Re: [PATCH 3.16 102/305] xfs: xfs_iflush_cluster fails to abort on error

Ben Hutchings
2016-08-16T19:45:17Z

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On Sun, 2016-08-14 at 09:36 +1000, Dave Chinner wrote:
> On Sat, Aug 13, 2016 at 06:42:51PM +0100, Ben Hutchings wrote:
> >
> > 3.16.37-rc1 review patch.  If anyone has any objections, please let me know.
> >
> > ------------------
> >
> > > > From: Dave Chinner <dchinner@redhat.com>
> >
> > commit b1438f477934f5a4d5a44df26f3079a7575d5946 upstream.
> >
> > When a failure due to an inode buffer occurs, the error handling
> > fails to abort the inode writeback correctly. This can result in the
> > inode being reclaimed whilst still in the AIL, leading to
> > use-after-free situations as well as filesystems that cannot be
> > unmounted as the inode log items left in the AIL never get removed.
> >
> > Fix this by ensuring fatal errors from xfs_imap_to_bp() result in
> > the inode flush being aborted correctly.
> ....
> >
> >
> > > >   /*
> > > > -  * Get the buffer containing the on-disk inode.
> > > > +  * Get the buffer containing the on-disk inode. We are doing a try-lock
> > > > +  * operation here, so we may get  an EAGAIN error. In that case, we
> > > > +  * simply want to return with the inode still dirty.
> > > > +  *
> > > > +  * If we get any other error, we effectively have a corruption situation
> > > > +  * and we cannot flush the inode, so we treat it the same as failing
> > > > +  * xfs_iflush_int().
> > > >    */
> > > >   error = xfs_imap_to_bp(mp, NULL, &ip->i_imap, &dip, &bp, XBF_TRYLOCK,
> > > >          0);
> > > > - if (error || !bp) {
> > > > + if (error == -EAGAIN) {
>
> Wrong. As was pointed out for other -stable trees after users
> reported regressions, the error signs in XFS changed from positive
> to negative in 3.17-rc1.

OK, so do I just need to delete the minus sign there?

Ben.

--
Ben Hutchings
If at first you don't succeed, you're doing about average.

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