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From: tytso@mit.edu
To: Jan Kara <jack@suse.cz>
Cc: linux-ext4@vger.kernel.org
Subject: Re: [PATCH 4/4] ext4: Wait for proper transaction commit on fsync
Date: Tue, 8 Dec 2009 22:51:20 -0500	[thread overview]
Message-ID: <20091209035120.GA27692@thunk.org> (raw)
In-Reply-To: <20091116104331.GB23231@duck.suse.cz>

On Mon, Nov 16, 2009 at 11:43:31AM +0100, Jan Kara wrote:
> > Why do we need an atomic_t here at all?  It's not clear it's
> > necessary.  What specific race are you worried about?
>   Well, i_[data]sync_tid are set and read from several places which aren't
> currently synchronized against each other and I din't want to introduce any
> synchronization. So atomic_t seemed like a clean way of making clear that
> loads / stores from those fields are atomic, regardless of architecture,
> memory alignment or whatever insanity that might make us see just half
> overwritten field.  On all archs where this means just plain stores / loads
> (such as x86), there's no performance hit since the operations are
> implemented as such.

Sorry for not responding to this one sooner, but see this URL:

http://digitalvampire.org/blog/index.php/2007/05/13/atomic-cargo-cults/

							- Ted



  reply	other threads:[~2009-12-09  3:51 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-10-27 12:48 [PATCH 0/4] Fix fsync on ext3 and ext4 (v2) Jan Kara
2009-10-27 12:48 ` [PATCH 1/4] ext3: Wait for proper transaction commit on fsync Jan Kara
2009-10-27 12:48 ` [PATCH 2/4] ext4: Avoid issuing barriers on error recovery path Jan Kara
2009-11-16  0:47   ` Theodore Tso
2009-11-16  2:40     ` [PATCH] ext4: Avoid issuing unnecessary barriers Theodore Ts'o
2009-11-16 10:29       ` Jan Kara
2009-10-27 12:48 ` [PATCH 3/4] ext4: Fix error handling ext4_ind_get_blocks Jan Kara
2009-11-16  2:57   ` Theodore Tso
2009-10-27 12:48 ` [PATCH 4/4] ext4: Wait for proper transaction commit on fsync Jan Kara
2009-11-04 14:57   ` Andi Kleen
2009-11-04 15:53     ` Jan Kara
2009-11-16  0:46   ` Theodore Tso
2009-11-16 10:43     ` Jan Kara
2009-12-09  3:51       ` tytso [this message]
2009-12-09  4:54         ` tytso
2009-12-09 11:29           ` Jan Kara
2009-12-09 14:32             ` tytso
2009-12-09 11:30         ` Jan Kara
2009-11-05 13:02 ` [PATCH 0/4] Fix fsync on ext3 and ext4 (v2) Jan Kara
2009-11-05 16:35   ` Aneesh Kumar K.V
2009-11-11 14:17     ` Jan Kara
  -- strict thread matches above, loose matches on Subject: below --
2009-10-20  7:24 [PATCH 0/4] Fix fsync bug in ext3 and ext4 Jan Kara
2009-10-20  7:24 ` [PATCH 4/4] ext4: Wait for proper transaction commit on fsync Jan Kara
2009-10-20 12:31   ` Aneesh Kumar K.V
2009-10-20 16:05     ` Jan Kara
2009-10-20 14:36   ` Curt Wohlgemuth
2009-10-20 15:52     ` Jan Kara

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