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, 2 deletions

diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index 37e0a8bb077e..58beace14b19 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -938,7 +938,8 @@ static int nfs_check_verifier(struct inode *dir, struct dentry *dentry)
  * component of the path.
  * We check for this using LOOKUP_CONTINUE and LOOKUP_PARENT.
  */
-static inline unsigned int nfs_lookup_check_intent(struct nameidata *nd, unsigned int mask)
+static inline unsigned int nfs_lookup_check_intent(struct nameidata *nd,
+                                                unsigned int mask)
 {
         if (nd->flags & (LOOKUP_CONTINUE|LOOKUP_PARENT))
                 return 0;
@@ -1018,7 +1019,7 @@ int nfs_neg_need_reval(struct inode *dir, struct dentry *dentry,
  * If the parent directory is seen to have changed, we throw out the
  * cached dentry and do a new lookup.
  */
-static int nfs_lookup_revalidate(struct dentry * dentry, struct nameidata *nd)
+static int nfs_lookup_revalidate(struct dentry *dentry, struct nameidata *nd)
 {
         struct inode *dir;
         struct inode *inode;
@@ -1027,6 +1028,9 @@ static int nfs_lookup_revalidate(struct dentry * dentry, struct nameidata *nd)
         struct nfs_fattr *fattr = NULL;
         int error;
 
+        if (nd->flags & LOOKUP_RCU)
+                return -ECHILD;
+
         parent = dget_parent(dentry);
         dir = parent->d_inode;
         nfs_inc_stats(dir, NFSIOS_DENTRYREVALIDATE);