Date: Sun, 1 May 2005 06:15:27 -0400 (EDT) From: Jeff Roberson <jroberson@chesapeake.net> To: Oleg Sharoiko <os@rsu.ru> Cc: Kris Kennaway <kris@obsecurity.org> Subject: Re: diskless/unionfs panics Message-ID: <20050501061323.X71837@mail.chesapeake.net> In-Reply-To: <20050501114837.V649@localhost> References: <E1DS8Gs-000OTa-1Y@cs1.cs.huji.ac.il> <20050501034520.N71837@mail.chesapeake.net> <20050501114837.V649@localhost>
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On Sun, 1 May 2005, Oleg Sharoiko wrote: > > On Sun, 1 May 2005, Jeff Roberson wrote: > > JR>Where is this patch? > > It was quoted by Danny in his mail http://docs.freebsd.org/cgi/mid.cgi?E1DRs0M-0006E4-9a > I sent it him privately, because I wasn't sure about the patch. Yes, unfortunately this is only part of the problem. The v_object can change on a unionfs vnode leading to inconsistent results for mmap/exec. This also causes problems for unionfs mounted on top of unionfs as the lower vp can also change v_object fields. This was one advantage to the VOP based solution. It would propagate all the way down the stack on each access. > > Here it is: > ----- > Index: union_vnops.c > =================================================================== > RCS file: /home/ncvs/src/sys/fs/unionfs/union_vnops.c,v > retrieving revision 1.131 > diff -u -r1.131 union_vnops.c > --- union_vnops.c 13 Apr 2005 10:59:08 -0000 1.131 > +++ union_vnops.c 1 May 2005 07:50:27 -0000 > @@ -748,6 +748,9 @@ > if (error == 0) > error = VOP_OPEN(tvp, mode, cred, td, -1); > > + if (error == 0) > + ap->a_vp->v_object = tvp->v_object; > + > /* > * Release any locks held. > */ > ----- > > I made it similar to the way it's done in nullfs. You can check my > explanaitons quoted by Danny. > > -- > Oleg Sharoiko. > Software and Network Engineer > Computer Center of Rostov State University. >
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