btrfs: move tree block wait and write helpers to tree-log

The wrapper names better describe what's happening so they're not
deleted though they're trivial, but at least moved closer to their place
of use.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/disk-io.c

@@ -1078,19 +1078,6 @@ struct extent_buffer *btrfs_find_create_tree_block(
 	return alloc_extent_buffer(fs_info, bytenr);
 }
 
-
-int btrfs_write_tree_block(struct extent_buffer *buf)
-{
-	return filemap_fdatawrite_range(buf->pages[0]->mapping, buf->start,
-					buf->start + buf->len - 1);
-}
-
-void btrfs_wait_tree_block_writeback(struct extent_buffer *buf)
-{
-	filemap_fdatawait_range(buf->pages[0]->mapping,
-			        buf->start, buf->start + buf->len - 1);
-}
-
 /*
  * Read tree block at logical address @bytenr and do variant basic but critical
  * verification.

fs/btrfs/disk-io.h

@@ -126,8 +126,6 @@ blk_status_t btrfs_wq_submit_bio(struct btrfs_fs_info *fs_info, struct bio *bio,
 			extent_submit_bio_start_t *submit_bio_start);
 blk_status_t btrfs_submit_bio_done(void *private_data, struct bio *bio,
 			  int mirror_num);
-int btrfs_write_tree_block(struct extent_buffer *buf);
-void btrfs_wait_tree_block_writeback(struct extent_buffer *buf);
 int btrfs_init_log_root_tree(struct btrfs_trans_handle *trans,
 			     struct btrfs_fs_info *fs_info);
 int btrfs_add_log_tree(struct btrfs_trans_handle *trans,

fs/btrfs/tree-log.c

@@ -225,6 +225,17 @@ void btrfs_end_log_trans(struct btrfs_root *root)
 	}
 }
 
+static int btrfs_write_tree_block(struct extent_buffer *buf)
+{
+	return filemap_fdatawrite_range(buf->pages[0]->mapping, buf->start,
+					buf->start + buf->len - 1);
+}
+
+static void btrfs_wait_tree_block_writeback(struct extent_buffer *buf)
+{
+	filemap_fdatawait_range(buf->pages[0]->mapping,
+			        buf->start, buf->start + buf->len - 1);
+}
 
 /*
  * the walk control struct is used to pass state down the chain when