Disable umount.zfs helper

For the moment, the only advantage in registering a umount helper
would be to automatically unshare a zfs filesystem.  Since under
Linux this would be unexpected (but nice) behavior there is no
harm in disabling it.

This is desirable because the 'zfs unmount' path invokes the system
umount.  This is done to ensure correct mtab locking but has the
side effect that the umount.zfs helper would be called if it exists.
By default this helper calls back in to zfs to do the unmount on
Solaris which we don't want under Linux.

Once libmount is available and we have a safe way to correctly
lock and update the /etc/mtab file we can reconsider the need
for a umount helper.  Using libmount is the prefered solution.

1 files changed, 103 insertions, 37 deletions

diff --git a/cmd/zfs/zfs_main.c b/cmd/zfs/zfs_main.c
index 2aa3e2ef1..e1cca2d91 100644
--- a/cmd/zfs/zfs_main.c
+++ b/cmd/zfs/zfs_main.c
@@ -4083,85 +4083,149 @@ manual_mount(int argc, char **argv)
 		else
 			(void) fprintf(stderr, gettext("too many arguments\n"));
 		(void) fprintf(stderr, "usage: mount <dataset> <mountpoint>\n");
-		return (2);
+		return (MOUNT_USAGE);
 	}
 
 	dataset = argv[0];
-	path = argv[1];
+	mntpoint = argv[1];
 
-	/* try to open the dataset */
-	if ((zhp = zfs_open(g_zfs, dataset, ZFS_TYPE_FILESYSTEM)) == NULL)
-		return (1);
+	/* try to open the dataset to access the mount point */
+	if ((zhp = zfs_open(g_zfs, dataset, ZFS_TYPE_FILESYSTEM)) == NULL) {
+		(void) fprintf(stderr, gettext("filesystem '%s' cannot be "
+		    "mounted, unable to open the dataset\n"), dataset);
+		return (MOUNT_USAGE);
+	}
 
-	(void) zfs_prop_get(zhp, ZFS_PROP_MOUNTPOINT, mountpoint,
-	    sizeof (mountpoint), NULL, NULL, 0, B_FALSE);
+	(void) zfs_prop_get(zhp, ZFS_PROP_MOUNTPOINT, legacy,
+	    sizeof (legacy), NULL, NULL, 0, B_FALSE);
 
-	/* check for legacy mountpoint and complain appropriately */
-	ret = 0;
-	if (strcmp(mountpoint, ZFS_MOUNTPOINT_LEGACY) == 0) {
-		if (mount(dataset, path, MS_OPTIONSTR | flags, MNTTYPE_ZFS,
-		    NULL, 0, mntopts, sizeof (mntopts)) != 0) {
-			(void) fprintf(stderr, gettext("mount failed: %s\n"),
-			    strerror(errno));
-			ret = 1;
-		}
-	} else {
+	zfs_close(zhp);
+
+	/* check for legacy mountpoint or util mount option */
+	if ((!strcmp(legacy, ZFS_MOUNTPOINT_LEGACY) == 0) &&
+	    (strstr(mntopts, MNTOPT_ZFSUTIL) == NULL)) {
 		(void) fprintf(stderr, gettext("filesystem '%s' cannot be "
-		    "mounted using 'mount -F zfs'\n"), dataset);
+		    "mounted using 'mount -a -t zfs'\n"), dataset);
 		(void) fprintf(stderr, gettext("Use 'zfs set mountpoint=%s' "
-		    "instead.\n"), path);
-		(void) fprintf(stderr, gettext("If you must use 'mount -F zfs' "
-		    "or /etc/vfstab, use 'zfs set mountpoint=legacy'.\n"));
-		(void) fprintf(stderr, gettext("See zfs(1M) for more "
+		    "instead.\n"), mntpoint);
+		(void) fprintf(stderr, gettext("If you must use 'mount -a -t "
+		    "zfs' or /etc/fstab, use 'zfs set mountpoint=legacy'.\n"));
+		(void) fprintf(stderr, gettext("See zfs(8) for more "
 		    "information.\n"));
-		ret = 1;
+		return (MOUNT_USAGE);
+	}
+
+	/* validate mount options and set mntflags */
+	rc = parse_options(mntopts, &mntflags, sloppy, badopt);
+	if (rc) {
+		switch (rc) {
+		case ENOMEM:
+			(void) fprintf(stderr, gettext("filesystem '%s' "
+			    "cannot be mounted due to a memory allocation "
+			    "failure\n"), dataset);
+			return (MOUNT_SYSERR);
+		case EINVAL:
+			(void) fprintf(stderr, gettext("filesystem '%s' "
+			    "cannot be mounted of due to the invalid option "
+			    "'%s'\n"), dataset, badopt);
+			(void) fprintf(stderr, gettext("Use the '-s' option "
+			    "to ignore the bad mount option.\n"));
+			return (MOUNT_USAGE);
+		default:
+			(void) fprintf(stderr, gettext("filesystem '%s' "
+			    "cannot be mounted due to internal error %d\n"),
+			    dataset, rc);
+			return (MOUNT_SOFTWARE);
+		}
 	}
 
-	return (ret);
+	if (verbose > 2)
+		printf("mount.zfs: dataset: \"%s\", mountpoint: \"%s\" "
+		    "mountflags: 0x%lx, mountopts: \"%s\"\n", dataset,
+		    mntpoint, mntflags, mntopts);
+
+	/* load the zfs posix layer module (zpl) */
+	if (libzfs_load_module("zpl")) {
+		(void) fprintf(stderr, gettext("filesystem '%s' cannot be "
+		    "mounted without the zpl kernel module\n"), dataset);
+		(void) fprintf(stderr, gettext("Use 'dmesg' to determine why "
+		    "the module could not be loaded.\n"));
+		return (MOUNT_SYSERR);
+	}
+
+	if (!fake) {
+		rc = mount(dataset, mntpoint, MNTTYPE_ZFS, mntflags, mntopts);
+		if (rc) {
+			(void) fprintf(stderr, gettext("filesystem '%s' can"
+			    "not be mounted due to error %d\n"), dataset, rc);
+			return (MOUNT_USAGE);
+		}
+	}
+
+	return (MOUNT_SUCCESS);
 }
 
+#ifdef HAVE_UNMOUNT_HELPER
 /*
- * Called when invoked as /etc/fs/zfs/umount.  Unlike a manual mount, we allow
- * unmounts of non-legacy filesystems, as this is the dominant administrative
- * interface.
+ * Called when invoked as /sbin/umount.zfs, mount helper for mount(8).
+ * Unlike a manual mount, we allow unmounts of non-legacy filesystems,
+ * as this is the dominant administrative interface.
  */
 static int
 manual_unmount(int argc, char **argv)
 {
-	int flags = 0;
+	int verbose = 0, flags = 0;
 	int c;
 
 	/* check options */
-	while ((c = getopt(argc, argv, "f")) != -1) {
+	while ((c = getopt(argc, argv, "nlfvrh?")) != -1) {
 		switch (c) {
+		case 'n':
+			/* Ignored, handled by mount(8) */
+			break;
+		case 'l':
+			flags = MS_DETACH;
+			break;
 		case 'f':
 			flags = MS_FORCE;
 			break;
+		case 'v':
+			verbose++;
+			break;
+		case 'r':
+			/* Remount read-only on umount failure, unsupported */
+			(void) fprintf(stderr, gettext("Unsupported option "
+			    "'%c'\n"), optopt);
+			return (MOUNT_USAGE);
+		case 'h':
 		case '?':
-			(void) fprintf(stderr, gettext("invalid option '%c'\n"),
+			(void) fprintf(stderr, gettext("Invalid option '%c'\n"),
 			    optopt);
-			(void) fprintf(stderr, gettext("usage: unmount [-f] "
-			    "<path>\n"));
-			return (2);
+			(void) fprintf(stderr, gettext("Usage: umount.zfs "
+			    "[-nlfvr] <mountpoint>\n"));
+			return (MOUNT_USAGE);
 		}
 	}
 
 	argc -= optind;
 	argv += optind;
 
-	/* check arguments */
+	/* check that we only have one argument */
 	if (argc != 1) {
 		if (argc == 0)
-			(void) fprintf(stderr, gettext("missing path "
+			(void) fprintf(stderr, gettext("missing mountpoint "
 			    "argument\n"));
 		else
 			(void) fprintf(stderr, gettext("too many arguments\n"));
-		(void) fprintf(stderr, gettext("usage: unmount [-f] <path>\n"));
-		return (2);
+
+		(void) fprintf(stderr, gettext("Usage: umount.zfs [-nlfvr] "
+		    "<mountpoint>\n"));
+		return (MOUNT_USAGE);
 	}
 
 	return (unshare_unmount_path(OP_MOUNT, argv[0], flags, B_TRUE));
 }
+#endif /* HAVE_UNMOUNT_HELPER */
 
 static int
 find_command_idx(char *command, int *idx)
@@ -4281,8 +4345,10 @@ main(int argc, char **argv)
 	progname = basename(argv[0]);
 	if (strcmp(progname, "mount.zfs") == 0) {
 		ret = manual_mount(argc, argv);
+#ifdef HAVE_UNMOUNT_HELPER
 	} else if (strcmp(progname, "umount.zfs") == 0) {
 		ret = manual_unmount(argc, argv);
+#endif /* HAVE_UNMOUNT_HELPER */
 	} else {
 		/*
 		 * Make sure the user has specified some command.