[PATCH v15 24/42] btrfs: zoned: cache if block-group is on a sequential zone

[Naohiro Aota <naohiro.aota@wdc.com>]

From: Johannes Thumshirn <johannes.thumshirn@wdc.com>

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
of data, therefore provide btrfs_use_zone_append() to figure out if I/O 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>
---
 fs/btrfs/block-group.h |  3 +++
 fs/btrfs/zoned.c       | 29 +++++++++++++++++++++++++++++
 fs/btrfs/zoned.h       |  6 ++++++
 3 files changed, 38 insertions(+)

diff --git a/fs/btrfs/block-group.h b/fs/btrfs/block-group.h
index d14ac03bb93d..31c7c5872b92 100644
--- a/fs/btrfs/block-group.h
+++ b/fs/btrfs/block-group.h
@@ -181,6 +181,9 @@ struct btrfs_block_group {
 	 */
 	int needs_free_space;
 
+	/* Flag indicating this block group is placed on a sequential zone */
+	bool seq_zone;
+
 	/* Record locked full stripes for RAID5/6 block group */
 	struct btrfs_full_stripe_locks_tree full_stripe_locks_root;
 
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;
+}
diff --git a/fs/btrfs/zoned.h b/fs/btrfs/zoned.h
index c105641a6ad3..14d578328cbe 100644
--- a/fs/btrfs/zoned.h
+++ b/fs/btrfs/zoned.h
@@ -46,6 +46,7 @@ void btrfs_calc_zone_unusable(struct btrfs_block_group *cache);
 void btrfs_redirty_list_add(struct btrfs_transaction *trans,
 			    struct extent_buffer *eb);
 void btrfs_free_redirty_list(struct btrfs_transaction *trans);
+bool btrfs_use_zone_append(struct btrfs_inode *inode, struct extent_map *em);
 #else /* CONFIG_BLK_DEV_ZONED */
 static inline int btrfs_get_dev_zone(struct btrfs_device *device, u64 pos,
 				     struct blk_zone *zone)
@@ -133,6 +134,11 @@ static inline void btrfs_redirty_list_add(struct btrfs_transaction *trans,
 					  struct extent_buffer *eb) { }
 static inline void btrfs_free_redirty_list(struct btrfs_transaction *trans) { }
 
+static inline bool btrfs_use_zone_append(struct btrfs_inode *inode,
+					 struct extent_map *em)
+{
+	return false;
+}
 #endif
 
 static inline bool btrfs_dev_is_sequential(struct btrfs_device *device, u64 pos)
-- 
2.30.0