Add '-u' - nomount flag for zfs set

This commit adds '-u' flag for zfs set operation. With this flag,
mountpoint, sharenfs and sharesmb properties can be updated
without actually mounting or sharing the dataset.

Previously, if dataset was unmounted, and mountpoint property was
updated, dataset was not mounted after the update. This behavior
is changed in openzfs#15240. We mount the dataset whenever mountpoint
property is updated, regardless if it's mounted or not.

To provide the user with option to keep the dataset unmounted and
still update the mountpoint without mounting the dataset, '-u'
flag can be used.

If any of mountpoint, sharenfs or sharesmb properties are updated
with '-u' flag, the property is set to desired value but the
operation to (re/un)mount and/or (re/un)share the dataset is not
performed and dataset remains as it was before.

Reviewed-by: Alexander Motin <[email protected]>
Reviewed-by: Brian Behlendorf <[email protected]>
Signed-off-by: Umer Saleem <[email protected]>
Closes openzfs#15322

cmd/zfs/zfs_main.c

@@ -339,7 +339,7 @@ get_usage(zfs_help_t idx)
 		    "\tsend [-nVvPe] -t <receive_resume_token>\n"
 		    "\tsend [-PnVv] --saved filesystem\n"));
 	case HELP_SET:
-		return (gettext("\tset <property=value> ... "
+		return (gettext("\tset [-u] <property=value> ... "
 		    "<filesystem|volume|snapshot> ...\n"));
 	case HELP_SHARE:
 		return (gettext("\tshare [-l] <-a [nfs|smb] | filesystem>\n"));
@@ -4202,8 +4202,8 @@ zfs_do_rollback(int argc, char **argv)
 static int
 set_callback(zfs_handle_t *zhp, void *data)
 {
-	nvlist_t *props = data;
-	int ret = zfs_prop_set_list(zhp, props);
+	zprop_set_cbdata_t *cb = data;
+	int ret = zfs_prop_set_list_flags(zhp, cb->cb_proplist, cb->cb_flags);
 
 	if (ret != 0 || libzfs_errno(g_zfs) != EZFS_SUCCESS) {
 		switch (libzfs_errno(g_zfs)) {
@@ -4223,25 +4223,35 @@ set_callback(zfs_handle_t *zhp, void *data)
 static int
 zfs_do_set(int argc, char **argv)
 {
-	nvlist_t *props = NULL;
+	zprop_set_cbdata_t cb = { 0 };
 	int ds_start = -1; /* argv idx of first dataset arg */
 	int ret = 0;
-	int i;
+	int i, c;
 
-	/* check for options */
-	if (argc > 1 && argv[1][0] == '-') {
-		(void) fprintf(stderr, gettext("invalid option '%c'\n"),
-		    argv[1][1]);
-		usage(B_FALSE);
+	/* check options */
+	while ((c = getopt(argc, argv, "u")) != -1) {
+		switch (c) {
+		case 'u':
+			cb.cb_flags |= ZFS_SET_NOMOUNT;
+			break;
+		case '?':
+		default:
+			(void) fprintf(stderr, gettext("invalid option '%c'\n"),
+			    optopt);
+			usage(B_FALSE);
+		}
 	}
 
+	argc -= optind;
+	argv += optind;
+
 	/* check number of arguments */
-	if (argc < 2) {
+	if (argc < 1) {
 		(void) fprintf(stderr, gettext("missing arguments\n"));
 		usage(B_FALSE);
 	}
-	if (argc < 3) {
-		if (strchr(argv[1], '=') == NULL) {
+	if (argc < 2) {
+		if (strchr(argv[0], '=') == NULL) {
 			(void) fprintf(stderr, gettext("missing property=value "
 			    "argument(s)\n"));
 		} else {
@@ -4252,7 +4262,7 @@ zfs_do_set(int argc, char **argv)
 	}
 
 	/* validate argument order:  prop=val args followed by dataset args */
-	for (i = 1; i < argc; i++) {
+	for (i = 0; i < argc; i++) {
 		if (strchr(argv[i], '=') != NULL) {
 			if (ds_start > 0) {
 				/* out-of-order prop=val argument */
@@ -4270,20 +4280,20 @@ zfs_do_set(int argc, char **argv)
 	}
 
 	/* Populate a list of property settings */
-	if (nvlist_alloc(&props, NV_UNIQUE_NAME, 0) != 0)
+	if (nvlist_alloc(&cb.cb_proplist, NV_UNIQUE_NAME, 0) != 0)
 		nomem();
-	for (i = 1; i < ds_start; i++) {
-		if (!parseprop(props, argv[i])) {
+	for (i = 0; i < ds_start; i++) {
+		if (!parseprop(cb.cb_proplist, argv[i])) {
 			ret = -1;
 			goto error;
 		}
 	}
 
 	ret = zfs_for_each(argc - ds_start, argv + ds_start, 0,
-	    ZFS_TYPE_DATASET, NULL, NULL, 0, set_callback, props);
+	    ZFS_TYPE_DATASET, NULL, NULL, 0, set_callback, &cb);
 
 error:
-	nvlist_free(props);
+	nvlist_free(cb.cb_proplist);
 	return (ret);
 }
 

include/libzfs.h

@@ -523,6 +523,7 @@ _LIBZFS_H nvlist_t *zfs_valid_proplist(libzfs_handle_t *, zfs_type_t,
 _LIBZFS_H const char *zfs_prop_to_name(zfs_prop_t);
 _LIBZFS_H int zfs_prop_set(zfs_handle_t *, const char *, const char *);
 _LIBZFS_H int zfs_prop_set_list(zfs_handle_t *, nvlist_t *);
+_LIBZFS_H int zfs_prop_set_list_flags(zfs_handle_t *, nvlist_t *, int);
 _LIBZFS_H int zfs_prop_get(zfs_handle_t *, zfs_prop_t, char *, size_t,
     zprop_source_t *, char *, size_t, boolean_t);
 _LIBZFS_H int zfs_prop_get_recvd(zfs_handle_t *, const char *, char *, size_t,
@@ -645,6 +646,13 @@ typedef struct zprop_get_cbdata {
 	vdev_cbdata_t cb_vdevs;
 } zprop_get_cbdata_t;
 
+#define	ZFS_SET_NOMOUNT		1
+
+typedef struct zprop_set_cbdata {
+	int cb_flags;
+	nvlist_t *cb_proplist;
+} zprop_set_cbdata_t;
+
 _LIBZFS_H void zprop_print_one_property(const char *, zprop_get_cbdata_t *,
     const char *, const char *, zprop_source_t, const char *,
     const char *);

lib/libzfs/libzfs.abi

@@ -396,6 +396,7 @@
     <elf-symbol name='zfs_prop_readonly' type='func-type' binding='global-binding' visibility='default-visibility' is-defined='yes'/>
     <elf-symbol name='zfs_prop_set' type='func-type' binding='global-binding' visibility='default-visibility' is-defined='yes'/>
     <elf-symbol name='zfs_prop_set_list' type='func-type' binding='global-binding' visibility='default-visibility' is-defined='yes'/>
+    <elf-symbol name='zfs_prop_set_list_flags' type='func-type' binding='global-binding' visibility='default-visibility' is-defined='yes'/>
     <elf-symbol name='zfs_prop_setonce' type='func-type' binding='global-binding' visibility='default-visibility' is-defined='yes'/>
     <elf-symbol name='zfs_prop_string_to_index' type='func-type' binding='global-binding' visibility='default-visibility' is-defined='yes'/>
     <elf-symbol name='zfs_prop_to_name' type='func-type' binding='global-binding' visibility='default-visibility' is-defined='yes'/>
@@ -4424,6 +4425,12 @@
       <parameter type-id='5ce45b60' name='props'/>
       <return type-id='95e97e5e'/>
     </function-decl>
+    <function-decl name='zfs_prop_set_list_flags' mangled-name='zfs_prop_set_list_flags' visibility='default' binding='global' size-in-bits='64' elf-symbol-id='zfs_prop_set_list_flags'>
+      <parameter type-id='9200a744' name='zhp'/>
+      <parameter type-id='5ce45b60' name='props'/>
+      <parameter type-id='95e97e5e' name='flags'/>
+      <return type-id='95e97e5e'/>
+    </function-decl>
     <function-decl name='zfs_prop_inherit' mangled-name='zfs_prop_inherit' visibility='default' binding='global' size-in-bits='64' elf-symbol-id='zfs_prop_inherit'>
       <parameter type-id='9200a744' name='zhp'/>
       <parameter type-id='80f4b756' name='propname'/>

lib/libzfs/libzfs_changelist.c

@@ -105,6 +105,15 @@ changelist_prefix(prop_changelist_t *clp)
 	    clp->cl_prop != ZFS_PROP_SHARESMB)
 		return (0);
 
+	/*
+	 * If CL_GATHER_DONT_UNMOUNT is set, don't want to unmount/unshare and
+	 * later (re)mount/(re)share the filesystem in postfix phase, so we
+	 * return from here. If filesystem is mounted or unmounted, leave it
+	 * as it is.
+	 */
+	if (clp->cl_gflags & CL_GATHER_DONT_UNMOUNT)
+		return (0);
+
 	if ((walk = uu_avl_walk_start(clp->cl_tree, UU_WALK_ROBUST)) == NULL)
 		return (-1);
 
@@ -129,8 +138,6 @@ changelist_prefix(prop_changelist_t *clp)
 			 */
 			switch (clp->cl_prop) {
 			case ZFS_PROP_MOUNTPOINT:
-				if (clp->cl_gflags & CL_GATHER_DONT_UNMOUNT)
-					break;
 				if (zfs_unmount(cn->cn_handle, NULL,
 				    clp->cl_mflags) != 0) {
 					ret = -1;
@@ -164,9 +171,8 @@ changelist_prefix(prop_changelist_t *clp)
  * reshare the filesystems as necessary.  In changelist_gather() we recorded
  * whether the filesystem was previously shared or mounted.  The action we take
  * depends on the previous state, and whether the value was previously 'legacy'.
- * For non-legacy properties, we only remount/reshare the filesystem if it was
- * previously mounted/shared.  Otherwise, we always remount/reshare the
- * filesystem.
+ * For non-legacy properties, we always remount/reshare the filesystem,
+ * if CL_GATHER_DONT_UNMOUNT is not set.
  */
 int
 changelist_postfix(prop_changelist_t *clp)
@@ -177,6 +183,14 @@ changelist_postfix(prop_changelist_t *clp)
 	boolean_t commit_smb_shares = B_FALSE;
 	boolean_t commit_nfs_shares = B_FALSE;
 
+	/*
+	 * If CL_GATHER_DONT_UNMOUNT is set, it means we don't want to (un)mount
+	 * or (re/un)share the filesystem, so we return from here. If filesystem
+	 * is mounted or unmounted, leave it as it is.
+	 */
+	if (clp->cl_gflags & CL_GATHER_DONT_UNMOUNT)
+		return (0);
+
 	/*
 	 * If we're changing the mountpoint, attempt to destroy the underlying
 	 * mountpoint.  All other datasets will have inherited from this dataset
@@ -239,8 +253,7 @@ changelist_postfix(prop_changelist_t *clp)
 		needs_key = (zfs_prop_get_int(cn->cn_handle,
 		    ZFS_PROP_KEYSTATUS) == ZFS_KEYSTATUS_UNAVAILABLE);
 
-		mounted = (clp->cl_gflags & CL_GATHER_DONT_UNMOUNT) ||
-		    zfs_is_mounted(cn->cn_handle, NULL);
+		mounted = zfs_is_mounted(cn->cn_handle, NULL);
 
 		if (!mounted && !needs_key && (cn->cn_mounted ||
 		    (((clp->cl_prop == ZFS_PROP_MOUNTPOINT &&

lib/libzfs/libzfs_dataset.c

@@ -1771,14 +1771,24 @@ zfs_prop_set(zfs_handle_t *zhp, const char *propname, const char *propval)
 	return (ret);
 }
 
-
-
 /*
  * Given an nvlist of property names and values, set the properties for the
  * given dataset.
  */
 int
 zfs_prop_set_list(zfs_handle_t *zhp, nvlist_t *props)
+{
+	return (zfs_prop_set_list_flags(zhp, props, 0));
+}
+
+/*
+ * Given an nvlist of property names, values and flags, set the properties
+ * for the given dataset. If ZFS_SET_NOMOUNT is set, it allows to update
+ * mountpoint, sharenfs and sharesmb properties without (un/re)mounting
+ * and (un/re)sharing the dataset.
+ */
+int
+zfs_prop_set_list_flags(zfs_handle_t *zhp, nvlist_t *props, int flags)
 {
 	zfs_cmd_t zc = {"\0"};
 	int ret = -1;
@@ -1848,7 +1858,9 @@ zfs_prop_set_list(zfs_handle_t *zhp, nvlist_t *props)
 		if (prop != ZFS_PROP_CANMOUNT ||
 		    (fnvpair_value_uint64(elem) == ZFS_CANMOUNT_OFF &&
 		    zfs_is_mounted(zhp, NULL))) {
-			cls[cl_idx] = changelist_gather(zhp, prop, 0, 0);
+			cls[cl_idx] = changelist_gather(zhp, prop,
+			    ((flags & ZFS_SET_NOMOUNT) ?
+			    CL_GATHER_DONT_UNMOUNT : 0), 0);
 			if (cls[cl_idx] == NULL)
 				goto error;
 		}

man/man7/zfsprops.7

@@ -1243,10 +1243,18 @@ Otherwise, they are automatically remounted in the new location if the property
 was previously
 .Sy legacy
 or
-.Sy none ,
-or if they were mounted before the property was changed.
+.Sy none .
 In addition, any shared file systems are unshared and shared in the new
 location.
+.Pp
+When the
+.Sy mountpoint
+property is set with
+.Nm zfs Cm set Fl u
+, the
+.Sy mountpoint
+property is updated but dataset is not mounted or unmounted and remains
+as it was before.
 .It Sy nbmand Ns = Ns Sy on Ns | Ns Sy off
 Controls whether the file system should be mounted with
 .Sy nbmand
@@ -1651,6 +1659,13 @@ by default.
 This means that any additional access control
 (disallow specific user specific access etc) must be done on the underlying file
 system.
+.Pp
+When the
+.Sy sharesmb
+property is updated with
+.Nm zfs Cm set Fl u
+, the property is set to desired value, but the operation to share, reshare
+or unshare the the dataset is not performed.
 .It Sy sharenfs Ns = Ns Sy on Ns | Ns Sy off Ns | Ns Ar opts
 Controls whether the file system is shared via NFS, and what options are to be
 used.
@@ -1694,6 +1709,13 @@ or if they were shared before the property was changed.
 If the new property is
 .Sy off ,
 the file systems are unshared.
+.Pp
+When the
+.Sy sharenfs
+property is updated with
+.Nm zfs Cm set Fl u
+, the property is set to desired value, but the operation to share, reshare
+or unshare the the dataset is not performed.
 .It Sy logbias Ns = Ns Sy latency Ns | Ns Sy throughput
 Provide a hint to ZFS about handling of synchronous requests in this dataset.
 If

man/man8/zfs-set.8

@@ -39,6 +39,7 @@
 .Sh SYNOPSIS
 .Nm zfs
 .Cm set
+.Op Fl u
 .Ar property Ns = Ns Ar value Oo Ar property Ns = Ns Ar value Oc Ns …
 .Ar filesystem Ns | Ns Ar volume Ns | Ns Ar snapshot Ns …
 .Nm zfs
@@ -60,6 +61,7 @@
 .It Xo
 .Nm zfs
 .Cm set
+.Op Fl u
 .Ar property Ns = Ns Ar value Oo Ar property Ns = Ns Ar value Oc Ns …
 .Ar filesystem Ns | Ns Ar volume Ns | Ns Ar snapshot Ns …
 .Xc
@@ -79,6 +81,11 @@ For more information, see the
 .Em User Properties
 section of
 .Xr zfsprops 7 .
+.Bl -tag -width "-u"
+.It Fl u
+Update mountpoint, sharenfs, sharesmb property but do not mount or share the
+dataset.
+.El
 .It Xo
 .Nm zfs
 .Cm get

tests/runfiles/common.run

@@ -281,7 +281,7 @@ tests = ['cache_001_pos', 'cache_002_neg', 'canmount_001_pos',
     'user_property_004_pos', 'version_001_neg', 'zfs_set_001_neg',
     'zfs_set_002_neg', 'zfs_set_003_neg', 'property_alias_001_pos',
     'mountpoint_003_pos', 'ro_props_001_pos', 'zfs_set_keylocation',
-    'zfs_set_feature_activation']
+    'zfs_set_feature_activation', 'zfs_set_nomount']
 tags = ['functional', 'cli_root', 'zfs_set']
 
 [tests/functional/cli_root/zfs_share]

tests/runfiles/sanity.run

@@ -212,7 +212,7 @@ tests = ['cache_001_pos', 'cache_002_neg', 'canmount_001_pos',
     'user_property_001_pos', 'user_property_003_neg', 'readonly_001_pos',
     'user_property_004_pos', 'version_001_neg',
     'zfs_set_003_neg', 'property_alias_001_pos',
-    'zfs_set_keylocation', 'zfs_set_feature_activation']
+    'zfs_set_keylocation', 'zfs_set_feature_activation', 'zfs_set_nomount']
 tags = ['functional', 'cli_root', 'zfs_set']
 
 [tests/functional/cli_root/zfs_snapshot]

tests/zfs-tests/tests/Makefile.am

@@ -870,6 +870,7 @@ nobase_dist_datadir_zfs_tests_tests_SCRIPTS += \
 	functional/cli_root/zfs_set/zfs_set_003_neg.ksh \
 	functional/cli_root/zfs_set/zfs_set_feature_activation.ksh \
 	functional/cli_root/zfs_set/zfs_set_keylocation.ksh \
+	functional/cli_root/zfs_set/zfs_set_nomount.ksh \
 	functional/cli_root/zfs_share/cleanup.ksh \
 	functional/cli_root/zfs_share/setup.ksh \
 	functional/cli_root/zfs_share/zfs_share_001_pos.ksh \