From 7b770617c072a5782863a4a7a535600cd4a425b8 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 f00165de6fbf5..08e65e9cf2aa9 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 4662d92a4b738..b6ebde231de7c 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; -- 2.39.5