From: Christoph Hellwig <hch@infradead.org>
To: David Howells <dhowells@redhat.com>
Cc: Dave Chinner <david@fromorbit.com>, NeilBrown <neilb@suse.de>,
linux-btrfs@vger.kernel.org, linux-cachefs@redhat.com,
linux-fsdevel@vger.kernel.org, linux-nfs@vger.kernel.org
Subject: Re: [PATCH/RFC] fscache/cachefiles versus btrfs
Date: Mon, 13 Apr 2015 10:30:40 -0700 [thread overview]
Message-ID: <20150413173040.GA30623@infradead.org> (raw)
In-Reply-To: <9282.1428672496@warthog.procyon.org.uk>
On Fri, Apr 10, 2015 at 02:28:16PM +0100, David Howells wrote:
> Dave Chinner <david@fromorbit.com> wrote:
>
> > SEEK_HOLE/SEEK_DATA is what you want, as they are page cache
> > coherent, not extent based operations. And, really if you need it to
> > really be able to find real holes, then a superblock flag might be a
> > better way of marking filesystems with the required capability.
>
> Actually, I wonder if what I want is a kernel_read() that returns ENODATA upon
> encountering a hole at the beginning of the area to be read.
NFS READ_PLUS could also make use of this, but someone needs to actually
implement it.
Until we have that lseek SEEK_HOLE/DATA is the way to go, and the
horrible ->bmap hack needs to die ASAP, I can't believe you managed to
sneak that in in the not too distant past.
next prev parent reply other threads:[~2015-04-13 17:30 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-04-09 7:49 [PATCH/RFC] fscache/cachefiles versus btrfs NeilBrown
2015-04-09 9:23 ` David Howells
2015-04-09 23:52 ` Dave Chinner
2015-04-10 0:42 ` NeilBrown
2015-04-10 1:08 ` Dave Chinner
2015-04-10 13:28 ` David Howells
2015-04-13 17:30 ` Christoph Hellwig [this message]
2015-04-10 1:24 ` NeilBrown
2015-04-20 4:49 ` NeilBrown
2015-04-20 9:27 ` David Howells
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