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, 7 insertions, 2 deletions

diff --git a/fs/ecryptfs/dentry.c b/fs/ecryptfs/dentry.c
index 906e803f7f79..6fc4f319b550 100644
--- a/fs/ecryptfs/dentry.c
+++ b/fs/ecryptfs/dentry.c
@@ -44,12 +44,17 @@
  */
 static int ecryptfs_d_revalidate(struct dentry *dentry, struct nameidata *nd)
 {
-        struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry);
-        struct vfsmount *lower_mnt = ecryptfs_dentry_to_lower_mnt(dentry);
+        struct dentry *lower_dentry;
+        struct vfsmount *lower_mnt;
         struct dentry *dentry_save;
         struct vfsmount *vfsmount_save;
         int rc = 1;
 
+        if (nd->flags & LOOKUP_RCU)
+                return -ECHILD;
+
+        lower_dentry = ecryptfs_dentry_to_lower(dentry);
+        lower_mnt = ecryptfs_dentry_to_lower_mnt(dentry);
         if (!lower_dentry->d_op || !lower_dentry->d_op->d_revalidate)
                 goto out;
         dentry_save = nd->path.dentry;