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From: Dave Jiang <dave.jiang@intel.com>
To: Jan Kara <jack@suse.cz>
Cc: tytso@mit.edu, linux-nvdimm@lists.01.org,
	darrick.wong@oracle.com, david@fromorbit.com,
	linux-xfs@vger.kernel.org, zwisler@kernel.org,
	linux-fsdevel@vger.kernel.org, lczerner@redhat.com,
	linux-ext4@vger.kernel.org, hch@lst.de
Subject: Re: [PATCH 2/2] [PATCH] xfs: Close race between direct IO and xfs_break_layouts()
Date: Wed, 8 Aug 2018 08:47:39 -0700	[thread overview]
Message-ID: <97fcc79a-2d2e-b2ba-562a-76533fe3696f@intel.com> (raw)
In-Reply-To: <20180808085339.GD15413@quack2.suse.cz>



On 08/08/2018 01:53 AM, Jan Kara wrote:
> On Tue 07-08-18 15:11:43, Dave Jiang wrote:
>> This patch is the duplicate of ross's fix for ext4 for xfs.
>>
>> If the refcount of a page is lowered between the time that it is returned
>> by dax_busy_page() and when the refcount is again checked in
>> xfs_break_layouts() => ___wait_var_event(), the waiting function
>> xfs_wait_dax_page() will never be called.  This means that
>> xfs_break_layouts() will still have 'retry' set to false, so we'll stop
>> looping and never check the refcount of other pages in this inode.
>>
>> Instead, always continue looping as long as dax_layout_busy_page() gives us
>> a page which it found with an elevated refcount.
>>
>> Signed-off-by: Dave Jiang <dave.jiang@intel.com>
> 
> The patch looks good to me. You can add:
> 
> Reviewed-by: Jan Kara <jack@suse.cz>
> 
> Just one minor nit below:
> 
>> @@ -746,9 +744,10 @@ xfs_break_dax_layouts(
>>  	if (!page)
>>  		return 0;
>>  
>> +	*did_unlock = true;
> 
> I think it would be more understandable to name the argument of
> xfs_break_dax_layouts() as 'retry' instead of 'did_unlock' as it's not
> about unlocking anymore.

Thanks for the review Jan! I will change. I was trying to decide between
less code change vs more clear definition. :)

> 
> 							Honza
> 
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  reply	other threads:[~2018-08-08 15:47 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-08-07 22:11 [PATCH 1/2] ext4: Close race between direct IO and ext4_break_layouts() Dave Jiang
2018-08-07 22:11 ` [PATCH 2/2] [PATCH] xfs: Close race between direct IO and xfs_break_layouts() Dave Jiang
2018-08-08  8:53   ` Jan Kara
2018-08-08 15:47     ` Dave Jiang [this message]
2018-08-08  8:49 ` [PATCH 1/2] ext4: Close race between direct IO and ext4_break_layouts() Jan Kara

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