* [Qemu-devel] [PATCH] raw-posix: improve detection of scsi-generic devices
@ 2010-09-06 15:06 Bernhard Kohl
2010-09-06 15:39 ` Alexander Graf
0 siblings, 1 reply; 6+ messages in thread
From: Bernhard Kohl @ 2010-09-06 15:06 UTC (permalink / raw)
To: qemu-devel; +Cc: kwolf, Bernhard Kohl, Bernhard Kohl
From: Bernhard Kohl <bernhard.kohl@gmx.net>
Allow symbolic links which point to /dev/sgX devices.
Signed-off-by: Bernhard Kohl <bernhard.kohl@nsn.com>
---
block/raw-posix.c | 10 ++++++++--
1 files changed, 8 insertions(+), 2 deletions(-)
diff --git a/block/raw-posix.c b/block/raw-posix.c
index 72fb8ce..4544a57 100644
--- a/block/raw-posix.c
+++ b/block/raw-posix.c
@@ -48,6 +48,7 @@
#endif
#ifdef __linux__
#include <sys/ioctl.h>
+#include <sys/param.h>
#include <linux/cdrom.h>
#include <linux/fd.h>
#endif
@@ -868,8 +869,13 @@ static int hdev_open(BlockDriverState *bs, const char *filename, int flags)
s->type = FTYPE_FILE;
#if defined(__linux__)
- if (strstart(filename, "/dev/sg", NULL)) {
- bs->sg = 1;
+ {
+ char resolved_path[ MAXPATHLEN ], *temp;
+
+ temp = realpath(filename, resolved_path);
+ if (temp && strstart(temp, "/dev/sg", NULL)) {
+ bs->sg = 1;
+ }
}
#endif
--
1.7.2.2
^ permalink raw reply related [flat|nested] 6+ messages in thread* Re: [Qemu-devel] [PATCH] raw-posix: improve detection of scsi-generic devices
2010-09-06 15:06 [Qemu-devel] [PATCH] raw-posix: improve detection of scsi-generic devices Bernhard Kohl
@ 2010-09-06 15:39 ` Alexander Graf
2010-09-07 2:04 ` Christoph Hellwig
0 siblings, 1 reply; 6+ messages in thread
From: Alexander Graf @ 2010-09-06 15:39 UTC (permalink / raw)
To: Bernhard Kohl; +Cc: kwolf, qemu-devel, Bernhard Kohl
On 06.09.2010, at 17:06, Bernhard Kohl wrote:
> From: Bernhard Kohl <bernhard.kohl@gmx.net>
>
> Allow symbolic links which point to /dev/sgX devices.
Couldn't you send an SG_IO test ioctl over and see if it works? I really dislike the whole file name magic matching.
Alex
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [Qemu-devel] [PATCH] raw-posix: improve detection of scsi-generic devices
2010-09-06 15:39 ` Alexander Graf
@ 2010-09-07 2:04 ` Christoph Hellwig
2010-09-07 9:40 ` Bernhard Kohl
2010-09-07 9:47 ` Kevin Wolf
0 siblings, 2 replies; 6+ messages in thread
From: Christoph Hellwig @ 2010-09-07 2:04 UTC (permalink / raw)
To: Alexander Graf; +Cc: kwolf, Bernhard Kohl, qemu-devel, Bernhard Kohl
On Mon, Sep 06, 2010 at 05:39:00PM +0200, Alexander Graf wrote:
>
> On 06.09.2010, at 17:06, Bernhard Kohl wrote:
>
> > From: Bernhard Kohl <bernhard.kohl@gmx.net>
> >
> > Allow symbolic links which point to /dev/sgX devices.
>
> Couldn't you send an SG_IO test ioctl over and see if it works? I really dislike the whole file name magic matching.
You could, but the result would not be what you expect, given that every
/dev/sd* device and more in Linux support it.
What we really need is to stop shoe-horning scsi pass through support
into the block layer. Once we finally get our generic thread offload
facilily there is no need for it anymore at all, scsi-generic can
simplify offload the SG_IO ioctl and be done with it. I even have an
old prototype for this, just waiting for the generic thread offload
to get merged before resurrecting it.
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [Qemu-devel] [PATCH] raw-posix: improve detection of scsi-generic devices
2010-09-07 2:04 ` Christoph Hellwig
@ 2010-09-07 9:40 ` Bernhard Kohl
2010-09-07 9:44 ` Alexander Graf
2010-09-07 9:47 ` Kevin Wolf
1 sibling, 1 reply; 6+ messages in thread
From: Bernhard Kohl @ 2010-09-07 9:40 UTC (permalink / raw)
To: ext Christoph Hellwig; +Cc: kwolf, Alexander Graf, Bernhard Kohl, qemu-devel
Am 07.09.2010 04:04, schrieb ext Christoph Hellwig:
> On Mon, Sep 06, 2010 at 05:39:00PM +0200, Alexander Graf wrote:
>
>> On 06.09.2010, at 17:06, Bernhard Kohl wrote:
>>
>>
>>> From: Bernhard Kohl<bernhard.kohl@gmx.net>
>>>
>>> Allow symbolic links which point to /dev/sgX devices.
>>>
>> Couldn't you send an SG_IO test ioctl over and see if it works? I really dislike the whole file name magic matching.
>>
> You could, but the result would not be what you expect, given that every
> /dev/sd* device and more in Linux support it.
>
> What we really need is to stop shoe-horning scsi pass through support
> into the block layer. Once we finally get our generic thread offload
> facilily there is no need for it anymore at all, scsi-generic can
> simplify offload the SG_IO ioctl and be done with it. I even have an
> old prototype for this, just waiting for the generic thread offload
> to get merged before resurrecting it.
>
Wouldn't it be OK to apply this patch in the meantime before we get
this complete new solution? I need to handle about 15 /dev/sg* disks
which are randomly numbered. With this patch I can use the udev
generated links in /dev/disk/by*, which makes life much easier.
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [Qemu-devel] [PATCH] raw-posix: improve detection of scsi-generic devices
2010-09-07 9:40 ` Bernhard Kohl
@ 2010-09-07 9:44 ` Alexander Graf
0 siblings, 0 replies; 6+ messages in thread
From: Alexander Graf @ 2010-09-07 9:44 UTC (permalink / raw)
To: Bernhard Kohl; +Cc: kwolf, ext Christoph Hellwig, Bernhard Kohl, qemu-devel
On 07.09.2010, at 11:40, Bernhard Kohl wrote:
> Am 07.09.2010 04:04, schrieb ext Christoph Hellwig:
>> On Mon, Sep 06, 2010 at 05:39:00PM +0200, Alexander Graf wrote:
>>
>>> On 06.09.2010, at 17:06, Bernhard Kohl wrote:
>>>
>>>
>>>> From: Bernhard Kohl<bernhard.kohl@gmx.net>
>>>>
>>>> Allow symbolic links which point to /dev/sgX devices.
>>>>
>>> Couldn't you send an SG_IO test ioctl over and see if it works? I really dislike the whole file name magic matching.
>>>
>> You could, but the result would not be what you expect, given that every
>> /dev/sd* device and more in Linux support it.
>>
>> What we really need is to stop shoe-horning scsi pass through support
>> into the block layer. Once we finally get our generic thread offload
>> facilily there is no need for it anymore at all, scsi-generic can
>> simplify offload the SG_IO ioctl and be done with it. I even have an
>> old prototype for this, just waiting for the generic thread offload
>> to get merged before resurrecting it.
>>
>
> Wouldn't it be OK to apply this patch in the meantime before we get
> this complete new solution? I need to handle about 15 /dev/sg* disks
> which are randomly numbered. With this patch I can use the udev
> generated links in /dev/disk/by*, which makes life much easier.
>
I agree. I'd take this one in for now, as it improves the situation and then when all world blossoms we can take Christoph's game-changing framework :).
Kevin, what do you think?
Alex
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [Qemu-devel] [PATCH] raw-posix: improve detection of scsi-generic devices
2010-09-07 2:04 ` Christoph Hellwig
2010-09-07 9:40 ` Bernhard Kohl
@ 2010-09-07 9:47 ` Kevin Wolf
1 sibling, 0 replies; 6+ messages in thread
From: Kevin Wolf @ 2010-09-07 9:47 UTC (permalink / raw)
To: Christoph Hellwig
Cc: Bernhard Kohl, Alexander Graf, Bernhard Kohl, qemu-devel
Am 07.09.2010 04:04, schrieb Christoph Hellwig:
> On Mon, Sep 06, 2010 at 05:39:00PM +0200, Alexander Graf wrote:
>>
>> On 06.09.2010, at 17:06, Bernhard Kohl wrote:
>>
>>> From: Bernhard Kohl <bernhard.kohl@gmx.net>
>>>
>>> Allow symbolic links which point to /dev/sgX devices.
>>
>> Couldn't you send an SG_IO test ioctl over and see if it works? I really dislike the whole file name magic matching.
>
> You could, but the result would not be what you expect, given that every
> /dev/sd* device and more in Linux support it.
>
> What we really need is to stop shoe-horning scsi pass through support
> into the block layer. Once we finally get our generic thread offload
> facilily there is no need for it anymore at all, scsi-generic can
> simplify offload the SG_IO ioctl and be done with it. I even have an
> old prototype for this, just waiting for the generic thread offload
> to get merged before resurrecting it.
Let's apply this patch for the time being then, and remove the code
altogether as soon as possible.
Kevin
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2010-09-07 9:47 UTC | newest]
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2010-09-06 15:06 [Qemu-devel] [PATCH] raw-posix: improve detection of scsi-generic devices Bernhard Kohl
2010-09-06 15:39 ` Alexander Graf
2010-09-07 2:04 ` Christoph Hellwig
2010-09-07 9:40 ` Bernhard Kohl
2010-09-07 9:44 ` Alexander Graf
2010-09-07 9:47 ` Kevin Wolf
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