From ef215e394eeb960ea0e8a0fd37ba2fa30260e05b Mon Sep 17 00:00:00 2001 From: Dave Chinner Date: Thu, 7 Jun 2018 07:36:08 -0700 Subject: [PATCH] xfs: setup VFS i_rwsem lockdep state correctly 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. This change is necessary because the equivalent fixes to the VFS code made in commit 1e2e547a93a0 ("do d_instantiate/unlock_new_inode combinations safely") are not relevant to XFS as it has it's own internal inode cache lookup and instantiation routines. Signed-Off-By: Dave Chinner Reviewed-by: Allison Henderson Reviewed-by: Brian Foster Reviewed-by: Darrick J. Wong Signed-off-by: Darrick J. Wong --- 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 { -- 2.45.2