btrfs: reinsert BGs failed to reclaim

The reclaim process can temporarily fail. For example, if the space is
getting tight, it fails to make the block group read-only. If there are no
further writes on that block group, the block group will never get back to
the reclaim list, and the BG never gets reclaimed. In a certain workload,
we can leave many such block groups never reclaimed.

So, let's get it back to the list and give it a chance to be reclaimed.

Fixes: 18bb8bb ("btrfs: zoned: automatically reclaim zones")
CC: stable@vger.kernel.org # 5.15+
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/block-group.c

@@ -1833,6 +1833,8 @@ void btrfs_reclaim_bgs_work(struct work_struct *work)
  }
 
 next:
+ if (ret)
+ btrfs_mark_bg_to_reclaim(bg);
  btrfs_put_block_group(bg);
 
  mutex_unlock(&fs_info->reclaim_bgs_lock);