From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from userp2120.oracle.com ([156.151.31.85]:41556 "EHLO userp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751428AbeFGFu3 (ORCPT ); Thu, 7 Jun 2018 01:50:29 -0400 Subject: Re: [PATCH 1/2] xfs: setup VFS i_rwsem lockdep state correctly References: <20180607052132.6207-1-david@fromorbit.com> <20180607052132.6207-2-david@fromorbit.com> From: Allison Henderson Message-ID: Date: Wed, 6 Jun 2018 22:50:23 -0700 MIME-Version: 1.0 In-Reply-To: <20180607052132.6207-2-david@fromorbit.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-xfs-owner@vger.kernel.org List-ID: List-Id: xfs To: Dave Chinner , linux-xfs@vger.kernel.org On 06/06/2018 10:21 PM, Dave Chinner wrote: > From: Dave Chinner > > When lockdep is enabled, it changes the type of the inode i_rwsem > semaphore before unlocking a newly instantiated inode. THere is the > possibility that there is already a waiter on that inode lock by the > time we unlock the new inode, so having lockdep re-initialise the > lock is a vector for trouble. > > Avoid this whole situation by setting up the i_rwsem lockdep class > at the same time we set up the XFS inode i_ilock classes and so the > VFS doesn't have to change the lock class itself when it is > potentially unsafe. > > Signed-Off-By: Dave Chinner > --- > fs/xfs/xfs_iops.c | 8 ++++++++ > 1 file changed, 8 insertions(+) > > diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c > index 29484091c0d2..3020c57fc125 100644 > --- a/fs/xfs/xfs_iops.c > +++ b/fs/xfs/xfs_iops.c > @@ -1258,6 +1258,14 @@ xfs_setup_inode( > xfs_diflags_to_iflags(inode, ip); > > if (S_ISDIR(inode->i_mode)) { > + /* > + * We set the i_rwsem class here to avoid potential races with > + * lockdep_annotate_inode_mutex_key() reinitialising the lock > + * after a filehandle lookup has already found the inode in > + * cache before it has been unlocked via unlock_new_inode(). > + */ > + lockdep_set_class(&inode->i_rwsem, > + &inode->i_sb->s_type->i_mutex_dir_key); > lockdep_set_class(&ip->i_lock.mr_lock, &xfs_dir_ilock_class); > ip->d_ops = ip->i_mount->m_dir_inode_ops; > } else { > Ok, you can add my review: Reviewed-by: Allison Henderson