From: Christoph Hellwig <hch@infradead.org>
To: Christoph Hellwig <hch@lst.de>,
Peter Zijlstra <peterz@infradead.org>,
Lachlan McIlroy <lachlan@sgi.com>,
Daniel J Blueman <daniel.blueman@gmail.com>,
Linux Kernel <linux-kernel@vger.kernel.org>,
xfs@oss.sgi.com
Subject: Re: [2.6.27-rc4] XFS i_lock vs i_iolock...
Date: Tue, 26 Aug 2008 15:35:08 -0400 [thread overview]
Message-ID: <20080826193508.GA17542@infradead.org> (raw)
In-Reply-To: <20080826024547.GX5706@disturbed>
On Tue, Aug 26, 2008 at 12:45:47PM +1000, Dave Chinner wrote:
> XFS: prevent lockdep false positives when locking two inodes
>
> If we call xfs_lock_two_inodes() to grab both the iolock and
> the ilock, then drop the ilocks on both inodes, then grab
> them again (as xfs_swap_extents() does) then lockdep will
> report a locking order problem. This is a false positive.
>
> To avoid this, disallow xfs_lock_two_inodes() fom locking both
> inode locks at once - force calers to make two separate calls.
> This means that nested dropping and regaining of the ilocks
> will retain the same lockdep subclass and so lockdep will
> not see anything wrong with this code.
Looks good. We probably don't need the #ifdef DEBUG as ASSERT is
debug-only anyway.
next prev parent reply other threads:[~2008-08-26 19:33 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-08-22 21:12 [2.6.27-rc4] XFS i_lock vs i_iolock Daniel J Blueman
2008-08-25 1:02 ` Dave Chinner
2008-08-25 2:12 ` Lachlan McIlroy
2008-08-25 3:55 ` Dave Chinner
2008-08-25 6:59 ` Peter Zijlstra
2008-08-25 21:55 ` Christoph Hellwig
2008-08-26 2:45 ` Dave Chinner
2008-08-26 19:35 ` Christoph Hellwig [this message]
2008-08-29 1:20 ` Peter Leckie
2008-08-29 1:37 ` Dave Chinner
2008-08-26 20:13 ` Daniel J Blueman
2008-08-26 21:34 ` Daniel J Blueman
2008-08-26 1:55 ` Dave Chinner
2008-08-25 6:57 ` Peter Zijlstra
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=20080826193508.GA17542@infradead.org \
--to=hch@infradead.org \
--cc=daniel.blueman@gmail.com \
--cc=hch@lst.de \
--cc=lachlan@sgi.com \
--cc=linux-kernel@vger.kernel.org \
--cc=peterz@infradead.org \
--cc=xfs@oss.sgi.com \
/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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox