From: Jan Kara <jack@suse.cz>
To: Dave Chinner <david@fromorbit.com>
Cc: Jan Kara <jack@suse.cz>,
linux-fsdevel@vger.kernel.org, Eric Sandeen <sandeen@sandeen.net>,
Dave Chinner <dchinner@redhat.com>,
Surbhi Palande <csurbhi@gmail.com>,
Kamal Mostafa <kamal@canonical.com>,
Christoph Hellwig <hch@infradead.org>,
LKML <linux-kernel@vger.kernel.org>,
xfs@oss.sgi.com, linux-ext4@vger.kernel.org
Subject: Re: [PATCH 2/8] vfs: Protect write paths by sb_start_write - sb_end_write
Date: Tue, 24 Jan 2012 12:44:49 +0100 [thread overview]
Message-ID: <20120124114449.GC15974@quack.suse.cz> (raw)
In-Reply-To: <20120124082119.GO15102@dastard>
On Tue 24-01-12 19:21:19, Dave Chinner wrote:
> On Fri, Jan 20, 2012 at 09:34:40PM +0100, Jan Kara wrote:
> > There are three entry points which dirty pages in a filesystem. mmap (handled
> > by block_page_mkwrite()), buffered write (handled by
> > __generic_file_aio_write()), and truncate (it can dirty last partial page -
> > handled inside each filesystem separately). Protect these places with
> > sb_start_write() and sb_end_write().
>
> fallocate can also dirty pages, either during preallocation or hole
> punching. Hence if you are going to promote truncate to
> SB_FREEZE_WRITE protection then you need to promote everything else
> that can zero partial blocks as well.
>
> That also means that anything the has implemented XFS_IOC_ ioctl
> interfaces for prellocation and hole punching (xfs, ocfs2 and gfs2
> IIRC) also needs to be protected in the same way.
Yeah, you are right. As I wrote in the introductory mail, there's problem
with metadata operations (e.g. directory modifications) anyway so we'll
have to audit all places where transactions are started. First I'll do this
for ext4 as a POC and then I'll try to do that for XFS if Eric doesn't beat
me to it (he promised to have a look at XFS part ;).
Honza
--
Jan Kara <jack@suse.cz>
SUSE Labs, CR
next prev parent reply other threads:[~2012-01-24 11:44 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-01-20 20:34 [PATCH 0/8] Fix filesystem freezing Jan Kara
2012-01-20 20:34 ` [PATCH 1/8] fs: Improve filesystem freezing handling Jan Kara
2012-02-04 3:03 ` Eric Sandeen
2012-02-06 15:17 ` Jan Kara
2012-01-20 20:34 ` [PATCH 2/8] vfs: Protect write paths by sb_start_write - sb_end_write Jan Kara
2012-01-24 8:21 ` Dave Chinner
2012-01-24 11:44 ` Jan Kara [this message]
2012-02-05 6:13 ` Eric Sandeen
2012-02-06 15:33 ` Jan Kara
2012-01-20 20:34 ` [PATCH 3/8] ext4: Protect ext4_page_mkwrite & ext4_setattr with " Jan Kara
2012-01-20 20:34 ` [PATCH 4/8] xfs: Move ilock before transaction start in xfs_setattr_size() Jan Kara
2012-01-24 6:59 ` Dave Chinner
2012-01-24 11:52 ` Jan Kara
2012-01-20 20:34 ` [PATCH 5/8] xfs: Protect xfs_file_aio_write() & xfs_setattr_size() with sb_start_write - sb_end_write Jan Kara
2012-01-24 7:19 ` Dave Chinner
2012-01-24 19:35 ` Jan Kara
2012-02-04 4:30 ` Eric Sandeen
2012-02-04 4:50 ` Eric Sandeen
2012-02-05 23:11 ` Dave Chinner
2012-01-20 20:34 ` [PATCH 6/8] xfs: Use generic writers counter instead of m_active_trans counter Jan Kara
2012-01-24 8:05 ` Dave Chinner
2012-02-04 2:13 ` Eric Sandeen
2012-02-04 2:42 ` Eric Sandeen
2012-02-04 4:34 ` Eric Sandeen
2012-01-20 20:34 ` [PATCH 7/8] Documentation: Correct s_umount state for freeze_fs/unfreeze_fs Jan Kara
2012-01-20 20:34 ` [PATCH 8/8] vfs: Document s_frozen state through freeze_super Jan Kara
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