Boris Burkov bf1e8c21f2 btrfs: retry block group reclaim without infinite loop
commit 4eb4e85c4f818491efc67e9373aa16b123c3f522 upstream.

If inc_block_group_ro systematically fails (e.g. due to ETXTBUSY from
swap) or btrfs_relocate_chunk systematically fails (from lack of
space), then this worker becomes an infinite loop.

At the very least, this strands the cleaner thread, but can also result
in hung tasks/RCU stalls on PREEMPT_NONE kernels and if the
reclaim_bgs_lock mutex is not contended.

I believe the best long term fix is to manage reclaim via work queue,
where we queue up a relocation on the triggering condition and re-queue
on failure. In the meantime, this is an easy fix to apply to avoid the
immediate pain.

Fixes: 7e2718099438 ("btrfs: reinsert BGs failed to reclaim")
CC: stable@vger.kernel.org # 6.6+
Signed-off-by: Boris Burkov <boris@bur.io>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-06-27 13:49:11 +02:00
..
2023-08-21 14:54:48 +02:00
2023-08-21 14:54:48 +02:00
2023-08-24 16:20:18 -07:00
2023-08-21 14:54:48 +02:00