From: Eric Blake <eblake@redhat.com>
To: Jamie Lokier <jamie@shareable.org>
Cc: Sunil Mushran <sunil.mushran@oracle.com>,
Markus Trippelsdorf <markus@trippelsdorf.de>,
Christoph Hellwig <hch@infradead.org>,
Josef Bacik <josef@toxicpanda.com>,
linux-kernel@vger.kernel.org, linux-btrfs@vger.kernel.org,
linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH 1/2] fs: add SEEK_HOLE and SEEK_DATA flags
Date: Mon, 25 Apr 2011 06:37:37 -0600 [thread overview]
Message-ID: <4DB56B11.5090505@redhat.com> (raw)
In-Reply-To: <20110424174902.GA20461@shareable.org>
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On 04/24/2011 11:49 AM, Jamie Lokier wrote:
>> My problem with FIND_* is that we are messing with the well understood
>> semantics of lseek().
>
> fcntl() looks a better fit for FIND_HOLE/DATA anyway.
With fcntl(), it would have to be something like:
off_t offset = start;
if (fcntl (fd, F_FIND_HOLE, &offset) != 0)
; // find failed
// offset is now set to the next location after start
That is, offset has to be passed as an input _and_ output parameter,
since we can't use the int return value of fcntl to convey off_t
information, and since the optional third argument of fcntl has
traditionally been no wider than a pointer which is not the case for
off_t on 32-bit platforms.
--
Eric Blake eblake@redhat.com +1-801-349-2682
Libvirt virtualization library http://libvirt.org
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next prev parent reply other threads:[~2011-04-25 12:37 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-04-21 19:42 [PATCH 1/2] fs: add SEEK_HOLE and SEEK_DATA flags Josef Bacik
2011-04-21 19:42 ` [PATCH 2/2] Btrfs: implement our own ->llseek Josef Bacik
2011-04-21 20:45 ` [PATCH 1/2] fs: add SEEK_HOLE and SEEK_DATA flags Theodore Tso
2011-04-21 21:29 ` Sunil Mushran
2011-04-22 3:23 ` Matthew Wilcox
2011-04-22 4:47 ` Christoph Hellwig
[not found] ` <loom.20110422T001650-760@post.gmane.org>
[not found] ` <BANLkTiknb+hzFAjpwESwMcqMVtkFc0HFQQ@mail.gmail.com>
2011-04-22 4:50 ` Christoph Hellwig
2011-04-22 11:28 ` Markus Trippelsdorf
2011-04-22 11:50 ` Eric Blake
2011-04-22 16:28 ` Sunil Mushran
2011-04-22 16:40 ` Eric Blake
2011-04-22 16:57 ` Sunil Mushran
2011-04-22 17:03 ` Eric Blake
2011-04-22 17:08 ` Sunil Mushran
2011-04-22 18:06 ` Andreas Dilger
2011-04-22 23:33 ` Sunil Mushran
2011-04-24 17:49 ` Jamie Lokier
2011-04-25 12:37 ` Eric Blake [this message]
2011-04-25 14:15 ` Jamie Lokier
[not found] ` <20110422112852.GB1627-tLCgZGx+iJ+kxVt8IV0GqQ@public.gmane.org>
2011-04-22 13:06 ` Eric Blake
2011-04-25 15:02 ` Nick Bowler
[not found] ` <20110425150227.GA10653-7BP4RkwGw0uXmMXjJBpWqg@public.gmane.org>
2011-04-25 15:48 ` Eric Blake
2011-04-22 20:10 ` Jonathan Nieder
2011-04-22 20:49 ` Sunil Mushran
2011-04-25 3:11 ` Valdis.Kletnieks
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