Date: Mon, 3 Mar 1997 23:50:57 -0600 From: Jonathan Lemon <jlemon@americantv.com> To: Michael Smith <msmith@atrad.adelaide.edu.au> Cc: proff@iq.org, hackers@FreeBSD.ORG Subject: Re: xemacs crashes kernel Message-ID: <19970303235057.26399@right.PCS> In-Reply-To: <199703040532.QAA10831@genesis.atrad.adelaide.edu.au>; from Michael Smith on Mar 03, 1997 at 04:02:00PM %2B1030 References: <19970303230157.25741@right.PCS> <199703040532.QAA10831@genesis.atrad.adelaide.edu.au>
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On Mar 03, 1997 at 04:02:00PM +1030, Michael Smith wrote:
> error = VOP_FSYNC(vp, fp->f_cred,
> (vp->v_mount->mnt_flag & MNT_ASYNC) ? MNT_NOWAIT : MNT_WAIT, p);
>
> MNT_ASYNC is 0x40, and mnt_flag looks to be about 0x18 offset in the
> mount structure. Looks like maybe someone trying to fsync something
> that's not a file, although a quick test here doesn't indicate that.
>
> Are non-file items supposed to have valid v_mount pointers? Other places
> in the kernel that look at vp->v_mount often check it against zero first;
> should that be done here, eg.
>
> (vp->v_mount && (vp->v_mount->mnt_flag & MNT_ASYNC)) ? MNT_NOWAIT...
>
> as well? This looks like it might have been overlooked when the async
> filesystem stuff came in, as old versions of this code read :
>
> error = VOP_FSYNC(vp, fp->f_cred, MNT_WAIT, p);
>
> Suggestions? Jonathan, can you try the above and see if it cures your
> problem?
I changed the fsync code to read:
error = VOP_FSYNC(vp, fp->f_cred,
(vp->v_mount && (vp->v_mount->mnt_flag & MNT_ASYNC)) ?
MNT_NOWAIT : MNT_WAIT, p);
And it doesn't crash the kernel any more. I'm not sure if this is
the right fix or not. Julian - you might want to try this as well.
(btw, mail to @iq.com bounces from here. :-( )
--
Jonathan
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