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From: Eric Sandeen <sandeen@redhat.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: Jan Kara <jack@suse.cz>, Ted Tso <tytso@mit.edu>,
	linux-ext4@vger.kernel.org, linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH 3/3] ext4: Block mmapped writes while the fs is frozen
Date: Wed, 18 May 2011 09:03:27 -0500	[thread overview]
Message-ID: <4DD3D1AF.9060809@redhat.com> (raw)
In-Reply-To: <20110518080731.GA2759@infradead.org>

On 5/18/11 3:07 AM, Christoph Hellwig wrote:
> On Wed, May 18, 2011 at 09:56:14AM +0200, Jan Kara wrote:
>> __block_page_mkwrite() and return some error value (EAGAIN translating to
>> VM_FAULT_RETRY would look logical, I just have to think off better error
>> value for VM_FAULT_NOPAGE). But vfs_check_frozen() cannot be in
>> __block_page_mkwrite() since ext4 needs to call that with a transaction
>> started so that would create a deadlock and we need to call
>> vfs_check_frozen() somewhere so that we don't busyloop.
>>
>> I can call vfs_check_frozen() inside block_page_mkwrite() but it would be a
>> bit surprising difference from __block_page_mkwrite() to me. Not sure what
>> the cleanest solution would be here...
> 
> block_page_mkwrite is supposed to be used directly by filesystems and
> do all the right things.  IIRC Eric even mentioned he added
> vfs_check_frozen to it for RHEL, but forgot to push it upstream.

Well, I tried, but it was rejected IIRC.  Still, mea culpa....

I can resurrect what I did for RHEL5 and repost if desired...

-Eric

  reply	other threads:[~2011-05-18 14:03 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-05-10 22:29 [PATCH 0/3] Rewrite ext4_page_mkwrite, fix fs freezing Jan Kara
2011-05-10 22:29 ` [PATCH 1/3] fs: Create __block_page_mkwrite() helper passing error values back Jan Kara
2011-05-17 15:09   ` Christoph Hellwig
2011-05-18  7:35     ` Jan Kara
2011-05-10 22:29 ` [PATCH 2/3] ext4: Rewrite ext4_page_mkwrite() to return locked page Jan Kara
2011-05-10 22:29 ` [PATCH 3/3] ext4: Block mmapped writes while the fs is frozen Jan Kara
2011-05-17 15:11   ` Christoph Hellwig
2011-05-18  7:56     ` Jan Kara
2011-05-18  8:07       ` Christoph Hellwig
2011-05-18 14:03         ` Eric Sandeen [this message]
2011-05-18 15:25           ` Jan Kara
2011-05-18 16:40             ` Eric Sandeen
2011-05-11  0:30 ` [PATCH 0/3] Rewrite ext4_page_mkwrite, fix fs freezing Ted Ts'o
2011-05-11  9:27   ` Jan Kara
2011-05-11 16:48     ` Darrick J. Wong
2011-05-11 17:03       ` Jan Kara
2011-05-11  7:33 ` Amir G.
2011-05-11  9:43   ` Jan Kara
2011-05-11 10:15     ` Amir G.

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