[Qemu-devel] [PATCH 2/2] [block]: Skip refresh_total_sectors() for scsi-generic devices

[Qemu-devel] [PATCH 2/2] [block]: Skip refresh_total_sectors() for scsi-generic devices

[Nicholas A. Bellinger]

From: Nicholas Bellinger <nab@linux-iscsi.org>

This patch adds a BlockDriverState->sg check in block.c:bdrv_common_open()
to skip the new refresh_total_sectors() call once we know we are working with
a scsi-generic device.

We go ahead and skip this call for scsi-generic devices because
block/raw-posix.c:raw_getlength() -> lseek() will return -ESPIPE.

Signed-off-by: Nicholas A. Bellinger <nab@linux-iscsi.org>
---
 block.c |   13 +++++++++----
 1 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/block.c b/block.c
index 02a22f6..1053161 100644
--- a/block.c
+++ b/block.c
@@ -444,10 +444,15 @@ static int bdrv_open_common(BlockDriverState *bs, const char *filename,
     }
 
     bs->keep_read_only = bs->read_only = !(open_flags & BDRV_O_RDWR);
-
-    ret = refresh_total_sectors(bs, bs->total_sectors);
-    if (ret < 0) {
-        goto free_and_fail;
+    /*
+     * For scsi-generic devices, do not call refresh_total_sectors() -> raw_getlength()
+     * because lseek() will return -ESPIPE.
+     */
+    if (!(bs->sg)) {
+    	ret = refresh_total_sectors(bs, bs->total_sectors);
+	if (ret < 0) {
+	    goto free_and_fail;
+	}
     }
 
 #ifndef _WIN32
-- 
1.5.6.5

[Qemu-devel] Re: [PATCH 2/2] [block]: Skip refresh_total_sectors() for scsi-generic devices

[Christoph Hellwig]

On Sat, May 15, 2010 at 06:30:59AM -0700, Nicholas A. Bellinger wrote:
> From: Nicholas Bellinger <nab@linux-iscsi.org>
> 
> This patch adds a BlockDriverState->sg check in block.c:bdrv_common_open()
> to skip the new refresh_total_sectors() call once we know we are working with
> a scsi-generic device.
> 
> We go ahead and skip this call for scsi-generic devices because
> block/raw-posix.c:raw_getlength() -> lseek() will return -ESPIPE.

How about moving that check into refresh_total_sectors?

[Qemu-devel] Re: [PATCH 2/2] [block]: Skip refresh_total_sectors() for scsi-generic devices

[Nicholas A. Bellinger]

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On Sun, 2010-05-16 at 15:30 +0200, Christoph Hellwig wrote:
> On Sat, May 15, 2010 at 06:30:59AM -0700, Nicholas A. Bellinger wrote:
> > From: Nicholas Bellinger <nab@linux-iscsi.org>
> > 
> > This patch adds a BlockDriverState->sg check in block.c:bdrv_common_open()
> > to skip the new refresh_total_sectors() call once we know we are working with
> > a scsi-generic device.
> > 
> > We go ahead and skip this call for scsi-generic devices because
> > block/raw-posix.c:raw_getlength() -> lseek() will return -ESPIPE.
> 
> How about moving that check into refresh_total_sectors?

Sounds good, attached is updated patch #2:

[PATCH 2/2] [block]: Add SG_IO device check in refresh_total_sectors()

Also, I am using the options in .vimrc to follow QEMU's indent style:

set smartindent
set tabstop=4
set shiftwidth=4
set expandtab

I assume this is what should be used when sending QEMU patches, yes..?

Best,

--nab

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