Fixes for loopback files in btrfs

Signed-off-by: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index a280b95..62fcd79 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -861,6 +861,7 @@
 	.llseek		= generic_file_llseek,
 	.read		= do_sync_read,
 	.aio_read       = generic_file_aio_read,
+	.splice_read	= generic_file_splice_read,
 	.write		= btrfs_file_write,
 	.mmap		= btrfs_file_mmap,
 	.open		= generic_file_open,