From: Ben Myers <bpm@sgi.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: Theodore Ts'o <tytso@mit.edu>, Paul Moore <paul@paul-moore.com>,
Matthew Wilcox <matthew@wil.cx>,
Linus Torvalds <torvalds@linux-foundation.org>,
Eric Paris <eparis@redhat.com>,
LKML <linux-kernel@vger.kernel.org>,
Steven Rostedt <rostedt@goodmis.org>,
xfs@oss.sgi.com, Al Viro <viro@ZenIV.linux.org.uk>,
James Morris <james.l.morris@oracle.com>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
stable <stable@vger.kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Paul McKenney <paulmck@linux.vnet.ibm.com>,
Stephen Smalley <sds@tycho.nsa.gov>
Subject: Re: [PATCH] vfs: Fix possible NULL pointer dereference in inode_permission()
Date: Fri, 10 Jan 2014 12:14:34 -0600 [thread overview]
Message-ID: <20140110181434.GH1935@sgi.com> (raw)
In-Reply-To: <20140110093148.GA26159@infradead.org>
Christoph,
On Fri, Jan 10, 2014 at 01:31:48AM -0800, Christoph Hellwig wrote:
> On Fri, Jan 10, 2014 at 12:06:42AM +0000, Al Viro wrote:
> > Check what XFS is doing ;-/ That's where those call_rcu() have come from.
> > Sure, we can separate the simple "just do call_rcu(...->free_inode)" case
> > and hit it whenever full ->free_inode is there and ->destroy_inode isn't.
> > Not too pretty, but removal of tons of boilerplate might be worth doing
> > that anyway. But ->destroy_inode() is still needed for cases where fs
> > has its own idea of inode lifetime rules. Again, check what XFS is doing
> > in that area...
>
> Btw, I'd really love to get rid of the XFS ->destroy_inode abuse, it's
> been a long time thorn in the flesh.
I believe this behavior is related to freeing of an inode cluster.
> What's really needed there to make XFS behave more similar to everyone
> else is a way for the filesystem to say: "I can't actually free this
> inode right now, but I'll come back to you later".
This test might read something like: "If my link count has gone to zero, and I
am the last inode in my cluster to be freed, and there are other inodes from my
cluster incore, I cannot be freed."
Should be doable. Maybe there are other reasons.
-Ben
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next prev parent reply other threads:[~2014-01-10 18:14 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-01-09 21:27 [PATCH] vfs: Fix possible NULL pointer dereference in inode_permission() Steven Rostedt
2014-01-09 21:42 ` Matthew Wilcox
2014-01-09 21:50 ` Steven Rostedt
2014-01-09 22:31 ` Al Viro
[not found] ` <CA+55aFzCTPYEQCPnLBi1CwmMTocVqCFiCuJ391HkVx1CMw61ug@mail.gmail.com>
2014-01-09 23:10 ` Paul E. McKenney
2014-01-09 23:25 ` Steven Rostedt
2014-01-09 23:27 ` Steven Rostedt
2014-01-09 23:37 ` Eric Paris
2014-01-09 23:45 ` Steven Rostedt
2014-01-09 23:53 ` Linus Torvalds
2014-01-10 0:06 ` Al Viro
2014-01-10 0:09 ` Al Viro
2014-01-10 0:18 ` Linus Torvalds
2014-01-10 2:36 ` James Morris
2014-01-10 9:31 ` Christoph Hellwig
2014-01-10 18:14 ` Ben Myers [this message]
2014-01-11 10:32 ` Christoph Hellwig
2014-01-09 23:45 ` Paul E. McKenney
2014-01-09 23:59 ` Steven Rostedt
2014-01-10 0:44 ` Paul E. McKenney
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