_AUTO) */

int dev_size_from_id(dev_t id, unsigned long long *size)
{
        char buf[20];
        int fd;

        sprintf(buf, "%d:%d", major(id), minor(id));
        fd = dev_open(buf, O_RDONLY);
        if (fd < 0)
                return 0;
        if (get_dev_size(fd, NULL, size)) {
                close(fd);
                return 1;
        }
        close(fd);
        return 0;
}

struct supertype *dup_super(struct supertype *orig)
{
        struct supertype *st;

        if (!orig)
                return orig;
        st = xcalloc(1, sizeof(*st));
        st->ss = orig->ss;
        st->max_devs = orig->max_devs;
        st->minor_version = orig->minor_version;
        st->ignore_hw_compat = orig->ignore_hw_compat;
        st->sb = NULL;
        st->info = NULL;
        return st;
}

struct supertype *guess_super_type(int fd, enum guess_types guess_type)
{
        /* try each load_super to find the best match,
         * and return the best superswitch
         */
        struct superswitch  *ss;
        struct supertype *st;
        time_t besttime = 0;
        int bestsuper = -1;
        int i;

        st = xcalloc(1, sizeof(*st));
        st->container_devnm[0] = 0;

        for (i = 0 ; superlist[i]; i++) {
                int rv;
                ss = superlist[i];
                if (guess_type == guess_array && ss->add_to_super == NULL)
                        continue;
                if (guess_type == guess_partitions && ss->add_to_super != NULL)
                        continue;
                memset(st, 0, sizeof(*st));
                st->ignore_hw_compat = 1;
                rv = ss->load_super(st, fd, NULL);
                if (rv == 0) {
                        struct mdinfo info;
                        st->ss->getinfo_super(st, &info, NULL);
                        if (bestsuper == -1 ||
                            besttime < info.array.ctime) {
                                bestsuper = i;
                                besttime = info.array.ctime;
                        }
                        ss->free_super(st);
                }
        }
        if (bestsuper != -1) {
                int rv;
                memset(st, 0, sizeof(*st));
                st->ignore_hw_compat = 1;
                rv = superlist[bestsuper]->load_super(st, fd, NULL);
                if (rv == 0) {
                        superlist[bestsuper]->free_super(st);
                        return st;
                }
        }
        free(st);
        return NULL;
}

/* Return size of device in bytes */
int get_dev_size(int fd, char *dname, unsigned long long *sizep)
{
        unsigned long long ldsize;
        struct stat st;

        if (fstat(fd, &st) != -1 && S_ISREG(st.st_mode))
                ldsize = (unsigned long long)st.st_size;
        else
#ifdef BLKGETSIZE64
        if (ioctl(fd, BLKGETSIZE64, &ldsize) != 0)
#endif
        {
                unsigned long dsize;
                if (ioctl(fd, BLKGETSIZE, &dsize) == 0) {
                        ldsize = dsize;
                        ldsize <<= 9;
                } else {
                        if (dname)
                                pr_err("Cannot get size of %s: %s\b",
                                        dname, strerror(errno));
                        return 0;
                }
        }
        *sizep = ldsize;
        return 1;
}

/* Return true if this can only be a container, not a member device.
 * i.e. is and md device and size is zero
 */
int must_be_container(int fd)
{
        unsigned long long size;
        if (md_get_version(fd) < 0)
                return 0;
        if (get_dev_size(fd, NULL, &size) == 0)
                return 1;
        if (size == 0)
                return 1;
        return 0;
}

/* Sets endofpart parameter to the last block used by the last GPT partition on the device.
 * Returns: 1 if successful
 *         -1 for unknown partition type
 *          0 for other errors
 */
static int get_gpt_last_partition_end(int fd, unsigned long long *endofpart)
{
        struct GPT gpt;
        unsigned char empty_gpt_entry[16]= {0};
        struct GPT_part_entry *part;
        char buf[512];
        unsigned long long curr_part_end;
        unsigned all_partitions, entry_size;
        unsigned part_nr;

        *endofpart = 0;

        BUILD_BUG_ON(sizeof(gpt) != 512);
        /* skip protective MBR */
        lseek(fd, 512, SEEK_SET);
        /* read GPT header */
        if (read(fd, &gpt, 512) != 512)
                return 0;

        /* get the number of partition entries and the entry size */
        all_partitions = __le32_to_cpu(gpt.part_cnt);
        entry_size = __le32_to_cpu(gpt.part_size);

        /* Check GPT signature*/
        if (gpt.magic != GPT_SIGNATURE_MAGIC)
                return -1;

        /* sanity checks */
        if (all_partitions > 1024 ||
            entry_size > sizeof(buf))
                return -1;

        part = (struct GPT_part_entry *)buf;

        for (part_nr = 0; part_nr < all_partitions; part_nr++) {
                /* read partition entry */
                if (read(fd, buf, entry_size) != (ssize_t)entry_size)
                        return 0;

                /* is this valid partition? */
                if (memcmp(part->type_guid, empty_gpt_entry, 16) != 0) {
                        /* check the last lba for the current partition */
                        curr_part_end = __le64_to_cpu(part->ending_lba);
                        if (curr_part_end > *endofpart)
                                *endofpart = curr_part_end;
                }

        }
        return 1;
}

/* Sets endofpart parameter to the last block used by the last partition on the device.
 * Returns: 1 if successful
 *         -1 for unknown partition type
 *          0 for other errors
 */
static int get_last_partition_end(int fd, unsigned long long *endofpart)
{
        struct MBR boot_sect;
        struct MBR_part_record *part;
        unsigned long long curr_part_end;
        unsigned part_nr;
        int retval = 0;

        *endofpart = 0;

        BUILD_BUG_ON(sizeof(boot_sect) != 512);
        /* read MBR */
        lseek(fd, 0, 0);
        if (read(fd, &boot_sect, 512) != 512)
                goto abort;

        /* check MBP signature */
        if (boot_sect.magic == MBR_SIGNATURE_MAGIC) {
                retval = 1;
                /* found the correct signature */
                part = boot_sect.parts;

                for (part_nr = 0; part_nr < MBR_PARTITIONS; part_nr++) {
                        /* check for GPT type */
                        if (part->part_type == MBR_GPT_PARTITION_TYPE) {
                                retval = get_gpt_last_partition_end(fd, endofpart);
                                break;
                        }
                        /* check the last used lba for the current partition  */
                        curr_part_end = __le32_to_cpu(part->first_sect_lba) +
                                __le32_to_cpu(part->blocks_num);
                        if (curr_part_end > *endofpart)
                                *endofpart = curr_part_end;

                        part++;
                }
        } else {
                /* Unknown partition table */
                retval = -1;
        }
 abort:
        return retval;
}

int check_partitions(int fd, char *dname, unsigned long long freesize,
                        unsigned long long size)
{
        /*
         * Check where the last partition ends
         */
        unsigned long long endofpart;
        int ret;

        if ((ret = get_last_partition_end(fd, &endofpart)) > 0) {
                /* There appears to be a partition table here */
                if (freesize == 0) {
                        /* partitions will not be visible in new device */
                        pr_err("partition table exists on %s but will be lost or\n"
                               "       meaningless after creating array\n",
                               dname);
                        return 1;
                } else if (endofpart > freesize) {
                        /* last partition overlaps metadata */
                        pr_err("metadata will over-write last partition on %s.\n",
                               dname);
                        return 1;
                } else if (size && endofpart > size) {
                        /* partitions will be truncated in new device */
                        pr_err("array size is too small to cover all partitions on %s.\n",
                               dname);
                        return 1;
                }
        }
        return 0;
}

int open_container(int fd)
{
        /* 'fd' is a block device.  Find out if it is in use
         * by a container, and return an open fd on that container.
         */
        char path[256];
        char *e;
        DIR *dir;
        struct dirent *de;
        int dfd, n;
        char buf[200];
        int major, minor;
        struct stat st;

        if (fstat(fd, &st) != 0)
                return -1;
        sprintf(path, "/sys/dev/block/%d:%d/holders",
                (int)major(st.st_rdev), (int)minor(st.st_rdev));
        e = path + strlen(path);

        dir = opendir(path);
        if (!dir)
                return -1;
        while ((de = readdir(dir))) {
                if (de->d_ino == 0)
                        continue;
                if (de->d_name[0] == '.')
                        continue;
                /* Need to make sure it is a container and not a volume */
                sprintf(e, "/%s/md/metadata_version", de->d_name);
                dfd = open(path, O_RDONLY);
                if (dfd < 0)
                        continue;
                n = read(dfd, buf, sizeof(buf));
                close(dfd);
                if (n <= 0 || (unsigned)n >= sizeof(buf))
                        continue;
                buf[n] = 0;
                if (strncmp(buf, "external", 8) != 0 ||
                    n < 10 ||
                    buf[9] == '/')
                        continue;
                sprintf(e, "/%s/dev", de->d_name);
                dfd = open(path, O_RDONLY);
                if (dfd < 0)
                        continue;
                n = read(dfd, buf, sizeof(buf));
                close(dfd);
                if (n <= 0 || (unsigned)n >= sizeof(buf))
                        continue;
                buf[n] = 0;
                if (sscanf(buf, "%d:%d", &major, &minor) != 2)
                        continue;
                sprintf(buf, "%d:%d", major, minor);
                dfd = dev_open(buf, O_RDONLY);
                if (dfd >= 0) {
                        closedir(dir);
                        return dfd;
                }
        }
        closedir(dir);
        return -1;
}

struct superswitch *version_to_superswitch(char *vers)
{
        int i;

        for (i = 0; superlist[i]; i++) {
                struct superswitch *ss = superlist[i];

                if (strcmp(vers, ss->name) == 0)
                        return ss;
        }

        return NULL;
}

int metadata_container_matches(char *metadata, char *devnm)
{
        /* Check if 'devnm' is the container named in 'metadata'
         * which is
         *   /containername/componentname  or
         *   -containername/componentname
         */
        int l;
        if (*metadata != '/' && *metadata != '-')
                return 0;
        l = strlen(devnm);
        if (strncmp(metadata+1, devnm, l) != 0)
                return 0;
        if (metadata[l+1] != '/')
                return 0;
        return 1;
}

int metadata_subdev_matches(char *metadata, char *devnm)
{
        /* Check if 'devnm' is the subdev named in 'metadata'
         * which is
         *   /containername/subdev  or
         *   -containername/subdev
         */
        char *sl;
        if (*metadata != '/' && *metadata != '-')
                return 0;
        sl = strchr(metadata+1, '/');
        if (!sl)
                return 0;
        if (strcmp(sl+1, devnm) == 0)
                return 1;
        return 0;
}

int is_container_member(struct mdstat_ent *mdstat, char *container)
{
        if (mdstat->metadata_version == NULL ||
            strncmp(mdstat->metadata_version, "external:", 9) != 0 ||
            !metadata_container_matches(mdstat->metadata_version+9, container))
                return 0;

        return 1;
}

int is_subarray_active(char *subarray, char *container)
{
        struct mdstat_ent *mdstat = mdstat_read(0, 0);
        struct mdstat_ent *ent;

        for (ent = mdstat; ent; ent = ent->next)
                if (is_container_member(ent, container))
                        if (strcmp(to_subarray(ent, container), subarray) == 0)
                                break;

        free_mdstat(mdstat);

        return ent != NULL;
}

/* open_subarray - opens a subarray in a container
 * @dev: container device name
 * @st: empty supertype
 * @quiet: block reporting errors flag
 *
 * On success returns an fd to a container and fills in *st
 */
int open_subarray(char *dev, char *subarray, struct supertype *st, int quiet)
{
        struct mdinfo *mdi;
        struct mdinfo *info;
        int fd, err = 1;
        char *_devnm;

        fd = open(dev, O_RDWR|O_EXCL);
        if (fd < 0) {
                if (!quiet)
                        pr_err("Couldn't open %s, aborting\n",
                                dev);
                return -1;
        }

        _devnm = fd2devnm(fd);
        if (_devnm == NULL) {
                if (!quiet)
                        pr_err("Failed to determine device number for %s\n",
                               dev);
                goto close_fd;
        }
        strcpy(st->devnm, _devnm);

        mdi = sysfs_read(fd, st->devnm, GET_VERSION|GET_LEVEL);
        if (!mdi) {
                if (!quiet)
                        pr_err("Failed to read sysfs for %s\n",
                                dev);
                goto close_fd;
        }

        if (mdi->array.level != UnSet) {
                if (!quiet)
                        pr_err("%s is not a container\n", dev);
                goto free_sysfs;
        }

        st->ss = version_to_superswitch(mdi->text_version);
        if (!st->ss) {
                if (!quiet)
                        pr_err("Operation not supported for %s metadata\n",
                               mdi->text_version);
                goto free_sysfs;
        }

        if (st->devnm[0] == 0) {
                if (!quiet)
                        pr_err("Failed to allocate device name\n");
                goto free_sysfs;
        }

        if (!st->ss->load_container) {
                if (!quiet)
                        pr_err("%s is not a container\n", dev);
                goto free_sysfs;
        }

        if (st->ss->load_container(st, fd, NULL)) {
                if (!quiet)
                        pr_err("Failed to load metadata for %s\n",
                                dev);
                goto free_sysfs;
        }

        info = st->ss->container_content(st, subarray);
        if (!info) {
                if (!quiet)
                        pr_err("Failed to find subarray-%s in %s\n",
                                subarray, dev);
                goto free_super;
        }
        free(info);

        err = 0;

 free_super:
        if (err)
                st->ss->free_super(st);
 free_sysfs:
        sysfs_free(mdi);
 close_fd:
        if (err)
                close(fd);

        if (err)
                return -1;
        else
                return fd;
}

int add_disk(int mdfd, struct supertype *st,
             struct mdinfo *sra, struct mdinfo *info)
{
        /* Add a device to an array, in one of 2 ways. */
        int rv;
#ifndef MDASSEMBLE
        if (st->ss->external) {
                if (info->disk.state & (1<<MD_DISK_SYNC))
                        info->recovery_start = MaxSector;
                else
                        info->recovery_start = 0;
                rv = sysfs_add_disk(sra, info, 0);
                if (! rv) {
                        struct mdinfo *sd2;
                        for (sd2 = sra->devs; sd2; sd2=sd2->next)
                                if (sd2 == info)
                                        break;
                        if (sd2 == NULL) {
                                sd2 = xmalloc(sizeof(*sd2));
                                *sd2 = *info;
                                sd2->next = sra->devs;
                                sra->devs = sd2;
                        }
                }
        } else
#endif
                rv = ioctl(mdfd, ADD_NEW_DISK, &info->disk);
        return rv;
}

int remove_disk(int mdfd, struct supertype *st,
                struct mdinfo *sra, struct mdinfo *info)
{
        int rv;
        /* Remove the disk given by 'info' from the array */
#ifndef MDASSEMBLE
        if (st->ss->external)
                rv = sysfs_set_str(sra, info, "slot", "none");
        else
#endif
                rv = ioctl(mdfd, HOT_REMOVE_DISK, makedev(info->disk.major,
                                                          info->disk.minor));
        return rv;
}

int set_array_info(int mdfd, struct supertype *st, struct mdinfo *info)
{
        /* Initialise kernel's knowledge of array.
         * This varies between externally managed arrays
         * and older kernels
         */
        int vers = md_get_version(mdfd);
        int rv;

#ifndef MDASSEMBLE
        if (st->ss->external)
                rv = sysfs_set_array(info, vers);
        else
#endif
                if ((vers % 100) >= 1) { /* can use different versions */
                mdu_array_info_t inf;
                memset(&inf, 0, sizeof(inf));
                inf.major_version = info->array.major_version;
                inf.minor_version = info->array.minor_version;
                rv = ioctl(mdfd, SET_ARRAY_INFO, &inf);
        } else
                rv = ioctl(mdfd, SET_ARRAY_INFO, NULL);
        return rv;
}

unsigned long long min_recovery_start(struct mdinfo *array)
{
        /* find the minimum recovery_start in an array for metadata
         * formats that only record per-array recovery progress instead
         * of per-device
         */
        unsigned long long recovery_start = MaxSector;
        struct mdinfo *d;

        for (d = array->devs; d; d = d->next)
                recovery_start = min(recovery_start, d->recovery_start);

        return recovery_start;
}

int mdmon_pid(char *devnm)
{
        char path[100];
        char pid[10];
        int fd;
        int n;

        sprintf(path, "%s/%s.pid", MDMON_DIR, devnm);

        fd = open(path, O_RDONLY | O_NOATIME, 0);

        if (fd < 0)
                return -1;
        n = read(fd, pid, 9);
        close(fd);
        if (n <= 0)
                return -1;
        return atoi(pid);
}

int mdmon_running(char *devnm)
{
        int pid = mdmon_pid(devnm);
        if (pid <= 0)
                return 0;
        if (kill(pid, 0) == 0)
                return 1;
        return 0;
}

int start_mdmon(char *devnm)
{
        int i, skipped;
        int len;
        pid_t pid;
        int status;
        char pathbuf[1024];
        char *paths[4] = {
                pathbuf,
                "/sbin/mdmon",
                "mdmon",
                NULL
        };

        if (check_env("MDADM_NO_MDMON"))
                return 0;

        len = readlink("/proc/self/exe", pathbuf, sizeof(pathbuf)-1);
        if (len > 0) {
                char *sl;
                pathbuf[len] = 0;
                sl = strrchr(pathbuf, '/');
                if (sl)
                        sl++;
                else
                        sl = pathbuf;
                strcpy(sl, "mdmon");
        } else
                pathbuf[0] = '\0';

        /* First try to run systemctl */
        switch(fork()) {
        case 0:
                /* FIXME yuk. CLOSE_EXEC?? */
                skipped = 0;
                for (i = 3; skipped < 20; i++)
                        if (close(i) < 0)
                                skipped++;
                        else
                                skipped = 0;

                /* Don't want to see error messages from systemctl.
                 * If the service doesn't exist, we start mdmon ourselves.
                 */
                close(2);
                open("/dev/null", O_WRONLY);
                snprintf(pathbuf, sizeof(pathbuf), "mdmon@%s.service",
                         devnm);
                status = execl("/usr/bin/systemctl", "systemctl", "start",
                               pathbuf, NULL);
                status = execl("/bin/systemctl", "systemctl", "start",
                               pathbuf, NULL);
                exit(1);
        case -1: pr_err("cannot run mdmon. "
                         "Array remains readonly\n");
                return -1;
        default: /* parent - good */
                pid = wait(&status);
                if (pid >= 0 && status == 0)
                        return 0;
        }

        /* That failed, try running mdmon directly */
        switch(fork()) {
        case 0:
                /* FIXME yuk. CLOSE_EXEC?? */
                skipped = 0;
                for (i = 3; skipped < 20; i++)
                        if (close(i) < 0)
                                skipped++;
                        else
                                skipped = 0;

                for (i = 0; paths[i]; i++)
                        if (paths[i][0]) {
                                execl(paths[i], "mdmon",
                                      devnm, NULL);
                        }
                exit(1);
        case -1: pr_err("cannot run mdmon. "
                         "Array remains readonly\n");
                return -1;
        default: /* parent - good */
                pid = wait(&status);
                if (pid < 0 || status != 0) {
                        pr_err("failed to launch mdmon. "
                               "Array remains readonly\n");
                        return -1;
                }
        }
        return 0;
}

__u32 random32(void)
{
        __u32 rv;
        int rfd = open("/dev/urandom", O_RDONLY);
        if (rfd < 0 || read(rfd, &rv, 4) != 4)
                rv = random();
        if (rfd >= 0)
                close(rfd);
        return rv;
}

#ifndef MDASSEMBLE
int flush_metadata_updates(struct supertype *st)
{
        int sfd;
        if (!st->updates) {
                st->update_tail = NULL;
                return -1;
        }

        sfd = connect_monitor(st->container_devnm);
        if (sfd < 0)
                return -1;

        while (st->updates) {
                struct metadata_update *mu = st->updates;
                st->updates = mu->next;

                send_message(sfd, mu, 0);
                wait_reply(sfd, 0);
                free(mu->buf);
                free(mu);
        }
        ack(sfd, 0);
        wait_reply(sfd, 0);
        close(sfd);
        st->update_tail = NULL;
        return 0;
}

void append_metadata_update(struct supertype *st, void *buf, int len)
{

        struct metadata_update *mu = xmalloc(sizeof(*mu));

        mu->buf = buf;
        mu->len = len;
        mu->space = NULL;
        mu->space_list = NULL;
        mu->next = NULL;
        *st->update_tail = mu;
        st->update_tail = &mu->next;
}
#endif /* MDASSEMBLE */

#ifdef __TINYC__
/* tinyc doesn't optimize this check in ioctl.h out ... */
unsigned int __invalid_size_argument_for_IOC = 0;
#endif

int experimental(void)
{
        if (check_env("MDADM_EXPERIMENTAL"))
                return 1;
        else {
                pr_err("To use this feature MDADM_EXPERIMENTAL"
                                " environment variable has to be defined.\n");
                return 0;
        }
}

/* Pick all spares matching given criteria from a container
 * if min_size == 0 do not check size
 * if domlist == NULL do not check domains
 * if spare_group given add it to domains of each spare
 * metadata allows to test domains using metadata of destination array */
struct mdinfo *container_choose_spares(struct supertype *st,
                                       unsigned long long min_size,
                                       struct domainlist *domlist,
                                       char *spare_group,
                                       const char *metadata, int get_one)
{
        struct mdinfo *d, **dp, *disks = NULL;

        /* get list of all disks in container */
        if (st->ss->getinfo_super_disks)
                disks = st->ss->getinfo_super_disks(st);

        if (!disks)
                return disks;
        /* find spare devices on the list */
        dp = &disks->devs;
        disks->array.spare_disks = 0;
        while (*dp) {
                int found = 0;
                d = *dp;
                if (d->disk.state == 0) {
                        /* check if size is acceptable */
                        unsigned long long dev_size;
                        dev_t dev = makedev(d->disk.major,d->disk.minor);

                        if (!min_size ||
                           (dev_size_from_id(dev,  &dev_size) &&
                            dev_size >= min_size))
                                found = 1;
                        /* check if domain matches */
                        if (found && domlist) {
                                struct dev_policy *pol = devid_policy(dev);
                                if (spare_group)
                                        pol_add(&pol, pol_domain,
                                                spare_group, NULL);
                                if (domain_test(domlist, pol, metadata) != 1)
                                        found = 0;
                                dev_policy_free(pol);
                        }
                }
                if (found) {
                        dp = &d->next;
                        disks->array.spare_disks++;
                        if (get_one) {
                                sysfs_free(*dp);
                                d->next = NULL;
                        }
                } else {
                        *dp = d->next;
                        d->next = NULL;
                        sysfs_free(d);
                }
        }
        return disks;
}

/* Checks if paths point to the same device
 * Returns 0 if they do.
 * Returns 1 if they don't.
 * Returns -1 if something went wrong,
 * e.g. paths are empty or the files
 * they point to don't exist */
int compare_paths (char* path1, char* path2)
{
        struct stat st1,st2;

        if (path1 == NULL || path2 == NULL)
                return -1;
        if (stat(path1,&st1) != 0)
                return -1;
        if (stat(path2,&st2) != 0)
                return -1;
        if ((st1.st_ino == st2.st_ino) && (st1.st_dev == st2.st_dev))
                return 0;
        return 1;
}

/* Make sure we can open as many devices as needed */
void enable_fds(int devices)
{
        unsigned int fds = 20 + devices;
        struct rlimit lim;
        if (getrlimit(RLIMIT_NOFILE, &lim) != 0
            || lim.rlim_cur >= fds)
                return;
        if (lim.rlim_max < fds)
                lim.rlim_max = fds;
        lim.rlim_cur = fds;
        setrlimit(RLIMIT_NOFILE, &lim);
}