From: Dave Chinner <david@fromorbit.com>
To: Hugh Dickins <hughd@google.com>
Cc: Allison Henderson <achender@linux.vnet.ibm.com>,
linux-ext4@vger.kernel.org
Subject: Re: punch-hole should go beyond i_size
Date: Thu, 12 Jan 2012 13:55:47 +1100 [thread overview]
Message-ID: <20120112025547.GC2806@dastard> (raw)
In-Reply-To: <alpine.LSU.2.00.1201111639240.1833@eggly.anvils>
On Wed, Jan 11, 2012 at 05:02:12PM -0800, Hugh Dickins wrote:
> Hi Allison,
>
> In thinking about fallocate() on tmpfs, I cross-check with ext4
> and find this bug in its implementation of FALLOC_FL_PUNCH_HOLE:
>
> rm -f temp
> fallocate -l 4096 temp
> du temp # shows 4, right
> fallocate -p -l 4096 temp
> du temp # shows 0, right
> rm -f temp
> fallocate -n -l 4096 temp
> du temp # shows 4, right
> fallocate -p -l 4096 temp
> du temp # shows 4, wrong
> rm temp
>
> ext4_ext_punch_hole() contains /* No need to punch hole beyond i_size */
> early return, and trimming to i_size below, but forgets that the other
> variety of fallocate(), with FALLOC_FL_KEEP_SIZE set, may have allocated
> blocks beyond i_size. They can be removed with ftruncate(), but it is
> unexpected for fallocate() not to undo its own work, and xfs does so.
I'm pretty sure that's a bug as XFS allows punching holes in extents
beyond EOF.
Cheers,
Dave.
--
Dave Chinner
david@fromorbit.com
next prev parent reply other threads:[~2012-01-12 2:55 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-01-12 1:02 punch-hole should go beyond i_size Hugh Dickins
2012-01-12 2:55 ` Dave Chinner [this message]
2012-01-12 16:23 ` Allison Henderson
2012-01-13 0:21 ` Hugh Dickins
2012-01-13 3:18 ` Allison Henderson
2012-05-13 21:13 ` Hugh Dickins
2012-05-15 21:36 ` Allison Henderson
2012-05-15 22:38 ` Hugh Dickins
2012-05-16 6:14 ` Lukáš Czerner
2012-05-16 18:09 ` Hugh Dickins
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=20120112025547.GC2806@dastard \
--to=david@fromorbit.com \
--cc=achender@linux.vnet.ibm.com \
--cc=hughd@google.com \
--cc=linux-ext4@vger.kernel.org \
/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.