[PATCH v14 25/42] btrfs: cache if block-group is on a sequential zone

[Naohiro Aota]

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

In zoned mode, 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 said
REQ_OP_ZONE_APPEND for data writing.

Reviewed-by: Josef Bacik <jo...@toxicpanda.com>
Signed-off-by: Johannes Thumshirn <johannes.thumsh...@wdc.com>
---
 fs/btrfs/block-group.h |  2 ++
 fs/btrfs/zoned.c       | 29 +++++++++++++++++++++++++++++
 fs/btrfs/zoned.h       |  5 +++++
 3 files changed, 36 insertions(+)

diff --git a/fs/btrfs/block-group.h b/fs/btrfs/block-group.h
index 9df00ada09f9..a1d96c4cfa3b 100644
--- a/fs/btrfs/block-group.h
+++ b/fs/btrfs/block-group.h
@@ -184,6 +184,8 @@ struct btrfs_block_group {
        /* Record locked full stripes for RAID5/6 block group */
        struct btrfs_full_stripe_locks_tree full_stripe_locks_root;
 
+       /* Flag indicating this block-group is placed on a sequential zone */
+       bool seq_zone;
        /*
         * Allocation offset for the block group to implement sequential
         * allocation. This is used only with ZONED mode enabled.
diff --git a/fs/btrfs/zoned.c b/fs/btrfs/zoned.c
index db6cb0070220..abe6b415de98 100644
--- a/fs/btrfs/zoned.c
+++ b/fs/btrfs/zoned.c
@@ -1103,6 +1103,9 @@ 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
@@ -1223,3 +1226,29 @@ 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 331951978487..92888eb86055 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)
@@ -134,6 +135,10 @@ 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) { }
 
+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)
-- 
2.27.0