OpenZFS 8264 - want support for promoting datasets in libzfs_core

Authored by: Andrew Stormont <astormont@racktopsystems.com>
Reviewed by: Andriy Gapon <avg@FreeBSD.org>
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Dan McDonald <danmcd@kebe.com>
Approved by: Dan McDonald <danmcd@kebe.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Ported-by: Giuseppe Di Natale <dinatale2@llnl.gov>

OpenZFS-issue: https://www.illumos.org/issues/8264
OpenZFS-commit: https://github.com/openzfs/openzfs/commit/a4b8c9a
Closes #6254

include/libzfs_core.h

@@ -22,6 +22,7 @@
 /*
  * Copyright (c) 2012, 2014 by Delphix. All rights reserved.
  * Copyright (c) 2017 Datto Inc.
+ * Copyright 2017 RackTop Systems.
  */
 
 #ifndef	_LIBZFS_CORE_H
@@ -50,6 +51,7 @@ enum lzc_dataset_type {
 int lzc_snapshot(nvlist_t *, nvlist_t *, nvlist_t **);
 int lzc_create(const char *, enum lzc_dataset_type, nvlist_t *);
 int lzc_clone(const char *, const char *, nvlist_t *);
+int lzc_promote(const char *, char *, int);
 int lzc_destroy_snaps(nvlist_t *, boolean_t, nvlist_t **);
 int lzc_bookmark(nvlist_t *, nvlist_t **);
 int lzc_get_bookmarks(const char *, nvlist_t *, nvlist_t **);

lib/libzfs/libzfs_dataset.c

@@ -29,6 +29,7 @@
  * Copyright (c) 2013 Steven Hartland. All rights reserved.
  * Copyright 2016 Nexenta Systems, Inc.
  * Copyright 2016 Igor Kozhukhov <ikozhukhov@gmail.com>
+ * Copyright 2017 RackTop Systems.
  */
 
 #include <ctype.h>
@@ -3731,8 +3732,7 @@ int
 zfs_promote(zfs_handle_t *zhp)
 {
 	libzfs_handle_t *hdl = zhp->zfs_hdl;
-	zfs_cmd_t zc = {"\0"};
-	char parent[MAXPATHLEN];
+	char snapname[ZFS_MAX_DATASET_NAME_LEN];
 	int ret;
 	char errbuf[1024];
 
@@ -3745,31 +3745,25 @@ zfs_promote(zfs_handle_t *zhp)
 		return (zfs_error(hdl, EZFS_BADTYPE, errbuf));
 	}
 
-	(void) strlcpy(parent, zhp->zfs_dmustats.dds_origin, sizeof (parent));
-	if (parent[0] == '\0') {
+	if (zhp->zfs_dmustats.dds_origin[0] == '\0') {
 		zfs_error_aux(hdl, dgettext(TEXT_DOMAIN,
 		    "not a cloned filesystem"));
 		return (zfs_error(hdl, EZFS_BADTYPE, errbuf));
 	}
 
-	(void) strlcpy(zc.zc_value, zhp->zfs_dmustats.dds_origin,
-	    sizeof (zc.zc_value));
-	(void) strlcpy(zc.zc_name, zhp->zfs_name, sizeof (zc.zc_name));
-	ret = zfs_ioctl(hdl, ZFS_IOC_PROMOTE, &zc);
+	ret = lzc_promote(zhp->zfs_name, snapname, sizeof (snapname));
 
 	if (ret != 0) {
-		int save_errno = errno;
-
-		switch (save_errno) {
+		switch (ret) {
 		case EEXIST:
 			/* There is a conflicting snapshot name. */
 			zfs_error_aux(hdl, dgettext(TEXT_DOMAIN,
 			    "conflicting snapshot '%s' from parent '%s'"),
-			    zc.zc_string, parent);
+			    snapname, zhp->zfs_dmustats.dds_origin);
 			return (zfs_error(hdl, EZFS_EXISTS, errbuf));
 
 		default:
-			return (zfs_standard_error(hdl, save_errno, errbuf));
+			return (zfs_standard_error(hdl, ret, errbuf));
 		}
 	}
 	return (ret);

lib/libzfs_core/libzfs_core.c

@@ -23,6 +23,7 @@
  * Copyright (c) 2012, 2014 by Delphix. All rights reserved.
  * Copyright (c) 2013 Steven Hartland. All rights reserved.
  * Copyright (c) 2017 Datto Inc.
+ * Copyright 2017 RackTop Systems.
  */
 
 /*
@@ -206,6 +207,28 @@ lzc_clone(const char *fsname, const char *origin,
 	return (error);
 }
 
+int
+lzc_promote(const char *fsname, char *snapnamebuf, int snapnamelen)
+{
+	/*
+	 * The promote ioctl is still legacy, so we need to construct our
+	 * own zfs_cmd_t rather than using lzc_ioctl().
+	 */
+	zfs_cmd_t zc = { "\0" };
+
+	ASSERT3S(g_refcount, >, 0);
+	VERIFY3S(g_fd, !=, -1);
+
+	(void) strlcpy(zc.zc_name, fsname, sizeof (zc.zc_name));
+	if (ioctl(g_fd, ZFS_IOC_PROMOTE, &zc) != 0) {
+		int error = errno;
+		if (error == EEXIST && snapnamebuf != NULL)
+			(void) strlcpy(snapnamebuf, zc.zc_string, snapnamelen);
+		return (error);
+	}
+	return (0);
+}
+
 /*
  * Creates snapshots.
  *
@@ -333,7 +356,7 @@ lzc_exists(const char *dataset)
 {
 	/*
 	 * The objset_stats ioctl is still legacy, so we need to construct our
-	 * own zfs_cmd_t rather than using zfsc_ioctl().
+	 * own zfs_cmd_t rather than using lzc_ioctl().
 	 */
 	zfs_cmd_t zc = {"\0"};
 

module/zfs/zfs_ioctl.c

@@ -35,6 +35,7 @@
  * Copyright (c) 2016 Actifio, Inc. All rights reserved.
  * Copyright (c) 2017, loli10K <ezomori.nozomu@gmail.com>. All rights reserved.
  * Copyright (c) 2017 Datto Inc.
+ * Copyright 2017 RackTop Systems.
  */
 
 /*
@@ -4963,7 +4964,6 @@ zfs_ioc_pool_reopen(zfs_cmd_t *zc)
 /*
  * inputs:
  * zc_name	name of filesystem
- * zc_value	name of origin snapshot
  *
  * outputs:
  * zc_string	name of conflicting snapshot, if there is one
@@ -4971,16 +4971,49 @@ zfs_ioc_pool_reopen(zfs_cmd_t *zc)
 static int
 zfs_ioc_promote(zfs_cmd_t *zc)
 {
+	dsl_pool_t *dp;
+	dsl_dataset_t *ds, *ods;
+	char origin[ZFS_MAX_DATASET_NAME_LEN];
 	char *cp;
+	int error;
+
+	error = dsl_pool_hold(zc->zc_name, FTAG, &dp);
+	if (error != 0)
+		return (error);
+
+	error = dsl_dataset_hold(dp, zc->zc_name, FTAG, &ds);
+	if (error != 0) {
+		dsl_pool_rele(dp, FTAG);
+		return (error);
+	}
+
+	if (!dsl_dir_is_clone(ds->ds_dir)) {
+		dsl_dataset_rele(ds, FTAG);
+		dsl_pool_rele(dp, FTAG);
+		return (SET_ERROR(EINVAL));
+	}
+
+	error = dsl_dataset_hold_obj(dp,
+	    dsl_dir_phys(ds->ds_dir)->dd_origin_obj, FTAG, &ods);
+	if (error != 0) {
+		dsl_dataset_rele(ds, FTAG);
+		dsl_pool_rele(dp, FTAG);
+		return (error);
+	}
+
+	dsl_dataset_name(ods, origin);
+	dsl_dataset_rele(ods, FTAG);
+	dsl_dataset_rele(ds, FTAG);
+	dsl_pool_rele(dp, FTAG);
 
 	/*
 	 * We don't need to unmount *all* the origin fs's snapshots, but
 	 * it's easier.
 	 */
-	cp = strchr(zc->zc_value, '@');
+	cp = strchr(origin, '@');
 	if (cp)
 		*cp = '\0';
-	(void) dmu_objset_find(zc->zc_value,
+	(void) dmu_objset_find(origin,
 	    zfs_unmount_snap_cb, NULL, DS_FIND_SNAPSHOTS);
 	return (dsl_dataset_promote(zc->zc_name, zc->zc_string));
 }