From: Christoph Hellwig <hch@lst.de>
To: David Howells <dhowells@redhat.com>
Cc: Carlos Maiolino <cmaiolino@redhat.com>,
Christoph Hellwig <hch@lst.de>,
linux-fsdevel@vger.kernel.org, adilger@dilger.ca,
jaegeuk@kernel.org, darrick.wong@oracle.com, miklos@szeredi.hu,
rpeterso@redhat.com, linux-xfs@vger.kernel.org
Subject: Re: [PATCH 2/9] cachefiles: drop direct usage of ->bmap method.
Date: Thu, 29 Aug 2019 09:13:12 +0200 [thread overview]
Message-ID: <20190829071312.GE11909@lst.de> (raw)
In-Reply-To: <7003.1566305430@warthog.procyon.org.uk>
On Tue, Aug 20, 2019 at 01:50:30PM +0100, David Howells wrote:
> Carlos Maiolino <cmaiolino@redhat.com> wrote:
>
> > > > + block = page->index;
> > > > + block <<= shift;
> > >
> > > Can't this cause overflows?
> >
> > Hmm, I honestly don't know. I did look at the code, and I couldn't really spot
> > anything concrete.
>
> Maybe, though we'd have to support file sizes over 16 Exabytes for that to be
> a problem.
On 32-bit sysems page->index is a 32-bit value, so you'd overflow at
pretty normal sizes of a few TB.
> Note that bmap() is *only* used to find out if the page is present in the
> cache - and even that I'm not actually doing very well, since I really *ought*
> to check every block in the page.
>
> I really want to replace the use of bmap entirely with iov_iter doing DIO.
> Cachefiles currently does double buffering because it works through the
> pagecache of the underlying to do actual read or write - and this appears to
> cause memory management problems.
Not related to this patch, but using iov_iter with dio is trivial, what
is the blocker therere?
next prev parent reply other threads:[~2019-08-29 7:13 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-08 8:27 [PATCH 0/9 V5] New ->fiemap infrastructure and ->bmap removal Carlos Maiolino
2019-08-08 8:27 ` [PATCH 1/9] fs: Enable bmap() function to properly return errors Carlos Maiolino
2019-08-08 21:24 ` kbuild test robot
2019-08-14 11:14 ` Christoph Hellwig
2019-08-20 11:36 ` Carlos Maiolino
2019-08-08 8:27 ` [PATCH 2/9] cachefiles: drop direct usage of ->bmap method Carlos Maiolino
2019-08-14 11:15 ` Christoph Hellwig
2019-08-20 11:57 ` Carlos Maiolino
2019-08-20 12:50 ` David Howells
2019-08-29 7:13 ` Christoph Hellwig [this message]
2019-08-30 16:17 ` David Howells
2019-08-30 16:59 ` Christoph Hellwig
2019-08-31 0:45 ` David Howells
2019-09-05 22:44 ` Dave Chinner
2019-08-20 13:31 ` David Howells
2019-08-08 8:27 ` [PATCH 3/9] ecryptfs: drop direct calls to ->bmap Carlos Maiolino
2019-08-08 22:50 ` kbuild test robot
2019-08-08 8:27 ` [PATCH 4/9] fibmap: Use bmap instead of ->bmap method in ioctl_fibmap Carlos Maiolino
2019-08-08 20:38 ` kbuild test robot
2019-08-14 11:01 ` Carlos Maiolino
2019-08-14 11:08 ` Christoph Hellwig
2019-08-08 8:27 ` [PATCH 5/9] fs: Move start and length fiemap fields into fiemap_extent_info Carlos Maiolino
2019-08-08 20:21 ` kbuild test robot
2019-08-08 8:27 ` [PATCH 6/9] iomap: Remove length and start fields from iomap_fiemap Carlos Maiolino
2019-08-08 8:27 ` [PATCH 7/9] fiemap: Use a callback to fill fiemap extents Carlos Maiolino
2019-08-09 0:04 ` kbuild test robot
2019-08-14 11:16 ` Christoph Hellwig
2019-08-08 8:27 ` [PATCH 8/9] Use FIEMAP for FIBMAP calls Carlos Maiolino
2019-08-08 8:27 ` Carlos Maiolino
2019-08-09 1:56 ` kbuild test robot
2019-08-14 11:18 ` Christoph Hellwig
2019-08-20 13:01 ` Carlos Maiolino
2019-08-29 7:15 ` Christoph Hellwig
2019-09-10 12:28 ` Carlos Maiolino
2019-09-16 15:58 ` Darrick J. Wong
2019-08-08 8:27 ` [PATCH 9/9] xfs: Get rid of ->bmap Carlos Maiolino
-- strict thread matches above, loose matches on Subject: below --
2019-09-11 13:43 [PATCH 0/9 V6] New ->fiemap infrastructure and ->bmap removal Carlos Maiolino
2019-09-11 13:43 ` [PATCH 2/9] cachefiles: drop direct usage of ->bmap method Carlos Maiolino
2019-07-31 14:12 [PATCH 0/9 V4] New ->fiemap infrastructure and ->bmap removal Carlos Maiolino
2019-07-31 14:12 ` [PATCH 2/9] cachefiles: drop direct usage of ->bmap method Carlos Maiolino
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