fs: rcu-walk aware d_revalidate method

Require filesystems be aware of .d_revalidate being called in rcu-walk
mode (nd->flags & LOOKUP_RCU). For now do a simple push down, returning
-ECHILD from all implementations.

Signed-off-by: Nick Piggin <npiggin@kernel.dk>

1 files changed, 13 insertions, 4 deletions

diff --git a/fs/gfs2/dentry.c b/fs/gfs2/dentry.c
index 50497f65763b..4a456338b873 100644
--- a/fs/gfs2/dentry.c
+++ b/fs/gfs2/dentry.c
@@ -11,6 +11,7 @@
 #include <linux/completion.h>
 #include <linux/buffer_head.h>
 #include <linux/gfs2_ondisk.h>
+#include <linux/namei.h>
 #include <linux/crc32.h>
 
 #include "gfs2.h"
@@ -34,15 +35,23 @@
 
 static int gfs2_drevalidate(struct dentry *dentry, struct nameidata *nd)
 {
-        struct dentry *parent = dget_parent(dentry);
-        struct gfs2_sbd *sdp = GFS2_SB(parent->d_inode);
-        struct gfs2_inode *dip = GFS2_I(parent->d_inode);
-        struct inode *inode = dentry->d_inode;
+        struct dentry *parent;
+        struct gfs2_sbd *sdp;
+        struct gfs2_inode *dip;
+        struct inode *inode;
         struct gfs2_holder d_gh;
         struct gfs2_inode *ip = NULL;
         int error;
         int had_lock = 0;
 
+        if (nd->flags & LOOKUP_RCU)
+                return -ECHILD;
+
+        parent = dget_parent(dentry);
+        sdp = GFS2_SB(parent->d_inode);
+        dip = GFS2_I(parent->d_inode);
+        inode = dentry->d_inode;
+
         if (inode) {
                 if (is_bad_inode(inode))
                         goto invalid;