From: Johannes Thumshirn johannes.thumshirn@wdc.com
commit 9cc0b837e14ae913581ec1ea6e979a738f71b0fd upstream.
If we can't acquire the reclaim_bgs_lock on block group reclaim, we block until it is free. This can potentially stall for a long time.
While reclaim of block groups is necessary for a good user experience on a zoned file system, there still is no need to block as it is best effort only, just like when we're deleting unused block groups.
CC: stable@vger.kernel.org # 5.13 Signed-off-by: Johannes Thumshirn johannes.thumshirn@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/block-group.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-)
--- a/fs/btrfs/block-group.c +++ b/fs/btrfs/block-group.c @@ -1499,7 +1499,15 @@ void btrfs_reclaim_bgs_work(struct work_ if (!btrfs_exclop_start(fs_info, BTRFS_EXCLOP_BALANCE)) return;
- mutex_lock(&fs_info->reclaim_bgs_lock); + /* + * Long running balances can keep us blocked here for eternity, so + * simply skip reclaim if we're unable to get the mutex. + */ + if (!mutex_trylock(&fs_info->reclaim_bgs_lock)) { + btrfs_exclop_finish(fs_info); + return; + } + spin_lock(&fs_info->unused_bgs_lock); while (!list_empty(&fs_info->reclaim_bgs)) { bg = list_first_entry(&fs_info->reclaim_bgs,