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Commit 5f316481 authored by Wang Shilong's avatar Wang Shilong Committed by Chris Mason
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Btrfs: fix race between balance recovery and root deletion 



Balance recovery is called when RW mounting or remounting from
RO to RW, it is called to finish roots merging.

When doing balance recovery, relocation root's corresponding
fs root(whose root refs is 0) might be destroyed by cleaner
thread, this will make btrfs fail to mount.

Fix this problem by holding @cleaner_mutex when doing balance
recovery.

Signed-off-by: default avatarWang Shilong <wangsl.fnst@cn.fujitsu.com>
Signed-off-by: default avatarChris Mason <clm@fb.com>
parent 3cc79392

fs/btrfs/disk-io.c

+2 −0
Original line number Diff line number Diff line
@@ -2905,7 +2905,9 @@ retry_root_backup: 
		if (ret)

			goto fail_qgroup;



		mutex_lock(&fs_info->cleaner_mutex);

		ret = btrfs_recover_relocation(tree_root);

		mutex_unlock(&fs_info->cleaner_mutex);

		if (ret < 0) {

			printk(KERN_WARNING

			       "BTRFS: failed to recover relocation\n");

fs/btrfs/super.c

+2 −0
Original line number Diff line number Diff line
@@ -1467,7 +1467,9 @@ static int btrfs_remount(struct super_block *sb, int *flags, char *data) 
			goto restore;



		/* recover relocation */

		mutex_lock(&fs_info->cleaner_mutex);

		ret = btrfs_recover_relocation(root);

		mutex_unlock(&fs_info->cleaner_mutex);

		if (ret)

			goto restore;