From: Christoph Hellwig <hch@lst.de>
To: Jan Kara <jack@suse.cz>
Cc: linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org,
reiserfs-devel@vger.kernel.org, ocfs2-devel@oss.oracle.com,
Al Viro <viro@ZenIV.linux.org.uk>, Christoph Hellwig <hch@lst.de>,
"Ted Ts'o" <tytso@mit.edu>, Joel Becker <joel.becker@oracle.com>
Subject: Re: [PATCH] quota: Fix deadlock during path resolution
Date: Thu, 16 Sep 2010 00:52:08 +0200 [thread overview]
Message-ID: <20100915225208.GA1490@lst.de> (raw)
In-Reply-To: <1284586791-8245-1-git-send-email-jack@suse.cz>
On Wed, Sep 15, 2010 at 11:39:51PM +0200, Jan Kara wrote:
> As Al Viro pointed out path resolution during Q_QUOTAON calls to quotactl
> is prone to deadlocks. We hold s_umount semaphore for reading during the
> path resolution and resolution itself may need to acquire the semaphore
> for writing when e. g. autofs mountpoint is passed.
>
> Solve the problem by performing the resolution before we get hold of the
> superblock (and thus s_umount semaphore). The whole thing is complicated
> by the fact that some filesystems (OCFS2) ignore the path argument. So to
> distinguish between filesystem which want the path and which do not we
> introduce new .quota_on_meta callback which does not get the path. OCFS2
> then uses this callback instead of old .quota_on.
FYI I have a patch that switches ocfs to share the quota_on method with
XFS which behaves the same, and consolidate the quota_off method for all
filesystems. I think that's better than adding yet another method.
I'll rebase it and send it out soon.
WARNING: multiple messages have this Message-ID (diff)
From: Christoph Hellwig <hch@lst.de>
To: Jan Kara <jack@suse.cz>
Cc: linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org,
reiserfs-devel@vger.kernel.org, ocfs2-devel@oss.oracle.com,
Al Viro <viro@ZenIV.linux.org.uk>, Christoph Hellwig <hch@lst.de>,
Ted Ts'o <tytso@mit.edu>, Joel Becker <joel.becker@oracle.com>
Subject: [Ocfs2-devel] [PATCH] quota: Fix deadlock during path resolution
Date: Thu, 16 Sep 2010 00:52:08 +0200 [thread overview]
Message-ID: <20100915225208.GA1490@lst.de> (raw)
In-Reply-To: <1284586791-8245-1-git-send-email-jack@suse.cz>
On Wed, Sep 15, 2010 at 11:39:51PM +0200, Jan Kara wrote:
> As Al Viro pointed out path resolution during Q_QUOTAON calls to quotactl
> is prone to deadlocks. We hold s_umount semaphore for reading during the
> path resolution and resolution itself may need to acquire the semaphore
> for writing when e. g. autofs mountpoint is passed.
>
> Solve the problem by performing the resolution before we get hold of the
> superblock (and thus s_umount semaphore). The whole thing is complicated
> by the fact that some filesystems (OCFS2) ignore the path argument. So to
> distinguish between filesystem which want the path and which do not we
> introduce new .quota_on_meta callback which does not get the path. OCFS2
> then uses this callback instead of old .quota_on.
FYI I have a patch that switches ocfs to share the quota_on method with
XFS which behaves the same, and consolidate the quota_off method for all
filesystems. I think that's better than adding yet another method.
I'll rebase it and send it out soon.
next prev parent reply other threads:[~2010-09-15 22:52 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-09-15 21:39 [PATCH] quota: Fix deadlock during path resolution Jan Kara
2010-09-15 21:39 ` [Ocfs2-devel] " Jan Kara
2010-09-15 22:52 ` Christoph Hellwig [this message]
2010-09-15 22:52 ` Christoph Hellwig
2010-09-16 9:55 ` Jan Kara
2010-09-16 9:55 ` [Ocfs2-devel] " Jan Kara
2011-01-07 21:59 ` Ted Ts'o
2011-01-07 21:59 ` [Ocfs2-devel] " Ted Ts'o
2011-01-08 7:47 ` Christoph Hellwig
2011-01-08 7:47 ` [Ocfs2-devel] " Christoph Hellwig
2011-01-12 18:06 ` Jan Kara
2011-01-12 18:06 ` [Ocfs2-devel] " Jan Kara
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