On 03/21/2012 05:31 PM, Myklebust, Trond wrote: > 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. > That's a good idea. The osd_login is a script supplied by us. And should be submitted to nfs-utils by Steve. See the 4th patch sent as part of the login patchset. I will change it to fork and timeout properly. Regardless, for the long run I would like to pursue the Kernel-side timeout as well, since that would be the more robust thing to do. Also in the light that we provide root with the means to register a new osd_login program. > Cheers > Trond Thanks Boaz -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
