From: Joel Becker <jlbec@evilplan.org>
To: Amir Goldstein <amir73il@gmail.com>
Cc: Tao Ma <tm@tao.ma>, linux-fsdevel <linux-fsdevel@vger.kernel.org>,
Ext4 Developers List <linux-ext4@vger.kernel.org>,
Theodore Tso <tytso@mit.edu>,
Chris Mason <chris.mason@oracle.com>,
Josef Bacik <josef@redhat.com>
Subject: Re: [LSF/FS TOPIC] Ext4 snapshots status update
Date: Wed, 30 Mar 2011 03:33:23 -0700 [thread overview]
Message-ID: <20110330103321.GB1564@noexit> (raw)
In-Reply-To: <AANLkTinV-WSj2c+dtNyaS-r8xf_c0R5UB-_f73XLm0Z8@mail.gmail.com>
On Wed, Mar 30, 2011 at 08:05:38AM +0200, Amir Goldstein wrote:
> Just wanted to clarify there are 2 differences I notice between mmap
> write to a hole
> and mmap write to COWed file with ENOSPC:
>
> 1. A "good" application can avoid mmap write to a hole.
>
> 2. when initiating a hole, the mkwrite callback is in used (in ext4) to
> reserve disk space for delayed allocation when a page becomes writable.
> with COW a page may already be writable when the flush encounters COW
> with ENOSPC. that flush can even happen after the application has exited,
> so the data will be dropped on the floor silently (like in ext3).
ocfs2 doesn't have delayed allocation yet, so we try and fail
the allocation in write_begin() right under mkwrite().
Joel
--
The Graham Corollary:
The longer a socially-moderated news website exists, the
probability of an old Paul Graham link appearing at the top
approaches certainty.
http://www.jlbec.org/
jlbec@evilplan.org
next prev parent reply other threads:[~2011-03-30 10:33 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-02-03 22:33 [LSF/FS TOPIC] Ext4 snapshots status update Amir Goldstein
2011-02-04 0:20 ` Joel Becker
2011-02-04 5:52 ` Amir Goldstein
2011-03-23 20:19 ` Amir Goldstein
2011-03-30 0:34 ` Joel Becker
2011-03-30 4:16 ` Amir Goldstein
2011-03-30 5:52 ` Tao Ma
2011-03-30 6:05 ` Amir Goldstein
2011-03-30 10:33 ` Joel Becker [this message]
2011-03-30 10:46 ` Amir Goldstein
2011-03-30 11:50 ` Chris Mason
2011-03-30 12:08 ` Amir Goldstein
2011-04-01 0:10 ` [Lsf-pc] " Trond Myklebust
2011-04-01 3:58 ` Amir Goldstein
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20110330103321.GB1564@noexit \
--to=jlbec@evilplan.org \
--cc=amir73il@gmail.com \
--cc=chris.mason@oracle.com \
--cc=josef@redhat.com \
--cc=linux-ext4@vger.kernel.org \
--cc=linux-fsdevel@vger.kernel.org \
--cc=tm@tao.ma \
--cc=tytso@mit.edu \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.