Want lazy unmount support

Add "-l" option to perform a lazy unmount in "zfs unmount", "zpool export"
and "zpool destroy".

Signed-off-by: Tim Chase <[email protected]>
Requires-builders: none

cmd/zfs/zfs_main.c

@@ -6563,13 +6563,16 @@ unshare_unmount(int op, int argc, char **argv)
 	char sharesmb[ZFS_MAXPROPLEN];
 
 	/* check options */
-	while ((c = getopt(argc, argv, op == OP_SHARE ? ":a" : "af")) != -1) {
+	while ((c = getopt(argc, argv, op == OP_SHARE ? ":a" : "afl")) != -1) {
 		switch (c) {
 		case 'a':
 			do_all = 1;
 			break;
 		case 'f':
-			flags = MS_FORCE;
+			flags |= MS_FORCE;
+			break;
+		case 'l':
+			flags |= MS_DETACH;
 			break;
 		case ':':
 			(void) fprintf(stderr, gettext("missing argument for "

cmd/zpool/zpool_main.c

@@ -307,7 +307,7 @@ get_usage(zpool_help_t idx)
 		    "\t    [-O file-system-property=value] ... \n"
 		    "\t    [-m mountpoint] [-R root] <pool> <vdev> ...\n"));
 	case HELP_DESTROY:
-		return (gettext("\tdestroy [-f] <pool>\n"));
+		return (gettext("\tdestroy [-fl] <pool>\n"));
 	case HELP_DETACH:
 		return (gettext("\tdetach <pool> <device>\n"));
 	case HELP_EXPORT:
@@ -1314,17 +1314,21 @@ int
 zpool_do_destroy(int argc, char **argv)
 {
 	boolean_t force = B_FALSE;
+	boolean_t lazy = B_FALSE;
 	int c;
 	char *pool;
 	zpool_handle_t *zhp;
 	int ret;
 
 	/* check options */
-	while ((c = getopt(argc, argv, "f")) != -1) {
+	while ((c = getopt(argc, argv, "fl")) != -1) {
 		switch (c) {
 		case 'f':
 			force = B_TRUE;
 			break;
+		case 'l':
+			lazy = B_TRUE;
+			break;
 		case '?':
 			(void) fprintf(stderr, gettext("invalid option '%c'\n"),
 			    optopt);
@@ -1358,7 +1362,7 @@ zpool_do_destroy(int argc, char **argv)
 		return (1);
 	}
 
-	if (zpool_disable_datasets(zhp, force) != 0) {
+	if (zpool_disable_datasets(zhp, force, lazy) != 0) {
 		(void) fprintf(stderr, gettext("could not destroy '%s': "
 		    "could not unmount datasets\n"), zpool_get_name(zhp));
 		zpool_close(zhp);
@@ -1378,6 +1382,7 @@ zpool_do_destroy(int argc, char **argv)
 typedef struct export_cbdata {
 	boolean_t force;
 	boolean_t hardforce;
+	boolean_t lazy;
 } export_cbdata_t;
 
 /*
@@ -1388,7 +1393,7 @@ zpool_export_one(zpool_handle_t *zhp, void *data)
 {
 	export_cbdata_t *cb = data;
 
-	if (zpool_disable_datasets(zhp, cb->force) != 0)
+	if (zpool_disable_datasets(zhp, cb->force, cb->lazy) != 0)
 		return (1);
 
 	/* The history must be logged as part of the export */
@@ -1421,10 +1426,11 @@ zpool_do_export(int argc, char **argv)
 	boolean_t do_all = B_FALSE;
 	boolean_t force = B_FALSE;
 	boolean_t hardforce = B_FALSE;
+	boolean_t lazy = B_FALSE;
 	int c, ret;
 
 	/* check options */
-	while ((c = getopt(argc, argv, "afF")) != -1) {
+	while ((c = getopt(argc, argv, "afFl")) != -1) {
 		switch (c) {
 		case 'a':
 			do_all = B_TRUE;
@@ -1435,6 +1441,9 @@ zpool_do_export(int argc, char **argv)
 		case 'F':
 			hardforce = B_TRUE;
 			break;
+		case 'l':
+			lazy = B_TRUE;
+			break;
 		case '?':
 			(void) fprintf(stderr, gettext("invalid option '%c'\n"),
 			    optopt);
@@ -1444,6 +1453,7 @@ zpool_do_export(int argc, char **argv)
 
 	cb.force = force;
 	cb.hardforce = hardforce;
+	cb.lazy = lazy;
 	argc -= optind;
 	argv += optind;
 

include/libzfs.h

@@ -872,7 +872,7 @@ int zfs_smb_acl_rename(libzfs_handle_t *, char *, char *, char *, char *);
  * sharing/unsharing them.
  */
 extern int zpool_enable_datasets(zpool_handle_t *, const char *, int);
-extern int zpool_disable_datasets(zpool_handle_t *, boolean_t);
+extern int zpool_disable_datasets(zpool_handle_t *, boolean_t, boolean_t);
 
 /*
  * Support for Linux libudev derived persistent device strings

lib/libzfs/libzfs_mount.c

@@ -1325,7 +1325,7 @@ mountpoint_compare(const void *a, const void *b)
  * and gather all the filesystems that are currently mounted.
  */
 int
-zpool_disable_datasets(zpool_handle_t *zhp, boolean_t force)
+zpool_disable_datasets(zpool_handle_t *zhp, boolean_t force, boolean_t lazy)
 {
 	int used, alloc;
 	struct mnttab entry;
@@ -1337,6 +1337,8 @@ zpool_disable_datasets(zpool_handle_t *zhp, boolean_t force)
 	int ret = -1;
 	int flags = (force ? MS_FORCE : 0);
 
+	if (lazy)
+		flags |= MS_DETACH;
 	namelen = strlen(zhp->zpool_name);
 
 	/* Reopen MNTTAB to prevent reading stale data from open file */

man/man8/zfs.8

@@ -153,7 +153,7 @@
 .Fl a | Ar filesystem
 .Nm
 .Cm unmount
-.Op Fl f
+.Op Fl fl
 .Fl a | Ar filesystem Ns | Ns Ar mountpoint
 .Nm
 .Cm share
@@ -3029,7 +3029,7 @@ Report mount progress.
 .It Xo
 .Nm
 .Cm unmount
-.Op Fl f
+.Op Fl fl
 .Fl a | Ar filesystem Ns | Ns Ar mountpoint
 .Xc
 Unmounts currently mounted ZFS file systems.
@@ -3043,6 +3043,9 @@ The command can also be given a path to a ZFS file system mount point on the
 system.
 .It Fl f
 Forcefully unmount the file system, even if it is currently in use.
+.It Fl l
+Lazy unmount.  Detaches the filesystem immediately and frees kernel
+resources once it is not busy any more.
 .El
 .It Xo
 .Nm

man/man8/zpool.8

@@ -62,6 +62,7 @@
 .Nm
 .Cm destroy
 .Op Fl f
+.Op Fl l
 .Ar pool
 .Nm
 .Cm detach
@@ -73,6 +74,7 @@
 .Cm export
 .Op Fl a
 .Op Fl f
+.Op Fl l
 .Ar pool Ns ...
 .Nm
 .Cm get
@@ -1003,13 +1005,16 @@ block devices.
 .Nm
 .Cm destroy
 .Op Fl f
+.Op Fl l
 .Ar pool
 .Xc
 Destroys the given pool, freeing up any devices for other use.
 This command tries to unmount any active datasets before destroying the pool.
 .Bl -tag -width Ds
 .It Fl f
 Forces any active datasets contained within the pool to be unmounted.
+.It Fl l
+Performs a lazy unmount for each mounted dataset within the pool.
 .El
 .It Xo
 .Nm
@@ -1052,6 +1057,7 @@ Print the entire payload for each event.
 .Cm export
 .Op Fl a
 .Op Fl f
+.Op Fl l
 .Ar pool Ns ...
 .Xc
 Exports the given pools from the system.
@@ -1078,6 +1084,8 @@ Exports all pools imported on the system.
 Forcefully unmount all datasets, using the
 .Nm unmount Fl f
 command.
+.It Fl l
+Performs a lazy unmount for each mounted dataset within the pool.
 .Pp
 This command will forcefully export the pool even if it has a shared spare that
 is currently being used.