From 93a8614e3a4dccd526aca34e892ac0b27f64b506 Mon Sep 17 00:00:00 2001 From: Dave Chinner Date: Thu, 27 Feb 2014 16:51:39 +1100 Subject: [PATCH] xfs: fix directory inode iolock lockdep false positive The change to add the IO lock to protect the directory extent map during readdir operations has cause lockdep to have a heart attack as it now sees a different locking order on inodes w.r.t. the mmap_sem because readdir has a different ordering to write(). Add a new lockdep class for directory inodes to avoid this false positive. Signed-off-by: Dave Chinner Reviewed-by: Christoph Hellwig Signed-off-by: Dave Chinner --- fs/xfs/xfs_iops.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c index f35d5c953ff9..234e84387ec5 100644 --- a/fs/xfs/xfs_iops.c +++ b/fs/xfs/xfs_iops.c @@ -48,6 +48,18 @@ #include #include +/* + * Directories have different lock order w.r.t. mmap_sem compared to regular + * files. This is due to readdir potentially triggering page faults on a user + * buffer inside filldir(), and this happens with the ilock on the directory + * held. For regular files, the lock order is the other way around - the + * mmap_sem is taken during the page fault, and then we lock the ilock to do + * block mapping. Hence we need a different class for the directory ilock so + * that lockdep can tell them apart. + */ +static struct lock_class_key xfs_nondir_ilock_class; +static struct lock_class_key xfs_dir_ilock_class; + static int xfs_initxattrs( struct inode *inode, @@ -1191,6 +1203,7 @@ xfs_setup_inode( xfs_diflags_to_iflags(inode, ip); ip->d_ops = ip->i_mount->m_nondir_inode_ops; + lockdep_set_class(&ip->i_lock.mr_lock, &xfs_nondir_ilock_class); switch (inode->i_mode & S_IFMT) { case S_IFREG: inode->i_op = &xfs_inode_operations; @@ -1198,6 +1211,7 @@ xfs_setup_inode( inode->i_mapping->a_ops = &xfs_address_space_operations; break; case S_IFDIR: + lockdep_set_class(&ip->i_lock.mr_lock, &xfs_dir_ilock_class); if (xfs_sb_version_hasasciici(&XFS_M(inode->i_sb)->m_sb)) inode->i_op = &xfs_dir_ci_inode_operations; else