linux-ext4 - Re: [RFC][PATCH] Re: [BUG] ext4: cannot unfreeze a filesystem due to a deadlock

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Message-ID: <20110502142617.GG4556@quack.suse.cz>
Date:	Mon, 2 May 2011 16:26:17 +0200
From:	Jan Kara <jack@...e.cz>
To:	Surbhi Palande <surbhi.palande@...ntu.com>
Cc:	Christoph Hellwig <hch@...radead.org>, Jan Kara <jack@...e.cz>,
	Dave Chinner <david@...morbit.com>,
	Toshiyuki Okajima <toshi.okajima@...fujitsu.com>,
	Ted Ts'o <tytso@....edu>,
	Masayoshi MIZUMA <m.mizuma@...fujitsu.com>,
	Andreas Dilger <adilger.kernel@...ger.ca>,
	linux-ext4@...r.kernel.org, linux-fsdevel@...r.kernel.org
Subject: Re: [RFC][PATCH] Re: [BUG] ext4: cannot unfreeze a filesystem due
 to a deadlock

On Mon 02-05-11 16:27:39, Surbhi Palande wrote:
> On 05/02/2011 04:24 PM, Christoph Hellwig wrote:
> >On Mon, May 02, 2011 at 04:22:45PM +0300, Surbhi Palande wrote:
> >>This has another advantage, that it rightfully does not let you
> >>update the access time when the F.S is frozen (touch_atime called
> >>from a read path when the F.S is frozen) Otherwise we also need to
> >>fix this path.
> >In most filesystens atime updates aren't transactional.  They just
> >get written into inode->i_atime, and at some later point when the
> >VFS tries to clean the inode it gets writtent back, either through
> >a transaction or not.
> >
> Yes, agreed. But then when a F.S is frozen the inode should not be
> dirtied? Right? So this has to be fixed?
> Also, in ext4, I think that updating atime starts a transaction.
  Yes, it does. Any mark_inode_dirty() call causes a transaction update.

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