btrfs: zoned: factor out zoned device lookup

To be able to construct a zone append bio we need to look up the
btrfs_device. The code doing the chunk map lookup to get the device is
present in btrfs_submit_compressed_write and submit_extent_page.

Factor out the lookup calls into a helper and use it in the submission
paths.
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/compression.c

@@ -427,24 +427,16 @@ blk_status_t btrfs_submit_compressed_write(struct btrfs_inode *inode, u64 start,
 	bio->bi_end_io = end_compressed_bio_write;
 
 	if (use_append) {
-		struct extent_map *em;
-		struct map_lookup *map;
-		struct block_device *bdev;
+		struct btrfs_device *device;
 
-		em = btrfs_get_chunk_map(fs_info, disk_start, PAGE_SIZE);
-		if (IS_ERR(em)) {
+		device = btrfs_zoned_get_device(fs_info, disk_start, PAGE_SIZE);
+		if (IS_ERR(device)) {
 			kfree(cb);
 			bio_put(bio);
 			return BLK_STS_NOTSUPP;
 		}
 
-		map = em->map_lookup;
-		/* We only support single profile for now */
-		ASSERT(map->num_stripes == 1);
-		bdev = map->stripes[0].dev->bdev;
-
-		bio_set_dev(bio, bdev);
-		free_extent_map(em);
+		bio_set_dev(bio, device->bdev);
 	}
 
 	if (blkcg_css) {

fs/btrfs/extent_io.c

@@ -3266,19 +3266,13 @@ static int submit_extent_page(unsigned int opf,
 		wbc_account_cgroup_owner(wbc, page, io_size);
 	}
 	if (btrfs_is_zoned(fs_info) && bio_op(bio) == REQ_OP_ZONE_APPEND) {
-		struct extent_map *em;
-		struct map_lookup *map;
+		struct btrfs_device *device;
 
-		em = btrfs_get_chunk_map(fs_info, disk_bytenr, io_size);
-		if (IS_ERR(em))
-			return PTR_ERR(em);
+		device = btrfs_zoned_get_device(fs_info, disk_bytenr, io_size);
+		if (IS_ERR(device))
+			return PTR_ERR(device);
 
-		map = em->map_lookup;
-		/* We only support single profile for now */
-		ASSERT(map->num_stripes == 1);
-		btrfs_io_bio(bio)->device = map->stripes[0].dev;
-
-		free_extent_map(em);
+		btrfs_io_bio(bio)->device = device;
 	}
 
 	*bio_ret = bio;

fs/btrfs/zoned.c

@@ -1533,3 +1533,24 @@ int btrfs_sync_zone_write_pointer(struct btrfs_device *tgt_dev, u64 logical,
 	length = wp - physical_pos;
 	return btrfs_zoned_issue_zeroout(tgt_dev, physical_pos, length);
 }
+
+struct btrfs_device *btrfs_zoned_get_device(struct btrfs_fs_info *fs_info,
+					    u64 logical, u64 length)
+{
+	struct btrfs_device *device;
+	struct extent_map *em;
+	struct map_lookup *map;
+
+	em = btrfs_get_chunk_map(fs_info, logical, length);
+	if (IS_ERR(em))
+		return ERR_CAST(em);
+
+	map = em->map_lookup;
+	/* We only support single profile for now */
+	ASSERT(map->num_stripes == 1);
+	device = map->stripes[0].dev;
+
+	free_extent_map(em);
+
+	return device;
+}

fs/btrfs/zoned.h

@@ -65,6 +65,8 @@ void btrfs_revert_meta_write_pointer(struct btrfs_block_group *cache,
 int btrfs_zoned_issue_zeroout(struct btrfs_device *device, u64 physical, u64 length);
 int btrfs_sync_zone_write_pointer(struct btrfs_device *tgt_dev, u64 logical,
 				  u64 physical_start, u64 physical_pos);
+struct btrfs_device *btrfs_zoned_get_device(struct btrfs_fs_info *fs_info,
+					    u64 logical, u64 length);
 #else /* CONFIG_BLK_DEV_ZONED */
 static inline int btrfs_get_dev_zone(struct btrfs_device *device, u64 pos,
 				     struct blk_zone *zone)
@@ -191,6 +193,13 @@ static inline int btrfs_sync_zone_write_pointer(struct btrfs_device *tgt_dev,
 	return -EOPNOTSUPP;
 }
 
+static inline struct btrfs_device *btrfs_zoned_get_device(
+						  struct btrfs_fs_info *fs_info,
+						  u64 logical, u64 length)
+{
+	return ERR_PTR(-EOPNOTSUPP);
+}
+
 #endif
 
 static inline bool btrfs_dev_is_sequential(struct btrfs_device *device, u64 pos)