Implement "automount -c".

MFC after:	1 month
Sponsored by:	The FreeBSD Foundation

2 files changed, 67 insertions, 4 deletions

diff --git a/usr.sbin/autofs/automount.8 b/usr.sbin/autofs/automount.8
index 2988c68..c111a99 100644
--- a/usr.sbin/autofs/automount.8
+++ b/usr.sbin/autofs/automount.8
@@ -27,7 +27,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd April 20, 2014
+.Dd November 22, 2014
 .Dt AUTOMOUNT 8
 .Os
 .Sh NAME
@@ -37,6 +37,7 @@
 .Nm
 .Op Fl D Ar name=value
 .Op Fl L
+.Op Fl c
 .Op Fl f
 .Op Fl o Ar options
 .Op Fl v
@@ -64,6 +65,9 @@ and any direct maps, then print them to standard output.
 When specified more than once, all the maps, including indirect ones,
 will be parsed and shown.
 This is useful when debugging configuration problems.
+.It Fl c
+Flush caches, discarding possibly stale information obtained from maps
+and directory services.
 .It Fl f
 Force unmount, to be used with
 .Fl u .
diff --git a/usr.sbin/autofs/automount.c b/usr.sbin/autofs/automount.c
index a956b08..3c59704 100644
--- a/usr.sbin/autofs/automount.c
+++ b/usr.sbin/autofs/automount.c
@@ -230,6 +230,57 @@ mount_unmount(struct node *root)
 }
 
 static void
+flush_autofs(const char *fspath)
+{
+	struct iovec *iov = NULL;
+	char errmsg[255];
+	int error, iovlen = 0;
+
+	log_debugx("flushing %s", fspath);
+	memset(errmsg, 0, sizeof(errmsg));
+
+	build_iovec(&iov, &iovlen, "fstype",
+	    __DECONST(void *, "autofs"), (size_t)-1);
+	build_iovec(&iov, &iovlen, "fspath",
+	    __DECONST(void *, fspath), (size_t)-1);
+	build_iovec(&iov, &iovlen, "errmsg",
+	    errmsg, sizeof(errmsg));
+
+	error = nmount(iov, iovlen, MNT_UPDATE);
+	if (error != 0) {
+		if (*errmsg != '\0') {
+			log_err(1, "cannot flush %s: %s",
+			    fspath, errmsg);
+		} else {
+			log_err(1, "cannot flush %s", fspath);
+		}
+	}
+}
+
+static void
+flush_caches(void)
+{
+	struct statfs *mntbuf;
+	int i, nitems;
+
+	nitems = getmntinfo(&mntbuf, MNT_WAIT);
+	if (nitems <= 0)
+		log_err(1, "getmntinfo");
+
+	log_debugx("flushing autofs caches");
+
+	for (i = 0; i < nitems; i++) {
+		if (strcmp(mntbuf[i].f_fstypename, "autofs") != 0) {
+			log_debugx("skipping %s, filesystem type is not autofs",
+			    mntbuf[i].f_mntonname);
+			continue;
+		}
+
+		flush_autofs(mntbuf[i].f_mntonname);
+	}
+}
+
+static void
 unmount_automounted(bool force)
 {
 	struct statfs *mntbuf;
@@ -262,7 +313,7 @@ static void
 usage_automount(void)
 {
 
-	fprintf(stderr, "usage: automount [-D name=value][-o opts][-Lfuv]\n");
+	fprintf(stderr, "usage: automount [-D name=value][-o opts][-Lcfuv]\n");
 	exit(1);
 }
 
@@ -272,7 +323,7 @@ main_automount(int argc, char **argv)
 	struct node *root;
 	int ch, debug = 0, show_maps = 0;
 	char *options = NULL;
-	bool do_unmount = false, force_unmount = false;
+	bool do_unmount = false, force_unmount = false, flush = false;
 
 	/*
 	 * Note that in automount(8), the only purpose of variable
@@ -280,7 +331,7 @@ main_automount(int argc, char **argv)
 	 */
 	defined_init();
 
-	while ((ch = getopt(argc, argv, "D:Lfo:uv")) != -1) {
+	while ((ch = getopt(argc, argv, "D:Lfco:uv")) != -1) {
 		switch (ch) {
 		case 'D':
 			defined_parse_and_add(optarg);
@@ -288,6 +339,9 @@ main_automount(int argc, char **argv)
 		case 'L':
 			show_maps++;
 			break;
+		case 'c':
+			flush = true;
+			break;
 		case 'f':
 			force_unmount = true;
 			break;
@@ -319,6 +373,11 @@ main_automount(int argc, char **argv)
 
 	log_init(debug);
 
+	if (flush) {
+		flush_caches();
+		return (0);
+	}
+
 	if (do_unmount) {
 		unmount_automounted(force_unmount);
 		return (0);