[PATCH v4 1/4] xfs_io: Disable -V if pwritev is not available

[PATCH v4 1/4] xfs_io: Disable -V if pwritev is not available

[Goldwyn Rodrigues]

From: Goldwyn Rodrigues <rgoldwyn@suse.com>

This results in default case which will display the error message
that command is not found. This is required for xfs_io builds which
did not support pwritev and an attempt is made to use -V.

Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
---
 io/pwrite.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/io/pwrite.c b/io/pwrite.c
index 1c5dfca1..5f149a68 100644
--- a/io/pwrite.c
+++ b/io/pwrite.c
@@ -312,6 +312,7 @@ pwrite_f(
 		case 'u':
 			uflag = 1;
 			break;
+#ifdef HAVE_PWRITEV
 		case 'V':
 			vectors = strtoul(optarg, &sp, 0);
 			if (!sp || sp == optarg) {
@@ -320,6 +321,7 @@ pwrite_f(
 				return 0;
 			}
 			break;
+#endif
 		case 'w':
 			wflag = 1;
 			break;
@@ -334,6 +336,7 @@ pwrite_f(
 			}
 			break;
 		default:
+			printf(_("command -%c not supported\n"), c);
 			return command_usage(&pwrite_cmd);
 		}
 	}
-- 
2.14.2

[PATCH v4 2/4] xfs_io: Add support for pwritev2()

[Goldwyn Rodrigues]

From: Goldwyn Rodrigues <rgoldwyn@suse.com>

Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>

Changes since v2:
	Line wrap to 80 chars
---
 configure.ac          |  1 +
 include/builddefs.in  |  1 +
 io/Makefile           |  4 ++++
 io/pwrite.c           | 43 ++++++++++++++++++++++++++++++-------------
 m4/package_libcdev.m4 | 16 ++++++++++++++++
 5 files changed, 52 insertions(+), 13 deletions(-)

diff --git a/configure.ac b/configure.ac
index 4161c3b4..2320e3e3 100644
--- a/configure.ac
+++ b/configure.ac
@@ -132,6 +132,7 @@ AC_HAVE_GETMNTENT
 AC_HAVE_GETMNTINFO
 AC_HAVE_FALLOCATE
 AC_HAVE_FIEMAP
+AC_HAVE_PWRITEV2
 AC_HAVE_PREADV
 AC_HAVE_COPY_FILE_RANGE
 AC_HAVE_SYNC_FILE_RANGE
diff --git a/include/builddefs.in b/include/builddefs.in
index ec630bd9..cd58ea8e 100644
--- a/include/builddefs.in
+++ b/include/builddefs.in
@@ -103,6 +103,7 @@ HAVE_GETMNTINFO = @have_getmntinfo@
 HAVE_FALLOCATE = @have_fallocate@
 HAVE_FIEMAP = @have_fiemap@
 HAVE_PREADV = @have_preadv@
+HAVE_PWRITEV2 = @have_pwritev2@
 HAVE_COPY_FILE_RANGE = @have_copy_file_range@
 HAVE_SYNC_FILE_RANGE = @have_sync_file_range@
 HAVE_SYNCFS = @have_syncfs@
diff --git a/io/Makefile b/io/Makefile
index 47b0a669..050d6bd0 100644
--- a/io/Makefile
+++ b/io/Makefile
@@ -90,6 +90,10 @@ ifeq ($(HAVE_PREADV),yes)
 LCFLAGS += -DHAVE_PREADV -DHAVE_PWRITEV
 endif
 
+ifeq ($(HAVE_PWRITEV2),yes)
+LCFLAGS += -DHAVE_PWRITEV2
+endif
+
 ifeq ($(HAVE_READDIR),yes)
 CFILES += readdir.c
 LCFLAGS += -DHAVE_READDIR
diff --git a/io/pwrite.c b/io/pwrite.c
index 5f149a68..2cdf0954 100644
--- a/io/pwrite.c
+++ b/io/pwrite.c
@@ -62,7 +62,8 @@ do_pwritev(
 	int		fd,
 	off64_t		offset,
 	ssize_t		count,
-	ssize_t		buffer_size)
+	ssize_t		buffer_size,
+	int 		pwritev2_flags)
 {
 	int vecs = 0;
 	ssize_t oldlen = 0;
@@ -81,7 +82,14 @@ do_pwritev(
 	} else {
 		vecs = vectors;
 	}
+#ifdef HAVE_PWRITEV2
+	if (pwritev2_flags)
+		bytes = pwritev2(fd, iov, vectors, offset, pwritev2_flags);
+	else
+		bytes = pwritev(fd, iov, vectors, offset);
+#else
 	bytes = pwritev(fd, iov, vectors, offset);
+#endif
 
 	/* restore trimmed iov */
 	if (oldlen)
@@ -98,12 +106,13 @@ do_pwrite(
 	int		fd,
 	off64_t		offset,
 	ssize_t		count,
-	ssize_t		buffer_size)
+	ssize_t		buffer_size,
+	int		pwritev2_flags)
 {
 	if (!vectors)
 		return pwrite(fd, buffer, min(count, buffer_size), offset);
 
-	return do_pwritev(fd, offset, count, buffer_size);
+	return do_pwritev(fd, offset, count, buffer_size, pwritev2_flags);
 }
 
 static int
@@ -111,7 +120,8 @@ write_random(
 	off64_t		offset,
 	long long	count,
 	unsigned int	seed,
-	long long	*total)
+	long long	*total,
+	int 		pwritev2_flags)
 {
 	off64_t		off, range;
 	ssize_t		bytes;
@@ -133,7 +143,8 @@ write_random(
 				buffersize;
 		else
 			off = offset;
-		bytes = do_pwrite(file->fd, off, buffersize, buffersize);
+		bytes = do_pwrite(file->fd, off, buffersize, buffersize,
+				pwritev2_flags);
 		if (bytes == 0)
 			break;
 		if (bytes < 0) {
@@ -153,7 +164,8 @@ static int
 write_backward(
 	off64_t		offset,
 	long long	*count,
-	long long	*total)
+	long long	*total,
+	int		pwritev2_flags)
 {
 	off64_t		end, off = offset;
 	ssize_t		bytes = 0, bytes_requested;
@@ -171,7 +183,8 @@ write_backward(
 	if ((bytes_requested = (off % buffersize))) {
 		bytes_requested = min(cnt, bytes_requested);
 		off -= bytes_requested;
-		bytes = do_pwrite(file->fd, off, bytes_requested, buffersize);
+		bytes = do_pwrite(file->fd, off, bytes_requested, buffersize,
+				pwritev2_flags);
 		if (bytes == 0)
 			return ops;
 		if (bytes < 0) {
@@ -189,7 +202,8 @@ write_backward(
 	while (cnt > end) {
 		bytes_requested = min(cnt, buffersize);
 		off -= bytes_requested;
-		bytes = do_pwrite(file->fd, off, cnt, buffersize);
+		bytes = do_pwrite(file->fd, off, cnt, buffersize,
+				pwritev2_flags);
 		if (bytes == 0)
 			break;
 		if (bytes < 0) {
@@ -212,7 +226,8 @@ write_buffer(
 	size_t		bs,
 	int		fd,
 	off64_t		skip,
-	long long	*total)
+	long long	*total,
+	int		pwritev2_flags)
 {
 	ssize_t		bytes;
 	long long	bar = min(bs, count);
@@ -224,7 +239,7 @@ write_buffer(
 			if (read_buffer(fd, skip + *total, bs, &bar, 0, 1) < 0)
 				break;
 		}
-		bytes = do_pwrite(file->fd, offset, count, bar);
+		bytes = do_pwrite(file->fd, offset, count, bar, pwritev2_flags);
 		if (bytes == 0)
 			break;
 		if (bytes < 0) {
@@ -258,6 +273,7 @@ pwrite_f(
 	int		Cflag, qflag, uflag, dflag, wflag, Wflag;
 	int		direction = IO_FORWARD;
 	int		c, fd = -1;
+	int		pwritev2_flags = 0;
 
 	Cflag = qflag = uflag = dflag = wflag = Wflag = 0;
 	init_cvtnum(&fsblocksize, &fssectsize);
@@ -368,13 +384,14 @@ pwrite_f(
 	case IO_RANDOM:
 		if (!zeed)	/* srandom seed */
 			zeed = time(NULL);
-		c = write_random(offset, count, zeed, &total);
+		c = write_random(offset, count, zeed, &total, pwritev2_flags);
 		break;
 	case IO_FORWARD:
-		c = write_buffer(offset, count, bsize, fd, skip, &total);
+		c = write_buffer(offset, count, bsize, fd, skip, &total,
+				pwritev2_flags);
 		break;
 	case IO_BACKWARD:
-		c = write_backward(offset, &count, &total);
+		c = write_backward(offset, &count, &total, pwritev2_flags);
 		break;
 	default:
 		total = 0;
diff --git a/m4/package_libcdev.m4 b/m4/package_libcdev.m4
index fa5b6397..48da0783 100644
--- a/m4/package_libcdev.m4
+++ b/m4/package_libcdev.m4
@@ -146,6 +146,22 @@ AC_DEFUN([AC_HAVE_PREADV],
     AC_SUBST(have_preadv)
   ])
 
+#
+# Check if we have a pwritev2 libc call (Linux)
+#
+AC_DEFUN([AC_HAVE_PWRITEV2],
+  [ AC_MSG_CHECKING([for pwritev2])
+    AC_TRY_LINK([
+#define _BSD_SOURCE
+#include <sys/uio.h>
+    ], [
+         pwritev2(0, 0, 0, 0, 0);
+    ], have_pwritev2=yes
+       AC_MSG_RESULT(yes),
+       AC_MSG_RESULT(no))
+    AC_SUBST(have_pwritev2)
+  ])
+
 #
 # Check if we have a copy_file_range system call (Linux)
 #
-- 
2.14.2

[PATCH v4 3/4] xfs_io: Add RWF_NOWAIT to pwritev2()

[Goldwyn Rodrigues]

From: Goldwyn Rodrigues <rgoldwyn@suse.com>

This allows to make pwritev2() calls with RWF_NOWAIT,
which would fail in case the call blocks.

Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
---
 io/pwrite.c       | 12 ++++++++++--
 man/man8/xfs_io.8 | 10 ++++++++++
 2 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/io/pwrite.c b/io/pwrite.c
index 2cdf0954..c218f686 100644
--- a/io/pwrite.c
+++ b/io/pwrite.c
@@ -53,6 +53,9 @@ pwrite_help(void)
 #ifdef HAVE_PWRITEV
 " -V N -- use vectored IO with N iovecs of blocksize each (pwritev)\n"
 #endif
+#ifdef HAVE_PWRITEV2
+" -N   -- Perform the pwritev2() with RWF_NOWAIT\n"
+#endif
 "\n"));
 }
 
@@ -279,7 +282,7 @@ pwrite_f(
 	init_cvtnum(&fsblocksize, &fssectsize);
 	bsize = fsblocksize;
 
-	while ((c = getopt(argc, argv, "b:BCdf:Fi:qRs:S:uV:wWZ:")) != EOF) {
+	while ((c = getopt(argc, argv, "b:BCdf:Fi:NqRs:S:uV:wWZ:")) != EOF) {
 		switch (c) {
 		case 'b':
 			tmp = cvtnum(fsblocksize, fssectsize, optarg);
@@ -308,6 +311,11 @@ pwrite_f(
 		case 'i':
 			infile = optarg;
 			break;
+#ifdef HAVE_PWRITEV2
+		case 'N':
+			pwritev2_flags |= RWF_NOWAIT;
+			break;
+#endif
 		case 's':
 			skip = cvtnum(fsblocksize, fssectsize, optarg);
 			if (skip < 0) {
@@ -426,7 +434,7 @@ pwrite_init(void)
 	pwrite_cmd.argmax = -1;
 	pwrite_cmd.flags = CMD_NOMAP_OK | CMD_FOREIGN_OK;
 	pwrite_cmd.args =
-_("[-i infile [-d] [-s skip]] [-b bs] [-S seed] [-wW] [-FBR [-Z N]] [-V N] off len");
+_("[-i infile [-d] [-s skip]] [-b bs] [-S seed] [-wW] [-FBR [-Z N]] [-N] [-V N] off len");
 	pwrite_cmd.oneline =
 		_("writes a number of bytes at a specified offset");
 	pwrite_cmd.help = pwrite_help;
diff --git a/man/man8/xfs_io.8 b/man/man8/xfs_io.8
index 0fd9b951..5c0565ec 100644
--- a/man/man8/xfs_io.8
+++ b/man/man8/xfs_io.8
@@ -282,6 +282,16 @@ Use the vectored IO write syscall
 with a number of blocksize length iovecs. The number of iovecs is set by the
 .I vectors
 parameter.
+.TP
+.B \-N
+Perform the
+.BR pwritev2 (2)
+call with
+.I RWF_NOWAIT.
+This option is available if
+.BR xfs_io
+was built on a kernel which supports
+.I pwritev2 (2)
 .RE
 .PD
 .TP
-- 
2.14.2

[PATCH v4 4/4] xfs_io: Allow partial writes

[Goldwyn Rodrigues]

From: Goldwyn Rodrigues <rgoldwyn@suse.com>

Partial writes are performed when there is an error midway
while performing the I/O. Perform the write exactly once and
return the number of bytes written so far, until the error.

Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
---
 io/io.h           |  1 +
 io/pwrite.c       | 25 ++++++++++++++++++++++++-
 man/man8/xfs_io.8 |  3 +++
 3 files changed, 28 insertions(+), 1 deletion(-)

diff --git a/io/io.h b/io/io.h
index 6a0fe657..3862985f 100644
--- a/io/io.h
+++ b/io/io.h
@@ -25,6 +25,7 @@
 #define IO_RANDOM	( 0)
 #define IO_FORWARD	( 1)
 #define IO_BACKWARD	(-1)
+#define IO_ONCE		( 2)
 
 /*
  * File descriptor options
diff --git a/io/pwrite.c b/io/pwrite.c
index c218f686..b77c0975 100644
--- a/io/pwrite.c
+++ b/io/pwrite.c
@@ -47,6 +47,7 @@ pwrite_help(void)
 " -W   -- call fsync(2) at the end (included in timing results)\n"
 " -B   -- write backwards through the range from offset (backwards N bytes)\n"
 " -F   -- write forwards through the range of bytes from offset (default)\n"
+" -O   -- perform pwrite call once and return (maybe partial) bytes written\n"
 " -R   -- write at random offsets in the specified range of bytes\n"
 " -Z N -- zeed the random number generator (used when writing randomly)\n"
 "         (heh, zorry, the -s/-S arguments were already in use in pwrite)\n"
@@ -261,6 +262,22 @@ write_buffer(
 	return ops;
 }
 
+static int
+write_once(
+	off64_t		offset,
+	long long	count,
+	long long	*total,
+	int		pwritev2_flags)
+{
+	size_t bytes;
+	bytes = do_pwrite(file->fd, offset, count, count, pwritev2_flags);
+	if (bytes < 0)
+		return -1;
+	*total = bytes;
+	return 1;
+}
+
+
 static int
 pwrite_f(
 	int		argc,
@@ -282,7 +299,7 @@ pwrite_f(
 	init_cvtnum(&fsblocksize, &fssectsize);
 	bsize = fsblocksize;
 
-	while ((c = getopt(argc, argv, "b:BCdf:Fi:NqRs:S:uV:wWZ:")) != EOF) {
+	while ((c = getopt(argc, argv, "b:BCdf:Fi:NqRs:OS:uV:wWZ:")) != EOF) {
 		switch (c) {
 		case 'b':
 			tmp = cvtnum(fsblocksize, fssectsize, optarg);
@@ -304,6 +321,9 @@ pwrite_f(
 		case 'R':
 			direction = IO_RANDOM;
 			break;
+		case 'O':
+			direction = IO_ONCE;
+			break;
 		case 'd':
 			dflag = 1;
 			break;
@@ -401,6 +421,9 @@ pwrite_f(
 	case IO_BACKWARD:
 		c = write_backward(offset, &count, &total, pwritev2_flags);
 		break;
+	case IO_ONCE:
+		c = write_once(offset, count, &total, pwritev2_flags);
+		break;
 	default:
 		total = 0;
 		ASSERT(0);
diff --git a/man/man8/xfs_io.8 b/man/man8/xfs_io.8
index 5c0565ec..ff48689d 100644
--- a/man/man8/xfs_io.8
+++ b/man/man8/xfs_io.8
@@ -263,6 +263,9 @@ write the buffers in a reserve sequential direction.
 .B \-R
 write the buffers in the give range in a random order.
 .TP
+.B \-O
+perform pwrite once and return the (maybe partial) bytes written.
+.TP
 .B \-Z seed
 specify the random number seed used for random write
 .TP
-- 
2.14.2

Re: [PATCH v4 1/4] xfs_io: Disable -V if pwritev is not available

[Eric Sandeen]

On 11/9/17 1:26 PM, Goldwyn Rodrigues wrote:
> From: Goldwyn Rodrigues <rgoldwyn@suse.com>
> 
> This results in default case which will display the error message
> that command is not found. This is required for xfs_io builds which
> did not support pwritev and an attempt is made to use -V.
> 
> Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
> ---
>  io/pwrite.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/io/pwrite.c b/io/pwrite.c
> index 1c5dfca1..5f149a68 100644
> --- a/io/pwrite.c
> +++ b/io/pwrite.c
> @@ -312,6 +312,7 @@ pwrite_f(
>  		case 'u':
>  			uflag = 1;
>  			break;
> +#ifdef HAVE_PWRITEV
>  		case 'V':
>  			vectors = strtoul(optarg, &sp, 0);
>  			if (!sp || sp == optarg) {
> @@ -320,6 +321,7 @@ pwrite_f(
>  				return 0;
>  			}
>  			break;
> +#endif
>  		case 'w':
>  			wflag = 1;
>  			break;
> @@ -334,6 +336,7 @@ pwrite_f(
>  			}
>  			break;
>  		default:
> +			printf(_("command -%c not supported\n"), c);
>  			return command_usage(&pwrite_cmd);
>  		}
>  	}

I think this is slightly better:

                default:
                        /* Handle ifdef'd-out options above */
                        if (c != '?')
                                printf(_("%s: command -%c not supported\n"), argv[0], c);
                        return command_usage(&pwrite_cmd);
                }

so we don't get the message for a completely bogus (not in getopt string)
argument on top of the one getopt already gives us.

I can do it on the way in.

Other than that, 

Reviewed-by: Eric Sandeen <sandeen@redhat.com>

Thanks,
-Eric

Re: [PATCH v4 4/4] xfs_io: Allow partial writes

[Eric Sandeen]

On 11/9/17 1:26 PM, Goldwyn Rodrigues wrote:
> From: Goldwyn Rodrigues <rgoldwyn@suse.com>
> 
> Partial writes are performed when there is an error midway
> while performing the I/O. Perform the write exactly once and
> return the number of bytes written so far, until the error.
> 
> Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
> Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
> Reviewed-by: Brian Foster <bfoster@redhat.com>
> ---
>  io/io.h           |  1 +
>  io/pwrite.c       | 25 ++++++++++++++++++++++++-
>  man/man8/xfs_io.8 |  3 +++
>  3 files changed, 28 insertions(+), 1 deletion(-)
> 
> diff --git a/io/io.h b/io/io.h
> index 6a0fe657..3862985f 100644
> --- a/io/io.h
> +++ b/io/io.h
> @@ -25,6 +25,7 @@
>  #define IO_RANDOM	( 0)
>  #define IO_FORWARD	( 1)
>  #define IO_BACKWARD	(-1)
> +#define IO_ONCE		( 2)
>  
>  /*
>   * File descriptor options
> diff --git a/io/pwrite.c b/io/pwrite.c
> index c218f686..b77c0975 100644
> --- a/io/pwrite.c
> +++ b/io/pwrite.c
> @@ -47,6 +47,7 @@ pwrite_help(void)
>  " -W   -- call fsync(2) at the end (included in timing results)\n"
>  " -B   -- write backwards through the range from offset (backwards N bytes)\n"
>  " -F   -- write forwards through the range of bytes from offset (default)\n"
> +" -O   -- perform pwrite call once and return (maybe partial) bytes written\n"

This also needs to be added to the short help; (and the synopsis
in the manpage; other options too ...)  I'll do it on the way in.

This is always a fun job to update new options in half a dozen references ;)

-Eric