btrfs: zoned: activate metadata block group on flush_space

For metadata space on zoned filesystem, reaching ALLOC_CHUNK{,_FORCE}
means we don't have enough space left in the active_total_bytes. Before
allocating a new chunk, we can try to activate an existing block group
in this case.

Also, allocating a chunk is not enough to grant a ticket for metadata
space on zoned filesystem we need to activate the block group to
increase the active_total_bytes.

btrfs_zoned_activate_one_bg() implements the activation feature. It will
activate a block group by (maybe) finishing a block group. It will give up
activating a block group if it cannot finish any block group.

CC: stable@vger.kernel.org # 5.16+
Fixes: afba2bc036b0 ("btrfs: zoned: implement active zone tracking")
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>

1 files changed, 53 insertions, 0 deletions

diff --git a/fs/btrfs/zoned.c b/fs/btrfs/zoned.c
index d0a0d62c5278..6c391b5b4172 100644
--- a/fs/btrfs/zoned.c
+++ b/fs/btrfs/zoned.c
@@ -2226,3 +2226,56 @@ int btrfs_zone_finish_one_bg(struct btrfs_fs_info *fs_info)
 
 	return ret < 0 ? ret : 1;
 }
+
+int btrfs_zoned_activate_one_bg(struct btrfs_fs_info *fs_info,
+				struct btrfs_space_info *space_info,
+				bool do_finish)
+{
+	struct btrfs_block_group *bg;
+	int index;
+
+	if (!btrfs_is_zoned(fs_info) || (space_info->flags & BTRFS_BLOCK_GROUP_DATA))
+		return 0;
+
+	/* No more block groups to activate */
+	if (space_info->active_total_bytes == space_info->total_bytes)
+		return 0;
+
+	for (;;) {
+		int ret;
+		bool need_finish = false;
+
+		down_read(&space_info->groups_sem);
+		for (index = 0; index < BTRFS_NR_RAID_TYPES; index++) {
+			list_for_each_entry(bg, &space_info->block_groups[index],
+					    list) {
+				if (!spin_trylock(&bg->lock))
+					continue;
+				if (btrfs_zoned_bg_is_full(bg) || bg->zone_is_active) {
+					spin_unlock(&bg->lock);
+					continue;
+				}
+				spin_unlock(&bg->lock);
+
+				if (btrfs_zone_activate(bg)) {
+					up_read(&space_info->groups_sem);
+					return 1;
+				}
+
+				need_finish = true;
+			}
+		}
+		up_read(&space_info->groups_sem);
+
+		if (!do_finish || !need_finish)
+			break;
+
+		ret = btrfs_zone_finish_one_bg(fs_info);
+		if (ret == 0)
+			break;
+		if (ret < 0)
+			return ret;
+	}
+
+	return 0;
+}