From 30b8feb730f9b9b3c5de02580897da03f59b6b16 Mon Sep 17 00:00:00 2001 From: NeilBrown Date: Thu, 14 Nov 2013 15:16:17 +1100 Subject: 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 Reported-by: Bian Yu Signed-off-by: NeilBrown --- drivers/md/md.c | 68 +++++++++++++++++++++++++++++++++++++++++---------------- 1 file changed, 49 insertions(+), 19 deletions(-) (limited to 'drivers/md') diff --git a/drivers/md/md.c b/drivers/md/md.c index a74045df7bab..47e7bc74ed38 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -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...*/ -- cgit v1.2.3-59-g8ed1b