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, 6 insertions, 1 deletions

diff --git a/fs/ceph/dir.c b/fs/ceph/dir.c
index cc01cf826769..fa7ca04ee816 100644
--- a/fs/ceph/dir.c
+++ b/fs/ceph/dir.c
@@ -990,7 +990,12 @@ static int dir_lease_is_valid(struct inode *dir, struct dentry *dentry)
  */
 static int ceph_d_revalidate(struct dentry *dentry, struct nameidata *nd)
 {
-        struct inode *dir = dentry->d_parent->d_inode;
+        struct inode *dir;
+
+        if (nd->flags & LOOKUP_RCU)
+                return -ECHILD;
+
+        dir = dentry->d_parent->d_inode;
 
         dout("d_revalidate %p '%.*s' inode %p offset %lld\n", dentry,
              dentry->d_name.len, dentry->d_name.name, dentry->d_inode,