fold try_to_ascend() into the sole remaining caller

There used to be a bunch of tree-walkers in dcache.c, all alike.
try_to_ascend() had been introduced to abstract a piece of logics
duplicated in all of them.  These days all these tree-walkers are
implemented via the same iterator (d_walk()), which is the only
remaining caller of try_to_ascend(), so let's fold it back...

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

1 files changed, 18 insertions, 31 deletions

diff --git a/fs/dcache.c b/fs/dcache.c
index 7f079d00475a..4bdb300b16e2 100644
--- 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;
         }