Merge branch 'xfs-stack-fixes' into for-next

[firefly-linux-kernel-4.4.55.git] / fs / xfs / xfs_iops.c

diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c
index 9ddfb8190ca1cd56b5f1cd2247e9f54925fce68f..bb3bb658e39cc7cc1021667030a87327dbeb2e57 100644 (file)
--- a/fs/xfs/xfs_iops.c
+++ b/fs/xfs/xfs_iops.c
@@ -48,6 +48,18 @@
 #include <linux/fiemap.h>
 #include <linux/slab.h>
 
+/*
+ * 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