linux-ext4 - Re: [PATCH] ext4: block direct I/O writes during ext4

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Message-ID: <20130718141117.GB10419@quack.suse.cz>
Date:	Thu, 18 Jul 2013 16:11:17 +0200
From:	Jan Kara <jack@...e.cz>
To:	Theodore Ts'o <tytso@....edu>
Cc:	Jan Kara <jack@...e.cz>,
	Ext4 Developers List <linux-ext4@...r.kernel.org>,
	stable@...r.kernel.org
Subject: Re: [PATCH] ext4: block direct I/O writes during ext4_truncate

On Wed 17-07-13 14:27:10, Ted Tso wrote:
> On Tue, Jul 16, 2013 at 12:49:42PM -0400, Theodore Ts'o wrote:
> > On Tue, Jul 16, 2013 at 05:46:58PM +0200, Jan Kara wrote:
> > > and ext4_setattr() does (again under i_mutex):
> > >                                         ext4_inode_block_unlocked_dio(inode);
> > >                                         inode_dio_wait(inode);
> > >                                         ext4_inode_resume_unlocked_dio(inode);
> > 
> > Ah, I missed this; thanks for pointing this out.
> 
> I took a closer look, and there are other code paths which call
> ext4_truncate() which don't call ext4_inode_block_unlocked_dio() and
> inode_dio_wait().  In particular, the orphan cleanup code and the
> SETFLAGS ioctl.
  True although both should be harmless. Also you have
ext4_truncate_failed_write() which is harmless as well.

> I suspect the right answer is to move these these calls, and possibly
> also the truncate_pagecache() call.
  Could be.

> The other thing that we probably will want to do as a cleanup for the
> next merge window is to look at merging more of the code paths for
> ext4_punch_hole() and ext4_truncate().
  Yeah, that would be definitely worthwhile effort.

								Honza
-- 
Jan Kara <jack@...e.cz>
SUSE Labs, CR
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