From: Jan Kara <jack@suse.cz>
To: "Fernando Luis Vázquez Cao" <fernando_b1@lab.ntt.co.jp>
Cc: Al Viro <viro@zeniv.linux.org.uk>,
Josef Bacik <jbacik@fusionio.com>,
Eric Sandeen <sandeen@redhat.com>,
Dave Chinner <dchinner@redhat.com>,
Christoph Hellwig <hch@infradead.org>, Jan Kara <jack@suse.cz>,
Luiz Capitulino <lcapitulino@redhat.com>,
linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH 7/17] fsfreeze: fix nested freezing of sb-less bdevs
Date: Wed, 9 Jan 2013 17:24:38 +0100 [thread overview]
Message-ID: <20130109162438.GC17353@quack.suse.cz> (raw)
In-Reply-To: <1357558238.8183.12.camel@nexus.lab.ntt.co.jp>
On Mon 07-01-13 20:30:38, Fernando Luis Vázquez Cao wrote:
> If a frozen bdev does not have a filesystem sitting on top of it any subsequent
> nested freeze will cause a null pointer dereference because freeze_bdev()
> calls drop_super() unconditionally. drop_super() should be called only when
> there is a superblock to drop.
Looks good. You can add:
Reviewed-by: Jan Kara <jack@suse.cz>
Honza
>
> Cc: linux-fsdevel@vger.kernel.org
> Cc: Josef Bacik <jbacik@fusionio.com>
> Cc: Eric Sandeen <sandeen@redhat.com>
> Cc: Christoph Hellwig <hch@infradead.org>
> Cc: Jan Kara <jack@suse.cz>
> Cc: Dave Chinner <dchinner@redhat.com>
> Cc: Luiz Capitulino <lcapitulino@redhat.com>
> Signed-off-by: Fernando Luis Vazquez Cao <fernando@oss.ntt.co.jp>
> ---
>
> diff -urNp linux-3.8-rc1-orig/fs/block_dev.c linux-3.8-rc1/fs/block_dev.c
> --- linux-3.8-rc1-orig/fs/block_dev.c 2012-12-25 11:38:05.072018000 +0900
> +++ linux-3.8-rc1/fs/block_dev.c 2012-12-25 11:50:43.060018000 +0900
> @@ -227,8 +227,8 @@ struct super_block *freeze_bdev(struct b
> * to freeze_bdev grab an active reference and only the last
> * thaw_bdev drops it.
> */
> - sb = get_super(bdev);
> - drop_super(sb);
> + if ((sb = get_super(bdev)) != NULL)
> + drop_super(sb);
> mutex_unlock(&bdev->bd_fsfreeze_mutex);
> return sb;
> }
>
>
--
Jan Kara <jack@suse.cz>
SUSE Labs, CR
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next prev parent reply other threads:[~2013-01-09 16:24 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-01-07 11:18 [PATCH v6 0/17] fsfreeze: miscellaneous fixes and cleanups Fernando Luis Vázquez Cao
2013-01-07 11:21 ` [PATCH 1/17] vfs: add __iterate_supers() and helpers around it Fernando Luis Vázquez Cao
2013-01-07 11:22 ` [PATCH 2/17] fsfreeze: add unlocked version of thaw_super Fernando Luis Vázquez Cao
2013-01-07 11:23 ` [PATCH 3/17] fsfreeze: fix emergency thaw infinite loop Fernando Luis Vázquez Cao
2013-01-07 11:26 ` [PATCH 4/17] fsfreeze: emergency thaw will deadlock on s_umount Fernando Luis Vázquez Cao
2013-01-09 16:12 ` Jan Kara
2013-01-07 11:27 ` [PATCH 5/17] xfs: switch to using super methods for fsfreeze Fernando Luis Vázquez Cao
2013-01-07 11:29 ` [PATCH 6/17] fsfreeze: move emergency thaw code to fs/super.c Fernando Luis Vázquez Cao
2013-01-07 11:30 ` [PATCH 7/17] fsfreeze: fix nested freezing of sb-less bdevs Fernando Luis Vázquez Cao
2013-01-09 16:24 ` Jan Kara [this message]
2013-01-07 11:32 ` [PATCH 8/17] fsfreeze: allow bdev level thaws when the sb is unfrozen Fernando Luis Vázquez Cao
2013-01-09 16:26 ` Jan Kara
2013-01-07 11:34 ` [PATCH 9/17] fsfreeze: freeze_super and thaw_bdev don't play well together Fernando Luis Vázquez Cao
2013-01-07 11:35 ` [PATCH 10/17] fsfreeze: automatically thaw on umount Fernando Luis Vázquez Cao
2013-01-09 17:20 ` Jan Kara
2013-01-10 9:14 ` Fernando Luis Vazquez Cao
2013-01-07 11:36 ` [PATCH 11/17] fsfreeze: add thaw_super_force Fernando Luis Vázquez Cao
2013-01-07 11:38 ` [PATCH 12/17] fsfreeze: sb-level/bdev-level fsfreeze integration Fernando Luis Vázquez Cao
2013-01-09 16:37 ` Jan Kara
2013-01-10 9:57 ` Fernando Luis Vazquez Cao
2013-01-07 11:39 ` [PATCH 13/17] fsfreeze: unfreeze bdevs in addition to filesystems during emergency thaw Fernando Luis Vázquez Cao
2013-01-09 16:41 ` Jan Kara
2013-01-07 11:41 ` [PATCH 14/17] vfs: leverage bd_super in get_super and get_active_super Fernando Luis Vázquez Cao
2013-01-09 16:44 ` Jan Kara
2013-01-07 11:42 ` [PATCH 15/17] btrfs: store pointer to superblock in bd_super Fernando Luis Vázquez Cao
2013-01-07 11:43 ` [PATCH 16/17] fsfreeze: allow freeze counter lock nesting Fernando Luis Vázquez Cao
2013-01-07 11:44 ` [PATCH 17/17] fsfreeze: export freeze_count through mountinfo Fernando Luis Vázquez Cao
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