[nfs-utils PATCH] nfsdctl: tweak the version subcommand behavior

[Scott Mayhew <smayhew@redhat.com>]

The section for the 'nfsdctl version' subcommand on the man page states
that the minorversion is optional, and if omitted it will cause all
minorversions to be enabled/disabled, but it currently doesn't work that
way.

Make it work that way, with one exception.  If v4.0 is disabled, then
'nfsdctl version +4' will not re-enable it; instead it must be
explicitly re-enabled via 'nfsdctl version +4.0'.  This mirrors the way
/proc/fs/nfsd/versions works.

Link: https://issues.redhat.com/browse/RHEL-72477
Signed-off-by: Scott Mayhew <smayhew@redhat.com>
---
 utils/nfsdctl/nfsdctl.8    |  9 ++++--
 utils/nfsdctl/nfsdctl.adoc |  5 +++-
 utils/nfsdctl/nfsdctl.c    | 58 +++++++++++++++++++++++++++++++++++---
 3 files changed, 64 insertions(+), 8 deletions(-)

diff --git a/utils/nfsdctl/nfsdctl.8 b/utils/nfsdctl/nfsdctl.8
index b08fe803..835d60b4 100644
--- a/utils/nfsdctl/nfsdctl.8
+++ b/utils/nfsdctl/nfsdctl.8
@@ -2,12 +2,12 @@
 .\"     Title: nfsdctl
 .\"    Author: Jeff Layton
 .\" Generator: Asciidoctor 2.0.20
-.\"      Date: 2024-12-30
+.\"      Date: 2025-01-08
 .\"    Manual: \ \&
 .\"    Source: \ \&
 .\"  Language: English
 .\"
-.TH "NFSDCTL" "8" "2024-12-30" "\ \&" "\ \&"
+.TH "NFSDCTL" "8" "2025-01-08" "\ \&" "\ \&"
 .ie \n(.g .ds Aq \(aq
 .el       .ds Aq '
 .ss \n[.ss] 0
@@ -172,7 +172,10 @@ MINOR: the minor version integer value
 .nf
 .fam C
 The minorversion field is optional. If not given, it will disable or enable
-all minorversions for that major version.
+all minorversions for that major version.  Note however that if NFSv4.0 was
+previously disabled, it can only be re\-enabled by explicitly specifying the
+minorversion (this mirrors the behavior of the /proc/fs/nfsd/versions
+interface).
 .fam
 .fi
 .if n .RE
diff --git a/utils/nfsdctl/nfsdctl.adoc b/utils/nfsdctl/nfsdctl.adoc
index c5921458..20e9bf8e 100644
--- a/utils/nfsdctl/nfsdctl.adoc
+++ b/utils/nfsdctl/nfsdctl.adoc
@@ -91,7 +91,10 @@ Each subcommand can also accept its own set of options and arguments. The
     MINOR: the minor version integer value
 
   The minorversion field is optional. If not given, it will disable or enable
-  all minorversions for that major version.
+  all minorversions for that major version.  Note however that if NFSv4.0 was
+  previously disabled, it can only be re-enabled by explicitly specifying the
+  minorversion (this mirrors the behavior of the /proc/fs/nfsd/versions
+  interface).
 
   Note that versions can only be set when there are no nfsd threads running.
 
diff --git a/utils/nfsdctl/nfsdctl.c b/utils/nfsdctl/nfsdctl.c
index 722bf4a0..d86ff80e 100644
--- a/utils/nfsdctl/nfsdctl.c
+++ b/utils/nfsdctl/nfsdctl.c
@@ -761,6 +761,32 @@ static int update_nfsd_version(int major, int minor, bool enabled)
 	return -EINVAL;
 }
 
+static bool v40_is_disabled(void)
+{
+	int i;
+
+	for (i = 0; i < MAX_NFS_VERSIONS; ++i) {
+		if (nfsd_versions[i].major == 0)
+			break;
+		if (nfsd_versions[i].major == 4 && nfsd_versions[i].minor == 0)
+			return !nfsd_versions[i].enabled;
+	}
+	return false;
+}
+
+static int get_max_minorversion(void)
+{
+	int i, max = 0;
+
+	for (i = 0; i < MAX_NFS_VERSIONS; ++i) {
+		if (nfsd_versions[i].major == 0)
+			break;
+		if (nfsd_versions[i].major == 4 && nfsd_versions[i].minor > max)
+			max = nfsd_versions[i].minor;
+	}
+	return max;
+}
+
 static void version_usage(void)
 {
 	printf("Usage: %s version { {+,-}major.minor } ...\n", taskname);
@@ -778,7 +804,8 @@ static void version_usage(void)
 
 static int version_func(struct nl_sock *sock, int argc, char ** argv)
 {
-	int ret, i;
+	int ret, i, j, max_minor;
+	bool v40_disabled;
 
 	/* help is only valid as first argument after command */
 	if (argc > 1 &&
@@ -792,6 +819,9 @@ static int version_func(struct nl_sock *sock, int argc, char ** argv)
 		return ret;
 
 	if (argc > 1) {
+		v40_disabled = v40_is_disabled();
+		max_minor = get_max_minorversion();
+
 		for (i = 1; i < argc; ++i) {
 			int ret, major, minor = 0;
 			char sign = '\0', *str = argv[i];
@@ -815,9 +845,29 @@ static int version_func(struct nl_sock *sock, int argc, char ** argv)
 				return -EINVAL;
 			}
 
-			ret = update_nfsd_version(major, minor, enabled);
-			if (ret)
-				return ret;
+			/*
+			 * The minorversion field is optional. If omitted, it should
+			 * cause all the minor versions for that major version to be
+			 * enabled/disabled.
+			 *
+			 * HOWEVER, we do not enable v4.0 in this manner if it was
+			 * previously disabled - it has to be explicitly enabled
+			 * instead.  This is to retain the behavior of the old
+			 * /proc/fs/nfsd/versions interface.
+			 */
+			if (major == 4 && ret == 2) {
+				for (j = 0; j <= max_minor; ++j) {
+					if (j == 0 && enabled && v40_disabled)
+						continue;
+					ret = update_nfsd_version(major, j, enabled);
+					if (ret)
+						return ret;
+				}
+			} else {
+				ret = update_nfsd_version(major, minor, enabled);
+				if (ret)
+					return ret;
+			}
 		}
 		return set_nfsd_versions(sock);
 	}
-- 
2.47.1