[PATCH 10/15] btrfs: add a btrfs_map_bio_wait helper

[Christoph Hellwig <hch@lst.de>]

This helpers works like submit_bio_wait, but goes through the btrfs bio
mapping using btrfs_map_bio.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 fs/btrfs/volumes.c | 21 +++++++++++++++++++++
 fs/btrfs/volumes.h |  2 ++
 2 files changed, 23 insertions(+)

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 0819db46dbc42..8925bc606db7e 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -6818,6 +6818,27 @@ blk_status_t btrfs_map_bio(struct btrfs_fs_info *fs_info, struct bio *bio,
 	return BLK_STS_OK;
 }
 
+static void btrfs_end_io_sync(struct bio *bio)
+{
+	complete(bio->bi_private);
+}
+
+blk_status_t btrfs_map_bio_wait(struct btrfs_fs_info *fs_info, struct bio *bio,
+		int mirror)
+{
+	DECLARE_COMPLETION_ONSTACK(done);
+	blk_status_t ret;
+
+	bio->bi_private = &done;
+	bio->bi_end_io = btrfs_end_io_sync;
+	ret = btrfs_map_bio(fs_info, bio, mirror);
+	if (ret)
+		return ret;
+
+	wait_for_completion_io(&done);
+	return bio->bi_status;
+}
+
 static bool dev_args_match_fs_devices(const struct btrfs_dev_lookup_args *args,
 				      const struct btrfs_fs_devices *fs_devices)
 {
diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
index 6f784d4f54664..b346f6c401515 100644
--- a/fs/btrfs/volumes.h
+++ b/fs/btrfs/volumes.h
@@ -555,6 +555,8 @@ struct btrfs_block_group *btrfs_create_chunk(struct btrfs_trans_handle *trans,
 void btrfs_mapping_tree_free(struct extent_map_tree *tree);
 blk_status_t btrfs_map_bio(struct btrfs_fs_info *fs_info, struct bio *bio,
 			   int mirror_num);
+blk_status_t btrfs_map_bio_wait(struct btrfs_fs_info *fs_info, struct bio *bio,
+		int mirror);
 int btrfs_open_devices(struct btrfs_fs_devices *fs_devices,
 		       fmode_t flags, void *holder);
 struct btrfs_device *btrfs_scan_one_device(const char *path,
-- 
2.30.2