Avoid panic with recordsize > 128k, raw sending and no large_blocks

The current codebase does not support raw sending buffers with block
size > 128kB when large_blocks is not active. Instead of panicking
due to a NULL pointer dereference in dmu_dump_write() print out an
error message.

Signed-off-by: George Amanakis <gamanakis@gmail.com>

lib/libzfs/libzfs_sendrecv.c

@@ -852,6 +852,11 @@ dump_ioctl(zfs_handle_t *zhp, const char *fromsnap, uint64_t fromsnap_obj,
 		case EINVAL:
 			zfs_error_aux(hdl, "%s", strerror(errno));
 			return (zfs_error(hdl, EZFS_BADBACKUP, errbuf));
+		case ENOTSUP:
+			zfs_error_aux(hdl, dgettext(TEXT_DOMAIN,
+			    "large blocks detected but large_blocks feature "
+			    "is inactive; raw send unsupported"));
+			return (zfs_error(hdl, EZFS_NOTSUP, errbuf));
 
 		default:
 			return (zfs_standard_error(hdl, errno, errbuf));
@@ -2567,6 +2572,11 @@ zfs_send_one(zfs_handle_t *zhp, const char *from, int fd, sendflags_t *flags,
 		case EROFS:
 			zfs_error_aux(hdl, "%s", strerror(errno));
 			return (zfs_error(hdl, EZFS_BADBACKUP, errbuf));
+		case ENOTSUP:
+			zfs_error_aux(hdl, dgettext(TEXT_DOMAIN,
+			    "large blocks detected but large_blocks feature "
+			    "is inactive; raw send unsupported"));
+			return (zfs_error(hdl, EZFS_NOTSUP, errbuf));
 
 		default:
 			return (zfs_standard_error(hdl, errno, errbuf));

module/zfs/dmu_send.c

@@ -488,6 +488,7 @@ dmu_dump_write(dmu_send_cookie_t *dscp, dmu_object_type_t type, uint64_t object,
 
 	/* only set the compression fields if the buf is compressed or raw */
 	if (raw || lsize != psize) {
+		ASSERT(bp != NULL);
 		ASSERT(raw || dscp->dsc_featureflags &
 		    DMU_BACKUP_FEATURE_COMPRESSED);
 		ASSERT(!BP_IS_EMBEDDED(bp));
@@ -1010,6 +1011,9 @@ do_dump(dmu_send_cookie_t *dscp, struct send_range *range)
 		if (srdp->datablksz > SPA_OLD_MAXBLOCKSIZE &&
 		    !(dscp->dsc_featureflags &
 		    DMU_BACKUP_FEATURE_LARGE_BLOCKS)) {
+			if (dscp->dsc_featureflags & DMU_BACKUP_FEATURE_RAW)
+				return (SET_ERROR(ENOTSUP));
+
 			while (srdp->datablksz > 0 && err == 0) {
 				int n = MIN(srdp->datablksz,
 				    SPA_OLD_MAXBLOCKSIZE);