Implement "automount -c".

MFC after:	1 month
Sponsored by:	The FreeBSD Foundation

sys/fs/autofs/autofs.c

@@ -318,6 +318,18 @@ autofs_cache_callout(void *context)
 	anp->an_cached = false;
 }
 
+void
+autofs_flush(struct autofs_mount *amp)
+{
+
+	/*
+	 * XXX: This will do for now, but ideally we should iterate
+	 * 	over all the nodes.
+	 */
+	amp->am_root->an_cached = false;
+	AUTOFS_DEBUG("%s flushed", amp->am_mountpoint);
+}
+
 /*
  * The set/restore sigmask functions are used to (temporarily) overwrite
  * the thread td_sigmask during triggering.

sys/fs/autofs/autofs.h

@@ -133,6 +133,7 @@ int	autofs_trigger(struct autofs_node *anp, const char *component,
 	    int componentlen);
 bool	autofs_cached(struct autofs_node *anp, const char *component,
 	    int componentlen);
+void	autofs_flush(struct autofs_mount *amp);
 bool	autofs_ignore_thread(const struct thread *td);
 int	autofs_node_new(struct autofs_node *parent, struct autofs_mount *amp,
 	    const char *name, int namelen, struct autofs_node **anpp);

sys/fs/autofs/autofs_vfsops.c

@@ -61,8 +61,10 @@ autofs_mount(struct mount *mp)
 	if (vfs_filteropt(mp->mnt_optnew, autofs_opts))
 		return (EINVAL);
 
-	if (mp->mnt_flag & MNT_UPDATE)
+	if (mp->mnt_flag & MNT_UPDATE) {
+		autofs_flush(VFSTOAUTOFS(mp));
 		return (0);
+	}
 
 	if (vfs_getopt(mp->mnt_optnew, "from", (void **)&from, NULL))
 		return (EINVAL);

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 .

usr.sbin/autofs/automount.c

@@ -229,6 +229,57 @@ 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)
 {
@@ -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);