cifs: Convert struct cifs_fattr to use kuid and kgids

In cifs_unix_to_basic_fattr only update the cifs_fattr with an id if
it is valid after conversion.

Cc: Steve French <smfrench@gmail.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>

fs/cifs/cifsglob.h

@@ -1245,8 +1245,8 @@ struct cifs_fattr {
 	u64		cf_eof;
 	u64		cf_bytes;
 	u64		cf_createtime;
-	uid_t		cf_uid;
-	gid_t		cf_gid;
+	kuid_t		cf_uid;
+	kgid_t		cf_gid;
 	umode_t		cf_mode;
 	dev_t		cf_rdev;
 	unsigned int	cf_nlink;

fs/cifs/inode.c

@@ -247,15 +247,21 @@ cifs_unix_basic_to_fattr(struct cifs_fattr *fattr, FILE_UNIX_BASIC_INFO *info,
 	fattr->cf_uid = cifs_sb->mnt_uid;
 	if (!(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_OVERR_UID)) {
 		u64 id = le64_to_cpu(info->Uid);
-		if (id < ((uid_t)-1))
-			fattr->cf_uid = id;
+		if (id < ((uid_t)-1)) {
+			kuid_t uid = make_kuid(&init_user_ns, id);
+			if (uid_valid(uid))
+				fattr->cf_uid = uid;
+		}
 	}
 
 	fattr->cf_gid = cifs_sb->mnt_gid;
 	if (!(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_OVERR_GID)) {
 		u64 id = le64_to_cpu(info->Gid);
-		if (id < ((gid_t)-1))
-			fattr->cf_gid = id;
+		if (id < ((gid_t)-1)) {
+			kgid_t gid = make_kgid(&init_user_ns, id);
+			if (gid_valid(gid))
+				fattr->cf_gid = gid;
+		}
 	}
 
 	fattr->cf_nlink = le64_to_cpu(info->Nlinks);