ceph: fix endianness bug in frag_tree_split_cmp

sparse says:

    fs/ceph/inode.c:308:36: warning: incorrect type in argument 1 (different base types)
    fs/ceph/inode.c:308:36:    expected unsigned int [unsigned] [usertype] a
    fs/ceph/inode.c:308:36:    got restricted __le32 [usertype] frag
    fs/ceph/inode.c:308:46: warning: incorrect type in argument 2 (different base types)
    fs/ceph/inode.c:308:46:    expected unsigned int [unsigned] [usertype] b
    fs/ceph/inode.c:308:46:    got restricted __le32 [usertype] frag

We need to convert these values to host-endian before calling the
comparator.

Fixes: a407846ef7c6 ("ceph: don't assume frag tree splits in mds reply are sorted")
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Reviewed-by: Sage Weil <sage@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

fs/ceph/inode.c

@@ -305,7 +305,8 @@ static int frag_tree_split_cmp(const void *l, const void *r)
 {
 	struct ceph_frag_tree_split *ls = (struct ceph_frag_tree_split*)l;
 	struct ceph_frag_tree_split *rs = (struct ceph_frag_tree_split*)r;
-	return ceph_frag_compare(ls->frag, rs->frag);
+	return ceph_frag_compare(le32_to_cpu(ls->frag),
+				 le32_to_cpu(rs->frag));
 }
 
 static bool is_frag_child(u32 f, struct ceph_inode_frag *frag)