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From: Jan Kara <jack@suse.cz>
To: Christoph Hellwig <hch@infradead.org>
Cc: Jan Kara <jack@suse.cz>,
	Surbhi Palande <surbhi.palande@ubuntu.com>,
	Dave Chinner <david@fromorbit.com>,
	Toshiyuki Okajima <toshi.okajima@jp.fujitsu.com>,
	Ted Ts'o <tytso@mit.edu>,
	Masayoshi MIZUMA <m.mizuma@jp.fujitsu.com>,
	Andreas Dilger <adilger.kernel@dilger.ca>,
	linux-ext4@vger.kernel.org, linux-fsdevel@vger.kernel.org
Subject: Re: [RFC][PATCH] Re: [BUG] ext4: cannot unfreeze a filesystem due to a deadlock
Date: Mon, 2 May 2011 16:20:55 +0200	[thread overview]
Message-ID: <20110502142055.GF4556@quack.suse.cz> (raw)
In-Reply-To: <20110502132204.GA7708@infradead.org>

On Mon 02-05-11 09:22:04, Christoph Hellwig wrote:
> On Mon, May 02, 2011 at 03:16:19PM +0200, Jan Kara wrote:
> > Dave, Christoph, any opinions on this?
> 
> The busyloop in xfs_quiesce_attr which waits for all active transactions
> to finish is supposed to fix this issue.
  Hmm, but what prevents the following race?

  Thread 1					Thread 2
..
xfs_trans_alloc()
  xfs_wait_for_freeze(mp, SB_FREEZE_TRANS);
						freeze_super()
						  ...
						  xfs_fs_freeze()
						    ...
						    xfs_quiesce_attr()
						    ...
  _xfs_trans_alloc()
    atomic_inc(&mp->m_active_trans);
    ... goes on modifying the filesystem

  It seems to be a similar problem as in ext4 - the atomic_inc() and
vfs_check_frozen() are in the wrong order...

> Note that XFS traditionally expects a two stage freeze process where
> we first freeze new VFS-level writes, then flush the caches and then
> stop transactions, wait for them to finish and do the remainder of
> the freeze process, but I really messed that process up when moving
> the sequence to generic code.  Funnily enough it seems to work
> neverless.

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

  reply	other threads:[~2011-05-02 14:20 UTC|newest]

Thread overview: 121+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-02-07 11:53 [BUG] ext4: cannot unfreeze a filesystem due to a deadlock Masayoshi MIZUMA
2011-02-15 16:06 ` Jan Kara
2011-02-15 17:03   ` Ted Ts'o
2011-02-15 17:29     ` Jan Kara
2011-02-15 18:04       ` Ted Ts'o
2011-02-15 19:11         ` Jan Kara
2011-02-15 23:17       ` Toshiyuki Okajima
2011-02-16 14:56         ` Jan Kara
2011-02-17  3:50           ` Toshiyuki Okajima
2011-02-17  5:13             ` Andreas Dilger
2011-02-17 10:41               ` Jan Kara
2011-02-17 10:45             ` Jan Kara
2011-03-28  8:06               ` [RFC][PATCH] " Toshiyuki Okajima
2011-03-30 14:12                 ` Jan Kara
2011-03-31  8:37                   ` Yongqiang Yang
2011-03-31  8:48                     ` Yongqiang Yang
2011-03-31 14:04                     ` Eric Sandeen
2011-03-31 14:36                       ` Yongqiang Yang
2011-03-31 15:25                         ` Eric Sandeen
2011-03-31 16:28                         ` Jan Kara
2011-03-31 12:03                   ` Toshiyuki Okajima
2011-04-05 10:25                     ` Toshiyuki Okajima
2011-04-05 22:54                       ` Jan Kara
2011-04-06  5:09                         ` Toshiyuki Okajima
2011-04-06  5:57                           ` Jan Kara
2011-04-06  7:40                             ` Toshiyuki Okajima
2011-04-06 17:46                               ` Jan Kara
2011-04-15 13:39                                 ` Toshiyuki Okajima
2011-04-15 17:13                                   ` Jan Kara
2011-04-15 17:17                                     ` Eric Sandeen
2011-04-15 17:37                                       ` Jan Kara
2011-04-18  9:05                                     ` Toshiyuki Okajima
2011-04-18 10:51                                       ` Jan Kara
2011-04-19  9:43                                         ` Toshiyuki Okajima
2011-04-22  6:58                                           ` Toshiyuki Okajima
2011-04-22 21:26                                             ` Peter M. Petrakis
2011-04-22 21:40                                               ` Jan Kara
2011-04-22 22:57                                                 ` Peter M. Petrakis
2011-04-22 22:10                                             ` Jan Kara
2011-04-25  6:28                                               ` Toshiyuki Okajima
2011-05-03  8:06                                                 ` Surbhi Palande
2011-05-03 11:01                                       ` Surbhi Palande
2011-05-03 13:08                                         ` (unknown), Surbhi Palande
2011-05-03 13:46                                           ` your mail Jan Kara
2011-05-03 13:56                                             ` Surbhi Palande
2011-05-03 15:26                                               ` Surbhi Palande
2011-05-03 15:36                                               ` Jan Kara
2011-05-03 15:43                                                 ` Surbhi Palande
2011-05-04 19:24                                                   ` Jan Kara
2011-05-06 15:20                                                     ` [RFC][PATCH] Do not accept a new handle when the F.S is frozen Surbhi Palande
2011-05-06 15:20                                                     ` [PATCH] Adding support to freeze and unfreeze a journal Surbhi Palande
2011-05-06 20:56                                                       ` Andreas Dilger
2011-05-07 20:04                                                         ` [PATCH v2] " Surbhi Palande
2011-05-08  8:24                                                           ` Marco Stornelli
2011-05-09  9:04                                                             ` Surbhi Palande
2011-05-09  9:24                                                               ` Jan Kara
2011-05-09  9:53                                                           ` Jan Kara
2011-05-09 13:49                                                             ` Surbhi Palande
2011-05-09 14:51                                                               ` [PATCH v3] " Surbhi Palande
2011-05-09 15:08                                                                 ` Jan Kara
2011-05-10 15:07                                                                   ` [PATCH] " Surbhi Palande
2011-05-10 21:07                                                                     ` Andreas Dilger
2011-05-11  7:46                                                                       ` Surbhi Palande
2011-05-09 15:23                                                                 ` [PATCH v3] " Eric Sandeen
2011-05-11  7:06                                                                   ` Surbhi Palande
2011-05-11  7:10                                                                     ` [PATCH] Attempt to sync the fsstress writes to a frozen F.S Surbhi Palande
2011-05-12 14:22                                                                       ` Eric Sandeen
2011-05-12 14:22                                                                         ` Eric Sandeen
2011-05-24 21:42                                                                       ` Ted Ts'o
2011-05-25 12:00                                                                         ` Surbhi Palande
2011-05-25 12:12                                                                           ` Theodore Tso
2011-05-27 16:28                                                                             ` Jan Kara
2011-05-11  9:05                                                                     ` [PATCH v3] Adding support to freeze and unfreeze a journal Andreas Dilger
2011-05-12  9:40                                                                       ` Surbhi Palande
2011-05-03 13:08                                         ` [PATCH] Prevent dirtying a page when ext4 F.S is frozen Surbhi Palande
2011-05-03 15:19                                         ` [RFC][PATCH] Re: [BUG] ext4: cannot unfreeze a filesystem due to a deadlock Jan Kara
2011-05-04 12:09                                           ` Surbhi Palande
2011-05-04 19:19                                             ` Jan Kara
2011-05-04 21:34                                               ` Surbhi Palande
2011-05-04 22:48                                                 ` Jan Kara
2011-05-05  6:06                                                   ` Surbhi Palande
2011-05-05 11:18                                                     ` Jan Kara
2011-05-05 14:01                                                       ` Surbhi Palande
2011-03-31 23:40                 ` Dave Chinner
2011-03-31 23:53                   ` Eric Sandeen
2011-04-01 14:08                   ` Jan Kara
2011-04-06  5:40                     ` Dave Chinner
2011-04-06  6:18                       ` Jan Kara
2011-04-06 11:21                         ` Dave Chinner
2011-04-06 13:44                           ` Christoph Hellwig
2011-04-06 22:59                             ` Dave Chinner
2011-04-06 17:40                           ` Jan Kara
2011-04-06 22:54                             ` Dave Chinner
2011-04-08 21:33                               ` Jan Kara
2011-05-02  9:07                           ` Surbhi Palande
2011-05-02 10:56                             ` Jan Kara
2011-05-02 11:27                               ` Surbhi Palande
2011-05-02 12:06                                 ` Surbhi Palande
2011-05-02 12:20                                 ` Jan Kara
2011-05-02 12:30                                   ` Surbhi Palande
2011-05-02 13:16                                     ` Jan Kara
2011-05-02 13:22                                       ` Christoph Hellwig
2011-05-02 14:20                                         ` Jan Kara [this message]
2011-05-02 14:41                                           ` Christoph Hellwig
2011-05-02 16:23                                             ` Jan Kara
2011-05-02 16:38                                               ` Christoph Hellwig
2011-05-02 13:22                                       ` Surbhi Palande
2011-05-02 13:24                                         ` Christoph Hellwig
2011-05-02 13:27                                           ` Surbhi Palande
2011-05-02 14:26                                             ` Jan Kara
2011-05-02 14:04                                         ` Eric Sandeen
2011-05-03  7:27                                           ` Surbhi Palande
2011-05-03 20:14                                             ` Eric Sandeen
2011-05-04  8:26                                               ` Surbhi Palande
2011-05-04 14:30                                                 ` Eric Sandeen
2011-05-02 14:01                                     ` Eric Sandeen
2011-04-05 10:44                   ` Toshiyuki Okajima
2011-12-09  1:56 ` Masayoshi MIZUMA
2011-12-15 12:41   ` Masayoshi MIZUMA
2013-11-29  4:58     ` Yongqiang Yang
2013-11-29  8:00       ` Jan Kara

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