vfs: In d_path don't call d_dname on a mount point

[platform/adaptation/renesas_rcar/renesas_kernel.git] / fs / dcache.c

diff --git a/fs/dcache.c b/fs/dcache.c
index 7f079d0..f7282eb 100644 (file)
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -438,7 +438,7 @@ static struct dentry *d_kill(struct dentry *dentry, struct dentry *parent)
 {
        list_del(&dentry->d_u.d_child);
        /*
-        * Inform try_to_ascend() that we are no longer attached to the
+        * Inform d_walk() that we are no longer attached to the
         * dentry tree
         */
        dentry->d_flags |= DCACHE_DENTRY_KILLED;
@@ -1038,34 +1038,6 @@ void shrink_dcache_sb(struct super_block *sb)
 }
 EXPORT_SYMBOL(shrink_dcache_sb);
 
-/*
- * This tries to ascend one level of parenthood, but
- * we can race with renaming, so we need to re-check
- * the parenthood after dropping the lock and check
- * that the sequence number still matches.
- */
-static struct dentry *try_to_ascend(struct dentry *old, unsigned seq)
-{
-       struct dentry *new = old->d_parent;
-
-       rcu_read_lock();
-       spin_unlock(&old->d_lock);
-       spin_lock(&new->d_lock);
-
-       /*
-        * might go back up the wrong parent if we have had a rename
-        * or deletion
-        */
-       if (new != old->d_parent ||
-                (old->d_flags & DCACHE_DENTRY_KILLED) ||
-                need_seqretry(&rename_lock, seq)) {
-               spin_unlock(&new->d_lock);
-               new = NULL;
-       }
-       rcu_read_unlock();
-       return new;
-}
-
 /**
  * enum d_walk_ret - action to talke during tree walk
  * @D_WALK_CONTINUE:   contrinue walk
@@ -1154,9 +1126,24 @@ resume:
         */
        if (this_parent != parent) {
                struct dentry *child = this_parent;
-               this_parent = try_to_ascend(this_parent, seq);
-               if (!this_parent)
+               this_parent = child->d_parent;
+
+               rcu_read_lock();
+               spin_unlock(&child->d_lock);
+               spin_lock(&this_parent->d_lock);
+
+               /*
+                * might go back up the wrong parent if we have had a rename
+                * or deletion
+                */
+               if (this_parent != child->d_parent ||
+                        (child->d_flags & DCACHE_DENTRY_KILLED) ||
+                        need_seqretry(&rename_lock, seq)) {
+                       spin_unlock(&this_parent->d_lock);
+                       rcu_read_unlock();
                        goto rename_retry;
+               }
+               rcu_read_unlock();
                next = child->d_u.d_child.next;
                goto resume;
        }
@@ -3074,8 +3061,13 @@ char *d_path(const struct path *path, char *buf, int buflen)
         * thus don't need to be hashed.  They also don't need a name until a
         * user wants to identify the object in /proc/pid/fd/.  The little hack
         * below allows us to generate a name for these objects on demand:
+        *
+        * Some pseudo inodes are mountable.  When they are mounted
+        * path->dentry == path->mnt->mnt_root.  In that case don't call d_dname
+        * and instead have d_path return the mounted path.
         */
-       if (path->dentry->d_op && path->dentry->d_op->d_dname)
+       if (path->dentry->d_op && path->dentry->d_op->d_dname &&
+           (!IS_ROOT(path->dentry) || path->dentry != path->mnt->mnt_root))
                return path->dentry->d_op->d_dname(path->dentry, buf, buflen);
 
        rcu_read_lock();