@@ -1254,6 +1254,13 @@ void btrfs_delete_unused_bgs(struct btrfs_fs_info *fs_info)
if (!test_bit(BTRFS_FS_OPEN, &fs_info->flags))
return;
+ /*
+ * Long running balances can keep us blocked here for eternity, so
+ * simply skip deletion if we're unable to get the mutex.
+ */
+ if (!mutex_trylock(&fs_info->delete_unused_bgs_mutex))
+ return;
+
spin_lock(&fs_info->unused_bgs_lock);
while (!list_empty(&fs_info->unused_bgs)) {
int trimming;
@@ -1273,8 +1280,6 @@ void btrfs_delete_unused_bgs(struct btrfs_fs_info *fs_info)
btrfs_discard_cancel_work(&fs_info->discard_ctl, block_group);
- mutex_lock(&fs_info->delete_unused_bgs_mutex);
-
/* Don't want to race with allocators so take the groups_sem */
down_write(&space_info->groups_sem);
@@ -1420,11 +1425,11 @@ void btrfs_delete_unused_bgs(struct btrfs_fs_info *fs_info)
end_trans:
btrfs_end_transaction(trans);
next:
- mutex_unlock(&fs_info->delete_unused_bgs_mutex);
btrfs_put_block_group(block_group);
spin_lock(&fs_info->unused_bgs_lock);
}
spin_unlock(&fs_info->unused_bgs_lock);
+ mutex_unlock(&fs_info->delete_unused_bgs_mutex);
return;
flip_async:
While running some stress tests I started getting hung task messages. This is because the delete unused bg's code has to take the delete_unused_bgs_mutex to do it's work, which is taken by balance to make sure we don't delete block groups while we're balancing. The problem is a balance can take a while, and so we were getting hung task warnings. We don't need to block and run these things, and the cleaner is needed to do other work, so trylock on this mutex and just bail if we can't acquire it right away. Signed-off-by: Josef Bacik <josef@toxicpanda.com> --- fs/btrfs/block-group.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-)