Date: Wed, 18 May 2016 07:17:02 -0600 From: Alan Somers <asomers@freebsd.org> To: Warner Losh <imp@bsdimp.com>, "src-committers@freebsd.org" <src-committers@freebsd.org>, "svn-src-all@freebsd.org" <svn-src-all@freebsd.org>, "svn-src-head@freebsd.org" <svn-src-head@freebsd.org>, "Kenneth D. Merry" <ken@freebsd.org> Subject: Re: svn commit: r299371 - in head: sbin/camcontrol sys/cam sys/cam/scsi Message-ID: <CAOtMX2iFHi7r%2BLWCcft6M_-c42z=W5X-WyX3YttJssOMbw0MVg@mail.gmail.com> In-Reply-To: <20160518095637.GA3536@brick> References: <201605101546.u4AFkX0w073701@repo.freebsd.org> <CAOtMX2jJTKMM=kjJy0uUnkK93cDs_N5c5ohYnLq3CAd-fOYW2A@mail.gmail.com> <20160510173351.GA4176@brick> <CANCZdfqBZTFNP8uEuUyBs%2B4CQuvHq2efsN9aMmA046iQ7MhZdg@mail.gmail.com> <20160518095637.GA3536@brick>
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On Wed, May 18, 2016 at 3:56 AM, Edward Tomasz Napiera=C5=82a <trasz@freebs= d.org> wrote: > On 0517T1158, Warner Losh wrote: > > On Tue, May 10, 2016 at 11:33 AM, Edward Tomasz Napierala < > trasz@freebsd.org > > > wrote: > > > > > On 0510T1020, Alan Somers wrote: > > > > On Tue, May 10, 2016 at 9:46 AM, Edward Tomasz Napierala < > > > trasz@freebsd.org> > > > > wrote: > > > > > > > > > Author: trasz > > > > > Date: Tue May 10 15:46:33 2016 > > > > > New Revision: 299371 > > > > > URL: https://svnweb.freebsd.org/changeset/base/299371 > > > > > > > > > > Log: > > > > > Add "camcontrol reprobe" subcommand, and implement it for da(4)= . > > > > > This makes it possible to manually force updating capacity data > > > > > after the disk got resized. Without it it might be neccessary t= o > > > > > reboot before FreeBSD notices updated disk size under eg VMWare= . > > > > > > > > > > Discussed with: imp@ > > > > > MFC after: 1 month > > > > > Sponsored by: The FreeBSD Foundation > > > > > Differential Revision: https://reviews.freebsd.org/D6108 > > > > > > > > > > Modified: > > > > > head/sbin/camcontrol/camcontrol.8 > > > > > head/sbin/camcontrol/camcontrol.c > > > > > head/sys/cam/cam_ccb.h > > > > > head/sys/cam/cam_xpt.c > > > > > head/sys/cam/scsi/scsi_da.c > > > > > > > > > > > > > > > > > > I too have been annoyed that "camcontrol rescan" won't update > capacity > > > > data. But could we solve the problem by simply adding logic to > > > "camcontrol > > > > rescan" instead of adding an entirely new command? Would a user ev= er > > > want > > > > to rescan a device without reprobing it too? > > > > > > Two reasons. First, I want to be able to pass the device name (like > > > 'da0') and not the CAM path (like 1:0:0) for usability reasons - it > seems > > > easy to figure out the latter from the former, using "camcontrol > devlist", > > > but it suddenly becomes complicated when you try to explain it in a m= an > > > page. > > > > > > You can look up one or the other. fwdownload uses the daX name. > > Indeed. But it would mean fixing "camcontrol rescan" first. > > > > Second - I don't understand the "camcontrol rescan" logic well > > > enough, and "camcontrol rescan all" sometimes fails for me anyway, > > > in a way I'm not sure how to debug. > > > > > > > That's a cop-out. CAM is hard, but if you aren't willing to figure itou= t, > > adding hacks that the other CAM maintainers have to cope with doesn't > > help. > > That's true. However, this hack is pretty non-intrusive - it only adds > a trivial amount of code, and the "reprobe" command could be replaced > with a simple alias to "rescan" if someone steps up to reimplement it. > > > Also, to be honest I'm not sure those two are actually that related. > > > Rescanning is about discovering new devices on the bus. "Reprobe" > > > is about updating... well, mostly updating the capacity. The former > > > requires enumerating the bus using a mechanism built into XPT; the > > > latter is just notifying the periph driver (in this case da(4)) that > > > it needs to query the capacity and call disk_resize(4). > > > > > > > The two are very related. Now we have two stupid paths in CAM instead o= f > > one. > > We have two clearly separated code paths, doing completely different > things - one scanning the bus, and only notifying periph drivers if > new device is discovered, and the other one to notify existing periph > driver instances, without scanning anything. I just don't see how > entangling them with each other would improve things. > > > and you didn't do ada like I asked. > > As I said in review, the ada(4) driver seems to lack resizing > capability. It doesn't contain a call to disk_resize(9). It's been > a few years since I've added resizing to da(4), but it took quite > some time to make sure it interfaces with existing code in exactly > the right way. I just don't have time for this kind of side quest > right now. And I'm not even sure how to test it. With da(4) it > was easy - I've just added LUN resizing to CTL. > You can test ada(4) resize by using "camcontrol hpa". Most SATA disks allow you to reduce the disk's capacity through the hpa command. > > > Not happy with this at all, but not asking for a back out. > > Thanks. > >
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