nfs: kuid and kgid conversions for nfs/inode.c

- Use uid_eq and gid_eq when comparing kuids and kgids.
- Use make_kuid(&init_user_ns, -2) and make_kgid(&init_user_ns, -2) as
  the initial uid and gid on nfs inodes, instead of using the typeunsafe
  value of -2.

Cc: "J. Bruce Fields" <bfields@fieldses.org>
Cc: Trond Myklebust <Trond.Myklebust@netapp.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>

fs/nfs/inode.c

@@ -332,8 +332,8 @@ nfs_fhget(struct super_block *sb, struct nfs_fh *fh, struct nfs_fattr *fattr)
 		inode->i_version = 0;
 		inode->i_size = 0;
 		clear_nlink(inode);
-		inode->i_uid = -2;
-		inode->i_gid = -2;
+		inode->i_uid = make_kuid(&init_user_ns, -2);
+		inode->i_gid = make_kgid(&init_user_ns, -2);
 		inode->i_blocks = 0;
 		memset(nfsi->cookieverf, 0, sizeof(nfsi->cookieverf));
 		nfsi->write_io = 0;
@@ -1009,9 +1009,9 @@ static int nfs_check_inode_attributes(struct inode *inode, struct nfs_fattr *fat
 	/* Have any file permissions changed? */
 	if ((fattr->valid & NFS_ATTR_FATTR_MODE) && (inode->i_mode & S_IALLUGO) != (fattr->mode & S_IALLUGO))
 		invalid |= NFS_INO_INVALID_ATTR | NFS_INO_INVALID_ACCESS | NFS_INO_INVALID_ACL;
-	if ((fattr->valid & NFS_ATTR_FATTR_OWNER) && inode->i_uid != fattr->uid)
+	if ((fattr->valid & NFS_ATTR_FATTR_OWNER) && !uid_eq(inode->i_uid, fattr->uid))
 		invalid |= NFS_INO_INVALID_ATTR | NFS_INO_INVALID_ACCESS | NFS_INO_INVALID_ACL;
-	if ((fattr->valid & NFS_ATTR_FATTR_GROUP) && inode->i_gid != fattr->gid)
+	if ((fattr->valid & NFS_ATTR_FATTR_GROUP) && !gid_eq(inode->i_gid, fattr->gid))
 		invalid |= NFS_INO_INVALID_ATTR | NFS_INO_INVALID_ACCESS | NFS_INO_INVALID_ACL;
 
 	/* Has the link count changed? */
@@ -1440,7 +1440,7 @@ static int nfs_update_inode(struct inode *inode, struct nfs_fattr *fattr)
 				| NFS_INO_REVAL_FORCED);
 
 	if (fattr->valid & NFS_ATTR_FATTR_OWNER) {
-		if (inode->i_uid != fattr->uid) {
+		if (!uid_eq(inode->i_uid, fattr->uid)) {
 			invalid |= NFS_INO_INVALID_ATTR|NFS_INO_INVALID_ACCESS|NFS_INO_INVALID_ACL;
 			inode->i_uid = fattr->uid;
 		}
@@ -1451,7 +1451,7 @@ static int nfs_update_inode(struct inode *inode, struct nfs_fattr *fattr)
 				| NFS_INO_REVAL_FORCED);
 
 	if (fattr->valid & NFS_ATTR_FATTR_GROUP) {
-		if (inode->i_gid != fattr->gid) {
+		if (!gid_eq(inode->i_gid, fattr->gid)) {
 			invalid |= NFS_INO_INVALID_ATTR|NFS_INO_INVALID_ACCESS|NFS_INO_INVALID_ACL;
 			inode->i_gid = fattr->gid;
 		}