From 3ed01616bad6c7e3de196676b542ae3df8058592 Mon Sep 17 00:00:00 2001 From: Naohiro Aota Date: Tue, 6 Jun 2023 14:36:33 +0900 Subject: [PATCH] btrfs: delete unused BGs while reclaiming BGs The reclaiming process only starts after the filesystem volumes are allocated to a certain level (75% by default). Thus, the list of reclaiming target block groups can build up so huge at the time the reclaim process kicks in. On a test run, there were over 1000 BGs in the reclaim list. As the reclaim involves rewriting the data, it takes really long time to reclaim the BGs. While the reclaim is running, btrfs_delete_unused_bgs() won't proceed because the reclaim side is holding fs_info->reclaim_bgs_lock. As a result, we will have a large number of unused BGs kept in the unused list. On my test run, I got 1057 unused BGs. Since deleting a block group is relatively easy and fast work, we can call btrfs_delete_unused_bgs() while it reclaims BGs, to avoid building up unused BGs. Fixes: 18bb8bbf13c1 ("btrfs: zoned: automatically reclaim zones") CC: stable@vger.kernel.org # 5.15+ Reviewed-by: Filipe Manana Reviewed-by: Johannes Thumshirn Signed-off-by: Naohiro Aota Signed-off-by: David Sterba --- fs/btrfs/block-group.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/fs/btrfs/block-group.c b/fs/btrfs/block-group.c index 618ba76..18305f5 100644 --- a/fs/btrfs/block-group.c +++ b/fs/btrfs/block-group.c @@ -1824,10 +1824,24 @@ void btrfs_reclaim_bgs_work(struct work_struct *work) next: btrfs_put_block_group(bg); + + mutex_unlock(&fs_info->reclaim_bgs_lock); + /* + * Reclaiming all the block groups in the list can take really + * long. Prioritize cleaning up unused block groups. + */ + btrfs_delete_unused_bgs(fs_info); + /* + * If we are interrupted by a balance, we can just bail out. The + * cleaner thread restart again if necessary. + */ + if (!mutex_trylock(&fs_info->reclaim_bgs_lock)) + goto end; spin_lock(&fs_info->unused_bgs_lock); } spin_unlock(&fs_info->unused_bgs_lock); mutex_unlock(&fs_info->reclaim_bgs_lock); +end: btrfs_exclop_finish(fs_info); sb_end_write(fs_info->sb); } -- 2.7.4