cmd/zfs receive: allow dry-run (-n) to check property args

zfs recv -n does not report some errors it could.  The code to bail 
out of the receive if in dry-run mode came a little early, skipping 
validation of cmdprops (recv -x and -o) among others.  Move the
check down to enable these additional checks.

Reviewed-by: Brian Behlendorf <[email protected]>
Signed-off-by: InsanePrawn <[email protected]>
Closes #11862

Author: InsanePrawn

lib/libzfs/libzfs_sendrecv.c

@@ -4586,26 +4586,6 @@ zfs_receive_one(libzfs_handle_t *hdl, int infd, const char *tosnap,
 		(void) fflush(stdout);
 	}
 
-	if (flags->dryrun) {
-		void *buf = zfs_alloc(hdl, SPA_MAXBLOCKSIZE);
-
-		/*
-		 * We have read the DRR_BEGIN record, but we have
-		 * not yet read the payload. For non-dryrun sends
-		 * this will be done by the kernel, so we must
-		 * emulate that here, before attempting to read
-		 * more records.
-		 */
-		err = recv_read(hdl, infd, buf, drr->drr_payloadlen,
-		    flags->byteswap, NULL);
-		free(buf);
-		if (err != 0)
-			goto out;
-
-		err = recv_skip(hdl, infd, flags->byteswap);
-		goto out;
-	}
-
 	/*
 	 * If this is the top-level dataset, record it so we can use it
 	 * for recursive operations later.
@@ -4650,6 +4630,26 @@ zfs_receive_one(libzfs_handle_t *hdl, int infd, const char *tosnap,
 		    zfs_prop_to_name(ZFS_PROP_ENCRYPTION), ZIO_CRYPT_OFF);
 	}
 
+	if (flags->dryrun) {
+		void *buf = zfs_alloc(hdl, SPA_MAXBLOCKSIZE);
+
+		/*
+		 * We have read the DRR_BEGIN record, but we have
+		 * not yet read the payload. For non-dryrun sends
+		 * this will be done by the kernel, so we must
+		 * emulate that here, before attempting to read
+		 * more records.
+		 */
+		err = recv_read(hdl, infd, buf, drr->drr_payloadlen,
+		    flags->byteswap, NULL);
+		free(buf);
+		if (err != 0)
+			goto out;
+
+		err = recv_skip(hdl, infd, flags->byteswap);
+		goto out;
+	}
+
 	err = ioctl_err = lzc_receive_with_cmdprops(destsnap, rcvprops,
 	    oxprops, wkeydata, wkeylen, origin, flags->force, flags->resumable,
 	    raw, infd, drr_noswap, -1, &read_bytes, &errflags,