/*
   md.c : Multiple Devices driver for Linux
          Copyright (C) 1998, 1999, 2000 Ingo Molnar

     completely rewritten, based on the MD driver code from Marc Zyngier

   Changes:

   - RAID-1/RAID-5 extensions by Miguel de Icaza, Gadi Oxman, Ingo Molnar
   - RAID-6 extensions by H. Peter Anvin <hpa@zytor.com>
   - boot support for linear and striped mode by Harald Hoyer <HarryH@Royal.Net>
   - kerneld support by Boris Tobotras <boris@xtalk.msk.su>
   - kmod support by: Cyrus Durgin
   - RAID0 bugfixes: Mark Anthony Lisher <markal@iname.com>
   - Devfs support by Richard Gooch <rgooch@atnf.csiro.au>

   - lots of fixes and improvements to the RAID1/RAID5 and generic
     RAID code (such as request based resynchronization):

     Neil Brown <neilb@cse.unsw.edu.au>.

   - persistent bitmap code
     Copyright (C) 2003-2004, Paul Clements, SteelEye Technology, Inc.

   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, or (at your option)
   any later version.

   You should have received a copy of the GNU General Public License
   (for example /usr/src/linux/COPYING); if not, write to the Free
   Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/kthread.h>
#include <linux/linkage.h>
#include <linux/raid/md.h>
#include <linux/raid/bitmap.h>
#include <linux/sysctl.h>
#include <linux/buffer_head.h> /* for invalidate_bdev */
#include <linux/poll.h>
#include <linux/mutex.h>
#include <linux/ctype.h>
#include <linux/freezer.h>

#include <linux/init.h>

#include <linux/file.h>

#ifdef CONFIG_KMOD
#include <linux/kmod.h>
#endif

#include <asm/unaligned.h>

#define MAJOR_NR MD_MAJOR
#define MD_DRIVER

/* 63 partitions with the alternate major number (mdp) */
#define MdpMinorShift 6

#define DEBUG 0
#define dprintk(x...) ((void)(DEBUG && printk(x)))


#ifndef MODULE
static void autostart_arrays (int part);
#endif

static LIST_HEAD(pers_list);
static DEFINE_SPINLOCK(pers_lock);

static void md_print_devices(void);

#define MD_BUG(x...) { printk("md: bug in file %s, line %d\n", __FILE__, __LINE__); md_print_devices(); }

/*
 * Current RAID-1,4,5 parallel reconstruction 'guaranteed speed limit'
 * is 1000 KB/sec, so the extra system load does not show up that much.
 * Increase it if you want to have more _guaranteed_ speed. Note that
 * the RAID driver will use the maximum available bandwidth if the IO
 * subsystem is idle. There is also an 'absolute maximum' reconstruction
 * speed limit - in case reconstruction slows down your system despite
 * idle IO detection.
 *
 * you can change it via /proc/sys/dev/raid/speed_limit_min and _max.
 * or /sys/block/mdX/md/sync_speed_{min,max}
 */

static int sysctl_speed_limit_min = 1000;
static int sysctl_speed_limit_max = 200000;
static inline int speed_min(mddev_t *mddev)
{
        return mddev->sync_speed_min ?
                mddev->sync_speed_min : sysctl_speed_limit_min;
}

static inline int speed_max(mddev_t *mddev)
{
        return mddev->sync_speed_max ?
                mddev->sync_speed_max : sysctl_speed_limit_max;
}

static struct ctl_table_header *raid_table_header;

static ctl_table raid_table[] = {
        {
                .ctl_name       = DEV_RAID_SPEED_LIMIT_MIN,
                .procname       = "speed_limit_min",
                .data           = &sysctl_speed_limit_min,
                .maxlen         = sizeof(int),
                .mode           = S_IRUGO|S_IWUSR,
                .proc_handler   = &proc_dointvec,
        },
        {
                .ctl_name       = DEV_RAID_SPEED_LIMIT_MAX,
                .procname       = "speed_limit_max",
                .data           = &sysctl_speed_limit_max,
                .maxlen         = sizeof(int),
                .mode           = S_IRUGO|S_IWUSR,
                .proc_handler   = &proc_dointvec,
        },
        { .ctl_name = 0 }
};

static ctl_table raid_dir_table[] = {
        {
                .ctl_name       = DEV_RAID,
                .procname       = "raid",
                .maxlen         = 0,
                .mode           = S_IRUGO|S_IXUGO,
                .child          = raid_table,
        },
        { .ctl_name = 0 }
};

static ctl_table raid_root_table[] = {
        {
                .ctl_name       = CTL_DEV,
                .procname       = "dev",
                .maxlen         = 0,
                .mode           = 0555,
                .child          = raid_dir_table,
        },
        { .ctl_name = 0 }
};

static struct block_device_operations md_fops;

static int start_readonly;

/*
 * We have a system wide 'event count' that is incremented
 * on any 'interesting' event, and readers of /proc/mdstat
 * can use 'poll' or 'select' to find out when the event
 * count increases.
 *
 * Events are:
 *  start array, stop array, error, add device, remove device,
 *  start build, activate spare
 */
static DECLARE_WAIT_QUEUE_HEAD(md_event_waiters);
static atomic_t md_event_count;
void md_new_event(mddev_t *mddev)
{
        atomic_inc(&md_event_count);
        wake_up(&md_event_waiters);
        sysfs_notify(&mddev->kobj, NULL, "sync_action");
}
EXPORT_SYMBOL_GPL(md_new_event);

/* Alternate version that can be called from interrupts
 * when calling sysfs_notify isn't needed.
 */
static void md_new_event_inintr(mddev_t *mddev)
{
        atomic_inc(&md_event_count);
        wake_up(&md_event_waiters);
}

/*
 * Enables to iterate over all existing md arrays
 * all_mddevs_lock protects this list.
 */
static LIST_HEAD(all_mddevs);
static DEFINE_SPINLOCK(all_mddevs_lock);


/*
 * iterates through all used mddevs in the system.
 * We take care to grab the all_mddevs_lock whenever navigating
 * the list, and to always hold a refcount when unlocked.
 * Any code which breaks out of this loop while own
 * a reference to the current mddev and must mddev_put it.
 */
#define ITERATE_MDDEV(mddev,tmp)                                        \
                                                                        \
        for (({ spin_lock(&all_mddevs_lock);                            \
                tmp = all_mddevs.next;                                  \
                mddev = NULL;});                                        \
             ({ if (tmp != &all_mddevs)                                 \
                        mddev_get(list_entry(tmp, mddev_t, all_mddevs));\
                spin_unlock(&all_mddevs_lock);                          \
                if (mddev) mddev_put(mddev);                            \
                mddev = list_entry(tmp, mddev_t, all_mddevs);           \
                tmp != &all_mddevs;});                                  \
             ({ spin_lock(&all_mddevs_lock);                            \
                tmp = tmp->next;})                                      \
                )


static int md_fail_request (struct request_queue *q, struct bio *bio)
{
        bio_io_error(bio);
        return 0;
}

static inline mddev_t *mddev_get(mddev_t *mddev)
{
        atomic_inc(&mddev->active);
        return mddev;
}

static void mddev_put(mddev_t *mddev)
{
        if (!atomic_dec_and_lock(&mddev->active, &all_mddevs_lock))
                return;
        if (!mddev->raid_disks && list_empty(&mddev->disks)) {
                list_del(&mddev->all_mddevs);
                spin_unlock(&all_mddevs_lock);
                blk_cleanup_queue(mddev->queue);
                kobject_unregister(&mddev->kobj);
        } else
                spin_unlock(&all_mddevs_lock);
}

static mddev_t * mddev_find(dev_t unit)
{
        mddev_t *mddev, *new = NULL;

 retry:
        spin_lock(&all_mddevs_lock);
        list_for_each_entry(mddev, &all_mddevs, all_mddevs)
                if (mddev->unit == unit) {
                        mddev_get(mddev);
                        spin_unlock(&all_mddevs_lock);
                        kfree(new);
                        return mddev;
                }

        if (new) {
                list_add(&new->all_mddevs, &all_mddevs);
                spin_unlock(&all_mddevs_lock);
                return new;
        }
        spin_unlock(&all_mddevs_lock);

        new = kzalloc(sizeof(*new), GFP_KERNEL);
        if (!new)
                return NULL;

        new->unit = unit;
        if (MAJOR(unit) == MD_MAJOR)
                new->md_minor = MINOR(unit);
        else
                new->md_minor = MINOR(unit) >> MdpMinorShift;

        mutex_init(&new->reconfig_mutex);
        INIT_LIST_HEAD(&new->disks);
        INIT_LIST_HEAD(&new->all_mddevs);
        init_timer(&new->safemode_timer);
        atomic_set(&new->active, 1);
        spin_lock_init(&new->write_lock);
        init_waitqueue_head(&new->sb_wait);
        new->reshape_position = MaxSector;

        new->queue = blk_alloc_queue(GFP_KERNEL);
        if (!new->queue) {
                kfree(new);
                return NULL;
        }
        set_bit(QUEUE_FLAG_CLUSTER, &new->queue->queue_flags);

        blk_queue_make_request(new->queue, md_fail_request);

        goto retry;
}

static inline int mddev_lock(mddev_t * mddev)
{
        return mutex_lock_interruptible(&mddev->reconfig_mutex);
}

static inline int mddev_trylock(mddev_t * mddev)
{
        return mutex_trylock(&mddev->reconfig_mutex);
}

static inline void mddev_unlock(mddev_t * mddev)
{
        mutex_unlock(&mddev->reconfig_mutex);

        md_wakeup_thread(mddev->thread);
}

static mdk_rdev_t * find_rdev_nr(mddev_t *mddev, int nr)
{
        mdk_rdev_t * rdev;
        struct list_head *tmp;

        ITERATE_RDEV(mddev,rdev,tmp) {
                if (rdev->desc_nr == nr)
                        return rdev;
        }
        return NULL;
}

static mdk_rdev_t * find_rdev(mddev_t * mddev, dev_t dev)
{
        struct list_head *tmp;
        mdk_rdev_t *rdev;

        ITERATE_RDEV(mddev,rdev,tmp) {
                if (rdev->bdev->bd_dev == dev)
                        return rdev;
        }
        return NULL;
}

static struct mdk_personality *find_pers(int level, char *clevel)
{
        struct mdk_personality *pers;
        list_for_each_entry(pers, &pers_list, list) {
                if (level != LEVEL_NONE && pers->level == level)
                        return pers;
                if (strcmp(pers->name, clevel)==0)
                        return pers;
        }
        return NULL;
}

static inline sector_t calc_dev_sboffset(struct block_device *bdev)
{
        sector_t size = bdev->bd_inode->i_size >> BLOCK_SIZE_BITS;
        return MD_NEW_SIZE_BLOCKS(size);
}

static sector_t calc_dev_size(mdk_rdev_t *rdev, unsigned chunk_size)
{
        sector_t size;

        size = rdev->sb_offset;

        if (chunk_size)
                size &= ~((sector_t)chunk_size/1024 - 1);
        return size;
}

static int alloc_disk_sb(mdk_rdev_t * rdev)
{
        if (rdev->sb_page)
                MD_BUG();

        rdev->sb_page = alloc_page(GFP_KERNEL);
        if (!rdev->sb_page) {
                printk(KERN_ALERT "md: out of memory.\n");
                return -EINVAL;
        }

        return 0;
}

static void free_disk_sb(mdk_rdev_t * rdev)
{
        if (rdev->sb_page) {
                put_page(rdev->sb_page);
                rdev->sb_loaded = 0;
                rdev->sb_page = NULL;
                rdev->sb_offset = 0;
                rdev->size = 0;
        }
}


static void super_written(struct bio *bio, int error)
{
        mdk_rdev_t *rdev = bio->bi_private;
        mddev_t *mddev = rdev->mddev;

        if (error || !test_bit(BIO_UPTODATE, &bio->bi_flags)) {
                printk("md: super_written gets error=%d, uptodate=%d\n",
                       error, test_bit(BIO_UPTODATE, &bio->bi_flags));
                WARN_ON(test_bit(BIO_UPTODATE, &bio->bi_flags));
                md_error(mddev, rdev);
        }

        if (atomic_dec_and_test(&mddev->pending_writes))
                wake_up(&mddev->sb_wait);
        bio_put(bio);
}

static void super_written_barrier(struct bio *bio, int error)
{
        struct bio *bio2 = bio->bi_private;
        mdk_rdev_t *rdev = bio2->bi_private;
        mddev_t *mddev = rdev->mddev;

        if (!test_bit(BIO_UPTODATE, &bio->bi_flags) &&
            error == -EOPNOTSUPP) {
                unsigned long flags;
                /* barriers don't appear to be supported :-( */
                set_bit(BarriersNotsupp, &rdev->flags);
                mddev->barriers_work = 0;
                spin_lock_irqsave(&mddev->write_lock, flags);
                bio2->bi_next = mddev->biolist;
                mddev->biolist = bio2;
                spin_unlock_irqrestore(&mddev->write_lock, flags);
                wake_up(&mddev->sb_wait);
                bio_put(bio);
        } else {
                bio_put(bio2);
                bio->bi_private = rdev;
                super_written(bio, error);
        }
}

void md_super_write(mddev_t *mddev, mdk_rdev_t *rdev,
                   sector_t sector, int size, struct page *page)
{
        /* write first size bytes of page to sector of rdev
         * Increment mddev->pending_writes before returning
         * and decrement it on completion, waking up sb_wait
         * if zero is reached.
         * If an error occurred, call md_error
         *
         * As we might need to resubmit the request if BIO_RW_BARRIER
         * causes ENOTSUPP, we allocate a spare bio...
         */
        struct bio *bio = bio_alloc(GFP_NOIO, 1);
        int rw = (1<<BIO_RW) | (1<<BIO_RW_SYNC);

        bio->bi_bdev = rdev->bdev;
        bio->bi_sector = sector;
        bio_add_page(bio, page, size, 0);
        bio->bi_private = rdev;
        bio->bi_end_io = super_written;
        bio->bi_rw = rw;

        atomic_inc(&mddev->pending_writes);
        if (!test_bit(BarriersNotsupp, &rdev->flags)) {
                struct bio *rbio;
                rw |= (1<<BIO_RW_BARRIER);
                rbio = bio_clone(bio, GFP_NOIO);
                rbio->bi_private = bio;
                rbio->bi_end_io = super_written_barrier;
                submit_bio(rw, rbio);
        } else
                submit_bio(rw, bio);
}

void md_super_wait(mddev_t *mddev)
{
        /* wait for all superblock writes that were scheduled to complete.
         * if any had to be retried (due to BARRIER problems), retry them
         */
        DEFINE_WAIT(wq);
        for(;;) {
                prepare_to_wait(&mddev->sb_wait, &wq, TASK_UNINTERRUPTIBLE);
                if (atomic_read(&mddev->pending_writes)==0)
                        break;
                while (mddev->biolist) {
                        struct bio *bio;
                        spin_lock_irq(&mddev->write_lock);
                        bio = mddev->biolist;
                        mddev->biolist = bio->bi_next ;
                        bio->bi_next = NULL;
                        spin_unlock_irq(&mddev->write_lock);
                        submit_bio(bio->bi_rw, bio);
                }
                schedule();
        }
        finish_wait(&mddev->sb_wait, &wq);
}

static void bi_complete(struct bio *bio, int error)
{
        complete((struct completion*)bio->bi_private);
}

int sync_page_io(struct block_device *bdev, sector_t sector, int size,
                   struct page *page, int rw)
{
        struct bio *bio = bio_alloc(GFP_NOIO, 1);
        struct completion event;
        int ret;

        rw |= (1 << BIO_RW_SYNC);

        bio->bi_bdev = bdev;
        bio->bi_sector = sector;
        bio_add_page(bio, page, size, 0);
        init_completion(&event);
        bio->bi_private = &event;
        bio->bi_end_io = bi_complete;
        submit_bio(rw, bio);
        wait_for_completion(&event);

        ret = test_bit(BIO_UPTODATE, &bio->bi_flags);
        bio_put(bio);
        return ret;
}
EXPORT_SYMBOL_GPL(sync_page_io);

static int read_disk_sb(mdk_rdev_t * rdev, int size)
{
        char b[BDEVNAME_SIZE];
        if (!rdev->sb_page) {
                MD_BUG();
                return -EINVAL;
        }
        if (rdev->sb_loaded)
                return 0;


        if (!sync_page_io(rdev->bdev, rdev->sb_offset<<1, size, rdev->sb_page, READ))
                goto fail;
        rdev->sb_loaded = 1;
        return 0;

fail:
        printk(KERN_WARNING "md: disabled device %s, could not read superblock.\n",
                bdevname(rdev->bdev,b));
        return -EINVAL;
}

static int uuid_equal(mdp_super_t *sb1, mdp_super_t *sb2)
{
        if (    (sb1->set_uuid0 == sb2->set_uuid0) &&
                (sb1->set_uuid1 == sb2->set_uuid1) &&
                (sb1->set_uuid2 == sb2->set_uuid2) &&
                (sb1->set_uuid3 == sb2->set_uuid3))

                return 1;

        return 0;
}


static int sb_equal(mdp_super_t *sb1, mdp_super_t *sb2)
{
        int ret;
        mdp_super_t *tmp1, *tmp2;

        tmp1 = kmalloc(sizeof(*tmp1),GFP_KERNEL);
        tmp2 = kmalloc(sizeof(*tmp2),GFP_KERNEL);

        if (!tmp1 || !tmp2) {
                ret = 0;
                printk(KERN_INFO "md.c: sb1 is not equal to sb2!\n");
                goto abort;
        }

        *tmp1 = *sb1;
        *tmp2 = *sb2;

        /*
         * nr_disks is not constant
         */
        tmp1->nr_disks = 0;
        tmp2->nr_disks = 0;

        if (memcmp(tmp1, tmp2, MD_SB_GENERIC_CONSTANT_WORDS * 4))
                ret = 0;
        else
                ret = 1;

abort:
        kfree(tmp1);
        kfree(tmp2);
        return ret;
}


static u32 md_csum_fold(u32 csum)
{
        csum = (csum & 0xffff) + (csum >> 16);
        return (csum & 0xffff) + (csum >> 16);
}

static unsigned int calc_sb_csum(mdp_super_t * sb)
{
        u64 newcsum = 0;
        u32 *sb32 = (u32*)sb;
        int i;
        unsigned int disk_csum, csum;

        disk_csum = sb->sb_csum;
        sb->sb_csum = 0;

        for (i = 0; i < MD_SB_BYTES/4 ; i++)
                newcsum += sb32[i];
        csum = (newcsum & 0xffffffff) + (newcsum>>32);


#ifdef CONFIG_ALPHA
        /* This used to use csum_partial, which was wrong for several
         * reasons including that different results are returned on
         * different architectures.  It isn't critical that we get exactly
         * the same return value as before (we always csum_fold before
         * testing, and that removes any differences).  However as we
         * know that csum_partial always returned a 16bit value on
         * alphas, do a fold to maximise conformity to previous behaviour.
         */
        sb->sb_csum = md_csum_fold(disk_csum);
#else
        sb->sb_csum = disk_csum;
#endif
        return csum;
}


/*
 * Handle superblock details.
 * We want to be able to handle multiple superblock formats
 * so we have a common interface to them all, and an array of
 * different handlers.
 * We rely on user-space to write the initial superblock, and support
 * reading and updating of superblocks.
 * Interface methods are:
 *   int load_super(mdk_rdev_t *dev, mdk_rdev_t *refdev, int minor_version)
 *      loads and validates a superblock on dev.
 *      if refdev != NULL, compare superblocks on both devices
 *    Return:
 *      0 - dev has a superblock that is compatible with refdev
 *      1 - dev has a superblock that is compatible and newer than refdev
 *          so dev should be used as the refdev in future
 *     -EINVAL superblock incompatible or invalid
 *     -othererror e.g. -EIO
 *
 *   int validate_super(mddev_t *mddev, mdk_rdev_t *dev)
 *      Verify that dev is acceptable into mddev.
 *       The first time, mddev->raid_disks will be 0, and data from
 *       dev should be merged in.  Subsequent calls check that dev
 *       is new enough.  Return 0 or -EINVAL
 *
 *   void sync_super(mddev_t *mddev, mdk_rdev_t *dev)
 *     Update the superblock for rdev with data in mddev
 *     This does not write to disc.
 *
 */

struct super_type  {
        char            *name;
        struct module   *owner;
        int             (*load_super)(mdk_rdev_t *rdev, mdk_rdev_t *refdev, int minor_version);
        int             (*validate_super)(mddev_t *mddev, mdk_rdev_t *rdev);
        void            (*sync_super)(mddev_t *mddev, mdk_rdev_t *rdev);
};

/*
 * load_super for 0.90.0 
 */
static int super_90_load(mdk_rdev_t *rdev, mdk_rdev_t *refdev, int minor_version)
{
        char b[BDEVNAME_SIZE], b2[BDEVNAME_SIZE];
        mdp_super_t *sb;
        int ret;
        sector_t sb_offset;

        /*
         * Calculate the position of the superblock,
         * it's at the end of the disk.
         *
         * It also happens to be a multiple of 4Kb.
         */
        sb_offset = calc_dev_sboffset(rdev->bdev);
        rdev->sb_offset = sb_offset;

        ret = read_disk_sb(rdev, MD_SB_BYTES);
        if (ret) return ret;

        ret = -EINVAL;

        bdevname(rdev->bdev, b);
        sb = (mdp_super_t*)page_address(rdev->sb_page);

        if (sb->md_magic != MD_SB_MAGIC) {
                printk(KERN_ERR "md: invalid raid superblock magic on %s\n",
                       b);
                goto abort;
        }

        if (sb->major_version != 0 ||
            sb->minor_version < 90 ||
            sb->minor_version > 91) {
                printk(KERN_WARNING "Bad version number %d.%d on %s\n",
                        sb->major_version, sb->minor_version,
                        b);
                goto abort;
        }

        if (sb->raid_disks <= 0)
                goto abort;

        if (md_csum_fold(calc_sb_csum(sb)) != md_csum_fold(sb->sb_csum)) {
                printk(KERN_WARNING "md: invalid superblock checksum on %s\n",
                        b);
                goto abort;
        }

        rdev->preferred_minor = sb->md_minor;
        rdev->data_offset = 0;
        rdev->sb_size = MD_SB_BYTES;

        if (sb->state & (1<<MD_SB_BITMAP_PRESENT)) {
                if (sb->level != 1 && sb->level != 4
                    && sb->level != 5 && sb->level != 6
                    && sb->level != 10) {
                        /* FIXME use a better test */
                        printk(KERN_WARNING
                               "md: bitmaps not supported for this level.\n");
                        goto abort;
                }
        }

        if (sb->level == LEVEL_MULTIPATH)
                rdev->desc_nr = -1;
        else
                rdev->desc_nr = sb->this_disk.number;

        if (refdev == 0)
                ret = 1;
        else {
                __u64 ev1, ev2;
                mdp_super_t *refsb = (mdp_super_t*)page_address(refdev->sb_page);
                if (!uuid_equal(refsb, sb)) {
                        printk(KERN_WARNING "md: %s has different UUID to %s\n",
                                b, bdevname(refdev->bdev,b2));
                        goto abort;
                }
                if (!sb_equal(refsb, sb)) {
                        printk(KERN_WARNING "md: %s has same UUID"
                               " but different superblock to %s\n",
                               b, bdevname(refdev->bdev, b2));
                        goto abort;
                }
                ev1 = md_event(sb);
                ev2 = md_event(refsb);
                if (ev1 > ev2)
                        ret = 1;
                else 
                        ret = 0;
        }
        rdev->size = calc_dev_size(rdev, sb->chunk_size);

        if (rdev->size < sb->size && sb->level > 1)
                /* "this cannot possibly happen" ... */
                ret = -EINVAL;

 abort:
        return ret;
}

/*
 * validate_super for 0.90.0
 */
static int super_90_validate(mddev_t *mddev, mdk_rdev_t *rdev)
{
        mdp_disk_t *desc;
        mdp_super_t *sb = (mdp_super_t *)page_address(rdev->sb_page);
        __u64 ev1 = md_event(sb);

        rdev->raid_disk = -1;
        rdev->flags = 0;
        if (mddev->raid_disks == 0) {
                mddev->major_version = 0;
                mddev->minor_version = sb->minor_version;
                mddev->patch_version = sb->patch_version;
                mddev->persistent = ! sb->not_persistent;
                mddev->chunk_size = sb->chunk_size;
                mddev->ctime = sb->ctime;
                mddev->utime = sb->utime;
                mddev->level = sb->level;
                mddev->clevel[0] = 0;
                mddev->layout = sb->layout;
                mddev->raid_disks = sb->raid_disks;
                mddev->size = sb->size;
                mddev->events = ev1;
                mddev->bitmap_offset = 0;
                mddev->default_bitmap_offset = MD_SB_BYTES >> 9;

                if (mddev->minor_version >= 91) {
                        mddev->reshape_position = sb->reshape_position;
                        mddev->delta_disks = sb->delta_disks;
                        mddev->new_level = sb->new_level;
                        mddev->new_layout = sb->new_layout;
                        mddev->new_chunk = sb->new_chunk;
                } else {
                        mddev->reshape_position = MaxSector;
                        mddev->delta_disks = 0;
                        mddev->new_level = mddev->level;
                        mddev->new_layout = mddev->layout;
                        mddev->new_chunk = mddev->chunk_size;
                }

                if (sb->state & (1<<MD_SB_CLEAN))
                        mddev->recovery_cp = MaxSector;
                else {
                        if (sb->events_hi == sb->cp_events_hi && 
                                sb->events_lo == sb->cp_events_lo) {
                                mddev->recovery_cp = sb->recovery_cp;
                        } else
                                mddev->recovery_cp = 0;
                }

                memcpy(mddev->uuid+0, &sb->set_uuid0, 4);
                memcpy(mddev->uuid+4, &sb->set_uuid1, 4);
                memcpy(mddev->uuid+8, &sb->set_uuid2, 4);
                memcpy(mddev->uuid+12,&sb->set_uuid3, 4);

                mddev->max_disks = MD_SB_DISKS;

                if (sb->state & (1<<MD_SB_BITMAP_PRESENT) &&
                    mddev->bitmap_file == NULL)
                        mddev->bitmap_offset = mddev->default_bitmap_offset;

        } else if (mddev->pers == NULL) {
                /* Insist on good event counter while assembling */
                ++ev1;
                if (ev1 < mddev->events) 
                        return -EINVAL;
        } else if (mddev->bitmap) {
                /* if adding to array with a bitmap, then we can accept an
                 * older device ... but not too old.
                 */
                if (ev1 < mddev->bitmap->events_cleared)
                        return 0;
        } else {
                if (ev1 < mddev->events)
                        /* just a hot-add of a new device, leave raid_disk at -1 */
                        return 0;
        }

        if (mddev->level != LEVEL_MULTIPATH) {
                desc = sb->disks + rdev->desc_nr;

                if (desc->state & (1<<MD_DISK_FAULTY))
                        set_bit(Faulty, &rdev->flags);
                else if (desc->state & (1<<MD_DISK_SYNC) /* &&
                            desc->raid_disk < mddev->raid_disks */) {
                        set_bit(In_sync, &rdev->flags);
                        rdev->raid_disk = desc->raid_disk;
                }
                if (desc->state & (1<<MD_DISK_WRITEMOSTLY))
                        set_bit(WriteMostly, &rdev->flags);
        } else /* MULTIPATH are always insync */
                set_bit(In_sync, &rdev->flags);
        return 0;
}

/*
 * sync_super for 0.90.0
 */
static void super_90_sync(mddev_t *mddev, mdk_rdev_t *rdev)
{
        mdp_super_t *sb;
        struct list_head *tmp;
        mdk_rdev_t *rdev2;
        int next_spare = mddev->raid_disks;


        /* make rdev->sb match mddev data..
         *
         * 1/ zero out disks
         * 2/ Add info for each disk, keeping track of highest desc_nr (next_spare);
         * 3/ any empty disks < next_spare become removed
         *
         * disks[0] gets initialised to REMOVED because
         * we cannot be sure from other fields if it has
         * been initialised or not.
         */
        int i;
        int active=0, working=0,failed=0,spare=0,nr_disks=0;

        rdev->sb_size = MD_SB_BYTES;

        sb = (mdp_super_t*)page_address(rdev->sb_page);

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

        sb->md_magic = MD_SB_MAGIC;
        sb->major_version = mddev->major_version;
        sb->patch_version = mddev->patch_version;
        sb->gvalid_words  = 0; /* ignored */
        memcpy(&sb->set_uuid0, mddev->uuid+0, 4);
        memcpy(&sb->set_uuid1, mddev->uuid+4, 4);
        memcpy(&sb->set_uuid2, mddev->uuid+8, 4);
        memcpy(&sb->set_uuid3, mddev->uuid+12,4);

        sb->ctime = mddev->ctime;
        sb->level = mddev->level;
        sb->size  = mddev->size;
        sb->raid_disks = mddev->raid_disks;
        sb->md_minor = mddev->md_minor;
        sb->not_persistent = !mddev->persistent;
        sb->utime = mddev->utime;
        sb->state = 0;
        sb->events_hi = (mddev->events>>32);
        sb->events_lo = (u32)mddev->events;

        if (mddev->reshape_position == MaxSector)
                sb->minor_version = 90;
        else {
                sb->minor_version = 91;
                sb->reshape_position = mddev->reshape_position;
                sb->new_level = mddev->new_level;
                sb->delta_disks = mddev->delta_disks;
                sb->new_layout = mddev->new_layout;
                sb->new_chunk = mddev->new_chunk;
        }
        mddev->minor_version = sb->minor_version;
        if (mddev->in_sync)
        {
                sb->recovery_cp = mddev->recovery_cp;
                sb->cp_events_hi = (mddev->events>>32);
                sb->cp_events_lo = (u32)mddev->events;
                if (mddev->recovery_cp == MaxSector)
                        sb->state = (1<< MD_SB_CLEAN);
        } else
                sb->recovery_cp = 0;

        sb->layout = mddev->layout;
        sb->chunk_size = mddev->chunk_size;

        if (mddev->bitmap && mddev->bitmap_file == NULL)
                sb->state |= (1<<MD_SB_BITMAP_PRESENT);

        sb->disks[0].state = (1<<MD_DISK_REMOVED);
        ITERATE_RDEV(mddev,rdev2,tmp) {
                mdp_disk_t *d;
                int desc_nr;
                if (rdev2->raid_disk >= 0 && test_bit(In_sync, &rdev2->flags)
                    && !test_bit(Faulty, &rdev2->flags))
                        desc_nr = rdev2->raid_disk;
                else
                        desc_nr = next_spare++;
                rdev2->desc_nr = desc_nr;
                d = &sb->disks[rdev2->desc_nr];
                nr_disks++;
                d->number = rdev2->desc_nr;
                d->major = MAJOR(rdev2->bdev->bd_dev);
                d->minor = MINOR(rdev2->bdev->bd_dev);
                if (rdev2->raid_disk >= 0 && test_bit(In_sync, &rdev2->flags)
                    && !test_bit(Faulty, &rdev2->flags))
                        d->raid_disk = rdev2->raid_disk;
                else
                        d->raid_disk = rdev2->desc_nr; /* compatibility */
                if (test_bit(Faulty, &rdev2->flags))
                        d->state = (1<<MD_DISK_FAULTY);
                else if (test_bit(In_sync, &rdev2->flags)) {
                        d->state = (1<<MD_DISK_ACTIVE);
                        d->state |= (1<<MD_DISK_SYNC);
                        active++;
                        working++;
                } else {
                        d->state = 0;
                        spare++;
                        working++;
                }
                if (test_bit(WriteMostly, &rdev2->flags))
                        d->state |= (1<<MD_DISK_WRITEMOSTLY);
        }
        /* now set the "removed" and "faulty" bits on any missing devices */
        for (i=0 ; i < mddev->raid_disks ; i++) {
                mdp_disk_t *d = &sb->disks[i];
                if (d->state == 0 && d->number == 0) {
                        d->number = i;
                        d->raid_disk = i;
                        d->state = (1<<MD_DISK_REMOVED);
                        d->state |= (1<<MD_DISK_FAULTY);
                        failed++;
                }
        }
        sb->nr_disks = nr_disks;
        sb->active_disks = active;
        sb->working_disks = working;
        sb->failed_disks = failed;
        sb->spare_disks = spare;

        sb->this_disk = sb->disks[rdev->desc_nr];
        sb->sb_csum = calc_sb_csum(sb);
}

/*
 * version 1 superblock
 */

static __le32 calc_sb_1_csum(struct mdp_superblock_1 * sb)

{
        __le32 disk_csum;
        u32 csum;
        unsigned long long newcsum;
        int size = 256 + le32_to_cpu(sb->max_dev)*2;
        __le32 *isuper = (__le32*)sb;
        int i;

        disk_csum = sb->sb_csum;
        sb->sb_csum = 0;
        newcsum = 0;
        for (i=0; size>=4; size -= 4 )
                newcsum += le32_to_cpu(*isuper++);

        if (size == 2)
                newcsum += le16_to_cpu(*(__le16*) isuper);

        csum = (newcsum & 0xffffffff) + (newcsum >> 32);
        sb->sb_csum = disk_csum;
        return cpu_to_le32(csum);
}

static int super_1_load(mdk_rdev_t *rdev, mdk_rdev_t *refdev, int minor_version)
{
        struct mdp_superblock_1 *sb;
        int ret;
        sector_t sb_offset;
        char b[BDEVNAME_SIZE], b2[BDEVNAME_SIZE];
        int bmask;

        /*
         * Calculate the position of the superblock.
         * It is always aligned to a 4K boundary and
         * depeding on minor_version, it can be:
         * 0: At least 8K, but less than 12K, from end of device
         * 1: At start of device
         * 2: 4K from start of device.
         */
        switch(minor_version) {
        case 0:
                sb_offset = rdev->bdev->bd_inode->i_size >> 9;
                sb_offset -= 8*2;
                sb_offset &= ~(sector_t)(4*2-1);
                /* convert from sectors to K */
                sb_offset /= 2;
                break;
        case 1:
                sb_offset = 0;
                break;
        case 2:
                sb_offset = 4;
                break;
        default:
                return -EINVAL;
        }
        rdev->sb_offset = sb_offset;

        /* superblock is rarely larger than 1K, but it can be larger,
         * and it is safe to read 4k, so we do that
         */
        ret = read_disk_sb(rdev, 4096);
        if (ret) return ret;


        sb = (struct mdp_superblock_1*)page_address(rdev->sb_page);

        if (sb->magic != cpu_to_le32(MD_SB_MAGIC) ||
            sb->major_version != cpu_to_le32(1) ||
            le32_to_cpu(sb->max_dev) > (4096-256)/2 ||
            le64_to_cpu(sb->super_offset) != (rdev->sb_offset<<1) ||
            (le32_to_cpu(sb->feature_map) & ~MD_FEATURE_ALL) != 0)
                return -EINVAL;

        if (calc_sb_1_csum(sb) != sb->sb_csum) {
                printk("md: invalid superblock checksum on %s\n",
                        bdevname(rdev->bdev,b));
                return -EINVAL;
        }
        if (le64_to_cpu(sb->data_size) < 10) {
                printk("md: data_size too small on %s\n",
                       bdevname(rdev->bdev,b));
                return -EINVAL;
        }
        if ((le32_to_cpu(sb->feature_map) & MD_FEATURE_BITMAP_OFFSET)) {
                if (sb->level != cpu_to_le32(1) &&
                    sb->level != cpu_to_le32(4) &&
                    sb->level != cpu_to_le32(5) &&
                    sb->level != cpu_to_le32(6) &&
                    sb->level != cpu_to_le32(10)) {
                        printk(KERN_WARNING
                               "md: bitmaps not supported for this level.\n");
                        return -EINVAL;
                }
        }

        rdev->preferred_minor = 0xffff;
        rdev->data_offset = le64_to_cpu(sb->data_offset);
        atomic_set(&rdev->corrected_errors, le32_to_cpu(sb->cnt_corrected_read));

        rdev->sb_size = le32_to_cpu(sb->max_dev) * 2 + 256;
        bmask = queue_hardsect_size(rdev->bdev->bd_disk->queue)-1;
        if (rdev->sb_size & bmask)
                rdev-> sb_size = (rdev->sb_size | bmask)+1;

        if (sb->level == cpu_to_le32(LEVEL_MULTIPATH))
                rdev->desc_nr = -1;
        else
                rdev->desc_nr = le32_to_cpu(sb->dev_number);

        if (refdev == 0)
                ret = 1;
        else {
                __u64 ev1, ev2;
                struct mdp_superblock_1 *refsb = 
                        (struct mdp_superblock_1*)page_address(refdev->sb_page);

                if (memcmp(sb->set_uuid, refsb->set_uuid, 16) != 0 ||
                    sb->level != refsb->level ||
                    sb->layout != refsb->layout ||
                    sb->chunksize != refsb->chunksize) {
                        printk(KERN_WARNING "md: %s has strangely different"
                                " superblock to %s\n",
                                bdevname(rdev->bdev,b),
                                bdevname(refdev->bdev,b2));
                        return -EINVAL;
                }
                ev1 = le64_to_cpu(sb->events);
                ev2 = le64_to_cpu(refsb->events);

                if (ev1 > ev2)
                        ret = 1;
                else
                        ret = 0;
        }
        if (minor_version) 
                rdev->size = ((rdev->bdev->bd_inode->i_size>>9) - le64_to_cpu(sb->data_offset)) / 2;
        else
                rdev->size = rdev->sb_offset;
        if (rdev->size < le64_to_cpu(sb->data_size)/2)
                return -EINVAL;
        rdev->size = le64_to_cpu(sb->data_size)/2;
        if (le32_to_cpu(sb->chunksize))
                rdev->size &= ~((sector_t)le32_to_cpu(sb->chunksize)/2 - 1);

        if (le64_to_cpu(sb->size) > rdev->size*2)
                return -EINVAL;
        return ret;
}

static int super_1_validate(mddev_t *mddev, mdk_rdev_t *rdev)
{
        struct mdp_superblock_1 *sb = (struct mdp_superblock_1*)page_address(rdev->sb_page);
        __u64 ev1 = le64_to_cpu(sb->events);

        rdev->raid_disk = -1;
        rdev->flags = 0;
        if (mddev->raid_disks == 0) {
                mddev->major_version = 1;
                mddev->patch_version = 0;
                mddev->persistent = 1;
                mddev->chunk_size = le32_to_cpu(sb->chunksize) << 9;
                mddev->ctime = le64_to_cpu(sb->ctime) & ((1ULL << 32)-1);
                mddev->utime = le64_to_cpu(sb->utime) & ((1ULL << 32)-1);
                mddev->level = le32_to_cpu(sb->level);
                mddev->clevel[0] = 0;
                mddev->layout = le32_to_cpu(sb->layout);
                mddev->raid_disks = le32_to_cpu(sb->raid_disks);
                mddev->size = le64_to_cpu(sb->size)/2;
                mddev->events = ev1;
                mddev->bitmap_offset = 0;
                mddev->default_bitmap_offset = 1024 >> 9;
                
                mddev->recovery_cp = le64_to_cpu(sb->resync_offset);
                memcpy(mddev->uuid, sb->set_uuid, 16);

                mddev->max_disks =  (4096-256)/2;

                if ((le32_to_cpu(sb->feature_map) & MD_FEATURE_BITMAP_OFFSET) &&
                    mddev->bitmap_file == NULL )
                        mddev->bitmap_offset = (__s32)le32_to_cpu(sb->bitmap_offset);

                if ((le32_to_cpu(sb->feature_map) & MD_FEATURE_RESHAPE_ACTIVE)) {
                        mddev->reshape_position = le64_to_cpu(sb->reshape_position);
                        mddev->delta_disks = le32_to_cpu(sb->delta_disks);
                        mddev->new_level = le32_to_cpu(sb->new_level);
                        mddev->new_layout = le32_to_cpu(sb->new_layout);
                        mddev->new_chunk = le32_to_cpu(sb->new_chunk)<<9;
                } else {
                        mddev->reshape_position = MaxSector;
                        mddev->delta_disks = 0;
                        mddev->new_level = mddev->level;
                        mddev->new_layout = mddev->layout;
                        mddev->new_chunk = mddev->chunk_size;
                }

        } else if (mddev->pers == NULL) {
                /* Insist of good event counter while assembling */
                ++ev1;
                if (ev1 < mddev->events)
                        return -EINVAL;
        } else if (mddev->bitmap) {
                /* If adding to array with a bitmap, then we can accept an
                 * older device, but not too old.
                 */
                if (ev1 < mddev->bitmap->events_cleared)
                        return 0;
        } else {
                if (ev1 < mddev->events)
                        /* just a hot-add of a new device, leave raid_disk at -1 */
                        return 0;
        }
        if (mddev->level != LEVEL_MULTIPATH) {
                int role;
                role = le16_to_cpu(sb->dev_roles[rdev->desc_nr]);
                switch(role) {
                case 0xffff: /* spare */
                        break;
                case 0xfffe: /* faulty */
                        set_bit(Faulty, &rdev->flags);
                        break;
                default:
                        if ((le32_to_cpu(sb->feature_map) &
                             MD_FEATURE_RECOVERY_OFFSET))
                                rdev->recovery_offset = le64_to_cpu(sb->recovery_offset);
                        else
                                set_bit(In_sync, &rdev->flags);
                        rdev->raid_disk = role;
                        break;
                }
                if (sb->devflags & WriteMostly1)
                        set_bit(WriteMostly, &rdev->flags);
        } else /* MULTIPATH are always insync */
                set_bit(In_sync, &rdev->flags);

        return 0;
}

static void super_1_sync(mddev_t *mddev, mdk_rdev_t *rdev)
{
        struct mdp_superblock_1 *sb;
        struct list_head *tmp;
        mdk_rdev_t *rdev2;
        int max_dev, i;
        /* make rdev->sb match mddev and rdev data. */

        sb = (struct mdp_superblock_1*)page_address(rdev->sb_page);

        sb->feature_map = 0;
        sb->pad0 = 0;
        sb->recovery_offset = cpu_to_le64(0);
        memset(sb->pad1, 0, sizeof(sb->pad1));
        memset(sb->pad2, 0, sizeof(sb->pad2));
        memset(sb->pad3, 0, sizeof(sb->pad3));

        sb->utime = cpu_to_le64((__u64)mddev->utime);
        sb->events = cpu_to_le64(mddev->events);
        if (mddev->in_sync)
                sb->resync_offset = cpu_to_le64(mddev->recovery_cp);
        else
                sb->resync_offset = cpu_to_le64(0);

        sb->cnt_corrected_read = cpu_to_le32(atomic_read(&rdev->corrected_errors));

        sb->raid_disks = cpu_to_le32(mddev->raid_disks);
        sb->size = cpu_to_le64(mddev->size<<1);

        if (mddev->bitmap && mddev->bitmap_file == NULL) {
                sb->bitmap_offset = cpu_to_le32((__u32)mddev->bitmap_offset);
                sb->feature_map = cpu_to_le32(MD_FEATURE_BITMAP_OFFSET);
        }

        if (rdev->raid_disk >= 0 &&
            !test_bit(In_sync, &rdev->flags) &&
            rdev->recovery_offset > 0) {
                sb->feature_map |= cpu_to_le32(MD_FEATURE_RECOVERY_OFFSET);
                sb->recovery_offset = cpu_to_le64(rdev->recovery_offset);
        }

        if (mddev->reshape_position != MaxSector) {
                sb->feature_map |= cpu_to_le32(MD_FEATURE_RESHAPE_ACTIVE);
                sb->reshape_position = cpu_to_le64(mddev->reshape_position);
                sb->new_layout = cpu_to_le32(mddev->new_layout);
                sb->delta_disks = cpu_to_le32(mddev->delta_disks);
                sb->new_level = cpu_to_le32(mddev->new_level);
                sb->new_chunk = cpu_to_le32(mddev->new_chunk>>9);
        }

        max_dev = 0;
        ITERATE_RDEV(mddev,rdev2,tmp)
                if (rdev2->desc_nr+1 > max_dev)
                        max_dev = rdev2->desc_nr+1;

        if (max_dev > le32_to_cpu(sb->max_dev))
                sb->max_dev = cpu_to_le32(max_dev);
        for (i=0; i<max_dev;i++)
                sb->dev_roles[i] = cpu_to_le16(0xfffe);
        
        ITERATE_RDEV(mddev,rdev2,tmp) {
                i = rdev2->desc_nr;
                if (test_bit(Faulty, &rdev2->flags))
                        sb->dev_roles[i] = cpu_to_le16(0xfffe);
                else if (test_bit(In_sync, &rdev2->flags))
                        sb->dev_roles[i] = cpu_to_le16(rdev2->raid_disk);
                else if (rdev2->raid_disk >= 0 && rdev2->recovery_offset > 0)
                        sb->dev_roles[i] = cpu_to_le16(rdev2->raid_disk);
                else
                        sb->dev_roles[i] = cpu_to_le16(0xffff);
        }

        sb->sb_csum = calc_sb_1_csum(sb);
}


static struct super_type super_types[] = {
        [0] = {
                .name   = "0.90.0",
                .owner  = THIS_MODULE,
                .load_super     = super_90_load,
                .validate_super = super_90_validate,
                .sync_super     = super_90_sync,
        },
        [1] = {
                .name   = "md-1",
                .owner  = THIS_MODULE,
                .load_super     = super_1_load,
                .validate_super = super_1_validate,
                .sync_super     = super_1_sync,
        },
};

static int match_mddev_units(mddev_t *mddev1, mddev_t *mddev2)
{
        struct list_head *tmp, *tmp2;
        mdk_rdev_t *rdev, *rdev2;

        ITERATE_RDEV(mddev1,rdev,tmp)
                ITERATE_RDEV(mddev2, rdev2, tmp2)
                        if (rdev->bdev->bd_contains ==
                            rdev2->bdev->bd_contains)
                                return 1;

        return 0;
}

static LIST_HEAD(pending_raid_disks);

static int bind_rdev_to_array(mdk_rdev_t * rdev, mddev_t * mddev)
{
        char b[BDEVNAME_SIZE];
        struct kobject *ko;
        char *s;
        int err;

        if (rdev->mddev) {
                MD_BUG();
                return -EINVAL;
        }
        /* make sure rdev->size exceeds mddev->size */
        if (rdev->size && (mddev->size == 0 || rdev->size < mddev->size)) {
                if (mddev->pers) {
                        /* Cannot change size, so fail
                         * If mddev->level <= 0, then we don't care
                         * about aligning sizes (e.g. linear)
                         */
                        if (mddev->level > 0)
                                return -ENOSPC;
                } else
                        mddev->size = rdev->size;
        }

        /* Verify rdev->desc_nr is unique.
         * If it is -1, assign a free number, else
         * check number is not in use
         */
        if (rdev->desc_nr < 0) {
                int choice = 0;
                if (mddev->pers) choice = mddev->raid_disks;
                while (find_rdev_nr(mddev, choice))
                        choice++;
                rdev->desc_nr = choice;
        } else {
                if (find_rdev_nr(mddev, rdev->desc_nr))
                        return -EBUSY;
        }
        bdevname(rdev->bdev,b);
        if (kobject_set_name(&rdev->kobj, "dev-%s", b) < 0)
                return -ENOMEM;
        while ( (s=strchr(rdev->kobj.k_name, '/')) != NULL)
                *s = '!';
                        
        rdev->mddev = mddev;
        printk(KERN_INFO "md: bind<%s>\n", b);

        rdev->kobj.parent = &mddev->kobj;
        if ((err = kobject_add(&rdev->kobj)))
                goto fail;

        if (rdev->bdev->bd_part)
                ko = &rdev->bdev->bd_part->kobj;
        else
                ko = &rdev->bdev->bd_disk->kobj;
        if ((err = sysfs_create_link(&rdev->kobj, ko, "block"))) {
                kobject_del(&rdev->kobj);
                goto fail;
        }
        list_add(&rdev->same_set, &mddev->disks);
        bd_claim_by_disk(rdev->bdev, rdev, mddev->gendisk);
        return 0;

 fail:
        printk(KERN_WARNING "md: failed to register dev-%s for %s\n",
               b, mdname(mddev));
        return err;
}

static void delayed_delete(struct work_struct *ws)
{
        mdk_rdev_t *rdev = container_of(ws, mdk_rdev_t, del_work);
        kobject_del(&rdev->kobj);
}

static void unbind_rdev_from_array(mdk_rdev_t * rdev)
{
        char b[BDEVNAME_SIZE];
        if (!rdev->mddev) {
                MD_BUG();
                return;
        }
        bd_release_from_disk(rdev->bdev, rdev->mddev->gendisk);
        list_del_init(&rdev->same_set);
        printk(KERN_INFO "md: unbind<%s>\n", bdevname(rdev->bdev,b));
        rdev->mddev = NULL;
        sysfs_remove_link(&rdev->kobj, "block");

        /* We need to delay this, otherwise we can deadlock when
         * writing to 'remove' to "dev/state"
         */
        INIT_WORK(&rdev->del_work, delayed_delete);
        schedule_work(&rdev->del_work);
}

/*
 * prevent the device from being mounted, repartitioned or
 * otherwise reused by a RAID array (or any other kernel
 * subsystem), by bd_claiming the device.
 */
static int lock_rdev(mdk_rdev_t *rdev, dev_t dev)
{
        int err = 0;
        struct block_device *bdev;
        char b[BDEVNAME_SIZE];

        bdev = open_by_devnum(dev, FMODE_READ|FMODE_WRITE);
        if (IS_ERR(bdev)) {
                printk(KERN_ERR "md: could not open %s.\n",
                        __bdevname(dev, b));
                return PTR_ERR(bdev);
        }
        err = bd_claim(bdev, rdev);
        if (err) {
                printk(KERN_ERR "md: could not bd_claim %s.\n",
                        bdevname(bdev, b));
                blkdev_put(bdev);
                return err;
        }
        rdev->bdev = bdev;
        return err;
}

static void unlock_rdev(mdk_rdev_t *rdev)
{
        struct block_device *bdev = rdev->bdev;
        rdev->bdev = NULL;
        if (!bdev)
                MD_BUG();
        bd_release(bdev);
        blkdev_put(bdev);
}

void md_autodetect_dev(dev_t dev);

static void export_rdev(mdk_rdev_t * rdev)
{
        char b[BDEVNAME_SIZE];
        printk(KERN_INFO "md: export_rdev(%s)\n",
                bdevname(rdev->bdev,b));
        if (rdev->mddev)
                MD_BUG();
        free_disk_sb(rdev);
        list_del_init(&rdev->same_set);
#ifndef MODULE
        md_autodetect_dev(rdev->bdev->bd_dev);
#endif
        unlock_rdev(rdev);
        kobject_put(&rdev->kobj);
}

static void kick_rdev_from_array(mdk_rdev_t * rdev)
{
        unbind_rdev_from_array(rdev);
        export_rdev(rdev);
}

static void export_array(mddev_t *mddev)
{
        struct list_head *tmp;
        mdk_rdev_t *rdev;

        ITERATE_RDEV(mddev,rdev,tmp) {
                if (!rdev->mddev) {
                        MD_BUG();
                        continue;
                }
                kick_rdev_from_array(rdev);
        }
        if (!list_empty(&mddev->disks))
                MD_BUG();
        mddev->raid_disks = 0;
        mddev->major_version = 0;
}

static void print_desc(mdp_disk_t *desc)
{
        printk(" DISK<N:%d,(%d,%d),R:%d,S:%d>\n", desc->number,
                desc->major,desc->minor,desc->raid_disk,desc->state);
}

static void print_sb(mdp_super_t *sb)
{
        int i;

        printk(KERN_INFO 
                "md:  SB: (V:%d.%d.%d) ID:<%08x.%08x.%08x.%08x> CT:%08x\n",
                sb->major_version, sb->minor_version, sb->patch_version,
                sb->set_uuid0, sb->set_uuid1, sb->set_uuid2, sb->set_uuid3,
                sb->ctime);
        printk(KERN_INFO "md:     L%d S%08d ND:%d RD:%d md%d LO:%d CS:%d\n",
                sb->level, sb->size, sb->nr_disks, sb->raid_disks,
                sb->md_minor, sb->layout, sb->chunk_size);
        printk(KERN_INFO "md:     UT:%08x ST:%d AD:%d WD:%d"
                " FD:%d SD:%d CSUM:%08x E:%08lx\n",
                sb->utime, sb->state, sb->active_disks, sb->working_disks,
                sb->failed_disks, sb->spare_disks,
                sb->sb_csum, (unsigned long)sb->events_lo);

        printk(KERN_INFO);
        for (i = 0; i < MD_SB_DISKS; i++) {
                mdp_disk_t *desc;

                desc = sb->disks + i;
                if (desc->number || desc->major || desc->minor ||
                    desc->raid_disk || (desc->state && (desc->state != 4))) {
                        printk("     D %2d: ", i);
                        print_desc(desc);
                }
        }
        printk(KERN_INFO "md:     THIS: ");
        print_desc(&sb->this_disk);

}

static void print_rdev(mdk_rdev_t *rdev)
{
        char b[BDEVNAME_SIZE];
        printk(KERN_INFO "md: rdev %s, SZ:%08llu F:%d S:%d DN:%u\n",
                bdevname(rdev->bdev,b), (unsigned long long)rdev->size,
                test_bit(Faulty, &rdev->flags), test_bit(In_sync, &rdev->flags),
                rdev->desc_nr);
        if (rdev->sb_loaded) {
                printk(KERN_INFO "md: rdev superblock:\n");
                print_sb((mdp_super_t*)page_address(rdev->sb_page));
        } else
                printk(KERN_INFO "md: no rdev superblock!\n");
}

static void md_print_devices(void)
{
        struct list_head *tmp, *tmp2;
        mdk_rdev_t *rdev;
        mddev_t *mddev;
        char b[BDEVNAME_SIZE];

        printk("\n");
        printk("md:     **********************************\n");
        printk("md:     * <COMPLETE RAID STATE PRINTOUT> *\n");
        printk("md:     **********************************\n");
        ITERATE_MDDEV(mddev,tmp) {

                if (mddev->bitmap)
                        bitmap_print_sb(mddev->bitmap);
                else
                        printk("%s: ", mdname(mddev));
                ITERATE_RDEV(mddev,rdev,tmp2)
                        printk("<%s>", bdevname(rdev->bdev,b));
                printk("\n");

                ITERATE_RDEV(mddev,rdev,tmp2)
                        print_rdev(rdev);
        }
        printk("md:     **********************************\n");
        printk("\n");
}


static void sync_sbs(mddev_t * mddev, int nospares)
{
        /* Update each superblock (in-memory image), but
         * if we are allowed to, skip spares which already
         * have the right event counter, or have one earlier
         * (which would mean they aren't being marked as dirty
         * with the rest of the array)
         */
        mdk_rdev_t *rdev;
        struct list_head *tmp;

        ITERATE_RDEV(mddev,rdev,tmp) {
                if (rdev->sb_events == mddev->events ||
                    (nospares &&
                     rdev->raid_disk < 0 &&
                     (rdev->sb_events&1)==0 &&
                     rdev->sb_events+1 == mddev->events)) {
                        /* Don't update this superblock */
                        rdev->sb_loaded = 2;
                } else {
                        super_types[mddev->major_version].
                                sync_super(mddev, rdev);
                        rdev->sb_loaded = 1;
                }
        }
}

static void md_update_sb(mddev_t * mddev, int force_change)
{
        struct list_head *tmp;
        mdk_rdev_t *rdev;
        int sync_req;
        int nospares = 0;

repeat:
        spin_lock_irq(&mddev->write_lock);

        set_bit(MD_CHANGE_PENDING, &mddev->flags);
        if (test_and_clear_bit(MD_CHANGE_DEVS, &mddev->flags))
                force_change = 1;
        if (test_and_clear_bit(MD_CHANGE_CLEAN, &mddev->flags))
                /* just a clean<-> dirty transition, possibly leave spares alone,
                 * though if events isn't the right even/odd, we will have to do
                 * spares after all
                 */
                nospares = 1;
        if (force_change)
                nospares = 0;
        if (mddev->degraded)
                /* If the array is degraded, then skipping spares is both
                 * dangerous and fairly pointless.
                 * Dangerous because a device that was removed from the array
                 * might have a event_count that still looks up-to-date,
                 * so it can be re-added without a resync.
                 * Pointless because if there are any spares to skip,
                 * then a recovery will happen and soon that array won't
                 * be degraded any more and the spare can go back to sleep then.
                 */
                nospares = 0;

        sync_req = mddev->in_sync;
        mddev->utime = get_seconds();

        /* If this is just a dirty<->clean transition, and the array is clean
         * and 'events' is odd, we can roll back to the previous clean state */
        if (nospares
            && (mddev->in_sync && mddev->recovery_cp == MaxSector)
            && (mddev->events & 1)
            && mddev->events != 1)
                mddev->events--;
        else {
                /* otherwise we have to go forward and ... */
                mddev->events ++;
                if (!mddev->in_sync || mddev->recovery_cp != MaxSector) { /* not clean */
                        /* .. if the array isn't clean, insist on an odd 'events' */
                        if ((mddev->events&1)==0) {
                                mddev->events++;
                                nospares = 0;
                        }
                } else {
                        /* otherwise insist on an even 'events' (for clean states) */
                        if ((mddev->events&1)) {
                                mddev->events++;
                                nospares = 0;
                        }
                }
        }

        if (!mddev->events) {
                /*
                 * oops, this 64-bit counter should never wrap.
                 * Either we are in around ~1 trillion A.C., assuming
                 * 1 reboot per second, or we have a bug:
                 */
                MD_BUG();
                mddev->events --;
        }
        sync_sbs(mddev, nospares);

        /*
         * do not write anything to disk if using
         * nonpersistent superblocks
         */
        if (!mddev->persistent) {
                clear_bit(MD_CHANGE_PENDING, &mddev->flags);
                spin_unlock_irq(&mddev->write_lock);
                wake_up(&mddev->sb_wait);
                return;
        }
        spin_unlock_irq(&mddev->write_lock);

        dprintk(KERN_INFO 
                "md: updating %s RAID superblock on device (in sync %d)\n",
                mdname(mddev),mddev->in_sync);

        bitmap_update_sb(mddev->bitmap);
        ITERATE_RDEV(mddev,rdev,tmp) {
                char b[BDEVNAME_SIZE];
                dprintk(KERN_INFO "md: ");
                if (rdev->sb_loaded != 1)
                        continue; /* no noise on spare devices */
                if (test_bit(Faulty, &rdev->flags))
                        dprintk("(skipping faulty ");

                dprintk("%s ", bdevname(rdev->bdev,b));
                if (!test_bit(Faulty, &rdev->flags)) {
                        md_super_write(mddev,rdev,
                                       rdev->sb_offset<<1, rdev->sb_size,
                                       rdev->sb_page);
                        dprintk(KERN_INFO "(write) %s's sb offset: %llu\n",
                                bdevname(rdev->bdev,b),
                                (unsigned long long)rdev->sb_offset);
                        rdev->sb_events = mddev->events;

                } else
                        dprintk(")\n");
                if (mddev->level == LEVEL_MULTIPATH)
                        /* only need to write one superblock... */
                        break;
        }
        md_super_wait(mddev);
        /* if there was a failure, MD_CHANGE_DEVS was set, and we re-write super */

        spin_lock_irq(&mddev->write_lock);
        if (mddev->in_sync != sync_req ||
            test_bit(MD_CHANGE_DEVS, &mddev->flags)) {
                /* have to write it out again */
                spin_unlock_irq(&mddev->write_lock);
                goto repeat;
        }
        clear_bit(MD_CHANGE_PENDING, &mddev->flags);
        spin_unlock_irq(&mddev->write_lock);
        wake_up(&mddev->sb_wait);

}

/* words written to sysfs files may, or my not, be \n terminated.
 * We want to accept with case. For this we use cmd_match.
 */
static int cmd_match(const char *cmd, const char *str)
{
        /* See if cmd, written into a sysfs file, matches
         * str.  They must either be the same, or cmd can
         * have a trailing newline
         */
        while (*cmd && *str && *cmd == *str) {
                cmd++;
                str++;
        }
        if (*cmd == '\n')
                cmd++;
        if (*str || *cmd)
                return 0;
        return 1;
}

struct rdev_sysfs_entry {
        struct attribute attr;
        ssize_t (*show)(mdk_rdev_t *, char *);
        ssize_t (*store)(mdk_rdev_t *, const char *, size_t);
};

static ssize_t
state_show(mdk_rdev_t *rdev, char *page)
{
        char *sep = "";
        int len=0;

        if (test_bit(Faulty, &rdev->flags)) {
                len+= sprintf(page+len, "%sfaulty",sep);
                sep = ",";
        }
        if (test_bit(In_sync, &rdev->flags)) {
                len += sprintf(page+len, "%sin_sync",sep);
                sep = ",";
        }
        if (test_bit(WriteMostly, &rdev->flags)) {
                len += sprintf(page+len, "%swrite_mostly",sep);
                sep = ",";
        }
        if (!test_bit(Faulty, &rdev->flags) &&
            !test_bit(In_sync, &rdev->flags)) {
                len += sprintf(page+len, "%sspare", sep);
                sep = ",";
        }
        return len+sprintf(page+len, "\n");
}

static ssize_t
state_store(mdk_rdev_t *rdev, const char *buf, size_t len)
{
        /* can write
         *  faulty  - simulates and error
         *  remove  - disconnects the device
         *  writemostly - sets write_mostly
         *  -writemostly - clears write_mostly
         */
        int err = -EINVAL;
        if (cmd_match(buf, "faulty") && rdev->mddev->pers) {
                md_error(rdev->mddev, rdev);
                err = 0;
        } else if (cmd_match(buf, "remove")) {
                if (rdev->raid_disk >= 0)
                        err = -EBUSY;
                else {
                        mddev_t *mddev = rdev->mddev;
                        kick_rdev_from_array(rdev);
                        if (mddev->pers)
                                md_update_sb(mddev, 1);
                        md_new_event(mddev);
                        err = 0;
                }
        } else if (cmd_match(buf, "writemostly")) {
                set_bit(WriteMostly, &rdev->flags);
                err = 0;
        } else if (cmd_match(buf, "-writemostly")) {
                clear_bit(WriteMostly, &rdev->flags);
                err = 0;
        }
        return err ? err : len;
}
static struct rdev_sysfs_entry rdev_state =
__ATTR(state, S_IRUGO|S_IWUSR, state_show, state_store);

static ssize_t
super_show(mdk_rdev_t *rdev, char *page)
{
        if (rdev->sb_loaded && rdev->sb_size) {
                memcpy(page, page_address(rdev->sb_page), rdev->sb_size);
                return rdev->sb_size;
        } else
                return 0;
}
static struct rdev_sysfs_entry rdev_super = __ATTR_RO(super);

static ssize_t
errors_show(mdk_rdev_t *rdev, char *page)
{
        return sprintf(page, "%d\n", atomic_read(&rdev->corrected_errors));
}

static ssize_t
errors_store(mdk_rdev_t *rdev, const char *buf, size_t len)
{
        char *e;
        unsigned long n = simple_strtoul(buf, &e, 10);
        if (*buf && (*e == 0 || *e == '\n')) {
                atomic_set(&rdev->corrected_errors, n);
                return len;
        }
        return -EINVAL;
}
static struct rdev_sysfs_entry rdev_errors =
__ATTR(errors, S_IRUGO|S_IWUSR, errors_show, errors_store);

static ssize_t
slot_show(mdk_rdev_t *rdev, char *page)
{
        if (rdev->raid_disk < 0)
                return sprintf(page, "none\n");
        else
                return sprintf(page, "%d\n", rdev->raid_disk);
}

static ssize_t
slot_store(mdk_rdev_t *rdev, const char *buf, size_t len)
{
        char *e;
        int slot = simple_strtoul(buf, &e, 10);
        if (strncmp(buf, "none", 4)==0)
                slot = -1;
        else if (e==buf || (*e && *e!= '\n'))
                return -EINVAL;
        if (rdev->mddev->pers)
                /* Cannot set slot in active array (yet) */
                return -EBUSY;
        if (slot >= rdev->mddev->raid_disks)
                return -ENOSPC;
        rdev->raid_disk = slot;
        /* assume it is working */
        rdev->flags = 0;
        set_bit(In_sync, &rdev->flags);
        return len;
}


static struct rdev_sysfs_entry rdev_slot =
__ATTR(slot, S_IRUGO|S_IWUSR, slot_show, slot_store);

static ssize_t
offset_show(mdk_rdev_t *rdev, char *page)
{
        return sprintf(page, "%llu\n", (unsigned long long)rdev->data_offset);
}

static ssize_t
offset_store(mdk_rdev_t *rdev, const char *buf, size_t len)
{
        char *e;
        unsigned long long offset = simple_strtoull(buf, &e, 10);
        if (e==buf || (*e && *e != '\n'))
                return -EINVAL;
        if (rdev->mddev->pers)
                return -EBUSY;
        rdev->data_offset = offset;
        return len;
}

static struct rdev_sysfs_entry rdev_offset =
__ATTR(offset, S_IRUGO|S_IWUSR, offset_show, offset_store);

static ssize_t
rdev_size_show(mdk_rdev_t *rdev, char *page)
{
        return sprintf(page, "%llu\n", (unsigned long long)rdev->size);
}

static ssize_t
rdev_size_store(mdk_rdev_t *rdev, const char *buf, size_t len)
{
        char *e;
        unsigned long long size = simple_strtoull(buf, &e, 10);
        if (e==buf || (*e && *e != '\n'))
                return -EINVAL;
        if (rdev->mddev->pers)
                return -EBUSY;
        rdev->size = size;
        if (size < rdev->mddev->size || rdev->mddev->size == 0)
                rdev->mddev->size = size;
        return len;
}

static struct rdev_sysfs_entry rdev_size =
__ATTR(size, S_IRUGO|S_IWUSR, rdev_size_show, rdev_size_store);

static struct attribute *rdev_default_attrs[] = {
        &rdev_state.attr,
        &rdev_super.attr,
        &rdev_errors.attr,
        &rdev_slot.attr,
        &rdev_offset.attr,
        &rdev_size.attr,
        NULL,
};
static ssize_t
rdev_attr_show(struct kobject *kobj, struct attribute *attr, char *page)
{
        struct rdev_sysfs_entry *entry = container_of(attr, struct rdev_sysfs_entry, attr);
        mdk_rdev_t *rdev = container_of(kobj, mdk_rdev_t, kobj);

        if (!entry->show)
                return -EIO;
        return entry->show(rdev, page);
}

static ssize_t
rdev_attr_store(struct kobject *kobj, struct attribute *attr,
              const char *page, size_t length)
{
        struct rdev_sysfs_entry *entry = container_of(attr, struct rdev_sysfs_entry, attr);
        mdk_rdev_t *rdev = container_of(kobj, mdk_rdev_t, kobj);

        if (!entry->store)
                return -EIO;
        if (!capable(CAP_SYS_ADMIN))
                return -EACCES;
        return entry->store(rdev, page, length);
}

static void rdev_free(struct kobject *ko)
{
        mdk_rdev_t *rdev = container_of(ko, mdk_rdev_t, kobj);
        kfree(rdev);
}
static struct sysfs_ops rdev_sysfs_ops = {
        .show           = rdev_attr_show,

        .store          = rdev_attr_store,
};
static struct kobj_type rdev_ktype = {
        .release        = rdev_free,
        .sysfs_ops      = &rdev_sysfs_ops,
        .default_attrs  = rdev_default_attrs,
};

/*
 * Import a device. If 'super_format' >= 0, then sanity check the superblock
 *
 * mark the device faulty if:
 *
 *   - the device is nonexistent (zero size)
 *   - the device has no valid superblock
 *
 * a faulty rdev _never_ has rdev->sb set.
 */
static mdk_rdev_t *md_import_device(dev_t newdev, int super_format, int super_minor)
{
        char b[BDEVNAME_SIZE];
        int err;
        mdk_rdev_t *rdev;
        sector_t size;

        rdev = kzalloc(sizeof(*rdev), GFP_KERNEL);
        if (!rdev) {
                printk(KERN_ERR "md: could not alloc mem for new device!\n");
                return ERR_PTR(-ENOMEM);
        }

        if ((err = alloc_disk_sb(rdev)))
                goto abort_free;

        err = lock_rdev(rdev, newdev);
        if (err)
                goto abort_free;

        rdev->kobj.parent = NULL;
        rdev->kobj.ktype = &rdev_ktype;
        kobject_init(&rdev->kobj);

        rdev->desc_nr = -1;
        rdev->saved_raid_disk = -1;
        rdev->raid_disk = -1;
        rdev->flags = 0;
        rdev->data_offset = 0;
        rdev->sb_events = 0;
        atomic_set(&rdev->nr_pending, 0);
        atomic_set(&rdev->read_errors, 0);
        atomic_set(&rdev->corrected_errors, 0);

        size = rdev->bdev->bd_inode->i_size >> BLOCK_SIZE_BITS;
        if (!size) {
                printk(KERN_WARNING 
                        "md: %s has zero or unknown size, marking faulty!\n",
                        bdevname(rdev->bdev,b));
                err = -EINVAL;
                goto abort_free;
        }

        if (super_format >= 0) {
                err = super_types[super_format].
                        load_super(rdev, NULL, super_minor);
                if (err == -EINVAL) {
                        printk(KERN_WARNING
                                "md: %s does not have a valid v%d.%d "
                               "superblock, not importing!\n",
                                bdevname(rdev->bdev,b),
                               super_format, super_minor);
                        goto abort_free;
                }
                if (err < 0) {
                        printk(KERN_WARNING 
                                "md: could not read %s's sb, not importing!\n",
                                bdevname(rdev->bdev,b));
                        goto abort_free;
                }
        }
        INIT_LIST_HEAD(&rdev->same_set);

        return rdev;

abort_free:
        if (rdev->sb_page) {
                if (rdev->bdev)
                        unlock_rdev(rdev);
                free_disk_sb(rdev);
        }
        kfree(rdev);
        return ERR_PTR(err);
}

/*
 * Check a full RAID array for plausibility
 */


static void analyze_sbs(mddev_t * mddev)
{
        int i;
        struct list_head *tmp;
        mdk_rdev_t *rdev, *freshest;
        char b[BDEVNAME_SIZE];

        freshest = NULL;
        ITERATE_RDEV(mddev,rdev,tmp)
                switch (super_types[mddev->major_version].
                        load_super(rdev, freshest, mddev->minor_version)) {
                case 1:
                        freshest = rdev;
                        break;
                case 0:
                        break;
                default:
                        printk( KERN_ERR \
                                "md: fatal superblock inconsistency in %s"
                                " -- removing from array\n", 
                                bdevname(rdev->bdev,b));
                        kick_rdev_from_array(rdev);
                }


        super_types[mddev->major_version].
                validate_super(mddev, freshest);

        i = 0;
        ITERATE_RDEV(mddev,rdev,tmp) {
                if (rdev != freshest)
                        if (super_types[mddev->major_version].
                            validate_super(mddev, rdev)) {
                                printk(KERN_WARNING "md: kicking non-fresh %s"
                                        " from array!\n",
                                        bdevname(rdev->bdev,b));
                                kick_rdev_from_array(rdev);
                                continue;
                        }
                if (mddev->level == LEVEL_MULTIPATH) {
                        rdev->desc_nr = i++;
                        rdev->raid_disk = rdev->desc_nr;
                        set_bit(In_sync, &rdev->flags);
                } else if (rdev->raid_disk >= mddev->raid_disks) {
                        rdev->raid_disk = -1;
                        clear_bit(In_sync, &rdev->flags);
                }
        }



        if (mddev->recovery_cp != MaxSector &&
            mddev->level >= 1)
                printk(KERN_ERR "md: %s: raid array is not clean"
                       " -- starting background reconstruction\n",
                       mdname(mddev));

}

static ssize_t
safe_delay_show(mddev_t *mddev, char *page)
{
        int msec = (mddev->safemode_delay*1000)/HZ;
        return sprintf(page, "%d.%03d\n", msec/1000, msec%1000);
}
static ssize_t
safe_delay_store(mddev_t *mddev, const char *cbuf, size_t len)
{
        int scale=1;
        int dot=0;
        int i;
        unsigned long msec;
        char buf[30];
        char *e;
        /* remove a period, and count digits after it */
        if (len >= sizeof(buf))
                return -EINVAL;
        strlcpy(buf, cbuf, len);
        buf[len] = 0;
        for (i=0; i<len; i++) {
                if (dot) {
                        if (isdigit(buf[i])) {
                                buf[i-1] = buf[i];
                                scale *= 10;
                        }
                        buf[i] = 0;
                } else if (buf[i] == '.') {
                        dot=1;
                        buf[i] = 0;
                }
        }
        msec = simple_strtoul(buf, &e, 10);
        if (e == buf || (*e && *e != '\n'))
                return -EINVAL;
        msec = (msec * 1000) / scale;
        if (msec == 0)
                mddev->safemode_delay = 0;
        else {
                mddev->safemode_delay = (msec*HZ)/1000;
                if (mddev->safemode_delay == 0)
                        mddev->safemode_delay = 1;
        }
        return len;
}
static struct md_sysfs_entry md_safe_delay =
__ATTR(safe_mode_delay, S_IRUGO|S_IWUSR,safe_delay_show, safe_delay_store);

static ssize_t
level_show(mddev_t *mddev, char *page)
{
        struct mdk_personality *p = mddev->pers;
        if (p)
                return sprintf(page, "%s\n", p->name);
        else if (mddev->clevel[0])
                return sprintf(page, "%s\n", mddev->clevel);
        else if (mddev->level != LEVEL_NONE)
                return sprintf(page, "%d\n", mddev->level);
        else
                return 0;
}

static ssize_t
level_store(mddev_t *mddev, const char *buf, size_t len)
{
        int rv = len;
        if (mddev->pers)
                return -EBUSY;
        if (len == 0)
                return 0;
        if (len >= sizeof(mddev->clevel))
                return -ENOSPC;
        strncpy(mddev->clevel, buf, len);
        if (mddev->clevel[len-1] == '\n')
                len--;
        mddev->clevel[len] = 0;
        mddev->level = LEVEL_NONE;
        return rv;
}

static struct md_sysfs_entry md_level =
__ATTR(level, S_IRUGO|S_IWUSR, level_show, level_store);


static ssize_t
layout_show(mddev_t *mddev, char *page)
{
        /* just a number, not meaningful for all levels */
        if (mddev->reshape_position != MaxSector &&
            mddev->layout != mddev->new_layout)
                return sprintf(page, "%d (%d)\n",
                               mddev->new_layout, mddev->layout);
        return sprintf(page, "%d\n", mddev->layout);
}

static ssize_t
layout_store(mddev_t *mddev, const char *buf, size_t len)
{
        char *e;
        unsigned long n = simple_strtoul(buf, &e, 10);

        if (!*buf || (*e && *e != '\n'))
                return -EINVAL;

        if (mddev->pers)
                return -EBUSY;
        if (mddev->reshape_position != MaxSector)
                mddev->new_layout = n;
        else
                mddev->layout = n;
        return len;
}
static struct md_sysfs_entry md_layout =
__ATTR(layout, S_IRUGO|S_IWUSR, layout_show, layout_store);


static ssize_t
raid_disks_show(mddev_t *mddev, char *page)
{
        if (mddev->raid_disks == 0)
                return 0;
        if (mddev->reshape_position != MaxSector &&
            mddev->delta_disks != 0)
                return sprintf(page, "%d (%d)\n", mddev->raid_disks,
                               mddev->raid_disks - mddev->delta_disks);
        return sprintf(page, "%d\n", mddev->raid_disks);
}

static int update_raid_disks(mddev_t *mddev, int raid_disks);

static ssize_t
raid_disks_store(mddev_t *mddev, const char *buf, size_t len)
{
        char *e;
        int rv = 0;
        unsigned long n = simple_strtoul(buf, &e, 10);

        if (!*buf || (*e && *e != '\n'))
                return -EINVAL;

        if (mddev->pers)
                rv = update_raid_disks(mddev, n);
        else if (mddev->reshape_position != MaxSector) {
                int olddisks = mddev->raid_disks - mddev->delta_disks;
                mddev->delta_disks = n - olddisks;
                mddev->raid_disks = n;
        } else
                mddev->raid_disks = n;
        return rv ? rv : len;
}
static struct md_sysfs_entry md_raid_disks =
__ATTR(raid_disks, S_IRUGO|S_IWUSR, raid_disks_show, raid_disks_store);

static ssize_t
chunk_size_show(mddev_t *mddev, char *page)
{
        if (mddev->reshape_position != MaxSector &&
            mddev->chunk_size != mddev->new_chunk)
                return sprintf(page, "%d (%d)\n", mddev->new_chunk,
                               mddev->chunk_size);
        return sprintf(page, "%d\n", mddev->chunk_size);
}

static ssize_t
chunk_size_store(mddev_t *mddev, const char *buf, size_t len)
{
        /* can only set chunk_size if array is not yet active */
        char *e;
        unsigned long n = simple_strtoul(buf, &e, 10);

        if (!*buf || (*e && *e != '\n'))
                return -EINVAL;

        if (mddev->pers)
                return -EBUSY;
        else if (mddev->reshape_position != MaxSector)
                mddev->new_chunk = n;
        else
                mddev->chunk_size = n;
        return len;
}
static struct md_sysfs_entry md_chunk_size =
__ATTR(chunk_size, S_IRUGO|S_IWUSR, chunk_size_show, chunk_size_store);

static ssize_t
resync_start_show(mddev_t *mddev, char *page)
{
        return sprintf(page, "%llu\n", (unsigned long long)mddev->recovery_cp);
}

static ssize_t
resync_start_store(mddev_t *mddev, const char *buf, size_t len)
{
        /* can only set chunk_size if array is not yet active */
        char *e;
        unsigned long long n = simple_strtoull(buf, &e, 10);

        if (mddev->pers)
                return -EBUSY;
        if (!*buf || (*e && *e != '\n'))
                return -EINVAL;

        mddev->recovery_cp = n;
        return len;
}
static struct md_sysfs_entry md_resync_start =
__ATTR(resync_start, S_IRUGO|S_IWUSR, resync_start_show, resync_start_store);

/*
 * The array state can be:
 *
 * clear
 *     No devices, no size, no level
 *     Equivalent to STOP_ARRAY ioctl
 * inactive
 *     May have some settings, but array is not active
 *        all IO results in error
 *     When written, doesn't tear down array, but just stops it
 * suspended (not supported yet)
 *     All IO requests will block. The array can be reconfigured.
 *     Writing this, if accepted, will block until array is quiessent
 * readonly
 *     no resync can happen.  no superblocks get written.
 *     write requests fail
 * read-auto
 *     like readonly, but behaves like 'clean' on a write request.
 *
 * clean - no pending writes, but otherwise active.
 *     When written to inactive array, starts without resync
 *     If a write request arrives then
 *       if metadata is known, mark 'dirty' and switch to 'active'.
 *       if not known, block and switch to write-pending
 *     If written to an active array that has pending writes, then fails.
 * active
 *     fully active: IO and resync can be happening.
 *     When written to inactive array, starts with resync
 *
 * write-pending
 *     clean, but writes are blocked waiting for 'active' to be written.
 *
 * active-idle
 *     like active, but no writes have been seen for a while (100msec).
 *
 */
enum array_state { clear, inactive, suspended, readonly, read_auto, clean, active,
                   write_pending, active_idle, bad_word};
static char *array_states[] = {
        "clear", "inactive", "suspended", "readonly", "read-auto", "clean", "active",
        "write-pending", "active-idle", NULL };

static int match_word(const char *word, char **list)
{
        int n;
        for (n=0; list[n]; n++)
                if (cmd_match(word, list[n]))
                        break;
        return n;
}

static ssize_t
array_state_show(mddev_t *mddev, char *page)
{
        enum array_state st = inactive;

        if (mddev->pers)
                switch(mddev->ro) {
                case 1:
                        st = readonly;
                        break;
                case 2:
                        st = read_auto;
                        break;
                case 0:
                        if (mddev->in_sync)
                                st = clean;
                        else if (mddev->safemode)
                                st = active_idle;
                        else
                                st = active;
                }
        else {
                if (list_empty(&mddev->disks) &&
                    mddev->raid_disks == 0 &&
                    mddev->size == 0)
                        st = clear;
                else
                        st = inactive;
        }
        return sprintf(page, "%s\n", array_states[st]);
}

static int do_md_stop(mddev_t * mddev, int ro);
static int do_md_run(mddev_t * mddev);
static int restart_array(mddev_t *mddev);

static ssize_t
array_state_store(mddev_t *mddev, const char *buf, size_t len)
{
        int err = -EINVAL;
        enum array_state st = match_word(buf, array_states);
        switch(st) {
        case bad_word:
                break;
        case clear:
                /* stopping an active array */
                if (mddev->pers) {
                        if (atomic_read(&mddev->active) > 1)
                                return -EBUSY;
                        err = do_md_stop(mddev, 0);
                }
                break;
        case inactive:
                /* stopping an active array */
                if (mddev->pers) {
                        if (atomic_read(&mddev->active) > 1)
                                return -EBUSY;
                        err = do_md_stop(mddev, 2);
                }
                break;
        case suspended:
                break; /* not supported yet */
        case readonly:
                if (mddev->pers)
                        err = do_md_stop(mddev, 1);
                else {
                        mddev->ro = 1;
                        err = do_md_run(mddev);
                }
                break;
        case read_auto:
                /* stopping an active array */
                if (mddev->pers) {
                        err = do_md_stop(mddev, 1);
                        if (err == 0)
                                mddev->ro = 2; /* FIXME mark devices writable */
                } else {
                        mddev->ro = 2;
                        err = do_md_run(mddev);
                }
                break;
        case clean:
                if (mddev->pers) {
                        restart_array(mddev);
                        spin_lock_irq(&mddev->write_lock);
                        if (atomic_read(&mddev->writes_pending) == 0) {
                                mddev->in_sync = 1;
                                set_bit(MD_CHANGE_CLEAN, &mddev->flags);
                        }
                        spin_unlock_irq(&mddev->write_lock);
                } else {
                        mddev->ro = 0;
                        mddev->recovery_cp = MaxSector;
                        err = do_md_run(mddev);
                }
                break;
        case active:
                if (mddev->pers) {
                        restart_array(mddev);
                        clear_bit(MD_CHANGE_CLEAN, &mddev->flags);
                        wake_up(&mddev->sb_wait);
                        err = 0;
                } else {
                        mddev->ro = 0;
                        err = do_md_run(mddev);
                }
                break;
        case write_pending:
        case active_idle:
                /* these cannot be set */
                break;
        }
        if (err)
                return err;
        else
                return len;
}
static struct md_sysfs_entry md_array_state =
__ATTR(array_state, S_IRUGO|S_IWUSR, array_state_show, array_state_store);

static ssize_t
null_show(mddev_t *mddev, char *page)
{
        return -EINVAL;
}

static ssize_t
new_dev_store(mddev_t *mddev, const char *buf, size_t len)
{
        /* buf must be %d:%d\n? giving major and minor numbers */
        /* The new device is added to the array.
         * If the array has a persistent superblock, we read the
         * superblock to initialise info and check validity.
         * Otherwise, only checking done is that in bind_rdev_to_array,
         * which mainly checks size.
         */
        char *e;
        int major = simple_strtoul(buf, &e, 10);
        int minor;
        dev_t dev;
        mdk_rdev_t *rdev;
        int err;

        if (!*buf || *e != ':' || !e[1] || e[1] == '\n')
                return -EINVAL;
        minor = simple_strtoul(e+1, &e, 10);
        if (*e && *e != '\n')
                return -EINVAL;
        dev = MKDEV(major, minor);
        if (major != MAJOR(dev) ||
            minor != MINOR(dev))
                return -EOVERFLOW;


        if (mddev->persistent) {
                rdev = md_import_device(dev, mddev->major_version,
                                        mddev->minor_version);
                if (!IS_ERR(rdev) && !list_empty(&mddev->disks)) {
                        mdk_rdev_t *rdev0 = list_entry(mddev->disks.next,
                                                       mdk_rdev_t, same_set);
                        err = super_types[mddev->major_version]
                                .load_super(rdev, rdev0, mddev->minor_version);
                        if (err < 0)
                                goto out;
                }
        } else
                rdev = md_import_device(dev, -1, -1);

        if (IS_ERR(rdev))
                return PTR_ERR(rdev);
        err = bind_rdev_to_array(rdev, mddev);
 out:
        if (err)
                export_rdev(rdev);
        return err ? err : len;
}

static struct md_sysfs_entry md_new_device =
__ATTR(new_dev, S_IWUSR, null_show, new_dev_store);

static ssize_t
bitmap_store(mddev_t *mddev, const char *buf, size_t len)
{
        char *end;
        unsigned long chunk, end_chunk;

        if (!mddev->bitmap)
                goto out;
        /* buf should be <chunk> <chunk> ... or <chunk>-<chunk> ... (range) */
        while (*buf) {
                chunk = end_chunk = simple_strtoul(buf, &end, 0);
                if (buf == end) break;
                if (*end == '-') { /* range */
                        buf = end + 1;
                        end_chunk = simple_strtoul(buf, &end, 0);
                        if (buf == end) break;
                }
                if (*end && !isspace(*end)) break;
                bitmap_dirty_bits(mddev->bitmap, chunk, end_chunk);
                buf = end;
                while (isspace(*buf)) buf++;
        }
        bitmap_unplug(mddev->bitmap); /* flush the bits to disk */
out:
        return len;
}

static struct md_sysfs_entry md_bitmap =
__ATTR(bitmap_set_bits, S_IWUSR, null_show, bitmap_store);

static ssize_t
size_show(mddev_t *mddev, char *page)
{
        return sprintf(page, "%llu\n", (unsigned long long)mddev->size);
}

static int update_size(mddev_t *mddev, unsigned long size);

static ssize_t
size_store(mddev_t *mddev, const char *buf, size_t len)
{
        /* If array is inactive, we can reduce the component size, but
         * not increase it (except from 0).
         * If array is active, we can try an on-line resize
         */
        char *e;
        int err = 0;
        unsigned long long size = simple_strtoull(buf, &e, 10);
        if (!*buf || *buf == '\n' ||
            (*e && *e != '\n'))
                return -EINVAL;

        if (mddev->pers) {
                err = update_size(mddev, size);
                md_update_sb(mddev, 1);
        } else {
                if (mddev->size == 0 ||
                    mddev->size > size)
                        mddev->size = size;
                else
                        err = -ENOSPC;
        }
        return err ? err : len;
}

static struct md_sysfs_entry md_size =
__ATTR(component_size, S_IRUGO|S_IWUSR, size_show, size_store);


/* Metdata version.
 * This is either 'none' for arrays with externally managed metadata,
 * or N.M for internally known formats
 */
static ssize_t
metadata_show(mddev_t *mddev, char *page)
{
        if (mddev->persistent)
                return sprintf(page, "%d.%d\n",
                               mddev->major_version, mddev->minor_version);
        else
                return sprintf(page, "none\n");
}

static ssize_t
metadata_store(mddev_t *mddev, const char *buf, size_t len)
{
        int major, minor;
        char *e;
        if (!list_empty(&mddev->disks))
                return -EBUSY;

        if (cmd_match(buf, "none")) {
                mddev->persistent = 0;
                mddev->major_version = 0;
                mddev->minor_version = 90;
                return len;
        }
        major = simple_strtoul(buf, &e, 10);
        if (e==buf || *e != '.')
                return -EINVAL;
        buf = e+1;
        minor = simple_strtoul(buf, &e, 10);
        if (e==buf || (*e && *e != '\n') )
                return -EINVAL;
        if (major >= ARRAY_SIZE(super_types) || super_types[major].name == NULL)
                return -ENOENT;
        mddev->major_version = major;
        mddev->minor_version = minor;
        mddev->persistent = 1;
        return len;
}

static struct md_sysfs_entry md_metadata =
__ATTR(metadata_version, S_IRUGO|S_IWUSR, metadata_show, metadata_store);

static ssize_t
action_show(mddev_t *mddev, char *page)
{
        char *type = "idle";
        if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery) ||
            (!mddev->ro && test_bit(MD_RECOVERY_NEEDED, &mddev->recovery))) {
                if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery))
                        type = "reshape";
                else if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
                        if (!test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery))
                                type = "resync";
                        else if (test_bit(MD_RECOVERY_CHECK, &mddev->recovery))
                                type = "check";
                        else
                                type = "repair";
                } else
                        type = "recover";
        }
        return sprintf(page, "%s\n", type);
}

static ssize_t
action_store(mddev_t *mddev, const char *page, size_t len)
{
        if (!mddev->pers || !mddev->pers->sync_request)
                return -EINVAL;

        if (cmd_match(page, "idle")) {
                if (mddev->sync_thread) {
                        set_bit(MD_RECOVERY_INTR, &mddev->recovery);
                        md_unregister_thread(mddev->sync_thread);
                        mddev->sync_thread = NULL;
                        mddev->recovery = 0;
                }
        } else if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery) ||
                   test_bit(MD_RECOVERY_NEEDED, &mddev->recovery))
                return -EBUSY;
        else if (cmd_match(page, "resync") || cmd_match(page, "recover"))
                set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
        else if (cmd_match(page, "reshape")) {
                int err;
                if (mddev->pers->start_reshape == NULL)
                        return -EINVAL;
                err = mddev->pers->start_reshape(mddev);
                if (err)
                        return err;
        } else {
                if (cmd_match(page, "check"))
                        set_bit(MD_RECOVERY_CHECK, &mddev->recovery);
                else if (!cmd_match(page, "repair"))
                        return -EINVAL;
                set_bit(MD_RECOVERY_REQUESTED, &mddev->recovery);
                set_bit(MD_RECOVERY_SYNC, &mddev->recovery);
        }
        set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
        md_wakeup_thread(mddev->thread);
        return len;
}

static ssize_t
mismatch_cnt_show(mddev_t *mddev, char *page)
{
        return sprintf(page, "%llu\n",
                       (unsigned long long) mddev->resync_mismatches);
}

static struct md_sysfs_entry md_scan_mode =
__ATTR(sync_action, S_IRUGO|S_IWUSR, action_show, action_store);


static struct md_sysfs_entry md_mismatches = __ATTR_RO(mismatch_cnt);

static ssize_t
sync_min_show(mddev_t *mddev, char *page)
{
        return sprintf(page, "%d (%s)\n", speed_min(mddev),
                       mddev->sync_speed_min ? "local": "system");
}

static ssize_t
sync_min_store(mddev_t *mddev, const char *buf, size_t len)
{
        int min;
        char *e;
        if (strncmp(buf, "system", 6)==0) {
                mddev->sync_speed_min = 0;
                return len;
        }
        min = simple_strtoul(buf, &e, 10);
        if (buf == e || (*e && *e != '\n') || min <= 0)
                return -EINVAL;
        mddev->sync_speed_min = min;
        return len;
}

static struct md_sysfs_entry md_sync_min =
__ATTR(sync_speed_min, S_IRUGO|S_IWUSR, sync_min_show, sync_min_store);

static ssize_t
sync_max_show(mddev_t *mddev, char *page)
{
        return sprintf(page, "%d (%s)\n", speed_max(mddev),
                       mddev->sync_speed_max ? "local": "system");
}

static ssize_t
sync_max_store(mddev_t *mddev, const char *buf, size_t len)
{
        int max;
        char *e;
        if (strncmp(buf, "system", 6)==0) {
                mddev->sync_speed_max = 0;
                return len;
        }
        max = simple_strtoul(buf, &e, 10);
        if (buf == e || (*e && *e != '\n') || max <= 0)
                return -EINVAL;
        mddev->sync_speed_max = max;
        return len;
}

static struct md_sysfs_entry md_sync_max =
__ATTR(sync_speed_max, S_IRUGO|S_IWUSR, sync_max_show, sync_max_store);

static ssize_t
degraded_show(mddev_t *mddev, char *page)
{
        return sprintf(page, "%d\n", mddev->degraded);
}
static struct md_sysfs_entry md_degraded = __ATTR_RO(degraded);

static ssize_t
sync_speed_show(mddev_t *mddev, char *page)
{
        unsigned long resync, dt, db;
        resync = (mddev->curr_mark_cnt - atomic_read(&mddev->recovery_active));
        dt = ((jiffies - mddev->resync_mark) / HZ);
        if (!dt) dt++;
        db = resync - (mddev->resync_mark_cnt);
        return sprintf(page, "%ld\n", db/dt/2); /* K/sec */
}

static struct md_sysfs_entry md_sync_speed = __ATTR_RO(sync_speed);

static ssize_t
sync_completed_show(mddev_t *mddev, char *page)
{
        unsigned long max_blocks, resync;

        if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery))
                max_blocks = mddev->resync_max_sectors;
        else
                max_blocks = mddev->size << 1;

        resync = (mddev->curr_resync - atomic_read(&mddev->recovery_active));
        return sprintf(page, "%lu / %lu\n", resync, max_blocks);
}

static struct md_sysfs_entry md_sync_completed = __ATTR_RO(sync_completed);

static ssize_t
suspend_lo_show(mddev_t *mddev, char *page)
{
        return sprintf(page, "%llu\n", (unsigned long long)mddev->suspend_lo);
}

static ssize_t
suspend_lo_store(mddev_t *mddev, const char *buf, size_t len)
{
        char *e;
        unsigned long long new = simple_strtoull(buf, &e, 10);

        if (mddev->pers->quiesce == NULL)
                return -EINVAL;
        if (buf == e || (*e && *e != '\n'))
                return -EINVAL;
        if (new >= mddev->suspend_hi ||
            (new > mddev->suspend_lo && new < mddev->suspend_hi)) {
                mddev->suspend_lo = new;
                mddev->pers->quiesce(mddev, 2);
                return len;
        } else
                return -EINVAL;
}
static struct md_sysfs_entry md_suspend_lo =
__ATTR(suspend_lo, S_IRUGO|S_IWUSR, suspend_lo_show, suspend_lo_store);


static ssize_t
suspend_hi_show(mddev_t *mddev, char *page)
{
        return sprintf(page, "%llu\n", (unsigned long long)mddev->suspend_hi);
}

static ssize_t
suspend_hi_store(mddev_t *mddev, const char *buf, size_t len)
{
        char *e;
        unsigned long long new = simple_strtoull(buf, &e, 10);

        if (mddev->pers->quiesce == NULL)
                return -EINVAL;
        if (buf == e || (*e && *e != '\n'))
                return -EINVAL;
        if ((new <= mddev->suspend_lo && mddev->suspend_lo >= mddev->suspend_hi) ||
            (new > mddev->suspend_lo && new > mddev->suspend_hi)) {
                mddev->suspend_hi = new;
                mddev->pers->quiesce(mddev, 1);
                mddev->pers->quiesce(mddev, 0);
                return len;
        } else
                return -EINVAL;
}
static struct md_sysfs_entry md_suspend_hi =
__ATTR(suspend_hi, S_IRUGO|S_IWUSR, suspend_hi_show, suspend_hi_store);

static ssize_t
reshape_position_show(mddev_t *mddev, char *page)
{
        if (mddev->reshape_position != MaxSector)
                return sprintf(page, "%llu\n",
                               (unsigned long long)mddev->reshape_position);
        strcpy(page, "none\n");
        return 5;
}

static ssize_t
reshape_position_store(mddev_t *mddev, const char *buf, size_t len)
{
        char *e;
        unsigned long long new = simple_strtoull(buf, &e, 10);
        if (mddev->pers)
                return -EBUSY;
        if (buf == e || (*e && *e != '\n'))
                return -EINVAL;
        mddev->reshape_position = new;
        mddev->delta_disks = 0;
        mddev->new_level = mddev->level;
        mddev->new_layout = mddev->layout;
        mddev->new_chunk = mddev->chunk_size;
        return len;
}

static struct md_sysfs_entry md_reshape_position =
__ATTR(reshape_position, S_IRUGO|S_IWUSR, reshape_position_show,
       reshape_position_store);


static struct attribute *md_default_attrs[] = {
        &md_level.attr,
        &md_layout.attr,
        &md_raid_disks.attr,
        &md_chunk_size.attr,
        &md_size.attr,
        &md_resync_start.attr,
        &md_metadata.attr,
        &md_new_device.attr,
        &md_safe_delay.attr,
        &md_array_state.attr,
        &md_reshape_position.attr,
        NULL,
};

static struct attribute *md_redundancy_attrs[] = {
        &md_scan_mode.attr,
        &md_mismatches.attr,
        &md_sync_min.attr,
        &md_sync_max.attr,
        &md_sync_speed.attr,
        &md_sync_completed.attr,
        &md_suspend_lo.attr,
        &md_suspend_hi.attr,
        &md_bitmap.attr,
        &md_degraded.attr,
        NULL,
};
static struct attribute_group md_redundancy_group = {
        .name = NULL,
        .attrs = md_redundancy_attrs,
};


static ssize_t
md_attr_show(struct kobject *kobj, struct attribute *attr, char *page)
{
        struct md_sysfs_entry *entry = container_of(attr, struct md_sysfs_entry, attr);
        mddev_t *mddev = container_of(kobj, struct mddev_s, kobj);
        ssize_t rv;