btrfs: zoned: cache if block group is on a sequential zone

On a zoned filesystem, cache if a block group is on a sequential write
only zone.

On sequential write only zones, we can use REQ_OP_ZONE_APPEND for
writing data, therefore provide btrfs_use_zone_append() to figure out if
IO is targeting a sequential write only zone and we can use
REQ_OP_ZONE_APPEND for data writing.

Reviewed-by: Josef Bacik <josef@toxicpanda.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>

1 files changed, 29 insertions, 0 deletions

diff --git a/fs/btrfs/zoned.c b/fs/btrfs/zoned.c
index 1de67d789b83..f6c68704c840 100644
--- a/fs/btrfs/zoned.c
+++ b/fs/btrfs/zoned.c
@@ -1101,6 +1101,9 @@ int btrfs_load_block_group_zone_info(struct btrfs_block_group *cache, bool new)
 		}
 	}
 
+	if (num_sequential > 0)
+		cache->seq_zone = true;
+
 	if (num_conventional > 0) {
 		/*
 		 * Avoid calling calculate_alloc_pointer() for new BG. It
@@ -1218,3 +1221,29 @@ void btrfs_free_redirty_list(struct btrfs_transaction *trans)
 	}
 	spin_unlock(&trans->releasing_ebs_lock);
 }
+
+bool btrfs_use_zone_append(struct btrfs_inode *inode, struct extent_map *em)
+{
+	struct btrfs_fs_info *fs_info = inode->root->fs_info;
+	struct btrfs_block_group *cache;
+	bool ret = false;
+
+	if (!btrfs_is_zoned(fs_info))
+		return false;
+
+	if (!fs_info->max_zone_append_size)
+		return false;
+
+	if (!is_data_inode(&inode->vfs_inode))
+		return false;
+
+	cache = btrfs_lookup_block_group(fs_info, em->block_start);
+	ASSERT(cache);
+	if (!cache)
+		return false;
+
+	ret = cache->seq_zone;
+	btrfs_put_block_group(cache);
+
+	return ret;
+}