nfsd: Properly compare and initialize kuids and kgids

Use uid_eq(uid, GLOBAL_ROOT_UID) instead of !uid.
Use gid_eq(gid, GLOBAL_ROOT_GID) instead of !gid.
Use uid_eq(uid, INVALID_UID) instead of uid == -1
Use gid_eq(uid, INVALID_GID) instead of gid == -1
Use uid = GLOBAL_ROOT_UID instead of uid = 0;
Use gid = GLOBAL_ROOT_GID instead of gid = 0;
Use !uid_eq(uid1, uid2) instead of uid1 != uid2.
Use !gid_eq(gid1, gid2) instead of gid1 != gid2.
Use uid_eq(uid1, uid2) instead of uid1 == uid2.

Cc: "J. Bruce Fields" <bfields@fieldses.org>
Cc: Trond Myklebust <Trond.Myklebust@netapp.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index ac8ed96..0af6d3c 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -1202,7 +1202,7 @@
 	if (g1->ngroups != g2->ngroups)
 		return false;
 	for (i=0; i<g1->ngroups; i++)
-		if (GROUP_AT(g1, i) != GROUP_AT(g2, i))
+		if (!gid_eq(GROUP_AT(g1, i), GROUP_AT(g2, i)))
 			return false;
 	return true;
 }
@@ -1227,8 +1227,8 @@
 same_creds(struct svc_cred *cr1, struct svc_cred *cr2)
 {
 	if ((is_gss_cred(cr1) != is_gss_cred(cr2))
-		|| (cr1->cr_uid != cr2->cr_uid)
-		|| (cr1->cr_gid != cr2->cr_gid)
+		|| (!uid_eq(cr1->cr_uid, cr2->cr_uid))
+		|| (!gid_eq(cr1->cr_gid, cr2->cr_gid))
 		|| !groups_equal(cr1->cr_group_info, cr2->cr_group_info))
 		return false;
 	if (cr1->cr_principal == cr2->cr_principal)