On Wed, 2012-03-21 at 17:18 -0700, Boaz Harrosh wrote: > On 03/21/2012 08:35 AM, Greg KH wrote: > > On Tue, Mar 20, 2012 at 04:18:49PM -0700, Boaz Harrosh wrote: > >> Andrew Hi > >> > >> I'm picking on you because I don't have any one else to pick on. > >> The 3 first patches here, are just good for today. Please see if > >> you would like to take them? or tell me who should take them? > >> > >> The 4th patch is an RFC, which got me looking into this. > >> > >> My motivation is that I added yet another Kernel dependency on the > >> call_usermodehelper() function and am not completely happy with the > >> error case of having the user-mode program stuck forever. In such > >> case I would like the Kernel part to timeout and properly error recover > >> and clean up. So therefor the proposed 4th patch. > > > > What is this new use of call_usermodhelper that you are doing this work > > for? Ideally, you never want to make this call, as it's slow and messy, > > as you have found out. Is there an in-kernel user that you have > > recently added? > > > > thanks, > > > > greg k-h > > I agree hence my comment in the 4th patch: > "In the blasphemous occasions that a the Kernel must call a user-mode program" > > I have added a new caller, to the nfs/objectlayoutdriver.ko that uses this > facility for auto-login into osd-targets (iscsi-targets) when new are requested > by the filesystem. This auto-login facility is mandated by the pnfs-objects > standard because in a large cluster filesystems for which pnfs was invented, storage > devices break and changed everyday, and a manual login by every client is not > feasible. > > You can see this patch as posted to the mailing list here: > http://article.gmane.org/gmane.linux.nfs/48024/match=login > [title: pnfs-obj: autologin: Add support for protocol autologin] > > It works very well and was heavily tested, with all error scenarios, but > the theoretical possibility that the user-mode program can be stuck forever > bothers me and I would like to do something about it. With this patch the > Kernel can recover cleanly and continue. I have actually tested this part > and it works as expected. Hi Boaz, As an alternative suggestion: since you are always calling the same /sbin/osd_login userspace program, wouldn't it be easier to add the timeout smarts into that program? If you can't modify the osd_login program itself, then it should still be trivial to wrap it with a script that adds the 'timeout' command prefix. Cheers Trond -- Trond Myklebust Linux NFS client maintainer NetApp Trond.Myklebust@xxxxxxxxxx www.netapp.com ��.n��������+%������w��{.n�����{���)�� jg��� �����ݢj����G���� ���j:+v���w�m������w�������h�����٥
