Re: [PATCH 5/7] iomap: write iomap validity checks

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On Wed, Nov 02, 2022 at 01:36:41AM -0700, Christoph Hellwig wrote:
> On Tue, Nov 01, 2022 at 11:34:10AM +1100, Dave Chinner wrote:
> > +	/*
> > +	 * Now we have a locked folio, before we do anything with it we need to
> > +	 * check that the iomap we have cached is not stale. The inode extent
> > +	 * mapping can change due to concurrent IO in flight (e.g.
> > +	 * IOMAP_UNWRITTEN state can change and memory reclaim could have
> > +	 * reclaimed a previously partially written page at this index after IO
> > +	 * completion before this write reaches this file offset) and hence we
> > +	 * could do the wrong thing here (zero a page range incorrectly or fail
> > +	 * to zero) and corrupt data.
> > +	 */
> > +	if (ops->iomap_valid) {
> > +		bool iomap_valid = ops->iomap_valid(iter->inode, &iter->iomap);
> > +
> > +		if (!iomap_valid) {
> > +			iter->iomap.flags |= IOMAP_F_STALE;
> > +			status = 0;
> > +			goto out_unlock;
> > +		}
> > +	}
> 
> So the design so far has been that everything that applies at a page (or
> now folio) level goes into iomap_page_ops, not iomap_ops which is just
> the generic iteration, and I think we should probably do it that way.

I disagree here -- IMHO the sequence number is an attribute of the
iomapping, not the folio.

> I'm a little disappointed that we need two callout almost next to each
> other, but given that we need to validate with the folio locked, and
> gfs2 wants the callback with the folio unlocked I think we have to do
> it that.

<nod>

--D



[Index of Archives]     [Linux Ext4 Filesystem]     [Union Filesystem]     [Filesystem Testing]     [Ceph Users]     [Ecryptfs]     [NTFS 3]     [AutoFS]     [Kernel Newbies]     [Share Photos]     [Security]     [Netfilter]     [Bugtraq]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux Cachefs]     [Reiser Filesystem]     [Linux RAID]     [NTFS 3]     [Samba]     [Device Mapper]     [CEPH Development]

  Powered by Linux