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>

1 files changed, 21 insertions, 0 deletions

diff --git a/fs/btrfs/zoned.c b/fs/btrfs/zoned.c
index c7243d392ca8..549912120cfe 100644
--- a/fs/btrfs/zoned.c
+++ b/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;
+}