[PATCH v2 1/3] xfs_io: Add support for preadv2

["Ritesh Harjani (IBM)" <ritesh.list@xxxxxxxxx>]

This patch adds support for preadv2() to xfs_io.

Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@xxxxxxxxx>
---
 io/Makefile |  2 +-
 io/pread.c  | 45 ++++++++++++++++++++++++++++++---------------
 2 files changed, 31 insertions(+), 16 deletions(-)

diff --git a/io/Makefile b/io/Makefile
index 8f835ec7..14a3fe20 100644
--- a/io/Makefile
+++ b/io/Makefile
@@ -66,7 +66,7 @@ LLDLIBS += $(LIBEDITLINE) $(LIBTERMCAP)
 endif
 
 ifeq ($(HAVE_PWRITEV2),yes)
-LCFLAGS += -DHAVE_PWRITEV2
+LCFLAGS += -DHAVE_PWRITEV2 -DHAVE_PREADV2
 endif
 
 ifeq ($(HAVE_MAP_SYNC),yes)
diff --git a/io/pread.c b/io/pread.c
index 62c771fb..b314fbc7 100644
--- a/io/pread.c
+++ b/io/pread.c
@@ -162,7 +162,8 @@ static ssize_t
 do_preadv(
 	int		fd,
 	off_t		offset,
-	long long	count)
+	long long	count,
+	int			preadv2_flags)
 {
 	int		vecs = 0;
 	ssize_t		oldlen = 0;
@@ -181,8 +182,14 @@ do_preadv(
 	} else {
 		vecs = vectors;
 	}
+#ifdef HAVE_PREADV2
+	if (preadv2_flags)
+		bytes = preadv2(fd, iov, vectors, offset, preadv2_flags);
+	else
+		bytes = preadv(fd, iov, vectors, offset);
+#else
 	bytes = preadv(fd, iov, vectors, offset);
-
+#endif
 	/* restore trimmed iov */
 	if (oldlen)
 		iov[vecs - 1].iov_len = oldlen;
@@ -195,12 +202,13 @@ do_pread(
 	int		fd,
 	off_t		offset,
 	long long	count,
-	size_t		buffer_size)
+	size_t		buffer_size,
+	int			preadv2_flags)
 {
 	if (!vectors)
 		return pread(fd, io_buffer, min(count, buffer_size), offset);
 
-	return do_preadv(fd, offset, count);
+	return do_preadv(fd, offset, count, preadv2_flags);
 }
 
 static int
@@ -210,7 +218,8 @@ read_random(
 	long long	count,
 	long long	*total,
 	unsigned int	seed,
-	int		eof)
+	int		eof,
+	int		preadv2_flags)
 {
 	off_t		end, off, range;
 	ssize_t		bytes;
@@ -234,7 +243,7 @@ read_random(
 				io_buffersize;
 		else
 			off = offset;
-		bytes = do_pread(fd, off, io_buffersize, io_buffersize);
+		bytes = do_pread(fd, off, io_buffersize, io_buffersize, preadv2_flags);
 		if (bytes == 0)
 			break;
 		if (bytes < 0) {
@@ -256,7 +265,8 @@ read_backward(
 	off_t		*offset,
 	long long	*count,
 	long long	*total,
-	int		eof)
+	int		eof,
+	int		preadv2_flags)
 {
 	off_t		end, off = *offset;
 	ssize_t		bytes = 0, bytes_requested;
@@ -276,7 +286,7 @@ read_backward(
 	/* Do initial unaligned read if needed */
 	if ((bytes_requested = (off % io_buffersize))) {
 		off -= bytes_requested;
-		bytes = do_pread(fd, off, bytes_requested, io_buffersize);
+		bytes = do_pread(fd, off, bytes_requested, io_buffersize, preadv2_flags);
 		if (bytes == 0)
 			return ops;
 		if (bytes < 0) {
@@ -294,7 +304,7 @@ read_backward(
 	while (cnt > end) {
 		bytes_requested = min(cnt, io_buffersize);
 		off -= bytes_requested;
-		bytes = do_pread(fd, off, cnt, io_buffersize);
+		bytes = do_pread(fd, off, cnt, io_buffersize, preadv2_flags);
 		if (bytes == 0)
 			break;
 		if (bytes < 0) {
@@ -318,14 +328,15 @@ read_forward(
 	long long	*total,
 	int		verbose,
 	int		onlyone,
-	int		eof)
+	int		eof,
+	int		preadv2_flags)
 {
 	ssize_t		bytes;
 	int		ops = 0;
 
 	*total = 0;
 	while (count > 0 || eof) {
-		bytes = do_pread(fd, offset, count, io_buffersize);
+		bytes = do_pread(fd, offset, count, io_buffersize, preadv2_flags);
 		if (bytes == 0)
 			break;
 		if (bytes < 0) {
@@ -353,7 +364,7 @@ read_buffer(
 	int		verbose,
 	int		onlyone)
 {
-	return read_forward(fd, offset, count, total, verbose, onlyone, 0);
+	return read_forward(fd, offset, count, total, verbose, onlyone, 0, 0);
 }
 
 static int
@@ -371,6 +382,7 @@ pread_f(
 	int		Cflag, qflag, uflag, vflag;
 	int		eof = 0, direction = IO_FORWARD;
 	int		c;
+	int		preadv2_flags = 0;
 
 	Cflag = qflag = uflag = vflag = 0;
 	init_cvtnum(&fsblocksize, &fssectsize);
@@ -463,15 +475,18 @@ pread_f(
 	case IO_RANDOM:
 		if (!zeed)	/* srandom seed */
 			zeed = time(NULL);
-		c = read_random(file->fd, offset, count, &total, zeed, eof);
+		c = read_random(file->fd, offset, count, &total, zeed, eof,
+						preadv2_flags);
 		break;
 	case IO_FORWARD:
-		c = read_forward(file->fd, offset, count, &total, vflag, 0, eof);
+		c = read_forward(file->fd, offset, count, &total, vflag, 0, eof,
+						 preadv2_flags);
 		if (eof)
 			count = total;
 		break;
 	case IO_BACKWARD:
-		c = read_backward(file->fd, &offset, &count, &total, eof);
+		c = read_backward(file->fd, &offset, &count, &total, eof,
+						  preadv2_flags);
 		break;
 	default:
 		ASSERT(0);
-- 
2.48.1