diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index ace88c1..a74edc7 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -1154,8 +1154,11 @@
 	u64 new_align = ~((u64)128 * 1024 - 1);
 	struct page **pages = NULL;
 
-	if (extent_thresh == 0)
-		extent_thresh = 256 * 1024;
+	if (isize == 0)
+		return 0;
+
+	if (range->start >= isize)
+		return -EINVAL;
 
 	if (range->flags & BTRFS_DEFRAG_RANGE_COMPRESS) {
 		if (range->compress_type > BTRFS_COMPRESS_TYPES)
@@ -1164,8 +1167,8 @@
 			compress_type = range->compress_type;
 	}
 
-	if (isize == 0)
-		return 0;
+	if (extent_thresh == 0)
+		extent_thresh = 256 * 1024;
 
 	/*
 	 * if we were not given a file, allocate a readahead