ecryptfs: don't leave RCU pathwalk immediately

If the underlying dentry doesn't have ->d_revalidate(), there's no need to
force dropping out of RCU mode.  All we need for that is to make freeing
ecryptfs_dentry_info RCU-delayed.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

2 files changed, 20 insertions, 15 deletions

diff --git a/fs/ecryptfs/dentry.c b/fs/ecryptfs/dentry.c
index 46e31c92e574..8cefa8e13bcc 100644
--- a/fs/ecryptfs/dentry.c
+++ b/fs/ecryptfs/dentry.c
@@ -44,15 +44,15 @@
  */
 static int ecryptfs_d_revalidate(struct dentry *dentry, unsigned int flags)
 {
-        struct dentry *lower_dentry;
-        int rc = 1;
+        struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry);
+        int rc;
+
+        if (!(lower_dentry->d_flags & DCACHE_OP_REVALIDATE))
+                return 1;
 
         if (flags & LOOKUP_RCU)
                 return -ECHILD;
 
-        lower_dentry = ecryptfs_dentry_to_lower(dentry);
-        if (!(lower_dentry->d_flags & DCACHE_OP_REVALIDATE))
-                goto out;
         rc = lower_dentry->d_op->d_revalidate(lower_dentry, flags);
         if (dentry->d_inode) {
                 struct inode *lower_inode =
@@ -60,12 +60,17 @@ static int ecryptfs_d_revalidate(struct dentry *dentry, unsigned int flags)
 
                 fsstack_copy_attr_all(dentry->d_inode, lower_inode);
         }
-out:
         return rc;
 }
 
 struct kmem_cache *ecryptfs_dentry_info_cache;
 
+static void ecryptfs_dentry_free_rcu(struct rcu_head *head)
+{
+        kmem_cache_free(ecryptfs_dentry_info_cache,
+                container_of(head, struct ecryptfs_dentry_info, rcu));
+}
+
 /**
  * ecryptfs_d_release
  * @dentry: The ecryptfs dentry
@@ -74,15 +79,12 @@ struct kmem_cache *ecryptfs_dentry_info_cache;
  */
 static void ecryptfs_d_release(struct dentry *dentry)
 {
-        if (ecryptfs_dentry_to_private(dentry)) {
-                if (ecryptfs_dentry_to_lower(dentry)) {
-                        dput(ecryptfs_dentry_to_lower(dentry));
-                        mntput(ecryptfs_dentry_to_lower_mnt(dentry));
-                }
-                kmem_cache_free(ecryptfs_dentry_info_cache,
-                                ecryptfs_dentry_to_private(dentry));
+        struct ecryptfs_dentry_info *p = dentry->d_fsdata;
+        if (p) {
+                if (p->lower_path.dentry)
+                        path_put(&p->lower_path);
+                call_rcu(&p->rcu, ecryptfs_dentry_free_rcu);
         }
-        return;
 }
 
 const struct dentry_operations ecryptfs_dops = {
diff --git a/fs/ecryptfs/ecryptfs_kernel.h b/fs/ecryptfs/ecryptfs_kernel.h
index df19d34a033b..e7ad2b3f24a7 100644
--- a/fs/ecryptfs/ecryptfs_kernel.h
+++ b/fs/ecryptfs/ecryptfs_kernel.h
@@ -261,7 +261,10 @@ struct ecryptfs_inode_info {
  * vfsmount too. */
 struct ecryptfs_dentry_info {
         struct path lower_path;
-        struct ecryptfs_crypt_stat *crypt_stat;
+        union {
+                struct ecryptfs_crypt_stat *crypt_stat;
+                struct rcu_head rcu;
+        };
 };
 
 /**