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md/raid5: avoid deadlock when raid5 array has unack badblocks during md_stop_writes. 

When raid5 recovery hits a fresh badblock, this badblock will flagged as unack
badblock until md_update_sb() is called.
But md_stop will take reconfig lock which means raid5d can't call
md_update_sb() in md_check_recovery(), the badblock will always
be unack, so raid5d thread enters an infinite loop and md_stop_write()
can never stop sync_thread. This causes deadlock.

To solve this, when STOP_ARRAY ioctl is issued and sync_thread is
running, we need set md->recovery FROZEN and INTR flags and wait for
sync_thread to stop before we (re)take reconfig lock.

This requires that raid5 reshape_request notices MD_RECOVERY_INTR
(which it probably should have noticed anyway) and stops waiting for a
metadata update in that case.

Reported-by: Jianpeng Ma <majianpeng@gmail.com>
Reported-by: Bian Yu <bianyu@kedacom.com>
Signed-off-by: NeilBrown <neilb@suse.de>
This commit is contained in:
NeilBrown 2013-11-14 15:16:17 +11:00
parent c91abf5a35
commit 30b8feb730
1 changed files with 49 additions and 19 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

68
drivers/md/md.c
View File

@ -5340,20 +5340,35 @@ EXPORT_SYMBOL_GPL(md_stop);
static int md_set_readonly(struct mddev *mddev, struct block_device *bdev)
{
int err = 0;
int did_freeze = 0;
if (!test_bit(MD_RECOVERY_FROZEN, &mddev->recovery)) {
did_freeze = 1;
set_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
md_wakeup_thread(mddev->thread);
}
if (mddev->sync_thread) {
set_bit(MD_RECOVERY_INTR, &mddev->recovery);
/* Thread might be blocked waiting for metadata update
* which will now never happen */
wake_up_process(mddev->sync_thread->tsk);
}
mddev_unlock(mddev);
wait_event(resync_wait, mddev->sync_thread == NULL);
mddev_lock_nointr(mddev);
mutex_lock(&mddev->open_mutex);
if (atomic_read(&mddev->openers) > !!bdev) {
if (atomic_read(&mddev->openers) > !!bdev ||
mddev->sync_thread ||
(bdev && !test_bit(MD_STILL_CLOSED, &mddev->flags))) {
printk("md: %s still in use.\n",mdname(mddev));
if (did_freeze) {
clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
md_wakeup_thread(mddev->thread);
}
err = -EBUSY;
goto out;
}
if (bdev && !test_bit(MD_STILL_CLOSED, &mddev->flags)) {
/* Someone opened the device since we flushed it
* so page cache could be dirty and it is too late
* to flush. So abort
*/
mutex_unlock(&mddev->open_mutex);
return -EBUSY;
}
if (mddev->pers) {
__md_stop_writes(mddev);
@ -5364,7 +5379,7 @@ static int md_set_readonly(struct mddev *mddev, struct block_device *bdev)
set_disk_ro(mddev->gendisk, 1);
clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
sysfs_notify_dirent_safe(mddev->sysfs_state);
err = 0;
err = 0;
}
out:
mutex_unlock(&mddev->open_mutex);
@ -5380,20 +5395,34 @@ static int do_md_stop(struct mddev * mddev, int mode,
{
struct gendisk *disk = mddev->gendisk;
struct md_rdev *rdev;
int did_freeze = 0;
if (!test_bit(MD_RECOVERY_FROZEN, &mddev->recovery)) {
did_freeze = 1;
set_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
md_wakeup_thread(mddev->thread);
}
if (mddev->sync_thread) {
set_bit(MD_RECOVERY_INTR, &mddev->recovery);
/* Thread might be blocked waiting for metadata update
* which will now never happen */
wake_up_process(mddev->sync_thread->tsk);
}
mddev_unlock(mddev);
wait_event(resync_wait, mddev->sync_thread == NULL);
mddev_lock_nointr(mddev);
mutex_lock(&mddev->open_mutex);
if (atomic_read(&mddev->openers) > !!bdev ||
mddev->sysfs_active) {
mddev->sysfs_active ||
mddev->sync_thread ||
(bdev && !test_bit(MD_STILL_CLOSED, &mddev->flags))) {
printk("md: %s still in use.\n",mdname(mddev));
mutex_unlock(&mddev->open_mutex);
return -EBUSY;
}
if (bdev && !test_bit(MD_STILL_CLOSED, &mddev->flags)) {
/* Someone opened the device since we flushed it
* so page cache could be dirty and it is too late
* to flush. So abort
*/
mutex_unlock(&mddev->open_mutex);
if (did_freeze) {
clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
md_wakeup_thread(mddev->thread);
}
return -EBUSY;
}
if (mddev->pers) {
@ -7931,6 +7960,7 @@ void md_reap_sync_thread(struct mddev *mddev)
/* resync has finished, collect result */
md_unregister_thread(&mddev->sync_thread);
wake_up(&resync_wait);
if (!test_bit(MD_RECOVERY_INTR, &mddev->recovery) &&
!test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery)) {
/* success...*/