diff --git a/fs/btrfs/btrfs_inode.h b/fs/btrfs/btrfs_inode.h
index 78c7979b8dcac7ffc0c768aba9213790e446bfb0..ba5f023aaf5573ba7aff76e666e4674fec45b24f 100644
--- a/fs/btrfs/btrfs_inode.h
+++ b/fs/btrfs/btrfs_inode.h
@@ -408,10 +408,6 @@ static inline void btrfs_inode_split_flags(u64 inode_item_flags,
 void btrfs_submit_data_write_bio(struct btrfs_inode *inode, struct bio *bio, int mirror_num);
 void btrfs_submit_data_read_bio(struct btrfs_inode *inode, struct bio *bio,
 			int mirror_num, enum btrfs_compression_type compress_type);
-blk_status_t btrfs_submit_bio_start(struct btrfs_inode *inode, struct bio *bio);
-blk_status_t btrfs_submit_bio_start_direct_io(struct btrfs_inode *inode,
-					      struct bio *bio,
-					      u64 dio_file_offset);
 int btrfs_check_sector_csum(struct btrfs_fs_info *fs_info, struct page *page,
 			    u32 pgoff, u8 *csum, const u8 * const csum_expected);
 bool btrfs_data_csum_ok(struct btrfs_bio *bbio, struct btrfs_device *dev,
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index cb8e495f981bc2cee9dbce6e9d1dcc28712d9a67..764ee9338637e61efdeefc5cdfdf79b6e70b355f 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -52,6 +52,7 @@
 #include "relocation.h"
 #include "scrub.h"
 #include "super.h"
+#include "file-item.h"
 
 #define BTRFS_SUPER_FLAG_SUPP	(BTRFS_HEADER_FLAG_WRITTEN |\
 				 BTRFS_HEADER_FLAG_RELOC |\
@@ -455,6 +456,24 @@ static int csum_dirty_buffer(struct btrfs_fs_info *fs_info, struct bio_vec *bvec
 	return csum_one_extent_buffer(eb);
 }
 
+static blk_status_t btree_csum_one_bio(struct bio *bio)
+{
+	struct bio_vec *bvec;
+	struct btrfs_root *root;
+	struct bvec_iter_all iter_all;
+	int ret = 0;
+
+	ASSERT(!bio_flagged(bio, BIO_CLONED));
+	bio_for_each_segment_all(bvec, bio, iter_all) {
+		root = BTRFS_I(bvec->bv_page->mapping->host)->root;
+		ret = csum_dirty_buffer(root->fs_info, bvec);
+		if (ret)
+			break;
+	}
+
+	return errno_to_blk_status(ret);
+}
+
 static int check_tree_block_fsid(struct extent_buffer *eb)
 {
 	struct btrfs_fs_info *fs_info = eb->fs_info;
@@ -708,14 +727,14 @@ static void run_one_async_start(struct btrfs_work *work)
 	async = container_of(work, struct  async_submit_bio, work);
 	switch (async->submit_cmd) {
 	case WQ_SUBMIT_METADATA:
-		ret = btree_submit_bio_start(async->bio);
+		ret = btree_csum_one_bio(async->bio);
 		break;
 	case WQ_SUBMIT_DATA:
-		ret = btrfs_submit_bio_start(async->inode, async->bio);
+		ret = btrfs_csum_one_bio(async->inode, async->bio, (u64)-1, false);
 		break;
 	case WQ_SUBMIT_DATA_DIO:
-		ret = btrfs_submit_bio_start_direct_io(async->inode,
-				async->bio, async->dio_file_offset);
+		ret = btrfs_csum_one_bio(async->inode, async->bio,
+					 async->dio_file_offset, false);
 		break;
 	default:
 		/* Can't happen so return something that would prevent the IO. */
@@ -800,33 +819,6 @@ bool btrfs_wq_submit_bio(struct btrfs_inode *inode, struct bio *bio, int mirror_
 	return true;
 }
 
-static blk_status_t btree_csum_one_bio(struct bio *bio)
-{
-	struct bio_vec *bvec;
-	struct btrfs_root *root;
-	int ret = 0;
-	struct bvec_iter_all iter_all;
-
-	ASSERT(!bio_flagged(bio, BIO_CLONED));
-	bio_for_each_segment_all(bvec, bio, iter_all) {
-		root = BTRFS_I(bvec->bv_page->mapping->host)->root;
-		ret = csum_dirty_buffer(root->fs_info, bvec);
-		if (ret)
-			break;
-	}
-
-	return errno_to_blk_status(ret);
-}
-
-blk_status_t btree_submit_bio_start(struct bio *bio)
-{
-	/*
-	 * when we're called for a write, we're already in the async
-	 * submission context.  Just jump into btrfs_submit_bio.
-	 */
-	return btree_csum_one_bio(bio);
-}
-
 static bool should_async_write(struct btrfs_fs_info *fs_info,
 			     struct btrfs_inode *bi)
 {
diff --git a/fs/btrfs/disk-io.h b/fs/btrfs/disk-io.h
index f2f295eb6103da3dd00e1d30c086a910c41747a5..5898beb648484a1beecbdfc1c4f3872da54fbbb4 100644
--- a/fs/btrfs/disk-io.h
+++ b/fs/btrfs/disk-io.h
@@ -122,7 +122,6 @@ enum btrfs_wq_submit_cmd {
 
 bool btrfs_wq_submit_bio(struct btrfs_inode *inode, struct bio *bio, int mirror_num,
 			 u64 dio_file_offset, enum btrfs_wq_submit_cmd cmd);
-blk_status_t btree_submit_bio_start(struct bio *bio);
 int btrfs_alloc_log_tree_node(struct btrfs_trans_handle *trans,
 			      struct btrfs_root *root);
 int btrfs_init_log_root_tree(struct btrfs_trans_handle *trans,
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 8e1d61b731ed6073248c315b39e80558815c957f..cdb0f8cb0d4f22f77a4f653f6faef5374c6d2896 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -2532,19 +2532,6 @@ void btrfs_clear_delalloc_extent(struct btrfs_inode *inode,
 	}
 }
 
-/*
- * in order to insert checksums into the metadata in large chunks,
- * we wait until bio submission time.   All the pages in the bio are
- * checksummed and sums are attached onto the ordered extent record.
- *
- * At IO completion time the cums attached on the ordered extent record
- * are inserted into the btree
- */
-blk_status_t btrfs_submit_bio_start(struct btrfs_inode *inode, struct bio *bio)
-{
-	return btrfs_csum_one_bio(inode, bio, (u64)-1, false);
-}
-
 /*
  * Split an extent_map at [start, start + len]
  *
@@ -7835,13 +7822,6 @@ static void btrfs_dio_private_put(struct btrfs_dio_private *dip)
 	bio_endio(&dip->bio);
 }
 
-blk_status_t btrfs_submit_bio_start_direct_io(struct btrfs_inode *inode,
-					      struct bio *bio,
-					      u64 dio_file_offset)
-{
-	return btrfs_csum_one_bio(inode, bio, dio_file_offset, false);
-}
-
 static void btrfs_end_dio_bio(struct btrfs_bio *bbio)
 {
 	struct btrfs_dio_private *dip = bbio->private;