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From: Eric Sandeen <sandeen@sandeen.net>
To: Jan Kara <jack@suse.cz>
Cc: linux-fsdevel@vger.kernel.org, Dave Chinner <dchinner@redhat.com>,
	Surbhi Palande <csurbhi@gmail.com>,
	Kamal Mostafa <kamal@canonical.com>,
	Christoph Hellwig <hch@infradead.org>,
	LKML <linux-kernel@vger.kernel.org>,
	xfs@oss.sgi.com, linux-ext4@vger.kernel.org
Subject: Re: [PATCH 6/8] xfs: Use generic writers counter instead of m_active_trans counter
Date: Fri, 03 Feb 2012 20:42:56 -0600	[thread overview]
Message-ID: <4F2C9B30.1030902@sandeen.net> (raw)
In-Reply-To: <1327091686-23177-7-git-send-email-jack@suse.cz>

On 1/20/12 2:34 PM, Jan Kara wrote:
> m_active_trans counter is racy wrt filesystem freezing. The patch replaces it
> with generic counter of running transactions which is properly synchronized
> with filesystem freezing. Things are a bit more complex because we need to log
> a dummy transaction and free block counters after the filesystem is frozen so
> we need to pass information to _xfs_trans_alloc() whether the transaction is
> part of filesystem freezing or not.
> 
> Signed-off-by: Jan Kara <jack@suse.cz>
> ---

...

>  xfs_trans_t *
>  _xfs_trans_alloc(
>  	xfs_mount_t	*mp,
>  	uint		type,
> -	uint		memflags)
> +	uint		memflags,
> +	bool		freezing)
>  {
>  	xfs_trans_t	*tp;
>  
> -	atomic_inc(&mp->m_active_trans);
> -
> +	if (!freezing)
> +		sb_start_write(mp->m_super, SB_FREEZE_TRANS);
> +	else
> +		WARN_ON(xfs_test_for_freeze(mp) != SB_FREEZE_TRANS);

Hm this could be an issue because for both the umount path and the 
freeze / xfs_quiesce_attr path, we call xfs_log_sbcount which sends
"true" for freezing and we'll trip up here because we won't be
in SB_FREEZE_TRANS during umount.

I think we have to push the flag all the way up to xfs_log_sbcount
callers?

-Eric

WARNING: multiple messages have this Message-ID (diff)
From: Eric Sandeen <sandeen@sandeen.net>
To: Jan Kara <jack@suse.cz>
Cc: Surbhi Palande <csurbhi@gmail.com>,
	Kamal Mostafa <kamal@canonical.com>,
	LKML <linux-kernel@vger.kernel.org>,
	xfs@oss.sgi.com, Christoph Hellwig <hch@infradead.org>,
	Dave Chinner <dchinner@redhat.com>,
	linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org
Subject: Re: [PATCH 6/8] xfs: Use generic writers counter instead of m_active_trans counter
Date: Fri, 03 Feb 2012 20:42:56 -0600	[thread overview]
Message-ID: <4F2C9B30.1030902@sandeen.net> (raw)
In-Reply-To: <1327091686-23177-7-git-send-email-jack@suse.cz>

On 1/20/12 2:34 PM, Jan Kara wrote:
> m_active_trans counter is racy wrt filesystem freezing. The patch replaces it
> with generic counter of running transactions which is properly synchronized
> with filesystem freezing. Things are a bit more complex because we need to log
> a dummy transaction and free block counters after the filesystem is frozen so
> we need to pass information to _xfs_trans_alloc() whether the transaction is
> part of filesystem freezing or not.
> 
> Signed-off-by: Jan Kara <jack@suse.cz>
> ---

...

>  xfs_trans_t *
>  _xfs_trans_alloc(
>  	xfs_mount_t	*mp,
>  	uint		type,
> -	uint		memflags)
> +	uint		memflags,
> +	bool		freezing)
>  {
>  	xfs_trans_t	*tp;
>  
> -	atomic_inc(&mp->m_active_trans);
> -
> +	if (!freezing)
> +		sb_start_write(mp->m_super, SB_FREEZE_TRANS);
> +	else
> +		WARN_ON(xfs_test_for_freeze(mp) != SB_FREEZE_TRANS);

Hm this could be an issue because for both the umount path and the 
freeze / xfs_quiesce_attr path, we call xfs_log_sbcount which sends
"true" for freezing and we'll trip up here because we won't be
in SB_FREEZE_TRANS during umount.

I think we have to push the flag all the way up to xfs_log_sbcount
callers?

-Eric

_______________________________________________
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xfs@oss.sgi.com
http://oss.sgi.com/mailman/listinfo/xfs

  parent reply	other threads:[~2012-02-04  2:42 UTC|newest]

Thread overview: 52+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-01-20 20:34 [PATCH 0/8] Fix filesystem freezing Jan Kara
2012-01-20 20:34 ` Jan Kara
2012-01-20 20:34 ` [PATCH 1/8] fs: Improve filesystem freezing handling Jan Kara
2012-01-20 20:34   ` Jan Kara
2012-02-04  3:03   ` Eric Sandeen
2012-02-04  3:03     ` Eric Sandeen
2012-02-06 15:17     ` Jan Kara
2012-02-06 15:17       ` Jan Kara
2012-01-20 20:34 ` [PATCH 2/8] vfs: Protect write paths by sb_start_write - sb_end_write Jan Kara
2012-01-20 20:34   ` Jan Kara
2012-01-24  8:21   ` Dave Chinner
2012-01-24  8:21     ` Dave Chinner
2012-01-24 11:44     ` Jan Kara
2012-01-24 11:44       ` Jan Kara
2012-02-05  6:13   ` Eric Sandeen
2012-02-05  6:13     ` Eric Sandeen
2012-02-06 15:33     ` Jan Kara
2012-02-06 15:33       ` Jan Kara
2012-01-20 20:34 ` [PATCH 3/8] ext4: Protect ext4_page_mkwrite & ext4_setattr with " Jan Kara
2012-01-20 20:34   ` Jan Kara
2012-01-20 20:34 ` [PATCH 4/8] xfs: Move ilock before transaction start in xfs_setattr_size() Jan Kara
2012-01-20 20:34   ` Jan Kara
2012-01-24  6:59   ` Dave Chinner
2012-01-24  6:59     ` Dave Chinner
2012-01-24 11:52     ` Jan Kara
2012-01-24 11:52       ` Jan Kara
2012-01-20 20:34 ` [PATCH 5/8] xfs: Protect xfs_file_aio_write() & xfs_setattr_size() with sb_start_write - sb_end_write Jan Kara
2012-01-20 20:34   ` Jan Kara
2012-01-24  7:19   ` Dave Chinner
2012-01-24  7:19     ` Dave Chinner
2012-01-24 19:35     ` Jan Kara
2012-01-24 19:35       ` Jan Kara
2012-02-04  4:30   ` Eric Sandeen
2012-02-04  4:30     ` Eric Sandeen
2012-02-04  4:50     ` Eric Sandeen
2012-02-04  4:50       ` Eric Sandeen
2012-02-05 23:11     ` Dave Chinner
2012-02-05 23:11       ` Dave Chinner
2012-01-20 20:34 ` [PATCH 6/8] xfs: Use generic writers counter instead of m_active_trans counter Jan Kara
2012-01-20 20:34   ` Jan Kara
2012-01-24  8:05   ` Dave Chinner
2012-01-24  8:05     ` Dave Chinner
2012-02-04  2:13     ` Eric Sandeen
2012-02-04  2:13       ` Eric Sandeen
2012-02-04  2:42   ` Eric Sandeen [this message]
2012-02-04  2:42     ` Eric Sandeen
2012-02-04  4:34   ` Eric Sandeen
2012-02-04  4:34     ` Eric Sandeen
2012-01-20 20:34 ` [PATCH 7/8] Documentation: Correct s_umount state for freeze_fs/unfreeze_fs Jan Kara
2012-01-20 20:34   ` Jan Kara
2012-01-20 20:34 ` [PATCH 8/8] vfs: Document s_frozen state through freeze_super Jan Kara
2012-01-20 20:34   ` Jan Kara

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