* [Qemu-devel] [PATCH 1/3] cow: use pread/pwrite
2010-05-07 15:16 [Qemu-devel] [PATCH 0/3] cow conversion to the block API Christoph Hellwig
@ 2010-05-07 15:17 ` Christoph Hellwig
0 siblings, 0 replies; 2+ messages in thread
From: Christoph Hellwig @ 2010-05-07 15:17 UTC (permalink / raw)
To: qemu-devel
Use pread/pwrite instead of lseek + read/write in preparation of using the
qemu block API.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Index: qemu/block/cow.c
===================================================================
--- qemu.orig/block/cow.c 2010-05-04 19:11:24.897004616 +0200
+++ qemu/block/cow.c 2010-05-04 19:12:29.010255070 +0200
@@ -78,7 +78,7 @@ static int cow_open(BlockDriverState *bs
}
s->fd = fd;
/* see if it is a cow image */
- if (read(fd, &cow_header, sizeof(cow_header)) != sizeof(cow_header)) {
+ if (pread(fd, &cow_header, sizeof(cow_header), 0) != sizeof(cow_header)) {
goto fail;
}
@@ -159,8 +159,8 @@ static int cow_read(BlockDriverState *bs
while (nb_sectors > 0) {
if (is_changed(s->cow_bitmap, sector_num, nb_sectors, &n)) {
- lseek(s->fd, s->cow_sectors_offset + sector_num * 512, SEEK_SET);
- ret = read(s->fd, buf, n * 512);
+ ret = pread(s->fd, buf, n * 512,
+ s->cow_sectors_offset + sector_num * 512);
if (ret != n * 512)
return -1;
} else {
@@ -186,8 +186,8 @@ static int cow_write(BlockDriverState *b
BDRVCowState *s = bs->opaque;
int ret, i;
- lseek(s->fd, s->cow_sectors_offset + sector_num * 512, SEEK_SET);
- ret = write(s->fd, buf, nb_sectors * 512);
+ ret = pwrite(s->fd, buf, nb_sectors * 512,
+ s->cow_sectors_offset + sector_num * 512);
if (ret != nb_sectors * 512)
return -1;
for (i = 0; i < nb_sectors; i++)
^ permalink raw reply [flat|nested] 2+ messages in thread
* [Qemu-devel] [PATCH 1/3] cow: use pread/pwrite
@ 2010-06-07 10:06 Christoph Hellwig
0 siblings, 0 replies; 2+ messages in thread
From: Christoph Hellwig @ 2010-06-07 10:06 UTC (permalink / raw)
To: qemu-devel
Use pread/pwrite instead of lseek + read/write in preparation of using the
qemu block API.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Index: qemu/block/cow.c
===================================================================
--- qemu.orig/block/cow.c 2010-05-04 19:11:24.897004616 +0200
+++ qemu/block/cow.c 2010-05-04 19:12:29.010255070 +0200
@@ -78,7 +78,7 @@ static int cow_open(BlockDriverState *bs
}
s->fd = fd;
/* see if it is a cow image */
- if (read(fd, &cow_header, sizeof(cow_header)) != sizeof(cow_header)) {
+ if (pread(fd, &cow_header, sizeof(cow_header), 0) != sizeof(cow_header)) {
goto fail;
}
@@ -159,8 +159,8 @@ static int cow_read(BlockDriverState *bs
while (nb_sectors > 0) {
if (is_changed(s->cow_bitmap, sector_num, nb_sectors, &n)) {
- lseek(s->fd, s->cow_sectors_offset + sector_num * 512, SEEK_SET);
- ret = read(s->fd, buf, n * 512);
+ ret = pread(s->fd, buf, n * 512,
+ s->cow_sectors_offset + sector_num * 512);
if (ret != n * 512)
return -1;
} else {
@@ -186,8 +186,8 @@ static int cow_write(BlockDriverState *b
BDRVCowState *s = bs->opaque;
int ret, i;
- lseek(s->fd, s->cow_sectors_offset + sector_num * 512, SEEK_SET);
- ret = write(s->fd, buf, nb_sectors * 512);
+ ret = pwrite(s->fd, buf, nb_sectors * 512,
+ s->cow_sectors_offset + sector_num * 512);
if (ret != nb_sectors * 512)
return -1;
for (i = 0; i < nb_sectors; i++)
^ permalink raw reply [flat|nested] 2+ messages in thread
end of thread, other threads:[~2010-06-07 10:06 UTC | newest]
Thread overview: 2+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2010-06-07 10:06 [Qemu-devel] [PATCH 1/3] cow: use pread/pwrite Christoph Hellwig
-- strict thread matches above, loose matches on Subject: below --
2010-05-07 15:16 [Qemu-devel] [PATCH 0/3] cow conversion to the block API Christoph Hellwig
2010-05-07 15:17 ` [Qemu-devel] [PATCH 1/3] cow: use pread/pwrite Christoph Hellwig
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).