/*
   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/kthread.h>
#include <linux/blkdev.h>
#include <linux/sysctl.h>
#include <linux/seq_file.h>
#include <linux/buffer_head.h> /* for invalidate_bdev */
#include <linux/poll.h>
#include <linux/ctype.h>
#include <linux/string.h>
#include <linux/hdreg.h>
#include <linux/proc_fs.h>
#include <linux/random.h>
#include <linux/reboot.h>
#include <linux/file.h>
#include <linux/compat.h>
#include <linux/delay.h>
#include <linux/raid/md_p.h>
#include <linux/raid/md_u.h>
#include "md.h"
#include "bitmap.h"

#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);

static DECLARE_WAIT_QUEUE_HEAD(resync_wait);

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

/*
 * Default number of read corrections we'll attempt on an rdev
 * before ejecting it from the array. We divide the read error
 * count by 2 for every hour elapsed between read errors.
 */
#define MD_DEFAULT_MAX_CORRECTED_READ_ERRORS 20
/*
 * 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[] = {
        {
                .procname       = "speed_limit_min",
                .data           = &sysctl_speed_limit_min,
                .maxlen         = sizeof(int),
                .mode           = S_IRUGO|S_IWUSR,
                .proc_handler   = proc_dointvec,
        },
        {
                .procname       = "speed_limit_max",
                .data           = &sysctl_speed_limit_max,
                .maxlen         = sizeof(int),
                .mode           = S_IRUGO|S_IWUSR,
                .proc_handler   = proc_dointvec,
        },
        { }
};

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

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

static const 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);
}
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 for_each_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;})                                      \
                )


/* Rather than calling directly into the personality make_request function,
 * IO requests come here first so that we can check if the device is
 * being suspended pending a reconfiguration.
 * We hold a refcount over the call to ->make_request.  By the time that
 * call has finished, the bio has been linked into some internal structure
 * and so is visible to ->quiesce(), so we don't need the refcount any more.
 */
static int md_make_request(struct request_queue *q, struct bio *bio)
{
        mddev_t *mddev = q->queuedata;
        int rv;
        if (mddev == NULL || mddev->pers == NULL) {
                bio_io_error(bio);
                return 0;
        }
        rcu_read_lock();
        if (mddev->suspended || mddev->barrier) {
                DEFINE_WAIT(__wait);
                for (;;) {
                        prepare_to_wait(&mddev->sb_wait, &__wait,
                                        TASK_UNINTERRUPTIBLE);
                        if (!mddev->suspended && !mddev->barrier)
                                break;
                        rcu_read_unlock();
                        schedule();
                        rcu_read_lock();
                }
                finish_wait(&mddev->sb_wait, &__wait);
        }
        atomic_inc(&mddev->active_io);
        rcu_read_unlock();
        rv = mddev->pers->make_request(q, bio);
        if (atomic_dec_and_test(&mddev->active_io) && mddev->suspended)
                wake_up(&mddev->sb_wait);

        return rv;
}

static void mddev_suspend(mddev_t *mddev)
{
        BUG_ON(mddev->suspended);
        mddev->suspended = 1;
        synchronize_rcu();
        wait_event(mddev->sb_wait, atomic_read(&mddev->active_io) == 0);
        mddev->pers->quiesce(mddev, 1);
        md_unregister_thread(mddev->thread);
        mddev->thread = NULL;
        /* we now know that no code is executing in the personality module,
         * except possibly the tail end of a ->bi_end_io function, but that
         * is certain to complete before the module has a chance to get
         * unloaded
         */
}

static void mddev_resume(mddev_t *mddev)
{
        mddev->suspended = 0;
        wake_up(&mddev->sb_wait);
        mddev->pers->quiesce(mddev, 0);
}

int mddev_congested(mddev_t *mddev, int bits)
{
        if (mddev->barrier)
                return 1;
        return mddev->suspended;
}
EXPORT_SYMBOL(mddev_congested);

/*
 * Generic barrier handling for md
 */

#define POST_REQUEST_BARRIER ((void*)1)

static void md_end_barrier(struct bio *bio, int err)
{
        mdk_rdev_t *rdev = bio->bi_private;
        mddev_t *mddev = rdev->mddev;
        if (err == -EOPNOTSUPP && mddev->barrier != POST_REQUEST_BARRIER)
                set_bit(BIO_EOPNOTSUPP, &mddev->barrier->bi_flags);

        rdev_dec_pending(rdev, mddev);

        if (atomic_dec_and_test(&mddev->flush_pending)) {
                if (mddev->barrier == POST_REQUEST_BARRIER) {
                        /* This was a post-request barrier */
                        mddev->barrier = NULL;
                        wake_up(&mddev->sb_wait);
                } else
                        /* The pre-request barrier has finished */
                        schedule_work(&mddev->barrier_work);
        }
        bio_put(bio);
}

static void submit_barriers(mddev_t *mddev)
{
        mdk_rdev_t *rdev;

        rcu_read_lock();
        list_for_each_entry_rcu(rdev, &mddev->disks, same_set)
                if (rdev->raid_disk >= 0 &&
                    !test_bit(Faulty, &rdev->flags)) {
                        /* Take two references, one is dropped
                         * when request finishes, one after
                         * we reclaim rcu_read_lock
                         */
                        struct bio *bi;
                        atomic_inc(&rdev->nr_pending);
                        atomic_inc(&rdev->nr_pending);
                        rcu_read_unlock();
                        bi = bio_alloc(GFP_KERNEL, 0);
                        bi->bi_end_io = md_end_barrier;
                        bi->bi_private = rdev;
                        bi->bi_bdev = rdev->bdev;
                        atomic_inc(&mddev->flush_pending);
                        submit_bio(WRITE_BARRIER, bi);
                        rcu_read_lock();
                        rdev_dec_pending(rdev, mddev);
                }
        rcu_read_unlock();
}

static void md_submit_barrier(struct work_struct *ws)
{
        mddev_t *mddev = container_of(ws, mddev_t, barrier_work);
        struct bio *bio = mddev->barrier;

        atomic_set(&mddev->flush_pending, 1);

        if (test_bit(BIO_EOPNOTSUPP, &bio->bi_flags))
                bio_endio(bio, -EOPNOTSUPP);
        else if (bio->bi_size == 0)
                /* an empty barrier - all done */
                bio_endio(bio, 0);
        else {
                bio->bi_rw &= ~(1<<BIO_RW_BARRIER);
                if (mddev->pers->make_request(mddev->queue, bio))
                        generic_make_request(bio);
                mddev->barrier = POST_REQUEST_BARRIER;
                submit_barriers(mddev);
        }
        if (atomic_dec_and_test(&mddev->flush_pending)) {
                mddev->barrier = NULL;
                wake_up(&mddev->sb_wait);
        }
}

void md_barrier_request(mddev_t *mddev, struct bio *bio)
{
        spin_lock_irq(&mddev->write_lock);
        wait_event_lock_irq(mddev->sb_wait,
                            !mddev->barrier,
                            mddev->write_lock, /*nothing*/);
        mddev->barrier = bio;
        spin_unlock_irq(&mddev->write_lock);

        atomic_set(&mddev->flush_pending, 1);
        INIT_WORK(&mddev->barrier_work, md_submit_barrier);

        submit_barriers(mddev);

        if (atomic_dec_and_test(&mddev->flush_pending))
                schedule_work(&mddev->barrier_work);
}
EXPORT_SYMBOL(md_barrier_request);

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

static void mddev_delayed_delete(struct work_struct *ws);

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) &&
            mddev->ctime == 0 && !mddev->hold_active) {
                /* Array is not configured at all, and not held active,
                 * so destroy it */
                list_del(&mddev->all_mddevs);
                if (mddev->gendisk) {
                        /* we did a probe so need to clean up.
                         * Call schedule_work inside the spinlock
                         * so that flush_scheduled_work() after
                         * mddev_find will succeed in waiting for the
                         * work to be done.
                         */
                        INIT_WORK(&mddev->del_work, mddev_delayed_delete);
                        schedule_work(&mddev->del_work);
                } else
                        kfree(mddev);
        }
        spin_unlock(&all_mddevs_lock);
}

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

 retry:
        spin_lock(&all_mddevs_lock);

        if (unit) {
                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);
                        new->hold_active = UNTIL_IOCTL;
                        return new;
                }
        } else if (new) {
                /* find an unused unit number */
                static int next_minor = 512;
                int start = next_minor;
                int is_free = 0;
                int dev = 0;
                while (!is_free) {
                        dev = MKDEV(MD_MAJOR, next_minor);
                        next_minor++;
                        if (next_minor > MINORMASK)
                                next_minor = 0;
                        if (next_minor == start) {
                                /* Oh dear, all in use. */
                                spin_unlock(&all_mddevs_lock);
                                kfree(new);
                                return NULL;
                        }
                                
                        is_free = 1;
                        list_for_each_entry(mddev, &all_mddevs, all_mddevs)
                                if (mddev->unit == dev) {
                                        is_free = 0;
                                        break;
                                }
                }
                new->unit = dev;
                new->md_minor = MINOR(dev);
                new->hold_active = UNTIL_STOP;
                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->open_mutex);
        mutex_init(&new->reconfig_mutex);
        mutex_init(&new->bitmap_info.mutex);
        INIT_LIST_HEAD(&new->disks);
        INIT_LIST_HEAD(&new->all_mddevs);
        init_timer(&new->safemode_timer);
        atomic_set(&new->active, 1);
        atomic_set(&new->openers, 0);
        atomic_set(&new->active_io, 0);
        spin_lock_init(&new->write_lock);
        atomic_set(&new->flush_pending, 0);
        init_waitqueue_head(&new->sb_wait);
        init_waitqueue_head(&new->recovery_wait);
        new->reshape_position = MaxSector;
        new->resync_min = 0;
        new->resync_max = MaxSector;
        new->level = LEVEL_NONE;

        goto retry;
}

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

static inline int mddev_is_locked(mddev_t *mddev)
{
        return mutex_is_locked(&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;

        list_for_each_entry(rdev, &mddev->disks, same_set)
                if (rdev->desc_nr == nr)
                        return rdev;

        return NULL;
}

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

        list_for_each_entry(rdev, &mddev->disks, same_set)
                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;
}

/* return the offset of the super block in 512byte sectors */
static inline sector_t calc_dev_sboffset(struct block_device *bdev)
{
        sector_t num_sectors = bdev->bd_inode->i_size / 512;
        return MD_NEW_SIZE_SECTORS(num_sectors);
}

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 -ENOMEM;
        }

        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_start = 0;
                rdev->sectors = 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_SYNCIO) | (1<<BIO_RW_UNPLUG);

        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_SYNCIO) | (1 << BIO_RW_UNPLUG);

        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_start, 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)
{
        return  sb1->set_uuid0 == sb2->set_uuid0 &&
                sb1->set_uuid1 == sb2->set_uuid1 &&
                sb1->set_uuid2 == sb2->set_uuid2 &&
                sb1->set_uuid3 == sb2->set_uuid3;
}

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 sb_equal(): failed to allocate memory!\n");
                goto abort;
        }

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

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

        ret = (memcmp(tmp1, tmp2, MD_SB_GENERIC_CONSTANT_WORDS * 4) == 0);
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);
        unsigned long long  (*rdev_size_change)(mdk_rdev_t *rdev,
                                                sector_t num_sectors);
};

/*
 * Check that the given mddev has no bitmap.
 *
 * This function is called from the run method of all personalities that do not
 * support bitmaps. It prints an error message and returns non-zero if mddev
 * has a bitmap. Otherwise, it returns 0.
 *
 */
int md_check_no_bitmap(mddev_t *mddev)
{
        if (!mddev->bitmap_info.file && !mddev->bitmap_info.offset)
                return 0;
        printk(KERN_ERR "%s: bitmaps are not supported for %s\n",
                mdname(mddev), mddev->pers->name);
        return 1;
}
EXPORT_SYMBOL(md_check_no_bitmap);

/*
 * 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;

        /*
         * Calculate the position of the superblock (512byte sectors),
         * it's at the end of the disk.
         *
         * It also happens to be a multiple of 4Kb.
         */
        rdev->sb_start = calc_dev_sboffset(rdev->bdev);

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

        if (!refdev) {
                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->sectors = rdev->sb_start;

        if (rdev->sectors < sb->size * 2 && 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;
        clear_bit(Faulty, &rdev->flags);
        clear_bit(In_sync, &rdev->flags);
        clear_bit(WriteMostly, &rdev->flags);
        clear_bit(BarriersNotsupp, &rdev->flags);

        if (mddev->raid_disks == 0) {
                mddev->major_version = 0;
                mddev->minor_version = sb->minor_version;
                mddev->patch_version = sb->patch_version;
                mddev->external = 0;
                mddev->chunk_sectors = sb->chunk_size >> 9;
                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->dev_sectors = sb->size * 2;
                mddev->events = ev1;
                mddev->bitmap_info.offset = 0;
                mddev->bitmap_info.default_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_sectors = 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_sectors = mddev->chunk_sectors;
                }

                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_info.file == NULL)
                        mddev->bitmap_info.offset =
                                mddev->bitmap_info.default_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;
                } else if (desc->state & (1<<MD_DISK_ACTIVE)) {
                        /* active but not in sync implies recovery up to
                         * reshape position.  We don't know exactly where
                         * that is, so set to zero for now */
                        if (mddev->minor_version >= 91) {
                                rdev->recovery_offset = 0;
                                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;
        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->dev_sectors / 2;
        sb->raid_disks = mddev->raid_disks;
        sb->md_minor = mddev->md_minor;
        sb->not_persistent = 0;
        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_sectors << 9;
        }
        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_sectors << 9;

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

        sb->disks[0].state = (1<<MD_DISK_REMOVED);
        list_for_each_entry(rdev2, &mddev->disks, same_set) {
                mdp_disk_t *d;
                int desc_nr;
                int is_active = test_bit(In_sync, &rdev2->flags);

                if (rdev2->raid_disk >= 0 &&
                    sb->minor_version >= 91)
                        /* we have nowhere to store the recovery_offset,
                         * but if it is not below the reshape_position,
                         * we can piggy-back on that.
                         */
                        is_active = 1;
                if (rdev2->raid_disk < 0 ||
                    test_bit(Faulty, &rdev2->flags))
                        is_active = 0;
                if (is_active)
                        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 (is_active)
                        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 (is_active) {
                        d->state = (1<<MD_DISK_ACTIVE);
                        if (test_bit(In_sync, &rdev2->flags))
                                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);
}

/*
 * rdev_size_change for 0.90.0
 */
static unsigned long long
super_90_rdev_size_change(mdk_rdev_t *rdev, sector_t num_sectors)
{
        if (num_sectors && num_sectors < rdev->mddev->dev_sectors)
                return 0; /* component must fit device */
        if (rdev->mddev->bitmap_info.offset)
                return 0; /* can't move bitmap */
        rdev->sb_start = calc_dev_sboffset(rdev->bdev);
        if (!num_sectors || num_sectors > rdev->sb_start)
                num_sectors = rdev->sb_start;
        md_super_write(rdev->mddev, rdev, rdev->sb_start, rdev->sb_size,
                       rdev->sb_page);
        md_super_wait(rdev->mddev);
        return num_sectors / 2; /* kB for sysfs */
}


/*
 * 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_start;
        char b[BDEVNAME_SIZE], b2[BDEVNAME_SIZE];
        int bmask;

        /*
         * Calculate the position of the superblock in 512byte sectors.
         * 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_start = rdev->bdev->bd_inode->i_size >> 9;
                sb_start -= 8*2;
                sb_start &= ~(sector_t)(4*2-1);
                break;
        case 1:
                sb_start = 0;
                break;
        case 2:
                sb_start = 8;
                break;
        default:
                return -EINVAL;
        }
        rdev->sb_start = sb_start;

        /* 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_start ||
            (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;
        }

        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_logical_block_size(rdev->bdev->bd_disk->queue)-1;
        if (rdev->sb_size & bmask)
                rdev->sb_size = (rdev->sb_size | bmask) + 1;

        if (minor_version
            && rdev->data_offset < sb_start + (rdev->sb_size/512))
                return -EINVAL;

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

        if (!refdev) {
                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->sectors = (rdev->bdev->bd_inode->i_size >> 9) -
                        le64_to_cpu(sb->data_offset);
        else
                rdev->sectors = rdev->sb_start;
        if (rdev->sectors < le64_to_cpu(sb->data_size))
                return -EINVAL;
        rdev->sectors = le64_to_cpu(sb->data_size);
        if (le64_to_cpu(sb->size) > rdev->sectors)
                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;
        clear_bit(Faulty, &rdev->flags);
        clear_bit(In_sync, &rdev->flags);
        clear_bit(WriteMostly, &rdev->flags);
        clear_bit(BarriersNotsupp, &rdev->flags);

        if (mddev->raid_disks == 0) {
                mddev->major_version = 1;
                mddev->patch_version = 0;
                mddev->external = 0;
                mddev->chunk_sectors = le32_to_cpu(sb->chunksize);
                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->dev_sectors = le64_to_cpu(sb->size);
                mddev->events = ev1;
                mddev->bitmap_info.offset = 0;
                mddev->bitmap_info.default_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_info.file == NULL )
                        mddev->bitmap_info.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_sectors = le32_to_cpu(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_sectors = mddev->chunk_sectors;
                }

        } 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;
                if (rdev->desc_nr < 0 ||
                    rdev->desc_nr >= le32_to_cpu(sb->max_dev)) {
                        role = 0xffff;
                        rdev->desc_nr = -1;
                } else
                        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;
        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->dev_sectors);
        sb->chunksize = cpu_to_le32(mddev->chunk_sectors);
        sb->level = cpu_to_le32(mddev->level);
        sb->layout = cpu_to_le32(mddev->layout);

        if (mddev->bitmap && mddev->bitmap_info.file == NULL) {
                sb->bitmap_offset = cpu_to_le32((__u32)mddev->bitmap_info.offset);
                sb->feature_map = cpu_to_le32(MD_FEATURE_BITMAP_OFFSET);
        }

        if (rdev->raid_disk >= 0 &&
            !test_bit(In_sync, &rdev->flags)) {
                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_sectors);
        }

        max_dev = 0;
        list_for_each_entry(rdev2, &mddev->disks, same_set)
                if (rdev2->desc_nr+1 > max_dev)
                        max_dev = rdev2->desc_nr+1;

        if (max_dev > le32_to_cpu(sb->max_dev)) {
                int bmask;
                sb->max_dev = cpu_to_le32(max_dev);
                rdev->sb_size = max_dev * 2 + 256;
                bmask = queue_logical_block_size(rdev->bdev->bd_disk->queue)-1;
                if (rdev->sb_size & bmask)
                        rdev->sb_size = (rdev->sb_size | bmask) + 1;
        }
        for (i=0; i<max_dev;i++)
                sb->dev_roles[i] = cpu_to_le16(0xfffe);
        
        list_for_each_entry(rdev2, &mddev->disks, same_set) {
                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)
                        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 unsigned long long
super_1_rdev_size_change(mdk_rdev_t *rdev, sector_t num_sectors)
{
        struct mdp_superblock_1 *sb;
        sector_t max_sectors;
        if (num_sectors && num_sectors < rdev->mddev->dev_sectors)
                return 0; /* component must fit device */
        if (rdev->sb_start < rdev->data_offset) {
                /* minor versions 1 and 2; superblock before data */
                max_sectors = rdev->bdev->bd_inode->i_size >> 9;
                max_sectors -= rdev->data_offset;
                if (!num_sectors || num_sectors > max_sectors)
                        num_sectors = max_sectors;
        } else if (rdev->mddev->bitmap_info.offset) {
                /* minor version 0 with bitmap we can't move */
                return 0;
        } else {
                /* minor version 0; superblock after data */
                sector_t sb_start;
                sb_start = (rdev->bdev->bd_inode->i_size >> 9) - 8*2;
                sb_start &= ~(sector_t)(4*2 - 1);
                max_sectors = rdev->sectors + sb_start - rdev->sb_start;
                if (!num_sectors || num_sectors > max_sectors)
                        num_sectors = max_sectors;
                rdev->sb_start = sb_start;
        }
        sb = (struct mdp_superblock_1 *) page_address(rdev->sb_page);
        sb->data_size = cpu_to_le64(num_sectors);
        sb->super_offset = rdev->sb_start;
        sb->sb_csum = calc_sb_1_csum(sb);
        md_super_write(rdev->mddev, rdev, rdev->sb_start, rdev->sb_size,
                       rdev->sb_page);
        md_super_wait(rdev->mddev);
        return num_sectors / 2; /* kB for sysfs */
}

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,
                .rdev_size_change   = super_90_rdev_size_change,
        },
        [1] = {
                .name   = "md-1",
                .owner  = THIS_MODULE,
                .load_super         = super_1_load,
                .validate_super     = super_1_validate,
                .sync_super         = super_1_sync,
                .rdev_size_change   = super_1_rdev_size_change,
        },
};

static int match_mddev_units(mddev_t *mddev1, mddev_t *mddev2)
{
        mdk_rdev_t *rdev, *rdev2;

        rcu_read_lock();
        rdev_for_each_rcu(rdev, mddev1)
                rdev_for_each_rcu(rdev2, mddev2)
                        if (rdev->bdev->bd_contains ==
                            rdev2->bdev->bd_contains) {
                                rcu_read_unlock();
                                return 1;
                        }
        rcu_read_unlock();
        return 0;
}

static LIST_HEAD(pending_raid_disks);

/*
 * Try to register data integrity profile for an mddev
 *
 * This is called when an array is started and after a disk has been kicked
 * from the array. It only succeeds if all working and active component devices
 * are integrity capable with matching profiles.
 */
int md_integrity_register(mddev_t *mddev)
{
        mdk_rdev_t *rdev, *reference = NULL;

        if (list_empty(&mddev->disks))
                return 0; /* nothing to do */
        if (blk_get_integrity(mddev->gendisk))
                return 0; /* already registered */
        list_for_each_entry(rdev, &mddev->disks, same_set) {
                /* skip spares and non-functional disks */
                if (test_bit(Faulty, &rdev->flags))
                        continue;
                if (rdev->raid_disk < 0)
                        continue;
                /*
                 * If at least one rdev is not integrity capable, we can not
                 * enable data integrity for the md device.
                 */
                if (!bdev_get_integrity(rdev->bdev))
                        return -EINVAL;
                if (!reference) {
                        /* Use the first rdev as the reference */
                        reference = rdev;
                        continue;
                }
                /* does this rdev's profile match the reference profile? */
                if (blk_integrity_compare(reference->bdev->bd_disk,
                                rdev->bdev->bd_disk) < 0)
                        return -EINVAL;
        }
        /*
         * All component devices are integrity capable and have matching
         * profiles, register the common profile for the md device.
         */
        if (blk_integrity_register(mddev->gendisk,
                        bdev_get_integrity(reference->bdev)) != 0) {
                printk(KERN_ERR "md: failed to register integrity for %s\n",
                        mdname(mddev));
                return -EINVAL;
        }
        printk(KERN_NOTICE "md: data integrity on %s enabled\n",
                mdname(mddev));
        return 0;
}
EXPORT_SYMBOL(md_integrity_register);

/* Disable data integrity if non-capable/non-matching disk is being added */
void md_integrity_add_rdev(mdk_rdev_t *rdev, mddev_t *mddev)
{
        struct blk_integrity *bi_rdev = bdev_get_integrity(rdev->bdev);
        struct blk_integrity *bi_mddev = blk_get_integrity(mddev->gendisk);

        if (!bi_mddev) /* nothing to do */
                return;
        if (rdev->raid_disk < 0) /* skip spares */
                return;
        if (bi_rdev && blk_integrity_compare(mddev->gendisk,
                                             rdev->bdev->bd_disk) >= 0)
                return;
        printk(KERN_NOTICE "disabling data integrity on %s\n", mdname(mddev));
        blk_integrity_unregister(mddev->gendisk);
}
EXPORT_SYMBOL(md_integrity_add_rdev);

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;
        }

        /* prevent duplicates */
        if (find_rdev(mddev, rdev->bdev->bd_dev))
                return -EEXIST;

        /* make sure rdev->sectors exceeds mddev->dev_sectors */
        if (rdev->sectors && (mddev->dev_sectors == 0 ||
                        rdev->sectors < mddev->dev_sectors)) {
                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->dev_sectors = rdev->sectors;
        }

        /* 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;
        }
        if (mddev->max_disks && rdev->desc_nr >= mddev->max_disks) {
                printk(KERN_WARNING "md: %s: array is limited to %d devices\n",
                       mdname(mddev), mddev->max_disks);
                return -EBUSY;
        }
        bdevname(rdev->bdev,b);
        while ( (s=strchr(b, '/')) != NULL)
                *s = '!';

        rdev->mddev = mddev;
        printk(KERN_INFO "md: bind<%s>\n", b);

        if ((err = kobject_add(&rdev->kobj, &mddev->kobj, "dev-%s", b)))
                goto fail;

        ko = &part_to_dev(rdev->bdev->bd_part)->kobj;
        if ((err = sysfs_create_link(&rdev->kobj, ko, "block"))) {
                kobject_del(&rdev->kobj);
                goto fail;
        }
        rdev->sysfs_state = sysfs_get_dirent(rdev->kobj.sd, "state");

        list_add_rcu(&rdev->same_set, &mddev->disks);
        bd_claim_by_disk(rdev->bdev, rdev->bdev->bd_holder, mddev->gendisk);

        /* May as well allow recovery to be retried once */
        mddev->recovery_disabled = 0;

        return 0;

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

static void md_delayed_delete(struct work_struct *ws)
{
        mdk_rdev_t *rdev = container_of(ws, mdk_rdev_t, del_work);
        kobject_del(&rdev->kobj);
        kobject_put(&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_rcu(&rdev->same_set);
        printk(KERN_INFO "md: unbind<%s>\n", bdevname(rdev->bdev,b));
        rdev->mddev = NULL;
        sysfs_remove_link(&rdev->kobj, "block");
        sysfs_put(rdev->sysfs_state);
        rdev->sysfs_state = NULL;
        /* We need to delay this, otherwise we can deadlock when
         * writing to 'remove' to "dev/state".  We also need
         * to delay it due to rcu usage.
         */
        synchronize_rcu();
        INIT_WORK(&rdev->del_work, md_delayed_delete);
        kobject_get(&rdev->kobj);
        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 shared)
{
        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, shared ? (mdk_rdev_t *)lock_rdev : rdev);
        if (err) {
                printk(KERN_ERR "md: could not bd_claim %s.\n",
                        bdevname(bdev, b));
                blkdev_put(bdev, FMODE_READ|FMODE_WRITE);
                return err;
        }
        if (!shared)
                set_bit(AllReserved, &rdev->flags);
        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, FMODE_READ|FMODE_WRITE);
}

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);
#ifndef MODULE
        if (test_bit(AutoDetected, &rdev->flags))
                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)
{
        mdk_rdev_t *rdev, *tmp;

        rdev_for_each(rdev, tmp, mddev) {
                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_90(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_sb_1(struct mdp_superblock_1 *sb)
{
        __u8 *uuid;

        uuid = sb->set_uuid;
        printk(KERN_INFO
               "md:  SB: (V:%u) (F:0x%08x) Array-ID:<%pU>\n"
               "md:    Name: \"%s\" CT:%llu\n",
                le32_to_cpu(sb->major_version),
                le32_to_cpu(sb->feature_map),
                uuid,
                sb->set_name,
                (unsigned long long)le64_to_cpu(sb->ctime)
                       & MD_SUPERBLOCK_1_TIME_SEC_MASK);

        uuid = sb->device_uuid;
        printk(KERN_INFO
               "md:       L%u SZ%llu RD:%u LO:%u CS:%u DO:%llu DS:%llu SO:%llu"
                        " RO:%llu\n"
               "md:     Dev:%08x UUID: %pU\n"
               "md:       (F:0x%08x) UT:%llu Events:%llu ResyncOffset:%llu CSUM:0x%08x\n"
               "md:         (MaxDev:%u) \n",
                le32_to_cpu(sb->level),
                (unsigned long long)le64_to_cpu(sb->size),
                le32_to_cpu(sb->raid_disks),
                le32_to_cpu(sb->layout),
                le32_to_cpu(sb->chunksize),
                (unsigned long long)le64_to_cpu(sb->data_offset),
                (unsigned long long)le64_to_cpu(sb->data_size),
                (unsigned long long)le64_to_cpu(sb->super_offset),
                (unsigned long long)le64_to_cpu(sb->recovery_offset),
                le32_to_cpu(sb->dev_number),
                uuid,
                sb->devflags,
                (unsigned long long)le64_to_cpu(sb->utime) & MD_SUPERBLOCK_1_TIME_SEC_MASK,
                (unsigned long long)le64_to_cpu(sb->events),
                (unsigned long long)le64_to_cpu(sb->resync_offset),
                le32_to_cpu(sb->sb_csum),
                le32_to_cpu(sb->max_dev)
                );
}

static void print_rdev(mdk_rdev_t *rdev, int major_version)
{
        char b[BDEVNAME_SIZE];
        printk(KERN_INFO "md: rdev %s, Sect:%08llu F:%d S:%d DN:%u\n",
                bdevname(rdev->bdev, b), (unsigned long long)rdev->sectors,
                test_bit(Faulty, &rdev->flags), test_bit(In_sync, &rdev->flags),
                rdev->desc_nr);
        if (rdev->sb_loaded) {
                printk(KERN_INFO "md: rdev superblock (MJ:%d):\n", major_version);
                switch (major_version) {
                case 0:
                        print_sb_90((mdp_super_t*)page_address(rdev->sb_page));
                        break;
                case 1:
                        print_sb_1((struct mdp_superblock_1 *)page_address(rdev->sb_page));
                        break;
                }
        } else
                printk(KERN_INFO "md: no rdev superblock!\n");
}

static void md_print_devices(void)
{
        struct list_head *tmp;

        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");
        for_each_mddev(mddev, tmp) {

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

                list_for_each_entry(rdev, &mddev->disks, same_set)
                        print_rdev(rdev, mddev->major_version);
        }
        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;

        /* First make sure individual recovery_offsets are correct */
        list_for_each_entry(rdev, &mddev->disks, same_set) {
                if (rdev->raid_disk >= 0 &&
                    !test_bit(In_sync, &rdev->flags) &&
                    mddev->curr_resync_completed > rdev->recovery_offset)
                                rdev->recovery_offset = mddev->curr_resync_completed;

        }       
        list_for_each_entry(rdev, &mddev->disks, same_set) {
                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)
{
        mdk_rdev_t *rdev;
        int sync_req;
        int nospares = 0;

        mddev->utime = get_seconds();
        if (mddev->external)
                return;
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;

        /* 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, an 'even' event must also go
                         * to spares. */
                        if ((mddev->events&1)==0)
                                nospares = 0;
                } else {
                        /* otherwise an 'odd' event must go to spares */
                        if ((mddev->events&1))
                                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 --;
        }

        /*
         * do not write anything to disk if using
         * nonpersistent superblocks
         */
        if (!mddev->persistent) {
                if (!mddev->external)
                        clear_bit(MD_CHANGE_PENDING, &mddev->flags);

                spin_unlock_irq(&mddev->write_lock);
                wake_up(&mddev->sb_wait);
                return;
        }
        sync_sbs(mddev, nospares);
        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);
        list_for_each_entry(rdev, &mddev->disks, same_set) {
                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_start, 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_start);
                        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);
        if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
                sysfs_notify(&mddev->kobj, NULL, "sync_completed");

}

/* words written to sysfs files may, or may 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 = "";
        size_t 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(Blocked, &rdev->flags)) {
                len += sprintf(page+len, "%sblocked", 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
         *  blocked - sets the Blocked flag
         *  -blocked - clears the Blocked flag
         *  insync - sets Insync providing device isn't active
         */
        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;
        } else if (cmd_match(buf, "blocked")) {
                set_bit(Blocked, &rdev->flags);
                err = 0;
        } else if (cmd_match(buf, "-blocked")) {
                clear_bit(Blocked, &rdev->flags);
                wake_up(&rdev->blocked_wait);
                set_bit(MD_RECOVERY_NEEDED, &rdev->mddev->recovery);
                md_wakeup_thread(rdev->mddev->thread);

                err = 0;
        } else if (cmd_match(buf, "insync") && rdev->raid_disk == -1) {
                set_bit(In_sync, &rdev->flags);
                err = 0;
        }
        if (!err && rdev->sysfs_state)
                sysfs_notify_dirent(rdev->sysfs_state);
        return err ? err : len;
}
static struct rdev_sysfs_entry rdev_state =
__ATTR(state, S_IRUGO|S_IWUSR, state_show, state_store);

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 err;
        char nm[20];
        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 && slot == -1) {
                /* Setting 'slot' on an active array requires also
                 * updating the 'rd%d' link, and communicating
                 * with the personality with ->hot_*_disk.
                 * For now we only support removing
                 * failed/spare devices.  This normally happens automatically,
                 * but not when the metadata is externally managed.
                 */
                if (rdev->raid_disk == -1)
                        return -EEXIST;
                /* personality does all needed checks */
                if (rdev->mddev->pers->hot_add_disk == NULL)
                        return -EINVAL;
                err = rdev->mddev->pers->
                        hot_remove_disk(rdev->mddev, rdev->raid_disk);
                if (err)
                        return err;
                sprintf(nm, "rd%d", rdev->raid_disk);
                sysfs_remove_link(&rdev->mddev->kobj, nm);
                set_bit(MD_RECOVERY_NEEDED, &rdev->mddev->recovery);
                md_wakeup_thread(rdev->mddev->thread);
        } else if (rdev->mddev->pers) {
                mdk_rdev_t *rdev2;
                /* Activating a spare .. or possibly reactivating
                 * if we ever get bitmaps working here.
                 */

                if (rdev->raid_disk != -1)
                        return -EBUSY;

                if (rdev->mddev->pers->hot_add_disk == NULL)
                        return -EINVAL;

                list_for_each_entry(rdev2, &rdev->mddev->disks, same_set)
                        if (rdev2->raid_disk == slot)
                                return -EEXIST;

                rdev->raid_disk = slot;
                if (test_bit(In_sync, &rdev->flags))
                        rdev->saved_raid_disk = slot;
                else
                        rdev->saved_raid_disk = -1;
                err = rdev->mddev->pers->
                        hot_add_disk(rdev->mddev, rdev);
                if (err) {
                        rdev->raid_disk = -1;
                        return err;
                } else
                        sysfs_notify_dirent(rdev->sysfs_state);
                sprintf(nm, "rd%d", rdev->raid_disk);
                if (sysfs_create_link(&rdev->mddev->kobj, &rdev->kobj, nm))
                        printk(KERN_WARNING
                               "md: cannot register "
                               "%s for %s\n",
                               nm, mdname(rdev->mddev));

                /* don't wakeup anyone, leave that to userspace. */
        } else {
                if (slot >= rdev->mddev->raid_disks)
                        return -ENOSPC;
                rdev->raid_disk = slot;
                /* assume it is working */
                clear_bit(Faulty, &rdev->flags);
                clear_bit(WriteMostly, &rdev->flags);
                set_bit(In_sync, &rdev->flags);
                sysfs_notify_dirent(rdev->sysfs_state);
        }
        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 && rdev->raid_disk >= 0)
                return -EBUSY;
        if (rdev->sectors && rdev->mddev->external)
                /* Must set offset before size, so overlap checks
                 * can be sane */
                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->sectors / 2);
}

static int overlaps(sector_t s1, sector_t l1, sector_t s2, sector_t l2)
{
        /* check if two start/length pairs overlap */
        if (s1+l1 <= s2)
                return 0;
        if (s2+l2 <= s1)
                return 0;
        return 1;
}

static int strict_blocks_to_sectors(const char *buf, sector_t *sectors)
{
        unsigned long long blocks;
        sector_t new;

        if (strict_strtoull(buf, 10, &blocks) < 0)
                return -EINVAL;

        if (blocks & 1ULL << (8 * sizeof(blocks) - 1))
                return -EINVAL; /* sector conversion overflow */

        new = blocks * 2;
        if (new != blocks * 2)
                return -EINVAL; /* unsigned long long to sector_t overflow */

        *sectors = new;
        return 0;
}

static ssize_t
rdev_size_store(mdk_rdev_t *rdev, const char *buf, size_t len)
{
        mddev_t *my_mddev = rdev->mddev;
        sector_t oldsectors = rdev->sectors;
        sector_t sectors;

        if (strict_blocks_to_sectors(buf, &sectors) < 0)
                return -EINVAL;
        if (my_mddev->pers && rdev->raid_disk >= 0) {
                if (my_mddev->persistent) {
                        sectors = super_types[my_mddev->major_version].
                                rdev_size_change(rdev, sectors);
                        if (!sectors)
                                return -EBUSY;
                } else if (!sectors)
                        sectors = (rdev->bdev->bd_inode->i_size >> 9) -
                                rdev->data_offset;
        }
        if (sectors < my_mddev->dev_sectors)
                return -EINVAL; /* component must fit device */

        rdev->sectors = sectors;
        if (sectors > oldsectors && my_mddev->external) {
                /* need to check that all other rdevs with the same ->bdev
                 * do not overlap.  We need to unlock the mddev to avoid
                 * a deadlock.  We have already changed rdev->sectors, and if
                 * we have to change it back, we will have the lock again.
                 */
                mddev_t *mddev;
                int overlap = 0;
                struct list_head *tmp;

                mddev_unlock(my_mddev);
                for_each_mddev(mddev, tmp) {
                        mdk_rdev_t *rdev2;

                        mddev_lock(mddev);
                        list_for_each_entry(rdev2, &mddev->disks, same_set)
                                if (test_bit(AllReserved, &rdev2->flags) ||
                                    (rdev->bdev == rdev2->bdev &&
                                     rdev != rdev2 &&
                                     overlaps(rdev->data_offset, rdev->sectors,
                                              rdev2->data_offset,
                                              rdev2->sectors))) {
                                        overlap = 1;
                                        break;
                                }
                        mddev_unlock(mddev);
                        if (overlap) {
                                mddev_put(mddev);
                                break;
                        }
                }
                mddev_lock(my_mddev);
                if (overlap) {
                        /* Someone else could have slipped in a size
                         * change here, but doing so is just silly.
                         * We put oldsectors back because we *know* it is
                         * safe, and trust userspace not to race with
                         * itself
                         */
                        rdev->sectors = oldsectors;
                        return -EBUSY;
                }
        }
        return len;
}

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


static ssize_t recovery_start_show(mdk_rdev_t *rdev, char *page)
{
        unsigned long long recovery_start = rdev->recovery_offset;

        if (test_bit(In_sync, &rdev->flags) ||
            recovery_start == MaxSector)
                return sprintf(page, "none\n");

        return sprintf(page, "%llu\n", recovery_start);
}

static ssize_t recovery_start_store(mdk_rdev_t *rdev, const char *buf, size_t len)
{
        unsigned long long recovery_start;

        if (cmd_match(buf, "none"))
                recovery_start = MaxSector;
        else if (strict_strtoull(buf, 10, &recovery_start))
                return -EINVAL;

        if (rdev->mddev->pers &&
            rdev->raid_disk >= 0)
                return -EBUSY;

        rdev->recovery_offset = recovery_start;
        if (recovery_start == MaxSector)
                set_bit(In_sync, &rdev->flags);
        else
                clear_bit(In_sync, &rdev->flags);
        return len;
}

static struct rdev_sysfs_entry rdev_recovery_start =
__ATTR(recovery_start, S_IRUGO|S_IWUSR, recovery_start_show, recovery_start_store);

static struct attribute *rdev_default_attrs[] = {
        &rdev_state.attr,
        &rdev_errors.attr,
        &rdev_slot.attr,
        &rdev_offset.attr,
        &rdev_size.attr,
        &rdev_recovery_start.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);
        mddev_t *mddev = rdev->mddev;
        ssize_t rv;

        if (!entry->show)
                return -EIO;

        rv = mddev ? mddev_lock(mddev) : -EBUSY;
        if (!rv) {
                if (rdev->mddev == NULL)
                        rv = -EBUSY;
                else
                        rv = entry->show(rdev, page);
                mddev_unlock(mddev);
        }
        return rv;
}

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);
        ssize_t rv;
        mddev_t *mddev = rdev->mddev;

        if (!entry->store)
                return -EIO;
        if (!capable(CAP_SYS_ADMIN))
                return -EACCES;
        rv = mddev ? mddev_lock(mddev): -EBUSY;
        if (!rv) {
                if (rdev->mddev == NULL)
                        rv = -EBUSY;
                else
                        rv = entry->store(rdev, page, length);
                mddev_unlock(mddev);
        }
        return rv;
}

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, super_format == -2);
        if (err)
                goto abort_free;

        kobject_init(&rdev->kobj, &rdev_ktype);

        rdev->desc_nr = -1;
        rdev->saved_raid_disk = -1;
        rdev->raid_disk = -1;
        rdev->flags = 0;
        rdev->data_offset = 0;
        rdev->sb_events = 0;
        rdev->last_read_error.tv_sec  = 0;
        rdev->last_read_error.tv_nsec = 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);
        init_waitqueue_head(&rdev->blocked_wait);

        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;
        mdk_rdev_t *rdev, *freshest, *tmp;
        char b[BDEVNAME_SIZE];

        freshest = NULL;
        rdev_for_each(rdev, tmp, mddev)
                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;
        rdev_for_each(rdev, tmp, mddev) {
                if (rdev->desc_nr >= mddev->max_disks ||
                    i > mddev->max_disks) {
                        printk(KERN_WARNING
                               "md: %s: %s: only %d devices permitted\n",
                               mdname(mddev), bdevname(rdev->bdev, b),
                               mddev->max_disks);
                        kick_rdev_from_array(rdev);
                        continue;
                }
                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 - min(0, mddev->delta_disks))) {
                        rdev->raid_disk = -1;
                        clear_bit(In_sync, &rdev->flags);
                }
        }
}

/* Read a fixed-point number.
 * Numbers in sysfs attributes should be in "standard" units where
 * possible, so time should be in seconds.
 * However we internally use a a much smaller unit such as 
 * milliseconds or jiffies.
 * This function takes a decimal number with a possible fractional
 * component, and produces an integer which is the result of
 * multiplying that number by 10^'scale'.
 * all without any floating-point arithmetic.
 */
int strict_strtoul_scaled(const char *cp, unsigned long *res, int scale)
{
        unsigned long result = 0;
        long decimals = -1;
        while (isdigit(*cp) || (*cp == '.' && decimals < 0)) {
                if (*cp == '.')
                        decimals = 0;
                else if (decimals < scale) {
                        unsigned int value;
                        value = *cp - '0';
                        result = result * 10 + value;
                        if (decimals >= 0)
                                decimals++;
                }
                cp++;
        }
        if (*cp == '\n')
                cp++;
        if (*cp)
                return -EINVAL;
        if (decimals < 0)
                decimals = 0;
        while (decimals < scale) {
                result *= 10;
                decimals ++;
        }
        *res = result;
        return 0;
}


static void md_safemode_timeout(unsigned long data);

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)
{
        unsigned long msec;

        if (strict_strtoul_scaled(cbuf, &msec, 3) < 0)
                return -EINVAL;
        if (msec == 0)
                mddev->safemode_delay = 0;
        else {
                unsigned long old_delay = mddev->safemode_delay;
                mddev->safemode_delay = (msec*HZ)/1000;
                if (mddev->safemode_delay == 0)
                        mddev->safemode_delay = 1;
                if (mddev->safemode_delay < old_delay)
                        md_safemode_timeout((unsigned long)mddev);
        }
        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)
{
        char level[16];
        ssize_t rv = len;
        struct mdk_personality *pers;
        void *priv;
        mdk_rdev_t *rdev;

        if (mddev->pers == NULL) {
                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;
        }

        /* request to change the personality.  Need to ensure:
         *  - array is not engaged in resync/recovery/reshape
         *  - old personality can be suspended
         *  - new personality will access other array.
         */

        if (mddev->sync_thread || mddev->reshape_position != MaxSector)
                return -EBUSY;

        if (!mddev->pers->quiesce) {
                printk(KERN_WARNING "md: %s: %s does not support online personality change\n",
                       mdname(mddev), mddev->pers->name);
                return -EINVAL;
        }

        /* Now find the new personality */
        if (len == 0 || len >= sizeof(level))
                return -EINVAL;
        strncpy(level, buf, len);
        if (level[len-1] == '\n')
                len--;
        level[len] = 0;

        request_module("md-%s", level);
        spin_lock(&pers_lock);
        pers = find_pers(LEVEL_NONE, level);
        if (!pers || !try_module_get(pers->owner)) {
                spin_unlock(&pers_lock);
                printk(KERN_WARNING "md: personality %s not loaded\n", level);
                return -EINVAL;
        }
        spin_unlock(&pers_lock);

        if (pers == mddev->pers) {
                /* Nothing to do! */
                module_put(pers->owner);
                return rv;
        }
        if (!pers->takeover) {
                module_put(pers->owner);
                printk(KERN_WARNING "md: %s: %s does not support personality takeover\n",
                       mdname(mddev), level);
                return -EINVAL;
        }

        /* ->takeover must set new_* and/or delta_disks
         * if it succeeds, and may set them when it fails.
         */
        priv = pers->takeover(mddev);
        if (IS_ERR(priv)) {
                mddev->new_level = mddev->level;
                mddev->new_layout = mddev->layout;
                mddev->new_chunk_sectors = mddev->chunk_sectors;
                mddev->raid_disks -= mddev->delta_disks;
                mddev->delta_disks = 0;
                module_put(pers->owner);
                printk(KERN_WARNING "md: %s: %s would not accept array\n",
                       mdname(mddev), level);
                return PTR_ERR(priv);
        }

        /* Looks like we have a winner */
        mddev_suspend(mddev);
        mddev->pers->stop(mddev);
        module_put(mddev->pers->owner);
        /* Invalidate devices that are now superfluous */
        list_for_each_entry(rdev, &mddev->disks, same_set)
                if (rdev->raid_disk >= mddev->raid_disks) {
                        rdev->raid_disk = -1;
                        clear_bit(In_sync, &rdev->flags);
                }
        mddev->pers = pers;
        mddev->private = priv;
        strlcpy(mddev->clevel, pers->name, sizeof(mddev->clevel));
        mddev->level = mddev->new_level;
        mddev->layout = mddev->new_layout;
        mddev->chunk_sectors = mddev->new_chunk_sectors;
        mddev->delta_disks = 0;
        pers->run(mddev);
        mddev_resume(mddev);
        set_bit(MD_CHANGE_DEVS, &mddev->flags);
        set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
        md_wakeup_thread(mddev->thread);
        return rv;
}

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