Some additional send stream validity checking

Check in the DMU whether an object record in a send stream being
received contains an unsupported dnode slot count, and return an
error if it does. Failure to catch an unsupported dnode slot count
would result in a panic when the SPA attempts to increment the
reference count for the large_dnode feature and the pool has the
feature disabled. This is not normally an issue for a well-formed
send stream which would have the DMU_BACKUP_FEATURE_LARGE_DNODE flag
set if it contains large dnodes, so it will be rejected as
unsupported if the required feature is disabled. This change adds a
missing object record field validation.

Add missing stream feature flag checks in
dmu_recv_resume_begin_check().

Consolidate repetitive comment blocks in dmu_recv_begin_check().

Update zstreamdump to print the dnode slot count (dn_slots) for an
object record when running in verbose mode.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Giuseppe Di Natale <dinatale2@llnl.gov>
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Signed-off-by: Ned Bass <bass6@llnl.gov>
Closes #6396

cmd/zstreamdump/zstreamdump.c

@@ -422,12 +422,14 @@ main(int argc, char *argv[])
 			}
 			if (verbose) {
 				(void) printf("OBJECT object = %llu type = %u "
-				    "bonustype = %u blksz = %u bonuslen = %u\n",
+				    "bonustype = %u blksz = %u bonuslen = %u "
+				    "dn_slots = %u\n",
 				    (u_longlong_t)drro->drr_object,
 				    drro->drr_type,
 				    drro->drr_bonustype,
 				    drro->drr_blksz,
-				    drro->drr_bonuslen);
+				    drro->drr_bonuslen,
+				    drro->drr_dn_slots);
 			}
 			if (drro->drr_bonuslen > 0) {
 				(void) ssread(buf,

module/zfs/dmu_send.c

@@ -1428,17 +1428,12 @@ dmu_recv_begin_check(void *arg, dmu_tx_t *tx)
 	/*
 	 * The receiving code doesn't know how to translate large blocks
 	 * to smaller ones, so the pool must have the LARGE_BLOCKS
-	 * feature enabled if the stream has LARGE_BLOCKS.
+	 * feature enabled if the stream has LARGE_BLOCKS. Same with
+	 * large dnodes.
 	 */
 	if ((featureflags & DMU_BACKUP_FEATURE_LARGE_BLOCKS) &&
 	    !spa_feature_is_enabled(dp->dp_spa, SPA_FEATURE_LARGE_BLOCKS))
 		return (SET_ERROR(ENOTSUP));
-
-	/*
-	 * The receiving code doesn't know how to translate large dnodes
-	 * to smaller ones, so the pool must have the LARGE_DNODE
-	 * feature enabled if the stream has LARGE_DNODE.
-	 */
 	if ((featureflags & DMU_BACKUP_FEATURE_LARGE_DNODE) &&
 	    !spa_feature_is_enabled(dp->dp_spa, SPA_FEATURE_LARGE_DNODE))
 		return (SET_ERROR(ENOTSUP));
@@ -1678,6 +1673,19 @@ dmu_recv_resume_begin_check(void *arg, dmu_tx_t *tx)
 	    !spa_feature_is_enabled(dp->dp_spa, SPA_FEATURE_LZ4_COMPRESS))
 		return (SET_ERROR(ENOTSUP));
 
+	/*
+	 * The receiving code doesn't know how to translate large blocks
+	 * to smaller ones, so the pool must have the LARGE_BLOCKS
+	 * feature enabled if the stream has LARGE_BLOCKS. Same with
+	 * large dnodes.
+	 */
+	if ((featureflags & DMU_BACKUP_FEATURE_LARGE_BLOCKS) &&
+	    !spa_feature_is_enabled(dp->dp_spa, SPA_FEATURE_LARGE_BLOCKS))
+		return (SET_ERROR(ENOTSUP));
+	if ((featureflags & DMU_BACKUP_FEATURE_LARGE_DNODE) &&
+	    !spa_feature_is_enabled(dp->dp_spa, SPA_FEATURE_LARGE_DNODE))
+		return (SET_ERROR(ENOTSUP));
+
 	(void) snprintf(recvname, sizeof (recvname), "%s/%s",
 	    tofs, recv_clone_name);
 
@@ -2121,7 +2129,9 @@ receive_object(struct receive_writer_arg *rwa, struct drr_object *drro,
 	    drro->drr_blksz < SPA_MINBLOCKSIZE ||
 	    drro->drr_blksz > spa_maxblocksize(dmu_objset_spa(rwa->os)) ||
 	    drro->drr_bonuslen >
-	    DN_BONUS_SIZE(spa_maxdnodesize(dmu_objset_spa(rwa->os)))) {
+	    DN_BONUS_SIZE(spa_maxdnodesize(dmu_objset_spa(rwa->os))) ||
+	    drro->drr_dn_slots >
+	    (spa_maxdnodesize(dmu_objset_spa(rwa->os)) >> DNODE_SHIFT))  {
 		return (SET_ERROR(EINVAL));
 	}