selftests: ublk: forbid multiple data copy modes

The kublk mock ublk server allows multiple data copy mode arguments to
be passed on the command line (--zero_copy, --get_data, and --auto_zc).
The ublk device will be created with all the requested feature flags,
however kublk will only use one of the modes to interact with request
data (arbitrarily preferring auto_zc over zero_copy over get_data). To
clarify the intent of the test, don't allow multiple data copy modes to
be specified. --zero_copy and --auto_zc are allowed together for
--auto_zc_fallback, which uses both copy modes.
Don't set UBLK_F_USER_COPY for zero_copy, as it's a separate feature.
Fix the test cases in test_stress_05 passing --get_data along with
--zero_copy or --auto_zc.

Signed-off-by: Caleb Sander Mateos <csander@purestorage.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Author: calebsander

tools/testing/selftests/ublk/kublk.c

@@ -1613,7 +1613,7 @@ int main(int argc, char *argv[])
 			ctx.queue_depth = strtol(optarg, NULL, 10);
 			break;
 		case 'z':
-			ctx.flags |= UBLK_F_SUPPORT_ZERO_COPY | UBLK_F_USER_COPY;
+			ctx.flags |= UBLK_F_SUPPORT_ZERO_COPY;
 			break;
 		case 'r':
 			value = strtol(optarg, NULL, 10);
@@ -1686,6 +1686,15 @@ int main(int argc, char *argv[])
 		return -EINVAL;
 	}
 
+	if (!!(ctx.flags & UBLK_F_NEED_GET_DATA) +
+	    !!(ctx.flags & UBLK_F_USER_COPY) +
+	    (ctx.flags & UBLK_F_SUPPORT_ZERO_COPY && !ctx.auto_zc_fallback) +
+	    (ctx.flags & UBLK_F_AUTO_BUF_REG && !ctx.auto_zc_fallback) +
+	    ctx.auto_zc_fallback > 1) {
+		fprintf(stderr, "too many data copy modes specified\n");
+		return -EINVAL;
+	}
+
 	i = optind;
 	while (i < argc && ctx.nr_files < MAX_BACK_FILES) {
 		ctx.files[ctx.nr_files++] = argv[i++];

tools/testing/selftests/ublk/test_stress_05.sh

@@ -58,17 +58,17 @@ done
 
 if _have_feature "ZERO_COPY"; then
 	for reissue in $(seq 0 1); do
-		ublk_io_and_remove 8G -t null -q 4 -g -z -r 1 -i "$reissue" &
-		ublk_io_and_remove 256M -t loop -q 4 -g -z -r 1 -i "$reissue" "${UBLK_BACKFILES[1]}" &
+		ublk_io_and_remove 8G -t null -q 4 -z -r 1 -i "$reissue" &
+		ublk_io_and_remove 256M -t loop -q 4 -z -r 1 -i "$reissue" "${UBLK_BACKFILES[1]}" &
 		wait
 	done
 fi
 
 if _have_feature "AUTO_BUF_REG"; then
 	for reissue in $(seq 0 1); do
-		ublk_io_and_remove 8G -t null -q 4 -g --auto_zc -r 1 -i "$reissue" &
-		ublk_io_and_remove 256M -t loop -q 4 -g --auto_zc -r 1 -i "$reissue" "${UBLK_BACKFILES[1]}" &
-		ublk_io_and_remove 8G -t null -q 4 -g -z --auto_zc --auto_zc_fallback -r 1 -i "$reissue" &
+		ublk_io_and_remove 8G -t null -q 4 --auto_zc -r 1 -i "$reissue" &
+		ublk_io_and_remove 256M -t loop -q 4 --auto_zc -r 1 -i "$reissue" "${UBLK_BACKFILES[1]}" &
+		ublk_io_and_remove 8G -t null -q 4 -z --auto_zc --auto_zc_fallback -r 1 -i "$reissue" &
 		wait
 	done
 fi