btrfs: zoned: don't skip block groups with 100% zone unusable

commit a8b70c7f8600bc77d03c0b032c0662259b9e615e upstream.

Commit f4a9f219411f ("btrfs: do not delete unused block group if it may be
used soon") changed the behaviour of deleting unused block-groups on zoned
filesystems. Starting with this commit, we're using
btrfs_space_info_used() to calculate the number of used bytes in a
space_info. But btrfs_space_info_used() also accounts
btrfs_space_info::bytes_zone_unusable as used bytes.

So if a block group is 100% zone_unusable it is skipped from the deletion
step.

In order not to skip fully zone_unusable block-groups, also check if the
block-group has bytes left that can be used on a zoned filesystem.

Fixes: f4a9f219411f ("btrfs: do not delete unused block group if it may be used soon")
CC: stable@vger.kernel.org # 6.1+
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/btrfs/block-group.c b/fs/btrfs/block-group.c
index 9f77565bd7f5afd25346274b7df538ecfb143a61..5993b627be58049193ebb32704270c21f01c5dc1 100644 (file)
--- a/fs/btrfs/block-group.c
+++ b/fs/btrfs/block-group.c
@@ -1413,7 +1413,8 @@ void btrfs_delete_unused_bgs(struct btrfs_fs_info *fs_info)
                 * needing to allocate extents from the block group.
                 */
                used = btrfs_space_info_used(space_info, true);
-               if (space_info->total_bytes - block_group->length < used) {
+               if (space_info->total_bytes - block_group->length < used &&
+                   block_group->zone_unusable < block_group->length) {
                        /*
                         * Add a reference for the list, compensate for the ref
                         * drop under the "next" label for the