From mboxrd@z Thu Jan 1 00:00:00 1970 From: "J. Bruce Fields" Subject: Re: [PATCH 5/5] vfs: change nondirectory i_mutex ordering to fix quota deadlock Date: Wed, 25 Apr 2012 15:58:15 -0400 Message-ID: <20120425195815.GG751@fieldses.org> References: <20120418215238.GA11959@fieldses.org> <1335367329-929-5-git-send-email-bfields@fieldses.org> <20120425152858.GB751@fieldses.org> <20120425195343.GC27193@quack.suse.cz> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Al Viro , Linus Torvalds , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, "J. Bruce Fields" , switeho@redhat.com To: Jan Kara Return-path: Content-Disposition: inline In-Reply-To: <20120425195343.GC27193@quack.suse.cz> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org On Wed, Apr 25, 2012 at 09:53:43PM +0200, Jan Kara wrote: > On Wed 25-04-12 11:28:58, J. Bruce Fields wrote: > > On Wed, Apr 25, 2012 at 11:22:09AM -0400, bfields@fieldses.org wrote: > > > diff --git a/fs/inode.c b/fs/inode.c > > > index 487c924..13d23b6 100644 > > > --- a/fs/inode.c > > > +++ b/fs/inode.c > > > @@ -961,6 +961,17 @@ void unlock_new_inode(struct inode *inode) > > > } > > > EXPORT_SYMBOL(unlock_new_inode); > > > > > > +/* > > > + * We order !IS_NOQUOTA files before ISNOQUOTA files, and by pointer > > > + * within each category. > > > + */ > > > +static bool nondir_mutex_ordered(struct inode *inode1, struct inode *inode2) > > > +{ > > > + if (IS_NOQUOTA(inode1) == IS_NOQUOTA(inode2)) > > > + return inode1 < inode2; > > > + return IS_NOQUOTA(inode2); > > > +} > > > > This seems kind of awful. Is it what you were thinking of originally, > > Al, and could we live with it? > Yeah, it's pretty ugly and also racy. I'm just now testing patches that > would get rid of I_MUTEX_QUOTA usage for filesystems (except GFS2) and > quota code. GFS2 could be certainly dealt with as well (at least by > introducing a new GFS2 internal lock) so this ugly code can go away. That would be great, thanks! --b.