[PATCH v4 0/5] fsstress,fsx: add io_uring test and do some fix

[PATCH v4 0/5] fsstress,fsx: add io_uring test and do some fix

[Zorro Lang]

This patchset tries to add new IO_URING test into fsstress [1/5] and fsx
[4/5 and 5/5]. And then do some changes and bug fix by the way [2/5 and 3/5].

fsstress and fsx are important tools in xfstests to do filesystem I/Os test,
lots of test cases use it. So add IO_URING operation into fsstress and fsx
will help to cover IO_URING test from fs side.

I'm not an IO_URING expert, so cc io-uring@ list, please feel free to
tell me if you find something wrong or have any suggestions to improve
the test.

V2 did below changes:
1) 1/4 change the definition of URING_ENTRIES to 1
2) 2/4 change the difinition of AIO_ENTRIES to 1, undo an unrelated changed line
3) 4/4 turn to use io_uring_prep_readv/io_uring_prep_writev, due to old
       liburing(0.2-2) doesn't support io_uring_prep_read/io_uring_prep_write.

V3 changed io_uring_submit(&ring) to io_uring_submit_and_wait(&ring, 1). I'm
not sure if this's the real mean of Jens Axboe's review point, please check.
  https://marc.info/?l=fstests&m=159811932808057&w=2

V4 did below changes:
1) 1/5 change the "goto" related code of do_uring_rw()
2) 3/5 similar change as above
3) 4/5 new patch, separated from original 4/4 patch
3) 5/5 change #elif to #else
4) 5/5 change __uring_rw to uring_rw.
5) 5/5 change the loop logic in uring_rw().

Thanks for Brian's review points.

Thanks,
Zorro

[PATCH v4 1/5] fsstress: add IO_URING read and write operations

[Zorro Lang]

IO_URING is a new feature of curent linux kernel, add basic IO_URING
read/write into fsstess to cover this kind of IO testing.

Signed-off-by: Zorro Lang <zlang@redhat.com>
---
 README                 |   4 +-
 configure.ac           |   1 +
 include/builddefs.in   |   1 +
 ltp/Makefile           |   5 ++
 ltp/fsstress.c         | 139 ++++++++++++++++++++++++++++++++++++++++-
 m4/Makefile            |   1 +
 m4/package_liburing.m4 |   4 ++
 7 files changed, 152 insertions(+), 3 deletions(-)
 create mode 100644 m4/package_liburing.m4

diff --git a/README b/README
index d0e23fcd..ae0f804d 100644
--- a/README
+++ b/README
@@ -8,13 +8,13 @@ _______________________
 	sudo apt-get install xfslibs-dev uuid-dev libtool-bin \
 	e2fsprogs automake gcc libuuid1 quota attr libattr1-dev make \
 	libacl1-dev libaio-dev xfsprogs libgdbm-dev gawk fio dbench \
-	uuid-runtime python sqlite3
+	uuid-runtime python sqlite3 liburing-dev
   For Fedora, RHEL, or CentOS:
 	yum install acl attr automake bc dbench dump e2fsprogs fio \
 	gawk gcc indent libtool lvm2 make psmisc quota sed \
 	xfsdump xfsprogs \
 	libacl-devel libattr-devel libaio-devel libuuid-devel \
-	xfsprogs-devel btrfs-progs-devel python sqlite
+	xfsprogs-devel btrfs-progs-devel python sqlite liburing-devel
 	(Older distributions may require xfsprogs-qa-devel as well.)
 	(Note that for RHEL and CentOS, you may need the EPEL repo.)
 - run make
diff --git a/configure.ac b/configure.ac
index 4bb50b32..8922c47e 100644
--- a/configure.ac
+++ b/configure.ac
@@ -61,6 +61,7 @@ AC_PACKAGE_NEED_ACLINIT_LIBACL
 
 AC_PACKAGE_WANT_GDBM
 AC_PACKAGE_WANT_AIO
+AC_PACKAGE_WANT_URING
 AC_PACKAGE_WANT_DMAPI
 AC_PACKAGE_WANT_LINUX_FIEMAP_H
 AC_PACKAGE_WANT_FALLOCATE
diff --git a/include/builddefs.in b/include/builddefs.in
index e7894b1a..fded3230 100644
--- a/include/builddefs.in
+++ b/include/builddefs.in
@@ -61,6 +61,7 @@ RPM_VERSION     = @rpm_version@
 ENABLE_SHARED = @enable_shared@
 HAVE_DB = @have_db@
 HAVE_AIO = @have_aio@
+HAVE_URING = @have_uring@
 HAVE_FALLOCATE = @have_fallocate@
 HAVE_OPEN_BY_HANDLE_AT = @have_open_by_handle_at@
 HAVE_DMAPI = @have_dmapi@
diff --git a/ltp/Makefile b/ltp/Makefile
index ebf40336..198d930f 100644
--- a/ltp/Makefile
+++ b/ltp/Makefile
@@ -24,6 +24,11 @@ LCFLAGS += -DAIO
 LLDLIBS += -laio -lpthread
 endif
 
+ifeq ($(HAVE_URING), true)
+LCFLAGS += -DURING
+LLDLIBS += -luring
+endif
+
 ifeq ($(HAVE_LIBBTRFSUTIL), true)
 LLDLIBS += -lbtrfsutil
 endif
diff --git a/ltp/fsstress.c b/ltp/fsstress.c
index 709fdeec..2c584ef0 100644
--- a/ltp/fsstress.c
+++ b/ltp/fsstress.c
@@ -30,6 +30,11 @@
 #include <libaio.h>
 io_context_t	io_ctx;
 #endif
+#ifdef URING
+#include <liburing.h>
+#define URING_ENTRIES	1
+struct io_uring	ring;
+#endif
 #include <sys/syscall.h>
 #include <sys/xattr.h>
 
@@ -139,6 +144,8 @@ typedef enum {
 	OP_TRUNCATE,
 	OP_UNLINK,
 	OP_UNRESVSP,
+	OP_URING_READ,
+	OP_URING_WRITE,
 	OP_WRITE,
 	OP_WRITEV,
 	OP_LAST
@@ -267,6 +274,8 @@ void	sync_f(int, long);
 void	truncate_f(int, long);
 void	unlink_f(int, long);
 void	unresvsp_f(int, long);
+void	uring_read_f(int, long);
+void	uring_write_f(int, long);
 void	write_f(int, long);
 void	writev_f(int, long);
 char	*xattr_flag_to_string(int);
@@ -335,6 +344,8 @@ opdesc_t	ops[] = {
 	{ OP_TRUNCATE, "truncate", truncate_f, 2, 1 },
 	{ OP_UNLINK, "unlink", unlink_f, 1, 1 },
 	{ OP_UNRESVSP, "unresvsp", unresvsp_f, 1, 1 },
+	{ OP_URING_READ, "uring_read", uring_read_f, 1, 0 },
+	{ OP_URING_WRITE, "uring_write", uring_write_f, 1, 1 },
 	{ OP_WRITE, "write", write_f, 4, 1 },
 	{ OP_WRITEV, "writev", writev_f, 4, 1 },
 }, *ops_end;
@@ -692,6 +703,12 @@ int main(int argc, char **argv)
 				fprintf(stderr, "io_setup failed");
 				exit(1);
 			}
+#endif
+#ifdef URING
+			if (io_uring_queue_init(URING_ENTRIES, &ring, 0)) {
+				fprintf(stderr, "io_uring_queue_init failed\n");
+				exit(1);
+			}
 #endif
 			for (i = 0; !loops || (i < loops); i++)
 				doproc();
@@ -701,7 +718,9 @@ int main(int argc, char **argv)
 				return 1;
 			}
 #endif
-
+#ifdef URING
+			io_uring_queue_exit(&ring);
+#endif
 			cleanup_flist();
 			free(freq_table);
 			return 0;
@@ -2170,6 +2189,108 @@ do_aio_rw(int opno, long r, int flags)
 }
 #endif
 
+#ifdef URING
+void
+do_uring_rw(int opno, long r, int flags)
+{
+	char		*buf = NULL;
+	int		e;
+	pathname_t	f;
+	int		fd = -1;
+	size_t		len;
+	int64_t		lr;
+	off64_t		off;
+	struct stat64	stb;
+	int		v;
+	char		st[1024];
+	struct io_uring_sqe	*sqe;
+	struct io_uring_cqe	*cqe;
+	struct iovec	iovec;
+	int		iswrite = (flags & (O_WRONLY | O_RDWR)) ? 1 : 0;
+
+	init_pathname(&f);
+	if (!get_fname(FT_REGFILE, r, &f, NULL, NULL, &v)) {
+		if (v)
+			printf("%d/%d: do_uring_rw - no filename\n", procid, opno);
+		goto uring_out;
+	}
+	fd = open_path(&f, flags);
+	e = fd < 0 ? errno : 0;
+	check_cwd();
+	if (fd < 0) {
+		if (v)
+			printf("%d/%d: do_uring_rw - open %s failed %d\n",
+			       procid, opno, f.path, e);
+		goto uring_out;
+	}
+	if (fstat64(fd, &stb) < 0) {
+		if (v)
+			printf("%d/%d: do_uring_rw - fstat64 %s failed %d\n",
+			       procid, opno, f.path, errno);
+		goto uring_out;
+	}
+	inode_info(st, sizeof(st), &stb, v);
+	if (!iswrite && stb.st_size == 0) {
+		if (v)
+			printf("%d/%d: do_uring_rw - %s%s zero size\n", procid, opno,
+			       f.path, st);
+		goto uring_out;
+	}
+	sqe = io_uring_get_sqe(&ring);
+	if (!sqe) {
+		if (v)
+			printf("%d/%d: do_uring_rw - io_uring_get_sqe failed\n",
+			       procid, opno);
+		goto uring_out;
+	}
+	lr = ((int64_t)random() << 32) + random();
+	len = (random() % FILELEN_MAX) + 1;
+	buf = malloc(len);
+	if (!buf) {
+		if (v)
+			printf("%d/%d: do_uring_rw - malloc failed\n",
+			       procid, opno);
+		goto uring_out;
+	}
+	iovec.iov_base = buf;
+	iovec.iov_len = len;
+	if (iswrite) {
+		off = (off64_t)(lr % MIN(stb.st_size + (1024 * 1024), MAXFSIZE));
+		off %= maxfsize;
+		memset(buf, nameseq & 0xff, len);
+		io_uring_prep_writev(sqe, fd, &iovec, 1, off);
+	} else {
+		off = (off64_t)(lr % stb.st_size);
+		io_uring_prep_readv(sqe, fd, &iovec, 1, off);
+	}
+
+	if ((e = io_uring_submit_and_wait(&ring, 1)) != 1) {
+		if (v)
+			printf("%d/%d: %s - io_uring_submit failed %d\n", procid, opno,
+			       iswrite ? "uring_write" : "uring_read", e);
+		goto uring_out;
+	}
+	if ((e = io_uring_wait_cqe(&ring, &cqe)) < 0) {
+		if (v)
+			printf("%d/%d: %s - io_uring_wait_cqe failed %d\n", procid, opno,
+			       iswrite ? "uring_write" : "uring_read", e);
+		goto uring_out;
+	}
+	if (v)
+		printf("%d/%d: %s %s%s [%lld, %d(res=%d)] %d\n",
+		       procid, opno, iswrite ? "uring_write" : "uring_read",
+		       f.path, st, (long long)off, (int)len, cqe->res, e);
+	io_uring_cqe_seen(&ring, cqe);
+
+ uring_out:
+	if (buf)
+		free(buf);
+	if (fd > 0)
+		close(fd);
+	free_pathname(&f);
+}
+#endif
+
 void
 aread_f(int opno, long r)
 {
@@ -5044,6 +5165,22 @@ unresvsp_f(int opno, long r)
 	close(fd);
 }
 
+void
+uring_read_f(int opno, long r)
+{
+#ifdef URING
+	do_uring_rw(opno, r, O_RDONLY);
+#endif
+}
+
+void
+uring_write_f(int opno, long r)
+{
+#ifdef URING
+	do_uring_rw(opno, r, O_WRONLY);
+#endif
+}
+
 void
 write_f(int opno, long r)
 {
diff --git a/m4/Makefile b/m4/Makefile
index 7fbff822..0352534d 100644
--- a/m4/Makefile
+++ b/m4/Makefile
@@ -14,6 +14,7 @@ LSRCFILES = \
 	package_dmapidev.m4 \
 	package_globals.m4 \
 	package_libcdev.m4 \
+	package_liburing.m4 \
 	package_ncurses.m4 \
 	package_pthread.m4 \
 	package_ssldev.m4 \
diff --git a/m4/package_liburing.m4 b/m4/package_liburing.m4
new file mode 100644
index 00000000..c92cc02a
--- /dev/null
+++ b/m4/package_liburing.m4
@@ -0,0 +1,4 @@
+AC_DEFUN([AC_PACKAGE_WANT_URING],
+  [ AC_CHECK_HEADERS(liburing.h, [ have_uring=true ], [ have_uring=false ])
+    AC_SUBST(have_uring)
+  ])
-- 
2.20.1

Re: [PATCH v4 1/5] fsstress: add IO_URING read and write operations

[Brian Foster]

On Mon, Sep 07, 2020 at 01:55:09AM +0800, Zorro Lang wrote:
> IO_URING is a new feature of curent linux kernel, add basic IO_URING
> read/write into fsstess to cover this kind of IO testing.
> 
> Signed-off-by: Zorro Lang <zlang@redhat.com>
> ---
>  README                 |   4 +-
>  configure.ac           |   1 +
>  include/builddefs.in   |   1 +
>  ltp/Makefile           |   5 ++
>  ltp/fsstress.c         | 139 ++++++++++++++++++++++++++++++++++++++++-
>  m4/Makefile            |   1 +
>  m4/package_liburing.m4 |   4 ++
>  7 files changed, 152 insertions(+), 3 deletions(-)
>  create mode 100644 m4/package_liburing.m4
> 
...
> diff --git a/ltp/fsstress.c b/ltp/fsstress.c
> index 709fdeec..2c584ef0 100644
> --- a/ltp/fsstress.c
> +++ b/ltp/fsstress.c
...
> @@ -2170,6 +2189,108 @@ do_aio_rw(int opno, long r, int flags)
>  }
>  #endif
>  
> +#ifdef URING
> +void
> +do_uring_rw(int opno, long r, int flags)
> +{
...
> +
> + uring_out:
> +	if (buf)
> +		free(buf);
> +	if (fd > 0)

Nit: I'd replace this with (fd != -1), but otherwise:

Reviewed-by: Brian Foster <bfoster@redhat.com>

> +		close(fd);
> +	free_pathname(&f);
> +}
> +#endif
> +
>  void
>  aread_f(int opno, long r)
>  {
> @@ -5044,6 +5165,22 @@ unresvsp_f(int opno, long r)
>  	close(fd);
>  }
>  
> +void
> +uring_read_f(int opno, long r)
> +{
> +#ifdef URING
> +	do_uring_rw(opno, r, O_RDONLY);
> +#endif
> +}
> +
> +void
> +uring_write_f(int opno, long r)
> +{
> +#ifdef URING
> +	do_uring_rw(opno, r, O_WRONLY);
> +#endif
> +}
> +
>  void
>  write_f(int opno, long r)
>  {
> diff --git a/m4/Makefile b/m4/Makefile
> index 7fbff822..0352534d 100644
> --- a/m4/Makefile
> +++ b/m4/Makefile
> @@ -14,6 +14,7 @@ LSRCFILES = \
>  	package_dmapidev.m4 \
>  	package_globals.m4 \
>  	package_libcdev.m4 \
> +	package_liburing.m4 \
>  	package_ncurses.m4 \
>  	package_pthread.m4 \
>  	package_ssldev.m4 \
> diff --git a/m4/package_liburing.m4 b/m4/package_liburing.m4
> new file mode 100644
> index 00000000..c92cc02a
> --- /dev/null
> +++ b/m4/package_liburing.m4
> @@ -0,0 +1,4 @@
> +AC_DEFUN([AC_PACKAGE_WANT_URING],
> +  [ AC_CHECK_HEADERS(liburing.h, [ have_uring=true ], [ have_uring=false ])
> +    AC_SUBST(have_uring)
> +  ])
> -- 
> 2.20.1
> 

[PATCH v4 2/5] fsstress: reduce the number of events when io_setup

[Zorro Lang]

The original number(128) of aio events for io_setup too big. When try
to run lots of fsstress processes(e.g. -p 1000) always hit io_setup
EAGAIN error, due to the nr_events exceeds the limit of available
events. Due to each fsstress process only does once libaio read/write
operation each time. So reduce the aio events number to 1, to make more
fsstress processes can do AIO test.

Signed-off-by: Zorro Lang <zlang@redhat.com>
---
 ltp/fsstress.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/ltp/fsstress.c b/ltp/fsstress.c
index 2c584ef0..b4a51376 100644
--- a/ltp/fsstress.c
+++ b/ltp/fsstress.c
@@ -28,6 +28,7 @@
 #endif
 #ifdef AIO
 #include <libaio.h>
+#define AIO_ENTRIES	1
 io_context_t	io_ctx;
 #endif
 #ifdef URING
@@ -699,8 +700,8 @@ int main(int argc, char **argv)
 			}
 			procid = i;
 #ifdef AIO
-			if (io_setup(128, &io_ctx) != 0) {
-				fprintf(stderr, "io_setup failed");
+			if (io_setup(AIO_ENTRIES, &io_ctx) != 0) {
+				fprintf(stderr, "io_setup failed\n");
 				exit(1);
 			}
 #endif
-- 
2.20.1

Re: [PATCH v4 2/5] fsstress: reduce the number of events when io_setup

[Brian Foster]

On Mon, Sep 07, 2020 at 01:55:10AM +0800, Zorro Lang wrote:
> The original number(128) of aio events for io_setup too big. When try
> to run lots of fsstress processes(e.g. -p 1000) always hit io_setup
> EAGAIN error, due to the nr_events exceeds the limit of available
> events. Due to each fsstress process only does once libaio read/write
> operation each time. So reduce the aio events number to 1, to make more
> fsstress processes can do AIO test.
> 
> Signed-off-by: Zorro Lang <zlang@redhat.com>
> ---

Same as the previous version..?

Reviewed-by: Brian Foster <bfoster@redhat.com>

>  ltp/fsstress.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/ltp/fsstress.c b/ltp/fsstress.c
> index 2c584ef0..b4a51376 100644
> --- a/ltp/fsstress.c
> +++ b/ltp/fsstress.c
> @@ -28,6 +28,7 @@
>  #endif
>  #ifdef AIO
>  #include <libaio.h>
> +#define AIO_ENTRIES	1
>  io_context_t	io_ctx;
>  #endif
>  #ifdef URING
> @@ -699,8 +700,8 @@ int main(int argc, char **argv)
>  			}
>  			procid = i;
>  #ifdef AIO
> -			if (io_setup(128, &io_ctx) != 0) {
> -				fprintf(stderr, "io_setup failed");
> +			if (io_setup(AIO_ENTRIES, &io_ctx) != 0) {
> +				fprintf(stderr, "io_setup failed\n");
>  				exit(1);
>  			}
>  #endif
> -- 
> 2.20.1
> 

[PATCH v4 3/5] fsstress: fix memory leak in do_aio_rw

[Zorro Lang]

If io_submit or io_getevents fails, the do_aio_rw() won't free the
"buf" and cause memory leak.

Signed-off-by: Zorro Lang <zlang@redhat.com>
---
 ltp/fsstress.c | 39 +++++++++++++++++++--------------------
 1 file changed, 19 insertions(+), 20 deletions(-)

diff --git a/ltp/fsstress.c b/ltp/fsstress.c
index b4a51376..c0e587a3 100644
--- a/ltp/fsstress.c
+++ b/ltp/fsstress.c
@@ -2078,11 +2078,11 @@ void
 do_aio_rw(int opno, long r, int flags)
 {
 	int64_t		align;
-	char		*buf;
+	char		*buf = NULL;
 	struct dioattr	diob;
 	int		e;
 	pathname_t	f;
-	int		fd;
+	int		fd = -1;
 	size_t		len;
 	int64_t		lr;
 	off64_t		off;
@@ -2099,8 +2099,7 @@ do_aio_rw(int opno, long r, int flags)
 	if (!get_fname(FT_REGFILE, r, &f, NULL, NULL, &v)) {
 		if (v)
 			printf("%d/%d: do_aio_rw - no filename\n", procid, opno);
-		free_pathname(&f);
-		return;
+		goto aio_out;
 	}
 	fd = open_path(&f, flags|O_DIRECT);
 	e = fd < 0 ? errno : 0;
@@ -2109,25 +2108,20 @@ do_aio_rw(int opno, long r, int flags)
 		if (v)
 			printf("%d/%d: do_aio_rw - open %s failed %d\n",
 			       procid, opno, f.path, e);
-		free_pathname(&f);
-		return;
+		goto aio_out;
 	}
 	if (fstat64(fd, &stb) < 0) {
 		if (v)
 			printf("%d/%d: do_aio_rw - fstat64 %s failed %d\n",
 			       procid, opno, f.path, errno);
-		free_pathname(&f);
-		close(fd);
-		return;
+		goto aio_out;
 	}
 	inode_info(st, sizeof(st), &stb, v);
 	if (!iswrite && stb.st_size == 0) {
 		if (v)
 			printf("%d/%d: do_aio_rw - %s%s zero size\n", procid, opno,
 			       f.path, st);
-		free_pathname(&f);
-		close(fd);
-		return;
+		goto aio_out;
 	}
 	if (xfsctl(f.path, fd, XFS_IOC_DIOINFO, &diob) < 0) {
 		if (v)
@@ -2150,6 +2144,12 @@ do_aio_rw(int opno, long r, int flags)
 	else if (len > diob.d_maxiosz)
 		len = diob.d_maxiosz;
 	buf = memalign(diob.d_mem, len);
+	if (!buf) {
+		if (v)
+			printf("%d/%d: do_aio_rw - memalign failed\n",
+			       procid, opno);
+		goto aio_out;
+	}
 
 	if (iswrite) {
 		off = (off64_t)(lr % MIN(stb.st_size + (1024 * 1024), MAXFSIZE));
@@ -2166,27 +2166,26 @@ do_aio_rw(int opno, long r, int flags)
 		if (v)
 			printf("%d/%d: %s - io_submit failed %d\n",
 			       procid, opno, iswrite ? "awrite" : "aread", e);
-		free_pathname(&f);
-		close(fd);
-		return;
+		goto aio_out;
 	}
 	if ((e = io_getevents(io_ctx, 1, 1, &event, NULL)) != 1) {
 		if (v)
 			printf("%d/%d: %s - io_getevents failed %d\n",
 			       procid, opno, iswrite ? "awrite" : "aread", e);
-		free_pathname(&f);
-		close(fd);
-		return;
+		goto aio_out;
 	}
 
 	e = event.res != len ? event.res2 : 0;
-	free(buf);
 	if (v)
 		printf("%d/%d: %s %s%s [%lld,%d] %d\n",
 		       procid, opno, iswrite ? "awrite" : "aread",
 		       f.path, st, (long long)off, (int)len, e);
+ aio_out:
+	if (buf)
+		free(buf);
+	if (fd > 0)
+		close(fd);
 	free_pathname(&f);
-	close(fd);
 }
 #endif
 
-- 
2.20.1

Re: [PATCH v4 3/5] fsstress: fix memory leak in do_aio_rw

[Brian Foster]

On Mon, Sep 07, 2020 at 01:55:11AM +0800, Zorro Lang wrote:
> If io_submit or io_getevents fails, the do_aio_rw() won't free the
> "buf" and cause memory leak.
> 
> Signed-off-by: Zorro Lang <zlang@redhat.com>
> ---
>  ltp/fsstress.c | 39 +++++++++++++++++++--------------------
>  1 file changed, 19 insertions(+), 20 deletions(-)
> 
> diff --git a/ltp/fsstress.c b/ltp/fsstress.c
> index b4a51376..c0e587a3 100644
> --- a/ltp/fsstress.c
> +++ b/ltp/fsstress.c
...
> @@ -2166,27 +2166,26 @@ do_aio_rw(int opno, long r, int flags)
>  		if (v)
>  			printf("%d/%d: %s - io_submit failed %d\n",
>  			       procid, opno, iswrite ? "awrite" : "aread", e);
> -		free_pathname(&f);
> -		close(fd);
> -		return;
> +		goto aio_out;
>  	}
>  	if ((e = io_getevents(io_ctx, 1, 1, &event, NULL)) != 1) {
>  		if (v)
>  			printf("%d/%d: %s - io_getevents failed %d\n",
>  			       procid, opno, iswrite ? "awrite" : "aread", e);
> -		free_pathname(&f);
> -		close(fd);
> -		return;
> +		goto aio_out;
>  	}
>  
>  	e = event.res != len ? event.res2 : 0;
> -	free(buf);
>  	if (v)
>  		printf("%d/%d: %s %s%s [%lld,%d] %d\n",
>  		       procid, opno, iswrite ? "awrite" : "aread",
>  		       f.path, st, (long long)off, (int)len, e);
> + aio_out:
> +	if (buf)
> +		free(buf);
> +	if (fd > 0)
> +		close(fd);

Same nit here as patch 1. Otherwise LGTM:

Reviewed-by: Brian Foster <bfoster@redhat.com>

>  	free_pathname(&f);
> -	close(fd);
>  }
>  #endif
>  
> -- 
> 2.20.1
> 

[PATCH v4 4/5] fsx: introduce fsx_rw to combine aio_rw with general read and write

[Zorro Lang]

The fsx contains different read and write operations, especially the
AIO and general IO read/write. The fsx chooses one kind of read/write
from AIO and general IO to run. To make the logic clear, use a common
fsx_rw() function to swith between these two kinds of read/write.

Signed-off-by: Zorro Lang <zlang@redhat.com>
---
 ltp/fsx.c | 32 +++++++++++++++++---------------
 1 file changed, 17 insertions(+), 15 deletions(-)

diff --git a/ltp/fsx.c b/ltp/fsx.c
index 7c76655a..92f506ba 100644
--- a/ltp/fsx.c
+++ b/ltp/fsx.c
@@ -181,16 +181,11 @@ int	mark_nr = 0;
 int page_size;
 int page_mask;
 int mmap_mask;
-#ifdef AIO
-int aio_rw(int rw, int fd, char *buf, unsigned len, unsigned offset);
+int fsx_rw(int rw, int fd, char *buf, unsigned len, unsigned offset);
 #define READ 0
 #define WRITE 1
-#define fsxread(a,b,c,d)	aio_rw(READ, a,b,c,d)
-#define fsxwrite(a,b,c,d)	aio_rw(WRITE, a,b,c,d)
-#else
-#define fsxread(a,b,c,d)	read(a,b,c)
-#define fsxwrite(a,b,c,d)	write(a,b,c)
-#endif
+#define fsxread(a,b,c,d)	fsx_rw(READ, a,b,c,d)
+#define fsxwrite(a,b,c,d)	fsx_rw(WRITE, a,b,c,d)
 
 const char *replayops = NULL;
 const char *recordops = NULL;
@@ -2347,7 +2342,8 @@ getnum(char *s, char **e)
 io_context_t	io_ctx;
 struct iocb 	iocb;
 
-int aio_setup()
+int
+aio_setup()
 {
 	int ret;
 	ret = io_queue_init(QSZ, &io_ctx);
@@ -2360,7 +2356,7 @@ int aio_setup()
 }
 
 int
-__aio_rw(int rw, int fd, char *buf, unsigned len, unsigned offset)
+aio_rw(int rw, int fd, char *buf, unsigned len, unsigned offset)
 {
 	struct io_event event;
 	static struct timespec ts;
@@ -2425,13 +2421,21 @@ out_error:
 	errno = -ret;
 	return -1;
 }
+#else
+aio_rw(int rw, int fd, char *buf, unsigned len, unsigned offset)
+{
+	fprintf(stderr, "io_rw: need AIO support!\n");
+	exit(111);
+}
+#endif
 
-int aio_rw(int rw, int fd, char *buf, unsigned len, unsigned offset)
+int
+fsx_rw(int rw, int fd, char *buf, unsigned len, unsigned offset)
 {
 	int ret;
 
 	if (aio) {
-		ret = __aio_rw(rw, fd, buf, len, offset);
+		ret = aio_rw(rw, fd, buf, len, offset);
 	} else {
 		if (rw == READ)
 			ret = read(fd, buf, len);
@@ -2441,8 +2445,6 @@ int aio_rw(int rw, int fd, char *buf, unsigned len, unsigned offset)
 	return ret;
 }
 
-#endif
-
 #define test_fallocate(mode) __test_fallocate(mode, #mode)
 
 int
@@ -2602,7 +2604,7 @@ main(int argc, char **argv)
 			do_fsync = 1;
 			break;
 		case 'A':
-		        aio = 1;
+			aio = 1;
 			break;
 		case 'D':
 			debugstart = getnum(optarg, &endp);
-- 
2.20.1

Re: [PATCH v4 4/5] fsx: introduce fsx_rw to combine aio_rw with general read and write

[Brian Foster]

On Mon, Sep 07, 2020 at 01:55:12AM +0800, Zorro Lang wrote:
> The fsx contains different read and write operations, especially the
> AIO and general IO read/write. The fsx chooses one kind of read/write
> from AIO and general IO to run. To make the logic clear, use a common
> fsx_rw() function to swith between these two kinds of read/write.
> 
> Signed-off-by: Zorro Lang <zlang@redhat.com>
> ---

Reviewed-by: Brian Foster <bfoster@redhat.com>

>  ltp/fsx.c | 32 +++++++++++++++++---------------
>  1 file changed, 17 insertions(+), 15 deletions(-)
> 
> diff --git a/ltp/fsx.c b/ltp/fsx.c
> index 7c76655a..92f506ba 100644
> --- a/ltp/fsx.c
> +++ b/ltp/fsx.c
> @@ -181,16 +181,11 @@ int	mark_nr = 0;
>  int page_size;
>  int page_mask;
>  int mmap_mask;
> -#ifdef AIO
> -int aio_rw(int rw, int fd, char *buf, unsigned len, unsigned offset);
> +int fsx_rw(int rw, int fd, char *buf, unsigned len, unsigned offset);
>  #define READ 0
>  #define WRITE 1
> -#define fsxread(a,b,c,d)	aio_rw(READ, a,b,c,d)
> -#define fsxwrite(a,b,c,d)	aio_rw(WRITE, a,b,c,d)
> -#else
> -#define fsxread(a,b,c,d)	read(a,b,c)
> -#define fsxwrite(a,b,c,d)	write(a,b,c)
> -#endif
> +#define fsxread(a,b,c,d)	fsx_rw(READ, a,b,c,d)
> +#define fsxwrite(a,b,c,d)	fsx_rw(WRITE, a,b,c,d)
>  
>  const char *replayops = NULL;
>  const char *recordops = NULL;
> @@ -2347,7 +2342,8 @@ getnum(char *s, char **e)
>  io_context_t	io_ctx;
>  struct iocb 	iocb;
>  
> -int aio_setup()
> +int
> +aio_setup()
>  {
>  	int ret;
>  	ret = io_queue_init(QSZ, &io_ctx);
> @@ -2360,7 +2356,7 @@ int aio_setup()
>  }
>  
>  int
> -__aio_rw(int rw, int fd, char *buf, unsigned len, unsigned offset)
> +aio_rw(int rw, int fd, char *buf, unsigned len, unsigned offset)
>  {
>  	struct io_event event;
>  	static struct timespec ts;
> @@ -2425,13 +2421,21 @@ out_error:
>  	errno = -ret;
>  	return -1;
>  }
> +#else
> +aio_rw(int rw, int fd, char *buf, unsigned len, unsigned offset)
> +{
> +	fprintf(stderr, "io_rw: need AIO support!\n");
> +	exit(111);
> +}
> +#endif
>  
> -int aio_rw(int rw, int fd, char *buf, unsigned len, unsigned offset)
> +int
> +fsx_rw(int rw, int fd, char *buf, unsigned len, unsigned offset)
>  {
>  	int ret;
>  
>  	if (aio) {
> -		ret = __aio_rw(rw, fd, buf, len, offset);
> +		ret = aio_rw(rw, fd, buf, len, offset);
>  	} else {
>  		if (rw == READ)
>  			ret = read(fd, buf, len);
> @@ -2441,8 +2445,6 @@ int aio_rw(int rw, int fd, char *buf, unsigned len, unsigned offset)
>  	return ret;
>  }
>  
> -#endif
> -
>  #define test_fallocate(mode) __test_fallocate(mode, #mode)
>  
>  int
> @@ -2602,7 +2604,7 @@ main(int argc, char **argv)
>  			do_fsync = 1;
>  			break;
>  		case 'A':
> -		        aio = 1;
> +			aio = 1;
>  			break;
>  		case 'D':
>  			debugstart = getnum(optarg, &endp);
> -- 
> 2.20.1
> 

[PATCH v4 5/5] fsx: add IO_URING test

[Zorro Lang]

New IO_URING test for fsx, use -U option to enable IO_URING test.

Signed-off-by: Zorro Lang <zlang@redhat.com>
---
 ltp/fsx.c | 134 ++++++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 131 insertions(+), 3 deletions(-)

diff --git a/ltp/fsx.c b/ltp/fsx.c
index 92f506ba..e7f23d15 100644
--- a/ltp/fsx.c
+++ b/ltp/fsx.c
@@ -34,6 +34,9 @@
 #ifdef AIO
 #include <libaio.h>
 #endif
+#ifdef URING
+#include <liburing.h>
+#endif
 #include <sys/syscall.h>
 
 #ifndef MAP_FILE
@@ -176,6 +179,7 @@ int	integrity = 0;			/* -i flag */
 int	fsxgoodfd = 0;
 int	o_direct;			/* -Z */
 int	aio = 0;
+int	uring = 0;
 int	mark_nr = 0;
 
 int page_size;
@@ -2237,7 +2241,7 @@ void
 usage(void)
 {
 	fprintf(stdout, "usage: %s",
-		"fsx [-dknqxABEFJLOWZ] [-b opnum] [-c Prob] [-g filldata] [-i logdev] [-j logid] [-l flen] [-m start:end] [-o oplen] [-p progressinterval] [-r readbdy] [-s style] [-t truncbdy] [-w writebdy] [-D startingop] [-N numops] [-P dirpath] [-S seed] fname\n\
+		"fsx [-dknqxBEFJLOWZ][-A|-U] [-b opnum] [-c Prob] [-g filldata] [-i logdev] [-j logid] [-l flen] [-m start:end] [-o oplen] [-p progressinterval] [-r readbdy] [-s style] [-t truncbdy] [-w writebdy] [-D startingop] [-N numops] [-P dirpath] [-S seed] fname\n\
 	-b opnum: beginning operation number (default 1)\n\
 	-c P: 1 in P chance of file close+open at each op (default infinity)\n\
 	-d: debug output for all operations\n\
@@ -2260,8 +2264,11 @@ usage(void)
 	-y synchronize changes to a file\n"
 
 #ifdef AIO
-"	-A: Use the AIO system calls\n"
+"	-A: Use the AIO system calls, -A excludes -U\n"
 #endif
+#ifdef URING
+"	-U: Use the IO_URING system calls, -U excludes -A\n"
+ #endif
 "	-D startingop: debug output starting at specified operation\n"
 #ifdef HAVE_LINUX_FALLOC_H
 "	-F: Do not use fallocate (preallocation) calls\n"
@@ -2429,6 +2436,113 @@ aio_rw(int rw, int fd, char *buf, unsigned len, unsigned offset)
 }
 #endif
 
+#ifdef URING
+
+struct io_uring ring;
+#define URING_ENTRIES	1024
+
+int
+uring_setup()
+{
+	int ret;
+
+	ret = io_uring_queue_init(URING_ENTRIES, &ring, 0);
+	if (ret != 0) {
+		fprintf(stderr, "uring_setup: io_uring_queue_init failed: %s\n",
+				strerror(ret));
+		return -1;
+	}
+	return 0;
+}
+
+int
+uring_rw(int rw, int fd, char *buf, unsigned len, unsigned offset)
+{
+	struct io_uring_sqe     *sqe;
+	struct io_uring_cqe     *cqe;
+	struct iovec            iovec;
+	int ret;
+	int res, res2 = 0;
+	char *p = buf;
+	unsigned l = len;
+	unsigned o = offset;
+
+	/*
+	 * Due to io_uring tries non-blocking IOs (especially read), that
+	 * always cause 'normal' short reading. To avoid this short read
+	 * fail, try to loop read/write (escpecilly read) data.
+	 */
+	while (l > 0) {
+		sqe = io_uring_get_sqe(&ring);
+		if (!sqe) {
+			fprintf(stderr, "uring_rw: io_uring_get_sqe failed: %s\n",
+					strerror(errno));
+			return -1;
+		}
+
+		iovec.iov_base = p;
+		iovec.iov_len = l;
+		if (rw == READ) {
+			io_uring_prep_readv(sqe, fd, &iovec, 1, o);
+		} else {
+			io_uring_prep_writev(sqe, fd, &iovec, 1, o);
+		}
+
+		ret = io_uring_submit_and_wait(&ring, 1);
+		if (ret != 1) {
+			fprintf(stderr, "errcode=%d\n", -ret);
+			fprintf(stderr, "uring %s: io_uring_submit failed: %s\n",
+					rw == READ ? "read":"write", strerror(-ret));
+			goto uring_error;
+		}
+
+		ret = io_uring_wait_cqe(&ring, &cqe);
+		if (ret != 0) {
+			fprintf(stderr, "errcode=%d\n", -ret);
+			fprintf(stderr, "uring %s: io_uring_wait_cqe failed: %s\n",
+					rw == READ ? "read":"write", strerror(-ret));
+			goto uring_error;
+		}
+
+		res = cqe->res;
+		io_uring_cqe_seen(&ring, cqe);
+
+		if (res > 0) {
+			o += res;
+			l -= res;
+			p += res;
+			res2 += res;
+		} else if (res < 0) {
+			ret = res;
+			fprintf(stderr, "errcode=%d\n", -ret);
+			fprintf(stderr, "uring %s: io_uring failed: %s\n",
+					rw == READ ? "read":"write", strerror(-ret));
+			goto uring_error;
+		} else {
+			fprintf(stderr, "uring %s bad io length: %d instead of %u\n",
+					rw == READ ? "read":"write", res2, len);
+			break;
+		}
+	}
+	return res2;
+
+ uring_error:
+	/*
+	 * The caller expects error return in traditional libc
+	 * convention, i.e. -1 and the errno set to error.
+	 */
+	errno = -ret;
+	return -1;
+}
+#else
+int
+uring_rw(int rw, int fd, char *buf, unsigned len, unsigned offset)
+{
+	fprintf(stderr, "io_rw: need IO_URING support!\n");
+	exit(111);
+}
+#endif
+
 int
 fsx_rw(int rw, int fd, char *buf, unsigned len, unsigned offset)
 {
@@ -2436,6 +2550,8 @@ fsx_rw(int rw, int fd, char *buf, unsigned len, unsigned offset)
 
 	if (aio) {
 		ret = aio_rw(rw, fd, buf, len, offset);
+	} else if (uring) {
+		ret = uring_rw(rw, fd, buf, len, offset);
 	} else {
 		if (rw == READ)
 			ret = read(fd, buf, len);
@@ -2498,7 +2614,7 @@ main(int argc, char **argv)
 	setvbuf(stdout, (char *)0, _IOLBF, 0); /* line buffered stdout */
 
 	while ((ch = getopt_long(argc, argv,
-				 "b:c:dfg:i:j:kl:m:no:p:qr:s:t:w:xyABD:EFJKHzCILN:OP:RS:WXZ",
+				 "b:c:dfg:i:j:kl:m:no:p:qr:s:t:w:xyABD:EFJKHzCILN:OP:RS:UWXZ",
 				 longopts, NULL)) != EOF)
 		switch (ch) {
 		case 'b':
@@ -2606,6 +2722,9 @@ main(int argc, char **argv)
 		case 'A':
 			aio = 1;
 			break;
+		case 'U':
+			uring = 1;
+			break;
 		case 'D':
 			debugstart = getnum(optarg, &endp);
 			if (debugstart < 1)
@@ -2696,6 +2815,11 @@ main(int argc, char **argv)
 	if (argc != 1)
 		usage();
 
+	if (aio && uring) {
+		fprintf(stderr, "-A and -U shouldn't be used together\n");
+		usage();
+	}
+
 	if (integrity && !dirpath) {
 		fprintf(stderr, "option -i <logdev> requires -P <dirpath>\n");
 		usage();
@@ -2786,6 +2910,10 @@ main(int argc, char **argv)
 	if (aio) 
 		aio_setup();
 #endif
+#ifdef URING
+	if (uring)
+		uring_setup();
+#endif
 
 	if (!(o_flags & O_TRUNC)) {
 		off_t ret;
-- 
2.20.1

Re: [PATCH v4 5/5] fsx: add IO_URING test

[Brian Foster]

On Mon, Sep 07, 2020 at 01:55:13AM +0800, Zorro Lang wrote:
> New IO_URING test for fsx, use -U option to enable IO_URING test.
> 
> Signed-off-by: Zorro Lang <zlang@redhat.com>
> ---

Just a couple nits...

>  ltp/fsx.c | 134 ++++++++++++++++++++++++++++++++++++++++++++++++++++--
>  1 file changed, 131 insertions(+), 3 deletions(-)
> 
> diff --git a/ltp/fsx.c b/ltp/fsx.c
> index 92f506ba..e7f23d15 100644
> --- a/ltp/fsx.c
> +++ b/ltp/fsx.c
...
> @@ -2429,6 +2436,113 @@ aio_rw(int rw, int fd, char *buf, unsigned len, unsigned offset)
...
> +int
> +uring_rw(int rw, int fd, char *buf, unsigned len, unsigned offset)
> +{
> +	struct io_uring_sqe     *sqe;
> +	struct io_uring_cqe     *cqe;
> +	struct iovec            iovec;
> +	int ret;
> +	int res, res2 = 0;
> +	char *p = buf;
> +	unsigned l = len;
> +	unsigned o = offset;

It looks a little odd that some variable names are aligned with tabs
while others use a single space.. I'm not sure we care one way or
another for xfstests, but perhaps use one approach or the other..?

> +
> +	/*
> +	 * Due to io_uring tries non-blocking IOs (especially read), that
> +	 * always cause 'normal' short reading. To avoid this short read
> +	 * fail, try to loop read/write (escpecilly read) data.
> +	 */
> +	while (l > 0) {
> +		sqe = io_uring_get_sqe(&ring);
> +		if (!sqe) {
> +			fprintf(stderr, "uring_rw: io_uring_get_sqe failed: %s\n",
> +					strerror(errno));
> +			return -1;
> +		}
> +
> +		iovec.iov_base = p;
> +		iovec.iov_len = l;
> +		if (rw == READ) {
> +			io_uring_prep_readv(sqe, fd, &iovec, 1, o);
> +		} else {
> +			io_uring_prep_writev(sqe, fd, &iovec, 1, o);
> +		}
> +
> +		ret = io_uring_submit_and_wait(&ring, 1);
> +		if (ret != 1) {
> +			fprintf(stderr, "errcode=%d\n", -ret);
> +			fprintf(stderr, "uring %s: io_uring_submit failed: %s\n",
> +					rw == READ ? "read":"write", strerror(-ret));
> +			goto uring_error;
> +		}
> +
> +		ret = io_uring_wait_cqe(&ring, &cqe);
> +		if (ret != 0) {
> +			fprintf(stderr, "errcode=%d\n", -ret);
> +			fprintf(stderr, "uring %s: io_uring_wait_cqe failed: %s\n",
> +					rw == READ ? "read":"write", strerror(-ret));
> +			goto uring_error;
> +		}
> +
> +		res = cqe->res;

If we assign ret here instead of res, it looks like we could optimize
away res entirely.

Nits and my limited experience with uring aside, the patch otherwise
LGTM. Are you planning any new tests to take advantage of this,
particularly since it looks like -A (-U disabled) is the default? In any
event, a quick test run of fsstress/fsx doesn't seem to explode:

Reviewed-by: Brian Foster <bfoster@redhat.com>

> +		io_uring_cqe_seen(&ring, cqe);
> +
> +		if (res > 0) {
> +			o += res;
> +			l -= res;
> +			p += res;
> +			res2 += res;
> +		} else if (res < 0) {
> +			ret = res;
> +			fprintf(stderr, "errcode=%d\n", -ret);
> +			fprintf(stderr, "uring %s: io_uring failed: %s\n",
> +					rw == READ ? "read":"write", strerror(-ret));
> +			goto uring_error;
> +		} else {
> +			fprintf(stderr, "uring %s bad io length: %d instead of %u\n",
> +					rw == READ ? "read":"write", res2, len);
> +			break;
> +		}
> +	}
> +	return res2;
> +
> + uring_error:
> +	/*
> +	 * The caller expects error return in traditional libc
> +	 * convention, i.e. -1 and the errno set to error.
> +	 */
> +	errno = -ret;
> +	return -1;
> +}
> +#else
> +int
> +uring_rw(int rw, int fd, char *buf, unsigned len, unsigned offset)
> +{
> +	fprintf(stderr, "io_rw: need IO_URING support!\n");
> +	exit(111);
> +}
> +#endif
> +
>  int
>  fsx_rw(int rw, int fd, char *buf, unsigned len, unsigned offset)
>  {
> @@ -2436,6 +2550,8 @@ fsx_rw(int rw, int fd, char *buf, unsigned len, unsigned offset)
>  
>  	if (aio) {
>  		ret = aio_rw(rw, fd, buf, len, offset);
> +	} else if (uring) {
> +		ret = uring_rw(rw, fd, buf, len, offset);
>  	} else {
>  		if (rw == READ)
>  			ret = read(fd, buf, len);
> @@ -2498,7 +2614,7 @@ main(int argc, char **argv)
>  	setvbuf(stdout, (char *)0, _IOLBF, 0); /* line buffered stdout */
>  
>  	while ((ch = getopt_long(argc, argv,
> -				 "b:c:dfg:i:j:kl:m:no:p:qr:s:t:w:xyABD:EFJKHzCILN:OP:RS:WXZ",
> +				 "b:c:dfg:i:j:kl:m:no:p:qr:s:t:w:xyABD:EFJKHzCILN:OP:RS:UWXZ",
>  				 longopts, NULL)) != EOF)
>  		switch (ch) {
>  		case 'b':
> @@ -2606,6 +2722,9 @@ main(int argc, char **argv)
>  		case 'A':
>  			aio = 1;
>  			break;
> +		case 'U':
> +			uring = 1;
> +			break;
>  		case 'D':
>  			debugstart = getnum(optarg, &endp);
>  			if (debugstart < 1)
> @@ -2696,6 +2815,11 @@ main(int argc, char **argv)
>  	if (argc != 1)
>  		usage();
>  
> +	if (aio && uring) {
> +		fprintf(stderr, "-A and -U shouldn't be used together\n");
> +		usage();
> +	}
> +
>  	if (integrity && !dirpath) {
>  		fprintf(stderr, "option -i <logdev> requires -P <dirpath>\n");
>  		usage();
> @@ -2786,6 +2910,10 @@ main(int argc, char **argv)
>  	if (aio) 
>  		aio_setup();
>  #endif
> +#ifdef URING
> +	if (uring)
> +		uring_setup();
> +#endif
>  
>  	if (!(o_flags & O_TRUNC)) {
>  		off_t ret;
> -- 
> 2.20.1
> 

Re: [PATCH v4 5/5] fsx: add IO_URING test

[Zorro Lang]

On Tue, Sep 08, 2020 at 02:36:25PM -0400, Brian Foster wrote:
> On Mon, Sep 07, 2020 at 01:55:13AM +0800, Zorro Lang wrote:
> > New IO_URING test for fsx, use -U option to enable IO_URING test.
> > 
> > Signed-off-by: Zorro Lang <zlang@redhat.com>
> > ---
> 
> Just a couple nits...
> 
> >  ltp/fsx.c | 134 ++++++++++++++++++++++++++++++++++++++++++++++++++++--
> >  1 file changed, 131 insertions(+), 3 deletions(-)
> > 
> > diff --git a/ltp/fsx.c b/ltp/fsx.c
> > index 92f506ba..e7f23d15 100644
> > --- a/ltp/fsx.c
> > +++ b/ltp/fsx.c
> ...
> > @@ -2429,6 +2436,113 @@ aio_rw(int rw, int fd, char *buf, unsigned len, unsigned offset)
> ...
> > +int
> > +uring_rw(int rw, int fd, char *buf, unsigned len, unsigned offset)
> > +{
> > +	struct io_uring_sqe     *sqe;
> > +	struct io_uring_cqe     *cqe;
> > +	struct iovec            iovec;
> > +	int ret;
> > +	int res, res2 = 0;
> > +	char *p = buf;
> > +	unsigned l = len;
> > +	unsigned o = offset;
> 
> It looks a little odd that some variable names are aligned with tabs
> while others use a single space.. I'm not sure we care one way or
> another for xfstests, but perhaps use one approach or the other..?
> 
> > +
> > +	/*
> > +	 * Due to io_uring tries non-blocking IOs (especially read), that
> > +	 * always cause 'normal' short reading. To avoid this short read
> > +	 * fail, try to loop read/write (escpecilly read) data.
> > +	 */
> > +	while (l > 0) {
> > +		sqe = io_uring_get_sqe(&ring);
> > +		if (!sqe) {
> > +			fprintf(stderr, "uring_rw: io_uring_get_sqe failed: %s\n",
> > +					strerror(errno));
> > +			return -1;
> > +		}
> > +
> > +		iovec.iov_base = p;
> > +		iovec.iov_len = l;
> > +		if (rw == READ) {
> > +			io_uring_prep_readv(sqe, fd, &iovec, 1, o);
> > +		} else {
> > +			io_uring_prep_writev(sqe, fd, &iovec, 1, o);
> > +		}
> > +
> > +		ret = io_uring_submit_and_wait(&ring, 1);
> > +		if (ret != 1) {
> > +			fprintf(stderr, "errcode=%d\n", -ret);
> > +			fprintf(stderr, "uring %s: io_uring_submit failed: %s\n",
> > +					rw == READ ? "read":"write", strerror(-ret));
> > +			goto uring_error;
> > +		}
> > +
> > +		ret = io_uring_wait_cqe(&ring, &cqe);
> > +		if (ret != 0) {
> > +			fprintf(stderr, "errcode=%d\n", -ret);
> > +			fprintf(stderr, "uring %s: io_uring_wait_cqe failed: %s\n",
> > +					rw == READ ? "read":"write", strerror(-ret));
> > +			goto uring_error;
> > +		}
> > +
> > +		res = cqe->res;
> 
> If we assign ret here instead of res, it looks like we could optimize
> away res entirely.

I think you're right, I'll think more about that, then send V5 patches out.
As you've ACKed this patchset, I'll add "Reviewed-by Brian" in V5, many
thanks for your review :)

> 
> Nits and my limited experience with uring aside, the patch otherwise
> LGTM. Are you planning any new tests to take advantage of this,
> particularly since it looks like -A (-U disabled) is the default? In any
> event, a quick test run of fsstress/fsx doesn't seem to explode:

Yes, I'm preparing more patches to use the -U option of fsx. I'll send them
out after this patchset get merged :)

> 
> Reviewed-by: Brian Foster <bfoster@redhat.com>
> 
> > +		io_uring_cqe_seen(&ring, cqe);
> > +
> > +		if (res > 0) {
> > +			o += res;
> > +			l -= res;
> > +			p += res;
> > +			res2 += res;
> > +		} else if (res < 0) {
> > +			ret = res;
> > +			fprintf(stderr, "errcode=%d\n", -ret);
> > +			fprintf(stderr, "uring %s: io_uring failed: %s\n",
> > +					rw == READ ? "read":"write", strerror(-ret));
> > +			goto uring_error;
> > +		} else {
> > +			fprintf(stderr, "uring %s bad io length: %d instead of %u\n",
> > +					rw == READ ? "read":"write", res2, len);
> > +			break;
> > +		}
> > +	}
> > +	return res2;
> > +
> > + uring_error:
> > +	/*
> > +	 * The caller expects error return in traditional libc
> > +	 * convention, i.e. -1 and the errno set to error.
> > +	 */
> > +	errno = -ret;
> > +	return -1;
> > +}
> > +#else
> > +int
> > +uring_rw(int rw, int fd, char *buf, unsigned len, unsigned offset)
> > +{
> > +	fprintf(stderr, "io_rw: need IO_URING support!\n");
> > +	exit(111);
> > +}
> > +#endif
> > +
> >  int
> >  fsx_rw(int rw, int fd, char *buf, unsigned len, unsigned offset)
> >  {
> > @@ -2436,6 +2550,8 @@ fsx_rw(int rw, int fd, char *buf, unsigned len, unsigned offset)
> >  
> >  	if (aio) {
> >  		ret = aio_rw(rw, fd, buf, len, offset);
> > +	} else if (uring) {
> > +		ret = uring_rw(rw, fd, buf, len, offset);
> >  	} else {
> >  		if (rw == READ)
> >  			ret = read(fd, buf, len);
> > @@ -2498,7 +2614,7 @@ main(int argc, char **argv)
> >  	setvbuf(stdout, (char *)0, _IOLBF, 0); /* line buffered stdout */
> >  
> >  	while ((ch = getopt_long(argc, argv,
> > -				 "b:c:dfg:i:j:kl:m:no:p:qr:s:t:w:xyABD:EFJKHzCILN:OP:RS:WXZ",
> > +				 "b:c:dfg:i:j:kl:m:no:p:qr:s:t:w:xyABD:EFJKHzCILN:OP:RS:UWXZ",
> >  				 longopts, NULL)) != EOF)
> >  		switch (ch) {
> >  		case 'b':
> > @@ -2606,6 +2722,9 @@ main(int argc, char **argv)
> >  		case 'A':
> >  			aio = 1;
> >  			break;
> > +		case 'U':
> > +			uring = 1;
> > +			break;
> >  		case 'D':
> >  			debugstart = getnum(optarg, &endp);
> >  			if (debugstart < 1)
> > @@ -2696,6 +2815,11 @@ main(int argc, char **argv)
> >  	if (argc != 1)
> >  		usage();
> >  
> > +	if (aio && uring) {
> > +		fprintf(stderr, "-A and -U shouldn't be used together\n");
> > +		usage();
> > +	}
> > +
> >  	if (integrity && !dirpath) {
> >  		fprintf(stderr, "option -i <logdev> requires -P <dirpath>\n");
> >  		usage();
> > @@ -2786,6 +2910,10 @@ main(int argc, char **argv)
> >  	if (aio) 
> >  		aio_setup();
> >  #endif
> > +#ifdef URING
> > +	if (uring)
> > +		uring_setup();
> > +#endif
> >  
> >  	if (!(o_flags & O_TRUNC)) {
> >  		off_t ret;
> > -- 
> > 2.20.1
> > 
>