* [Qemu-devel] [PATCH (trivial)] no need to use bdrv_pread() in format guessing code when we can use bdrv_read() directly
@ 2012-03-13 16:18 Michael Tokarev
2012-03-13 16:22 ` Michael Tokarev
0 siblings, 1 reply; 3+ messages in thread
From: Michael Tokarev @ 2012-03-13 16:18 UTC (permalink / raw)
To: qemu-devel; +Cc: Stefan Hajnoczi, Michael Tokarev
block.c:find_image_format() calls bdrv_pread() to read first 2048
bytes from the device to guess its format. This function can use
bdrv_read() directly since the the read is done on sector boundary.
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
---
block.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/block.c b/block.c
index b88ee90..6b5bcaf 100644
--- a/block.c
+++ b/block.c
@@ -469,7 +469,7 @@ static int find_image_format(const char *filename, BlockDriver **pdrv)
return ret;
}
- ret = bdrv_pread(bs, 0, buf, sizeof(buf));
+ ret = bdrv_read(bs, 0, buf, sizeof(buf) / BDRV_BLOCK_SIZE);
bdrv_delete(bs);
if (ret < 0) {
*pdrv = NULL;
--
1.7.9.1
^ permalink raw reply related [flat|nested] 3+ messages in thread* [Qemu-devel] [PATCH (trivial)] no need to use bdrv_pread() in format guessing code when we can use bdrv_read() directly
2012-03-13 16:18 [Qemu-devel] [PATCH (trivial)] no need to use bdrv_pread() in format guessing code when we can use bdrv_read() directly Michael Tokarev
@ 2012-03-13 16:22 ` Michael Tokarev
2012-03-14 9:25 ` Stefan Hajnoczi
0 siblings, 1 reply; 3+ messages in thread
From: Michael Tokarev @ 2012-03-13 16:22 UTC (permalink / raw)
To: qemu-devel; +Cc: Stefan Hajnoczi, Michael Tokarev
[Sorry - sent the wrong patch, should have been
BDRV_SECTOR_SIZE, not BDRV_BLOCK_SIZE....]
block.c:find_image_format() calls bdrv_pread() to read first 2048
bytes from the device to guess its format. This function can use
bdrv_read() directly since the the read is done on sector boundary.
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
---
block.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/block.c b/block.c
index b88ee90..b3af1f6 100644
--- a/block.c
+++ b/block.c
@@ -469,7 +469,7 @@ static int find_image_format(const char *filename, BlockDriver **pdrv)
return ret;
}
- ret = bdrv_pread(bs, 0, buf, sizeof(buf));
+ ret = bdrv_read(bs, 0, buf, sizeof(buf) / BDRV_SECTOR_SIZE);
bdrv_delete(bs);
if (ret < 0) {
*pdrv = NULL;
--
1.7.9.1
^ permalink raw reply related [flat|nested] 3+ messages in thread* Re: [Qemu-devel] [PATCH (trivial)] no need to use bdrv_pread() in format guessing code when we can use bdrv_read() directly
2012-03-13 16:22 ` Michael Tokarev
@ 2012-03-14 9:25 ` Stefan Hajnoczi
0 siblings, 0 replies; 3+ messages in thread
From: Stefan Hajnoczi @ 2012-03-14 9:25 UTC (permalink / raw)
To: Michael Tokarev; +Cc: qemu-devel
On Tue, Mar 13, 2012 at 4:22 PM, Michael Tokarev <mjt@tls.msk.ru> wrote:
> [Sorry - sent the wrong patch, should have been
> BDRV_SECTOR_SIZE, not BDRV_BLOCK_SIZE....]
>
> block.c:find_image_format() calls bdrv_pread() to read first 2048
> bytes from the device to guess its format. This function can use
> bdrv_read() directly since the the read is done on sector boundary.
>
> Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
> ---
> block.c | 2 +-
> 1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/block.c b/block.c
> index b88ee90..b3af1f6 100644
> --- a/block.c
> +++ b/block.c
> @@ -469,7 +469,7 @@ static int find_image_format(const char *filename, BlockDriver **pdrv)
> return ret;
> }
>
> - ret = bdrv_pread(bs, 0, buf, sizeof(buf));
> + ret = bdrv_read(bs, 0, buf, sizeof(buf) / BDRV_SECTOR_SIZE);
Why do this? The code is nicer to read without the sector division
and there's no real difference at execution time.
Stefan
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2012-03-14 9:25 UTC | newest]
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2012-03-13 16:18 [Qemu-devel] [PATCH (trivial)] no need to use bdrv_pread() in format guessing code when we can use bdrv_read() directly Michael Tokarev
2012-03-13 16:22 ` Michael Tokarev
2012-03-14 9:25 ` Stefan Hajnoczi
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