It is possible to recursively destroy snapshots even if the snapshot

doesn't exist on a dataset we are starting from. For example if we
have the following configuration:

	tank
	tank/foo
	tank/foo@snap
	tank/bar
	tank/bar@snap

We can execute:

	# zfs destroy -t tank@snap

eventhough tank@snap doesn't exit.

Unfortunately it is not possible to do the same with recursive rename:

	# zfs rename -r tank@snap tank@pans
	cannot open 'tank@snap': dataset does not exist

...until now. This change allows to recursively rename snapshots even if
snapshot doesn't exist on the starting dataset.

Sponsored by:	rsync.net
MFC after:	2 weeks

3 files changed, 47 insertions, 3 deletions

diff --git a/cddl/contrib/opensolaris/cmd/zfs/zfs_main.c b/cddl/contrib/opensolaris/cmd/zfs/zfs_main.c
index e0bc3d7..ea313ba 100644
--- a/cddl/contrib/opensolaris/cmd/zfs/zfs_main.c
+++ b/cddl/contrib/opensolaris/cmd/zfs/zfs_main.c
@@ -3081,6 +3081,7 @@ zfs_do_rename(int argc, char **argv)
 	int ret = 0;
 	int types;
 	boolean_t parents = B_FALSE;
+	char *snapshot = NULL;
 
 	/* check options */
 	while ((c = getopt(argc, argv, "fpru")) != -1) {
@@ -3149,6 +3150,19 @@ zfs_do_rename(int argc, char **argv)
 	else
 		types = ZFS_TYPE_DATASET;
 
+	if (flags.recurse) {
+		/*
+		 * When we do recursive rename we are fine when the given
+		 * snapshot for the given dataset doesn't exist - it can
+		 * still exists below.
+		 */
+
+		snapshot = strchr(argv[0], '@');
+		assert(snapshot != NULL);
+		*snapshot = '\0';
+		snapshot++;
+	}
+
 	if ((zhp = zfs_open(g_zfs, argv[0], types)) == NULL)
 		return (1);
 
@@ -3159,7 +3173,7 @@ zfs_do_rename(int argc, char **argv)
 		return (1);
 	}
 
-	ret = (zfs_rename(zhp, argv[1], flags) != 0);
+	ret = (zfs_rename(zhp, snapshot, argv[1], flags) != 0);
 
 	zfs_close(zhp);
 	return (ret);
diff --git a/cddl/contrib/opensolaris/lib/libzfs/common/libzfs.h b/cddl/contrib/opensolaris/lib/libzfs/common/libzfs.h
index 3a35410..2660059 100644
--- a/cddl/contrib/opensolaris/lib/libzfs/common/libzfs.h
+++ b/cddl/contrib/opensolaris/lib/libzfs/common/libzfs.h
@@ -571,7 +571,8 @@ typedef struct renameflags {
 	int forceunmount : 1;
 } renameflags_t;
 
-extern int zfs_rename(zfs_handle_t *, const char *, renameflags_t flags);
+extern int zfs_rename(zfs_handle_t *, const char *, const char *,
+    renameflags_t flags);
 
 typedef struct sendflags {
 	/* print informational messages (ie, -v was specified) */
diff --git a/cddl/contrib/opensolaris/lib/libzfs/common/libzfs_dataset.c b/cddl/contrib/opensolaris/lib/libzfs/common/libzfs_dataset.c
index 4116e1b..2261978 100644
--- a/cddl/contrib/opensolaris/lib/libzfs/common/libzfs_dataset.c
+++ b/cddl/contrib/opensolaris/lib/libzfs/common/libzfs_dataset.c
@@ -611,6 +611,22 @@ zfs_open(libzfs_handle_t *hdl, const char *path, int types)
 		return (NULL);
 	}
 
+	if (zhp == NULL) {
+		char *at = strchr(path, '@');
+
+		if (at != NULL)
+			*at = '\0';
+		errno = 0;
+		if ((zhp = make_dataset_handle(hdl, path)) == NULL) {
+			(void) zfs_standard_error(hdl, errno, errbuf);
+			return (NULL);
+		}
+		if (at != NULL)
+			*at = '@';
+		(void) strlcpy(zhp->zfs_name, path, sizeof (zhp->zfs_name));
+		zhp->zfs_type = ZFS_TYPE_SNAPSHOT;
+	}
+
 	if (!(types & zhp->zfs_type)) {
 		(void) zfs_error(hdl, EZFS_BADTYPE, errbuf);
 		zfs_close(zhp);
@@ -3614,7 +3630,8 @@ zfs_rollback(zfs_handle_t *zhp, zfs_handle_t *snap, boolean_t force)
  * Renames the given dataset.
  */
 int
-zfs_rename(zfs_handle_t *zhp, const char *target, renameflags_t flags)
+zfs_rename(zfs_handle_t *zhp, const char *source, const char *target,
+    renameflags_t flags)
 {
 	int ret;
 	zfs_cmd_t zc = { 0 };
@@ -3634,6 +3651,18 @@ zfs_rename(zfs_handle_t *zhp, const char *target, renameflags_t flags)
 	(void) snprintf(errbuf, sizeof (errbuf), dgettext(TEXT_DOMAIN,
 	    "cannot rename to '%s'"), target);
 
+	if (source != NULL) {
+		/*
+		 * This is recursive snapshots rename, put snapshot name
+		 * (that might not exist) into zfs_name.
+		 */
+		assert(flags.recurse);
+
+		(void) strlcat(zhp->zfs_name, "@", sizeof(zhp->zfs_name));
+		(void) strlcat(zhp->zfs_name, source, sizeof(zhp->zfs_name));
+		zhp->zfs_type = ZFS_TYPE_SNAPSHOT;
+	}
+
 	/*
 	 * Make sure the target name is valid
 	 */