MFC: r344755:

Fix integer overflow possibility.

Reported by:    Christopher Krah, Thomas Barabosch, and Jan-Niclas Hilgert of Fraunhofer FKIE
Reported as:    FS-2-EXT2-1: Out-of-Bounds Write in nmount (ext2_vget)
Reviewed by:    pfg

Differential Revision:    https://reviews.freebsd.org/D19326

sys/fs/ext2fs/ext2_vfsops.c

@@ -1156,8 +1156,8 @@ ext2_vget(struct mount *mp, ino_t ino, int flags, struct vnode **vpp)
 	struct buf *bp;
 	struct vnode *vp;
 	struct thread *td;
-	int i, error;
-	int used_blocks;
+	unsigned int i, used_blocks;
+	int error;
 
 	td = curthread;
 	error = vfs_hash_get(mp, ino, flags, td, vpp, NULL, NULL);