From: Johannes Thumshirn Date: Tue, 10 Feb 2026 11:04:22 +0000 (+0100) Subject: btrfs: zoned: move partially zone_unusable block groups to reclaim list X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=258e46a6385c57a3caef3fb1dc888e2efcfe5b18;p=thirdparty%2Flinux.git btrfs: zoned: move partially zone_unusable block groups to reclaim list On zoned block devices, block groups accumulate zone_unusable space (space between the write pointer and zone end that cannot be allocated until the zone is reset). When a block group becomes mostly zone_unusable but still contains some valid data and it gets added to the unused_bgs list it can never be deleted because it's not actually empty. The deletion code (btrfs_delete_unused_bgs) skips these block groups due to the btrfs_is_block_group_used() check, leaving them on the unused_bgs list indefinitely. This causes two problems: 1. The block groups are never reclaimed, permanently wasting space 2. Eventually leads to ENOSPC even though reclaimable space exists Fix by detecting block groups where zone_unusable exceeds 50% of the block group size. Move these to the reclaim_bgs list instead of skipping them. This triggers btrfs_reclaim_bgs_work() which: 1. Marks the block group read-only 2. Relocates the remaining valid data via btrfs_relocate_chunk() 3. Removes the emptied block group 4. Resets the zones, converting zone_unusable back to usable space The 50% threshold ensures we only reclaim block groups where most space is unusable, making relocation worthwhile. Block groups with less zone_unusable are left on unused_bgs to potentially become fully empty through normal deletion. Reviewed-by: Filipe Manana Signed-off-by: Johannes Thumshirn Signed-off-by: David Sterba --- diff --git a/fs/btrfs/block-group.c b/fs/btrfs/block-group.c index a021a6dab8f9..d0d7051d4417 100644 --- a/fs/btrfs/block-group.c +++ b/fs/btrfs/block-group.c @@ -1613,6 +1613,24 @@ void btrfs_delete_unused_bgs(struct btrfs_fs_info *fs_info) spin_lock(&space_info->lock); spin_lock(&block_group->lock); + + if (btrfs_is_zoned(fs_info) && btrfs_is_block_group_used(block_group) && + block_group->zone_unusable >= div_u64(block_group->length, 2)) { + /* + * If the block group has data left, but at least half + * of the block group is zone_unusable, mark it as + * reclaimable before continuing with the next block group. + */ + + spin_unlock(&block_group->lock); + spin_unlock(&space_info->lock); + up_write(&space_info->groups_sem); + + btrfs_mark_bg_to_reclaim(block_group); + + goto next; + } + if (btrfs_is_block_group_used(block_group) || (block_group->ro && !(block_group->flags & BTRFS_BLOCK_GROUP_REMAPPED)) || list_is_singular(&block_group->list) ||