Add support for zfs mount -R <filesystem>

This commit adds support for mounting a dataset along with all of
it's children with '-R' flag for zfs mount. There can be scenarios
where we want to mount all datasets under one hierarchy instead of
mounting all datasets present on system with '-a' flag.

'-R' flag should work on all root and non-root datasets. Usage
information and man page has been updated for zfs mount. A test
for verifying the behavior for '-R' flag is also added.

Reviewed-by: Ameer Hamza <ahamza@ixsystems.com>
Reviewed-by: Alexander Motin <mav@FreeBSD.org>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Umer Saleem <usaleem@ixsystems.com>
Closes #16015

cmd/zfs/zfs_main.c

@@ -309,7 +309,8 @@ get_usage(zfs_help_t idx)
 		    "[filesystem|volume|snapshot] ...\n"));
 	case HELP_MOUNT:
 		return (gettext("\tmount\n"
-		    "\tmount [-flvO] [-o opts] <-a | filesystem>\n"));
+		    "\tmount [-flvO] [-o opts] <-a|-R filesystem|"
+		    "filesystem>\n"));
 	case HELP_PROMOTE:
 		return (gettext("\tpromote <clone-filesystem>\n"));
 	case HELP_RECEIVE:
@@ -6754,6 +6755,8 @@ zfs_do_holds(int argc, char **argv)
 #define	MOUNT_TIME 1		/* seconds */
 
 typedef struct get_all_state {
+	char		**ga_datasets;
+	int		ga_count;
 	boolean_t	ga_verbose;
 	get_all_cb_t	*ga_cbp;
 } get_all_state_t;
@@ -6800,19 +6803,35 @@ get_one_dataset(zfs_handle_t *zhp, void *data)
 	return (0);
 }
 
-static void
+static int
-get_all_datasets(get_all_cb_t *cbp, boolean_t verbose)
+get_recursive_datasets(zfs_handle_t *zhp, void *data)
 {
-	get_all_state_t state = {
+	get_all_state_t *state = data;
-	    .ga_verbose = verbose,
+	int len = strlen(zfs_get_name(zhp));
-	    .ga_cbp = cbp
+	for (int i = 0; i < state->ga_count; ++i) {
-	};
+		if (strcmp(state->ga_datasets[i], zfs_get_name(zhp)) == 0)
+			return (get_one_dataset(zhp, data));
+		else if ((strncmp(state->ga_datasets[i], zfs_get_name(zhp),
+		    len) == 0) && state->ga_datasets[i][len] == '/') {
+			(void) zfs_iter_filesystems_v2(zhp, 0,
+			    get_recursive_datasets, data);
+		}
+	}
+	zfs_close(zhp);
+	return (0);
+}
 
-	if (verbose)
+static void
+get_all_datasets(get_all_state_t *state)
+{
+	if (state->ga_verbose)
 		set_progress_header(gettext("Reading ZFS config"));
-	(void) zfs_iter_root(g_zfs, get_one_dataset, &state);
+	if (state->ga_datasets == NULL)
+		(void) zfs_iter_root(g_zfs, get_one_dataset, state);
+	else
+		(void) zfs_iter_root(g_zfs, get_recursive_datasets, state);
 
-	if (verbose)
+	if (state->ga_verbose)
 		finish_progress(gettext("done."));
 }
 
@@ -7158,18 +7177,22 @@ static int
 share_mount(int op, int argc, char **argv)
 {
 	int do_all = 0;
+	int recursive = 0;
 	boolean_t verbose = B_FALSE;
 	int c, ret = 0;
 	char *options = NULL;
 	int flags = 0;
 
 	/* check options */
-	while ((c = getopt(argc, argv, op == OP_MOUNT ? ":alvo:Of" : "al"))
+	while ((c = getopt(argc, argv, op == OP_MOUNT ? ":aRlvo:Of" : "al"))
 	    != -1) {
 		switch (c) {
 		case 'a':
 			do_all = 1;
 			break;
+		case 'R':
+			recursive = 1;
+			break;
 		case 'v':
 			verbose = B_TRUE;
 			break;
@@ -7211,7 +7234,7 @@ share_mount(int op, int argc, char **argv)
 	argv += optind;
 
 	/* check number of arguments */
-	if (do_all) {
+	if (do_all || recursive) {
 		enum sa_protocol protocol = SA_NO_PROTOCOL;
 
 		if (op == OP_SHARE && argc > 0) {
@@ -7220,14 +7243,38 @@ share_mount(int op, int argc, char **argv)
 			argv++;
 		}
 
-		if (argc != 0) {
+		if (argc != 0 && do_all) {
 			(void) fprintf(stderr, gettext("too many arguments\n"));
 			usage(B_FALSE);
 		}
 
+		if (argc == 0 && recursive) {
+			(void) fprintf(stderr,
+			    gettext("no dataset provided\n"));
+			usage(B_FALSE);
+		}
+
 		start_progress_timer();
 		get_all_cb_t cb = { 0 };
-		get_all_datasets(&cb, verbose);
+		get_all_state_t state = { 0 };
+		if (argc == 0) {
+			state.ga_datasets = NULL;
+			state.ga_count = -1;
+		} else {
+			zfs_handle_t *zhp;
+			for (int i = 0; i < argc; i++) {
+				zhp = zfs_open(g_zfs, argv[i],
+				    ZFS_TYPE_FILESYSTEM);
+				if (zhp == NULL)
+					usage(B_FALSE);
+				zfs_close(zhp);
+			}
+			state.ga_datasets = argv;
+			state.ga_count = argc;
+		}
+		state.ga_verbose = verbose;
+		state.ga_cbp = &cb;
+		get_all_datasets(&state);
 
 		if (cb.cb_used == 0) {
 			free(options);

man/man8/zfs-mount.8

@@ -43,7 +43,7 @@
 .Cm mount
 .Op Fl Oflv
 .Op Fl o Ar options
-.Fl a Ns | Ns Ar filesystem
+.Fl a Ns | Ns Fl R Ar filesystem Ns | Ns Ar filesystem
 .Nm zfs
 .Cm unmount
 .Op Fl fu
@@ -61,7 +61,7 @@ Displays all ZFS file systems currently mounted.
 .Cm mount
 .Op Fl Oflv
 .Op Fl o Ar options
-.Fl a Ns | Ns Ar filesystem
+.Fl a Ns | Ns Fl R Ar filesystem Ns | Ns Ar filesystem
 .Xc
 Mount ZFS filesystem on a path described by its
 .Sy mountpoint
@@ -83,6 +83,8 @@ for more information.
 .It Fl a
 Mount all available ZFS file systems.
 Invoked automatically as part of the boot process if configured.
+.It Fl R
+Mount the specified filesystems along with all their children.
 .It Ar filesystem
 Mount the specified filesystem.
 .It Fl o Ar options

tests/runfiles/common.run

@@ -252,7 +252,7 @@ tests = ['zfs_mount_001_pos', 'zfs_mount_002_pos', 'zfs_mount_003_pos',
     'zfs_mount_009_neg', 'zfs_mount_010_neg', 'zfs_mount_011_neg',
     'zfs_mount_012_pos', 'zfs_mount_all_001_pos', 'zfs_mount_encrypted',
     'zfs_mount_remount', 'zfs_mount_all_fail', 'zfs_mount_all_mountpoints',
-    'zfs_mount_test_race']
+    'zfs_mount_test_race', 'zfs_mount_recursive']
 tags = ['functional', 'cli_root', 'zfs_mount']
 
 [tests/functional/cli_root/zfs_program]

tests/runfiles/sanity.run

@@ -155,7 +155,8 @@ tests = ['zfs_mount_001_pos', 'zfs_mount_002_pos', 'zfs_mount_003_pos',
     'zfs_mount_004_pos', 'zfs_mount_005_pos', 'zfs_mount_007_pos',
     'zfs_mount_009_neg', 'zfs_mount_010_neg', 'zfs_mount_011_neg',
     'zfs_mount_012_pos', 'zfs_mount_encrypted', 'zfs_mount_remount',
-    'zfs_mount_all_fail', 'zfs_mount_all_mountpoints', 'zfs_mount_test_race']
+    'zfs_mount_all_fail', 'zfs_mount_all_mountpoints',
+    'zfs_mount_test_race', 'zfs_mount_recursive']
 tags = ['functional', 'cli_root', 'zfs_mount']
 
 [tests/functional/cli_root/zfs_program]

tests/zfs-tests/tests/Makefile.am

@@ -770,6 +770,7 @@ nobase_dist_datadir_zfs_tests_tests_SCRIPTS += \
 	functional/cli_root/zfs_mount/zfs_mount_all_fail.ksh \
 	functional/cli_root/zfs_mount/zfs_mount_all_mountpoints.ksh \
 	functional/cli_root/zfs_mount/zfs_mount_encrypted.ksh \
+	functional/cli_root/zfs_mount/zfs_mount_recursive.ksh \
 	functional/cli_root/zfs_mount/zfs_mount_remount.ksh \
 	functional/cli_root/zfs_mount/zfs_mount_test_race.ksh \
 	functional/cli_root/zfs_mount/zfs_multi_mount.ksh \

tests/zfs-tests/tests/functional/cli_root/zfs_mount/zfs_mount.cfg

@@ -31,6 +31,7 @@
 export mountcmd=mount
 export mountforce="$mountcmd -f"
 export mountall="$mountcmd -a"
+export mountrecursive="$mountcmd -R"
 
 export unmountcmd=unmount
 export unmountforce="$unmountcmd -f"

tests/zfs-tests/tests/functional/cli_root/zfs_mount/zfs_mount_recursive.ksh

@@ -0,0 +1,146 @@
+#!/bin/ksh -p
+#
+# CDDL HEADER START
+#
+# The contents of this file are subject to the terms of the
+# Common Development and Distribution License (the "License").
+# You may not use this file except in compliance with the License.
+#
+# You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
+# or https://opensource.org/licenses/CDDL-1.0.
+# See the License for the specific language governing permissions
+# and limitations under the License.
+#
+# When distributing Covered Code, include this CDDL HEADER in each
+# file and include the License file at usr/src/OPENSOLARIS.LICENSE.
+# If applicable, add the following below this CDDL HEADER, with the
+# fields enclosed by brackets "[]" replaced with your own identifying
+# information: Portions Copyright [yyyy] [name of copyright owner]
+#
+# CDDL HEADER END
+#
+
+#
+# Copyright 2024, iXsystems Inc. All rights reserved.
+#
+
+. $STF_SUITE/include/libtest.shlib
+. $STF_SUITE/tests/functional/cli_root/zfs_mount/zfs_mount.kshlib
+
+#
+# DESCRIPTION:
+# Verify zfs mount -R <filesystems/s> functionality.
+#
+# STRATEGY:
+# 1. Create nested datasets
+# 2. Unmount all datasets
+# 3. Recusrively mount root datasets, this should mount all datasets
+#    present in a pool
+# 4. Unmount all datasets
+# 5. Recusrsively mount child datasets with children. This should mount
+#    child datasets, but not the root dataset or parent datasets
+# 6. Unmount all datasets
+# 7. Mount root dataset recursively again and confirm all child
+#    datasets are mounted.
+#
+
+verify_runnable "both"
+
+function cleanup
+{
+	log_must datasetexists $TESTPOOL/$TESTFS1 && \
+		destroy_dataset $TESTPOOL/$TESTFS1 -R
+	log_must datasetexists $TESTPOOL/$TESTFS2 && \
+		destroy_dataset $TESTPOOL/$TESTFS2 -R
+	log_must datasetexists $TESTPOOL/$TESTFS3 && \
+		destroy_dataset $TESTPOOL/$TESTFS3 -R
+}
+
+function setup_all
+{
+	log_must datasetexists $TESTPOOL/$TESTFS || zfs create $TESTPOOL/$TESTFS
+	log_must zfs create $TESTPOOL/$TESTFS1
+	log_must zfs create $TESTPOOL/$TESTFS2
+	log_must zfs create $TESTPOOL/$TESTFS3
+	log_must zfs create $TESTPOOL/$TESTFS2/child1
+	log_must zfs create $TESTPOOL/$TESTFS2/child2
+	log_must zfs create $TESTPOOL/$TESTFS2/child3
+	log_must zfs create $TESTPOOL/$TESTFS2/child2/subchild
+	log_must zfs create $TESTPOOL/$TESTFS3/child
+}
+
+log_assert "Verify that 'zfs $mountrecursive' successfully, " \
+	"mounts the dataset along with all its children."
+
+log_onexit cleanup
+
+log_must setup_all
+
+log_must zfs $unmountall
+
+log_must zfs $mountrecursive $TESTPOOL
+
+log_must mounted $TESTPOOL
+log_must mounted $TESTPOOL/$TESTFS
+log_must mounted $TESTPOOL/$TESTFS1
+log_must mounted $TESTPOOL/$TESTFS2
+log_must mounted $TESTPOOL/$TESTFS3
+log_must mounted $TESTPOOL/$TESTFS2/child1
+log_must mounted $TESTPOOL/$TESTFS2/child2
+log_must mounted $TESTPOOL/$TESTFS2/child3
+log_must mounted $TESTPOOL/$TESTFS2/child2/subchild
+log_must mounted $TESTPOOL/$TESTFS3/child
+
+log_must zfs $unmountall
+
+log_mustnot mounted $TESTPOOL
+log_mustnot mounted $TESTPOOL/$TESTFS
+log_mustnot mounted $TESTPOOL/$TESTFS1
+log_mustnot mounted $TESTPOOL/$TESTFS2
+log_mustnot mounted $TESTPOOL/$TESTFS3
+log_mustnot mounted $TESTPOOL/$TESTFS2/child1
+log_mustnot mounted $TESTPOOL/$TESTFS2/child2
+log_mustnot mounted $TESTPOOL/$TESTFS2/child3
+log_mustnot mounted $TESTPOOL/$TESTFS2/child2/subchild
+log_mustnot mounted $TESTPOOL/$TESTFS3/child
+
+log_must zfs $mountrecursive $TESTPOOL/$TESTFS2 $TESTPOOL/$TESTFS3
+
+log_mustnot mounted $TESTPOOL
+log_mustnot mounted $TESTPOOL/$TESTFS
+log_mustnot mounted $TESTPOOL/$TESTFS1
+log_must mounted $TESTPOOL/$TESTFS2
+log_must mounted $TESTPOOL/$TESTFS3
+log_must mounted $TESTPOOL/$TESTFS2/child1
+log_must mounted $TESTPOOL/$TESTFS2/child2
+log_must mounted $TESTPOOL/$TESTFS2/child3
+log_must mounted $TESTPOOL/$TESTFS2/child2/subchild
+log_must mounted $TESTPOOL/$TESTFS3/child
+
+log_must zfs $unmountall
+
+log_mustnot mounted $TESTPOOL
+log_mustnot mounted $TESTPOOL/$TESTFS
+log_mustnot mounted $TESTPOOL/$TESTFS1
+log_mustnot mounted $TESTPOOL/$TESTFS2
+log_mustnot mounted $TESTPOOL/$TESTFS3
+log_mustnot mounted $TESTPOOL/$TESTFS2/child1
+log_mustnot mounted $TESTPOOL/$TESTFS2/child2
+log_mustnot mounted $TESTPOOL/$TESTFS2/child3
+log_mustnot mounted $TESTPOOL/$TESTFS2/child2/subchild
+log_mustnot mounted $TESTPOOL/$TESTFS3/child
+
+log_must zfs $mountrecursive $TESTPOOL/$TESTFS2/child2
+
+log_must mounted $TESTPOOL/$TESTFS2/child2
+log_must mounted $TESTPOOL/$TESTFS2/child2/subchild
+log_mustnot mounted $TESTPOOL
+log_mustnot mounted $TESTPOOL/$TESTFS
+log_mustnot mounted $TESTPOOL/$TESTFS1
+log_mustnot mounted $TESTPOOL/$TESTFS2
+log_mustnot mounted $TESTPOOL/$TESTFS3
+log_mustnot mounted $TESTPOOL/$TESTFS2/child1
+log_mustnot mounted $TESTPOOL/$TESTFS2/child3
+log_mustnot mounted $TESTPOOL/$TESTFS3/child
+
+log_pass "'zfs $mountrecursive' behaves as expected."