From: Naohiro Aota naohiro.aota@wdc.com
commit a690e5f2db4d1dca742ce734aaff9f3112d63764 upstream.
When btrfs balance is interrupted with umount, the background balance resumes on the next mount. There is a potential deadlock with FS freezing here like as described in commit 26559780b953 ("btrfs: zoned: mark relocation as writing"). Mark the process as sb_writing to avoid it.
Reviewed-by: Filipe Manana fdmanana@suse.com CC: stable@vger.kernel.org # 4.9+ Signed-off-by: Naohiro Aota naohiro.aota@wdc.com Reviewed-by: David Sterba dsterba@suse.com Signed-off-by: David Sterba dsterba@suse.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/btrfs/volumes.c | 2 ++ 1 file changed, 2 insertions(+)
--- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -4320,10 +4320,12 @@ static int balance_kthread(void *data) struct btrfs_fs_info *fs_info = data; int ret = 0;
+ sb_start_write(fs_info->sb); mutex_lock(&fs_info->balance_mutex); if (fs_info->balance_ctl) ret = btrfs_balance(fs_info, fs_info->balance_ctl, NULL); mutex_unlock(&fs_info->balance_mutex); + sb_end_write(fs_info->sb);
return ret; }