nfsd: fix configuration of supported minor versions

When the user turns off all minor versions of NFSv4, that should be
equivalent to turning off NFSv4 support, so a mount attempt using NFSv4
should get RPC_PROG_MISMATCH, not NFSERR_MINOR_VERS_MISMATCH.

Allow the user to use either '4.0' or '4' to enable or disable minor
version 0.  Other minor versions are still enabled or disabled using the
'4.x' format.
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

fs/nfsd/nfsctl.c

@@ -561,6 +561,7 @@ static ssize_t __write_versions(struct file *file, char *buf, size_t size)
 		len = qword_get(&mesg, vers, size);
 		if (len <= 0) return -EINVAL;
 		do {
+			enum vers_op cmd;
 			sign = *vers;
 			if (sign == '+' || sign == '-')
 				num = simple_strtol((vers+1), &minorp, 0);
@@ -571,21 +572,20 @@ static ssize_t __write_versions(struct file *file, char *buf, size_t size)
 					return -EINVAL;
 				if (kstrtouint(minorp+1, 0, &minor) < 0)
 					return -EINVAL;
-				if (nfsd_minorversion(minor, sign == '-' ?
-						     NFSD_CLEAR : NFSD_SET) < 0)
-					return -EINVAL;
-				goto next;
-			}
+			} else
+				minor = 0;
+			cmd = sign == '-' ? NFSD_CLEAR : NFSD_SET;
 			switch(num) {
 			case 2:
 			case 3:
-			case 4:
-				nfsd_vers(num, sign == '-' ? NFSD_CLEAR : NFSD_SET);
+				nfsd_vers(num, cmd);
 				break;
+			case 4:
+				if (nfsd_minorversion(minor, cmd) >= 0)
+					break;
 			default:
 				return -EINVAL;
 			}
-		next:
 			vers += len + 1;
 		} while ((len = qword_get(&mesg, vers, size)) > 0);
 		/* If all get turned off, turn them back on, as

fs/nfsd/nfssvc.c

@@ -153,6 +153,18 @@ int nfsd_vers(int vers, enum vers_op change)
 	return 0;
 }
 
+static void
+nfsd_adjust_nfsd_versions4(void)
+{
+	unsigned i;
+
+	for (i = 0; i <= NFSD_SUPPORTED_MINOR_VERSION; i++) {
+		if (nfsd_supported_minorversions[i])
+			return;
+	}
+	nfsd_vers(4, NFSD_CLEAR);
+}
+
 int nfsd_minorversion(u32 minorversion, enum vers_op change)
 {
 	if (minorversion > NFSD_SUPPORTED_MINOR_VERSION)
@@ -160,9 +172,11 @@ int nfsd_minorversion(u32 minorversion, enum vers_op change)
 	switch(change) {
 	case NFSD_SET:
 		nfsd_supported_minorversions[minorversion] = true;
+		nfsd_vers(4, NFSD_SET);
 		break;
 	case NFSD_CLEAR:
 		nfsd_supported_minorversions[minorversion] = false;
+		nfsd_adjust_nfsd_versions4();
 		break;
 	case NFSD_TEST:
 		return nfsd_supported_minorversions[minorversion];