From 5f3164813b90f7dbcb5c3ab9006906222ce471b7 Mon Sep 17 00:00:00 2001 From: Wang Shilong Date: Thu, 26 Jun 2014 11:08:16 +0800 Subject: [PATCH] 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: Wang Shilong Signed-off-by: Chris Mason --- fs/btrfs/disk-io.c | 2 ++ fs/btrfs/super.c | 2 ++ 2 files changed, 4 insertions(+) diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index f00165d..08e65e9 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -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"); diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c index 4662d92..b6ebde2 100644 --- a/fs/btrfs/super.c +++ b/fs/btrfs/super.c @@ -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; -- 2.7.4