linux-kernel - [PATCH v2 6/8] selftests: ublk: forbid multiple data copy modes

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Message-ID: <20251212051658.1618543-7-csander@purestorage.com>
Date: Thu, 11 Dec 2025 22:16:56 -0700
From: Caleb Sander Mateos <csander@...estorage.com>
To: Ming Lei <ming.lei@...hat.com>,
	Shuah Khan <shuah@...nel.org>
Cc: linux-block@...r.kernel.org,
	linux-kselftest@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Caleb Sander Mateos <csander@...estorage.com>
Subject: [PATCH v2 6/8] 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@...estorage.com>
---
 tools/testing/selftests/ublk/kublk.c           | 11 ++++++++++-
 tools/testing/selftests/ublk/test_stress_05.sh | 10 +++++-----
 2 files changed, 15 insertions(+), 6 deletions(-)

diff --git a/tools/testing/selftests/ublk/kublk.c b/tools/testing/selftests/ublk/kublk.c
index f8fa102a627f..4dd02cb083ba 100644
--- a/tools/testing/selftests/ublk/kublk.c
+++ b/tools/testing/selftests/ublk/kublk.c
@@ -1611,11 +1611,11 @@ int main(int argc, char *argv[])
 			break;
 		case 'd':
 			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);
 			if (value)
 				ctx.flags |= UBLK_F_USER_RECOVERY;
@@ -1684,10 +1684,19 @@ int main(int argc, char *argv[])
 				"F_AUTO_BUF_REG nor F_SUPPORT_ZERO_COPY is enabled\n",
 					__func__);
 		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++];
 	}
 
diff --git a/tools/testing/selftests/ublk/test_stress_05.sh b/tools/testing/selftests/ublk/test_stress_05.sh
index 274295061042..68a194144302 100755
--- a/tools/testing/selftests/ublk/test_stress_05.sh
+++ b/tools/testing/selftests/ublk/test_stress_05.sh
@@ -56,21 +56,21 @@ for reissue in $(seq 0 1); do
 	wait
 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
 
 if _have_feature "PER_IO_DAEMON"; then
-- 
2.45.2