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From:   NeilBrown <neilb@suse.de>
To:     Steve Dickson <SteveD@RedHat.com>
Date:   Thu, 25 Feb 2021 13:42:47 +1100
Subject: [PATCH 4/5] mountd: add --cache-use-ipaddr option to force use_ipaddr
Cc:     Linux NFS Mailing list <linux-nfs@vger.kernel.org>
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From: NeilBrown <neil@brown.name>

When logging authentication requests, it can be easier to read the logs
if clients are always identified by IP address, not intermediate names
like netgroups or subnets.

To allow this, add --cache-use-ipaddr or -i which tell mountd to always
enable use_ipaddr.

Signed-off-by: NeilBrown <neil@brown.name>
---
 support/export/auth.c   |    4 ++++
 utils/mountd/mountd.c   |    8 +++++++-
 utils/mountd/mountd.man |   18 ++++++++++++++++++
 3 files changed, 29 insertions(+), 1 deletion(-)

diff --git a/support/export/auth.c b/support/export/auth.c
index 0bfa77d18469..cea376300d01 100644
--- a/support/export/auth.c
+++ b/support/export/auth.c
@@ -66,6 +66,10 @@ check_useipaddr(void)
 	int old_use_ipaddr = use_ipaddr;
 	unsigned int len = 0;
 
+	if (use_ipaddr > 1)
+		/* fixed - don't check */
+		return;
+
 	/* add length of m_hostname + 1 for the comma */
 	for (clp = clientlist[MCL_NETGROUP]; clp; clp = clp->m_next)
 		len += (strlen(clp->m_hostname) + 1);
diff --git a/utils/mountd/mountd.c b/utils/mountd/mountd.c
index 59eddf79fd2e..dafcc35ca9c2 100644
--- a/utils/mountd/mountd.c
+++ b/utils/mountd/mountd.c
@@ -75,9 +75,10 @@ static struct option longopts[] =
 	{ "manage-gids", 0, 0, 'g' },
 	{ "no-udp", 0, 0, 'u' },
 	{ "log-auth", 0, 0, 'l'},
+	{ "cache-use-ipaddr", 0, 0, 'i'},
 	{ NULL, 0, 0, 0 }
 };
-static char shortopts[] = "o:nFd:p:P:hH:N:V:vurs:t:gl";
+static char shortopts[] = "o:nFd:p:P:hH:N:V:vurs:t:gli";
 
 #define NFSVERSBIT(vers)	(0x1 << (vers - 1))
 #define NFSVERSBIT_ALL		(NFSVERSBIT(2) | NFSVERSBIT(3) | NFSVERSBIT(4))
@@ -681,6 +682,8 @@ read_mountd_conf(char **argv)
 	num_threads = conf_get_num("mountd", "threads", num_threads);
 	reverse_resolve = conf_get_bool("mountd", "reverse-lookup", reverse_resolve);
 	ha_callout_prog = conf_get_str("mountd", "ha-callout");
+	if (conf_get_bool("mountd", "cache-use-ipaddr", 0))
+		use_ipaddr = 2;
 
 	s = conf_get_str("mountd", "state-directory-path");
 	if (s && !state_setup_basedir(argv[0], s))
@@ -803,6 +806,9 @@ main(int argc, char **argv)
 		case 'l':
 			xlog_sconfig("auth", 1);
 			break;
+		case 'i':
+			use_ipaddr = 2;
+			break;
 		case 0:
 			break;
 		case '?':
diff --git a/utils/mountd/mountd.man b/utils/mountd/mountd.man
index df4e5356cb05..44d237e56110 100644
--- a/utils/mountd/mountd.man
+++ b/utils/mountd/mountd.man
@@ -118,6 +118,23 @@ section.
 will always log authentication responses to MOUNT requests when NFSv3 is
 used, but to get similar logs for NFSv4, this option is required.
 .TP
+.BR \-i " or " \-\-cache\-use\-ipaddr
+Normally each client IP address is matched against each host identifier
+(name, wildcard, netgroup etc) found in
+.B /etc/exports
+and a combined identity is formed from all matching identifiers.
+Often many clients will map to the same combined identity so performing
+this mapping reduces the number of distinct access details that the
+kernel needs to store.
+Specifying the
+.B \-i
+option suppresses this mapping so that access to each filesystem is
+requested and cached separately for each client IP address.  Doing this
+can increase the burden of updating the cache slightly, but can make the
+log messages produced by the
+.B -l
+option easier to read.
+.TP
 .B \-F " or " \-\-foreground
 Run in foreground (do not daemonize)
 .TP
@@ -248,6 +265,7 @@ Values recognized in the
 .B [mountd]
 section include
 .BR manage-gids ,
+.BR cache\-use\-ipaddr ,
 .BR descriptors ,
 .BR port ,
 .BR threads ,