Add zfs create dryrun

Adds the ability to sanity check zfs create arguments and to see the
value of any additional properties that will local to the dataset.  For
example, automation that may need to adjust quota on a parent filesystem
before creating a volume may call `zfs create -nP -V <size> <volume>` to
obtain the value of refreservation.  This adds the following options to
zfs create:

- -n dry-run (no-op)
- -v verbose
- -P parseable (implies verbose)

Reviewed-by: Ryan Moeller <[email protected]>
Reviewed-by: Brian Behlendorf <[email protected]>
Reviewed-by: Matt Ahrens <[email protected]>
Reviewed-by: Jerry Jelinek <[email protected]>
Signed-off-by: Mike Gerdts <[email protected]>
Closes #8974 

1 files changed, 92 insertions, 22 deletions

diff --git a/cmd/zfs/zfs_main.c b/cmd/zfs/zfs_main.c
index 0ebd16f6d..53b76e25d 100644
--- a/cmd/zfs/zfs_main.c
+++ b/cmd/zfs/zfs_main.c
@@ -254,9 +254,9 @@ get_usage(zfs_help_t idx)
 		return (gettext("\tclone [-p] [-o property=value] ... "
 		    "<snapshot> <filesystem|volume>\n"));
 	case HELP_CREATE:
-		return (gettext("\tcreate [-p] [-o property=value] ... "
+		return (gettext("\tcreate [-Pnpv] [-o property=value] ... "
 		    "<filesystem>\n"
-		    "\tcreate [-ps] [-b blocksize] [-o property=value] ... "
+		    "\tcreate [-Pnpsv] [-b blocksize] [-o property=value] ... "
 		    "-V <size> <volume>\n"));
 	case HELP_DESTROY:
 		return (gettext("\tdestroy [-fnpRrv] <filesystem|volume>\n"
@@ -867,8 +867,8 @@ usage:
 }
 
 /*
- * zfs create [-p] [-o prop=value] ... fs
- * zfs create [-ps] [-b blocksize] [-o prop=value] ... -V vol size
+ * zfs create [-Pnpv] [-o prop=value] ... fs
+ * zfs create [-Pnpsv] [-b blocksize] [-o prop=value] ... -V vol size
  *
  * Create a new dataset.  This command can be used to create filesystems
  * and volumes.  Snapshot creation is handled by 'zfs snapshot'.
@@ -880,16 +880,29 @@ usage:
  * SPA_VERSION_REFRESERVATION, we set a refreservation instead.
  *
  * The '-p' flag creates all the non-existing ancestors of the target first.
+ *
+ * The '-n' flag is no-op (dry run) mode.  This will perform a user-space sanity
+ * check of arguments and properties, but does not check for permissions,
+ * available space, etc.
+ *
+ * The '-v' flag is for verbose output.
+ *
+ * The '-P' flag is used for parseable output.  It implies '-v'.
  */
 static int
 zfs_do_create(int argc, char **argv)
 {
 	zfs_type_t type = ZFS_TYPE_FILESYSTEM;
+	zpool_handle_t *zpool_handle = NULL;
+	nvlist_t *real_props = NULL;
 	uint64_t volsize = 0;
 	int c;
 	boolean_t noreserve = B_FALSE;
 	boolean_t bflag = B_FALSE;
 	boolean_t parents = B_FALSE;
+	boolean_t dryrun = B_FALSE;
+	boolean_t verbose = B_FALSE;
+	boolean_t parseable = B_FALSE;
 	int ret = 1;
 	nvlist_t *props;
 	uint64_t intval;
@@ -898,7 +911,7 @@ zfs_do_create(int argc, char **argv)
 		nomem();
 
 	/* check options */
-	while ((c = getopt(argc, argv, ":V:b:so:p")) != -1) {
+	while ((c = getopt(argc, argv, ":PV:b:nso:pv")) != -1) {
 		switch (c) {
 		case 'V':
 			type = ZFS_TYPE_VOLUME;
@@ -914,6 +927,10 @@ zfs_do_create(int argc, char **argv)
 				nomem();
 			volsize = intval;
 			break;
+		case 'P':
+			verbose = B_TRUE;
+			parseable = B_TRUE;
+			break;
 		case 'p':
 			parents = B_TRUE;
 			break;
@@ -931,6 +948,9 @@ zfs_do_create(int argc, char **argv)
 			    intval) != 0)
 				nomem();
 			break;
+		case 'n':
+			dryrun = B_TRUE;
+			break;
 		case 'o':
 			if (!parseprop(props, optarg))
 				goto error;
@@ -938,6 +958,9 @@ zfs_do_create(int argc, char **argv)
 		case 's':
 			noreserve = B_TRUE;
 			break;
+		case 'v':
+			verbose = B_TRUE;
+			break;
 		case ':':
 			(void) fprintf(stderr, gettext("missing size "
 			    "argument\n"));
@@ -969,14 +992,9 @@ zfs_do_create(int argc, char **argv)
 		goto badusage;
 	}
 
-	if (type == ZFS_TYPE_VOLUME && !noreserve) {
-		zpool_handle_t *zpool_handle;
-		nvlist_t *real_props = NULL;
-		uint64_t spa_version;
+	if (dryrun || (type == ZFS_TYPE_VOLUME && !noreserve)) {
+		char msg[ZFS_MAX_DATASET_NAME_LEN * 2];
 		char *p;
-		zfs_prop_t resv_prop;
-		char *strval;
-		char msg[1024];
 
 		if ((p = strchr(argv[0], '/')) != NULL)
 			*p = '\0';
@@ -985,25 +1003,31 @@ zfs_do_create(int argc, char **argv)
 			*p = '/';
 		if (zpool_handle == NULL)
 			goto error;
-		spa_version = zpool_get_prop_int(zpool_handle,
-		    ZPOOL_PROP_VERSION, NULL);
-		if (spa_version >= SPA_VERSION_REFRESERVATION)
-			resv_prop = ZFS_PROP_REFRESERVATION;
-		else
-			resv_prop = ZFS_PROP_RESERVATION;
 
 		(void) snprintf(msg, sizeof (msg),
+		    dryrun ? gettext("cannot verify '%s'") :
 		    gettext("cannot create '%s'"), argv[0]);
 		if (props && (real_props = zfs_valid_proplist(g_zfs, type,
 		    props, 0, NULL, zpool_handle, B_TRUE, msg)) == NULL) {
 			zpool_close(zpool_handle);
 			goto error;
 		}
+	}
+
+	if (type == ZFS_TYPE_VOLUME && !noreserve) {
+		uint64_t spa_version;
+		zfs_prop_t resv_prop;
+		char *strval;
+
+		spa_version = zpool_get_prop_int(zpool_handle,
+		    ZPOOL_PROP_VERSION, NULL);
+		if (spa_version >= SPA_VERSION_REFRESERVATION)
+			resv_prop = ZFS_PROP_REFRESERVATION;
+		else
+			resv_prop = ZFS_PROP_RESERVATION;
 
 		volsize = zvol_volsize_to_reservation(zpool_handle, volsize,
 		    real_props);
-		nvlist_free(real_props);
-		zpool_close(zpool_handle);
 
 		if (nvlist_lookup_string(props, zfs_prop_to_name(resv_prop),
 		    &strval) != 0) {
@@ -1014,6 +1038,10 @@ zfs_do_create(int argc, char **argv)
 			}
 		}
 	}
+	if (zpool_handle != NULL) {
+		zpool_close(zpool_handle);
+		nvlist_free(real_props);
+	}
 
 	if (parents && zfs_name_valid(argv[0], type)) {
 		/*
@@ -1025,8 +1053,50 @@ zfs_do_create(int argc, char **argv)
 			ret = 0;
 			goto error;
 		}
-		if (zfs_create_ancestors(g_zfs, argv[0]) != 0)
-			goto error;
+		if (verbose) {
+			(void) printf(parseable ? "create_ancestors\t%s\n" :
+			    dryrun ?  "would create ancestors of %s\n" :
+			    "create ancestors of %s\n", argv[0]);
+		}
+		if (!dryrun) {
+			if (zfs_create_ancestors(g_zfs, argv[0]) != 0) {
+				goto error;
+			}
+		}
+	}
+
+	if (verbose) {
+		nvpair_t *nvp = NULL;
+		(void) printf(parseable ? "create\t%s\n" :
+		    dryrun ? "would create %s\n" : "create %s\n", argv[0]);
+		while ((nvp = nvlist_next_nvpair(props, nvp)) != NULL) {
+			uint64_t uval;
+			char *sval;
+
+			switch (nvpair_type(nvp)) {
+			case DATA_TYPE_UINT64:
+				VERIFY0(nvpair_value_uint64(nvp, &uval));
+				(void) printf(parseable ?
+				    "property\t%s\t%llu\n" : "\t%s=%llu\n",
+				    nvpair_name(nvp), (u_longlong_t)uval);
+				break;
+			case DATA_TYPE_STRING:
+				VERIFY0(nvpair_value_string(nvp, &sval));
+				(void) printf(parseable ?
+				    "property\t%s\t%s\n" : "\t%s=%s\n",
+				    nvpair_name(nvp), sval);
+				break;
+			default:
+				(void) fprintf(stderr, "property '%s' "
+				    "has illegal type %d\n",
+				    nvpair_name(nvp), nvpair_type(nvp));
+				abort();
+			}
+		}
+	}
+	if (dryrun) {
+		ret = 0;
+		goto error;
 	}
 
 	/* pass to libzfs */