Illumos #3996

3996 want a libzfs_core API to rollback to latest snapshot
Reviewed by: Christopher Siden <[email protected]>
Reviewed by: Adam Leventhal <[email protected]>
Reviewed by: George Wilson <[email protected]>
Reviewed by: Andy Stormont <[email protected]>
Approved by: Richard Lowe <[email protected]>

References:
  https://www.illumos.org/issues/3996
  illumos/illumos-gate@a7027df17fad220a20367b9d1eb251bc6300d203

Ported-by: Richard Yao <[email protected]>
Signed-off-by: Brian Behlendorf <[email protected]>
Issue #1775

2 files changed, 27 insertions, 13 deletions

diff --git a/module/zfs/dsl_dataset.c b/module/zfs/dsl_dataset.c
index ca0c4aae8..9a9e24684 100644
--- a/module/zfs/dsl_dataset.c
+++ b/module/zfs/dsl_dataset.c
@@ -1703,6 +1703,7 @@ dsl_dataset_handoff_check(dsl_dataset_t *ds, void *owner, dmu_tx_t *tx)
 typedef struct dsl_dataset_rollback_arg {
 	const char *ddra_fsname;
 	void *ddra_owner;
+	nvlist_t *ddra_result;
 } dsl_dataset_rollback_arg_t;
 
 static int
@@ -1774,9 +1775,13 @@ dsl_dataset_rollback_sync(void *arg, dmu_tx_t *tx)
 	dsl_pool_t *dp = dmu_tx_pool(tx);
 	dsl_dataset_t *ds, *clone;
 	uint64_t cloneobj;
+	char namebuf[ZFS_MAXNAMELEN];
 
 	VERIFY0(dsl_dataset_hold(dp, ddra->ddra_fsname, FTAG, &ds));
 
+	dsl_dataset_name(ds->ds_prev, namebuf);
+	fnvlist_add_string(ddra->ddra_result, "target", namebuf);
+
 	cloneobj = dsl_dataset_create_sync(ds->ds_dir, "%rollback",
 	    ds->ds_prev, DS_CREATE_FLAG_NODIRTY, kcred, tx);
 
@@ -1792,8 +1797,11 @@ dsl_dataset_rollback_sync(void *arg, dmu_tx_t *tx)
 }
 
 /*
- * If owner != NULL:
+ * Rolls back the given filesystem or volume to the most recent snapshot.
+ * The name of the most recent snapshot will be returned under key "target"
+ * in the result nvlist.
  *
+ * If owner != NULL:
  * - The existing dataset MUST be owned by the specified owner at entry
  * - Upon return, dataset will still be held by the same owner, whether we
  *   succeed or not.
@@ -1802,15 +1810,16 @@ dsl_dataset_rollback_sync(void *arg, dmu_tx_t *tx)
  * notes above zfs_suspend_fs() for further details.
  */
 int
-dsl_dataset_rollback(const char *fsname, void *owner)
+dsl_dataset_rollback(const char *fsname, void *owner, nvlist_t *result)
 {
 	dsl_dataset_rollback_arg_t ddra;
 
 	ddra.ddra_fsname = fsname;
 	ddra.ddra_owner = owner;
+	ddra.ddra_result = result;
 
 	return (dsl_sync_task(fsname, dsl_dataset_rollback_check,
-	    dsl_dataset_rollback_sync, (void *)&ddra, 1));
+	    dsl_dataset_rollback_sync, &ddra, 1));
 }
 
 struct promotenode {
diff --git a/module/zfs/zfs_ioctl.c b/module/zfs/zfs_ioctl.c
index 4ad885ac6..8eb879d32 100644
--- a/module/zfs/zfs_ioctl.c
+++ b/module/zfs/zfs_ioctl.c
@@ -3488,29 +3488,32 @@ zfs_ioc_destroy(zfs_cmd_t *zc)
 }
 
 /*
- * inputs:
- * zc_name	name of dataset to rollback (to most recent snapshot)
+ * fsname is name of dataset to rollback (to most recent snapshot)
  *
- * outputs:	none
+ * innvl is not used.
+ *
+ * outnvl: "target" -> name of most recent snapshot
+ * }
  */
+/* ARGSUSED */
 static int
-zfs_ioc_rollback(zfs_cmd_t *zc)
+zfs_ioc_rollback(const char *fsname, nvlist_t *args, nvlist_t *outnvl)
 {
 	zfs_sb_t *zsb;
 	int error;
 
-	if (get_zfs_sb(zc->zc_name, &zsb) == 0) {
+	if (get_zfs_sb(fsname, &zsb) == 0) {
 		error = zfs_suspend_fs(zsb);
 		if (error == 0) {
 			int resume_err;
 
-			error = dsl_dataset_rollback(zc->zc_name, zsb);
-			resume_err = zfs_resume_fs(zsb, zc->zc_name);
+			error = dsl_dataset_rollback(fsname, zsb, outnvl);
+			resume_err = zfs_resume_fs(zsb, fsname);
 			error = error ? error : resume_err;
 		}
 		deactivate_super(zsb->z_sb);
 	} else {
-		error = dsl_dataset_rollback(zc->zc_name, NULL);
+		error = dsl_dataset_rollback(fsname, NULL, outnvl);
 	}
 	return (error);
 }
@@ -5273,6 +5276,10 @@ zfs_ioctl_init(void)
 	    zfs_ioc_get_holds, zfs_secpolicy_read, DATASET_NAME,
 	    POOL_CHECK_SUSPENDED, B_FALSE, B_FALSE);
 
+	zfs_ioctl_register("rollback", ZFS_IOC_ROLLBACK,
+	    zfs_ioc_rollback, zfs_secpolicy_rollback, DATASET_NAME,
+	    POOL_CHECK_SUSPENDED | POOL_CHECK_READONLY, B_FALSE, B_TRUE);
+
 	/* IOCTLS that use the legacy function signature */
 
 	zfs_ioctl_register_legacy(ZFS_IOC_POOL_FREEZE, zfs_ioc_pool_freeze,
@@ -5384,8 +5391,6 @@ zfs_ioctl_init(void)
 	    zfs_secpolicy_none);
 	zfs_ioctl_register_dataset_modify(ZFS_IOC_DESTROY, zfs_ioc_destroy,
 	    zfs_secpolicy_destroy);
-	zfs_ioctl_register_dataset_modify(ZFS_IOC_ROLLBACK, zfs_ioc_rollback,
-	    zfs_secpolicy_rollback);
 	zfs_ioctl_register_dataset_modify(ZFS_IOC_RENAME, zfs_ioc_rename,
 	    zfs_secpolicy_rename);
 	zfs_ioctl_register_dataset_modify(ZFS_IOC_RECV, zfs_ioc_recv,