btrfs: Replace kmalloc with kmalloc_array

Replace kmalloc(size * nr, ) with kmalloc_array(nr, size), thus making
it easier to check is that the calculation doesn't wrap or return a smaller allocation

Signed-off-by: Dulshani Gunawardhana <dulshani.gunawardhana89@gmail.com>
Reviewed-by: Zach Brown <zab@redhat.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
diff --git a/fs/btrfs/delayed-inode.c b/fs/btrfs/delayed-inode.c
index 2bb8e1a..8d292fb 100644
--- a/fs/btrfs/delayed-inode.c
+++ b/fs/btrfs/delayed-inode.c
@@ -770,13 +770,13 @@
 	 */
 	btrfs_set_path_blocking(path);
 
-	keys = kmalloc(sizeof(struct btrfs_key) * nitems, GFP_NOFS);
+	keys = kmalloc_array(nitems, sizeof(struct btrfs_key), GFP_NOFS);
 	if (!keys) {
 		ret = -ENOMEM;
 		goto out;
 	}
 
-	data_size = kmalloc(sizeof(u32) * nitems, GFP_NOFS);
+	data_size = kmalloc_array(nitems, sizeof(u32), GFP_NOFS);
 	if (!data_size) {
 		ret = -ENOMEM;
 		goto error;