Illumos 4953, 4954, 4955

4953 zfs rename <snapshot> need not involve libshare
4954 "zfs create" need not involve libshare if we are not sharing
4955 libshare's get_zfs_dataset need not sort the datasets
Reviewed by: George Wilson <george.wilson@delphix.com>
Reviewed by: Sebastien Roy <sebastien.roy@delphix.com>
Reviewed by: Dan McDonald <danmcd@omniti.com>
Reviewed by: Gordon Ross <gordon.ross@nexenta.com>
Approved by: Garrett D'Amore <garrett@damore.org>

References:
  https://www.illumos.org/issues/4953
  https://www.illumos.org/issues/4954
  https://www.illumos.org/issues/4955
  illumos/illumos-gate@33cde0d

Porting notes:
- Dropped qsort libshare_zfs.c hunk, no equivalent ZoL code.

Ported-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #4219

lib/libzfs/libzfs_dataset.c

@@ -3992,7 +3992,6 @@ zfs_rename(zfs_handle_t *zhp, const char *target, boolean_t recursive,
 	}
 
 	if (recursive) {
-
 		parentname = zfs_strdup(zhp->zfs_hdl, zhp->zfs_name);
 		if (parentname == NULL) {
 			ret = -1;
@@ -4005,8 +4004,7 @@ zfs_rename(zfs_handle_t *zhp, const char *target, boolean_t recursive,
 			ret = -1;
 			goto error;
 		}
-
-	} else {
+	} else if (zhp->zfs_type != ZFS_TYPE_SNAPSHOT) {
 		if ((cl = changelist_gather(zhp, ZFS_PROP_NAME, 0,
 		    force_unmount ? MS_FORCE : 0)) == NULL)
 			return (-1);
@@ -4055,23 +4053,23 @@ zfs_rename(zfs_handle_t *zhp, const char *target, boolean_t recursive,
 		 * On failure, we still want to remount any filesystems that
 		 * were previously mounted, so we don't alter the system state.
 		 */
-		if (!recursive)
+		if (cl != NULL)
 			(void) changelist_postfix(cl);
 	} else {
-		if (!recursive) {
+		if (cl != NULL) {
 			changelist_rename(cl, zfs_get_name(zhp), target);
 			ret = changelist_postfix(cl);
 		}
 	}
 
 error:
-	if (parentname) {
+	if (parentname != NULL) {
 		free(parentname);
 	}
-	if (zhrp) {
+	if (zhrp != NULL) {
 		zfs_close(zhrp);
 	}
-	if (cl) {
+	if (cl != NULL) {
 		changelist_free(cl);
 	}
 	return (ret);

lib/libzfs/libzfs_mount.c

@@ -22,6 +22,7 @@
 /*
  * Copyright 2015 Nexenta Systems, Inc.  All rights reserved.
  * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2014 by Delphix. All rights reserved.
  */
 
 /*
@@ -745,13 +746,6 @@ zfs_share_proto(zfs_handle_t *zhp, zfs_share_proto_t *proto)
 	if (!zfs_is_mountable(zhp, mountpoint, sizeof (mountpoint), NULL))
 		return (0);
 
-	if ((ret = zfs_init_libshare(hdl, SA_INIT_SHARE_API)) != SA_OK) {
-		(void) zfs_error_fmt(hdl, EZFS_SHARENFSFAILED,
-		    dgettext(TEXT_DOMAIN, "cannot share '%s': %s"),
-		    zfs_get_name(zhp), sa_errorstr(ret));
-		return (-1);
-	}
-
 	for (curr_proto = proto; *curr_proto != PROTO_END; curr_proto++) {
 		/*
 		 * Return success if there are no share options.
@@ -762,6 +756,14 @@ zfs_share_proto(zfs_handle_t *zhp, zfs_share_proto_t *proto)
 		    strcmp(shareopts, "off") == 0)
 			continue;
 
+		ret = zfs_init_libshare(hdl, SA_INIT_SHARE_API);
+		if (ret != SA_OK) {
+			(void) zfs_error_fmt(hdl, EZFS_SHARENFSFAILED,
+			    dgettext(TEXT_DOMAIN, "cannot share '%s': %s"),
+			    zfs_get_name(zhp), sa_errorstr(ret));
+			return (-1);
+		}
+
 		/*
 		 * If the 'zoned' property is set, then zfs_is_mountable()
 		 * will have already bailed out if we are in the global zone.