selftests: ublk: add stripe target

Add ublk stripe target which can take 1~4 underlying backing files
or block device, with stripe size 4k ~ 512K.

Add two basic tests(write verify & mkfs/mount/umount) over ublk/stripe.

This target is helpful to cover multiple IOs aiming at same
fixed/registered IO kernel buffer.

It is also capable of verifying vectored registered (kernel)buffers
in future for zero copy, so far it isn't supported yet.

Todo: support vectored registered kernel buffer for ublk/zc.

Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20250322093218.431419-9-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Author: Ming Lei

tools/testing/selftests/ublk/Makefile

@@ -11,6 +11,8 @@ TEST_PROGS += test_loop_01.sh
 TEST_PROGS += test_loop_02.sh
 TEST_PROGS += test_loop_03.sh
 TEST_PROGS += test_loop_04.sh
+TEST_PROGS += test_stripe_01.sh
+TEST_PROGS += test_stripe_02.sh
 
 TEST_PROGS += test_stress_01.sh
 TEST_PROGS += test_stress_02.sh
@@ -19,7 +21,7 @@ TEST_GEN_PROGS_EXTENDED = kublk
 
 include ../lib.mk
 
-$(TEST_GEN_PROGS_EXTENDED): kublk.c null.c file_backed.c common.c
+$(TEST_GEN_PROGS_EXTENDED): kublk.c null.c file_backed.c common.c stripe.c
 
 check:
 	shellcheck -x -f gcc *.sh

tools/testing/selftests/ublk/kublk.c

@@ -9,6 +9,7 @@ unsigned int ublk_dbg_mask = UBLK_LOG;
 static const struct ublk_tgt_ops *tgt_ops_list[] = {
 	&null_tgt_ops,
 	&loop_tgt_ops,
+	&stripe_tgt_ops,
 };
 
 static const struct ublk_tgt_ops *ublk_find_tgt(const char *name)
@@ -1060,8 +1061,9 @@ int main(int argc, char *argv[])
 		{ "depth",		1,	NULL, 'd' },
 		{ "debug_mask",		1,	NULL,  0  },
 		{ "quiet",		0,	NULL,  0  },
-		{ "zero_copy",          1,      NULL, 'z' },
+		{ "zero_copy",          0,      NULL, 'z' },
 		{ "foreground",		0,	NULL,  0  },
+		{ "chunk_size", 	1,	NULL,  0  },
 		{ 0, 0, 0, 0 }
 	};
 	int option_idx, opt;
@@ -1071,6 +1073,7 @@ int main(int argc, char *argv[])
 		.nr_hw_queues	=	2,
 		.dev_id		=	-1,
 		.tgt_type	=	"unknown",
+		.chunk_size 	= 	65536, 	/* def chunk size is 64K */
 	};
 	int ret = -EINVAL, i;
 
@@ -1107,6 +1110,8 @@ int main(int argc, char *argv[])
 				ublk_dbg_mask = 0;
 			if (!strcmp(longopts[option_idx].name, "foreground"))
 				ctx.fg = 1;
+			if (!strcmp(longopts[option_idx].name, "chunk_size"))
+				ctx.chunk_size = strtol(optarg, NULL, 10);
 		}
 	}
 

tools/testing/selftests/ublk/kublk.h

@@ -19,6 +19,7 @@
 #include <sys/inotify.h>
 #include <sys/wait.h>
 #include <sys/eventfd.h>
+#include <sys/uio.h>
 #include <liburing.h>
 #include <linux/ublk_cmd.h>
 #include "ublk_dep.h"
@@ -66,6 +67,9 @@ struct dev_ctx {
 	unsigned int	all:1;
 	unsigned int	fg:1;
 
+	/* stripe */
+	unsigned int    chunk_size;
+
 	int _evtfd;
 };
 
@@ -352,7 +356,15 @@ static inline int ublk_queue_use_zc(const struct ublk_queue *q)
 
 extern const struct ublk_tgt_ops null_tgt_ops;
 extern const struct ublk_tgt_ops loop_tgt_ops;
+extern const struct ublk_tgt_ops stripe_tgt_ops;
 
 void backing_file_tgt_deinit(struct ublk_dev *dev);
 int backing_file_tgt_init(struct ublk_dev *dev);
+
+static inline unsigned int ilog2(unsigned int x)
+{
+	if (x == 0)
+		return 0;
+	return (sizeof(x) * 8 - 1) - __builtin_clz(x);
+}
 #endif