| Message ID | 1283785562-31830-1-git-send-email-bernhard.kohl@nsn.com |
|---|---|
| State | New |
| Headers | show |
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
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.
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.
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
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
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