1 files changed, 40 insertions, 12 deletions

diff --git a/module/zfs/zfs_ioctl.c b/module/zfs/zfs_ioctl.c
index f5137d09e..7a890cf3f 100644
--- a/module/zfs/zfs_ioctl.c
+++ b/module/zfs/zfs_ioctl.c
@@ -5245,7 +5245,8 @@ zfs_ioc_send_new(const char *snapname, nvlist_t *innvl, nvlist_t *outnvl)
  * of bytes that will be written to the fd supplied to zfs_ioc_send_new().
  *
  * innvl: {
- *     (optional) "fromsnap" -> full snap name to send an incremental from
+ *     (optional) "from" -> full snap or bookmark name to send an incremental
+ *                          from
  * }
  *
  * outnvl: {
@@ -5256,7 +5257,6 @@ static int
 zfs_ioc_send_space(const char *snapname, nvlist_t *innvl, nvlist_t *outnvl)
 {
 	dsl_pool_t *dp;
-	dsl_dataset_t *fromsnap = NULL;
 	dsl_dataset_t *tosnap;
 	int error;
 	char *fromname;
@@ -5272,27 +5272,55 @@ zfs_ioc_send_space(const char *snapname, nvlist_t *innvl, nvlist_t *outnvl)
 		return (error);
 	}
 
-	error = nvlist_lookup_string(innvl, "fromsnap", &fromname);
+	error = nvlist_lookup_string(innvl, "from", &fromname);
 	if (error == 0) {
-		error = dsl_dataset_hold(dp, fromname, FTAG, &fromsnap);
-		if (error != 0) {
-			dsl_dataset_rele(tosnap, FTAG);
-			dsl_pool_rele(dp, FTAG);
-			return (error);
+		if (strchr(fromname, '@') != NULL) {
+			/*
+			 * If from is a snapshot, hold it and use the more
+			 * efficient dmu_send_estimate to estimate send space
+			 * size using deadlists.
+			 */
+			dsl_dataset_t *fromsnap;
+			error = dsl_dataset_hold(dp, fromname, FTAG, &fromsnap);
+			if (error != 0)
+				goto out;
+			error = dmu_send_estimate(tosnap, fromsnap, &space);
+			dsl_dataset_rele(fromsnap, FTAG);
+		} else if (strchr(fromname, '#') != NULL) {
+			/*
+			 * If from is a bookmark, fetch the creation TXG of the
+			 * snapshot it was created from and use that to find
+			 * blocks that were born after it.
+			 */
+			zfs_bookmark_phys_t frombm;
+
+			error = dsl_bookmark_lookup(dp, fromname, tosnap,
+			    &frombm);
+			if (error != 0)
+				goto out;
+			error = dmu_send_estimate_from_txg(tosnap,
+			    frombm.zbm_creation_txg, &space);
+		} else {
+			/*
+			 * from is not properly formatted as a snapshot or
+			 * bookmark
+			 */
+			error = SET_ERROR(EINVAL);
+			goto out;
 		}
+	} else {
+		// If estimating the size of a full send, use dmu_send_estimate
+		error = dmu_send_estimate(tosnap, NULL, &space);
 	}
 
-	error = dmu_send_estimate(tosnap, fromsnap, &space);
 	fnvlist_add_uint64(outnvl, "space", space);
 
-	if (fromsnap != NULL)
-		dsl_dataset_rele(fromsnap, FTAG);
+out:
 	dsl_dataset_rele(tosnap, FTAG);
 	dsl_pool_rele(dp, FTAG);
 	return (error);
 }
 
-
 static zfs_ioc_vec_t zfs_ioc_vec[ZFS_IOC_LAST - ZFS_IOC_FIRST];
 
 static void