1 files changed, 61 insertions, 37 deletions

diff --git a/fs/dcache.c b/fs/dcache.c
index 87bdb5329c3c..5aa53bc056ba 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -229,7 +229,7 @@ static void __d_free(struct rcu_head *head)
  */
 static void d_free(struct dentry *dentry)
 {
-	BUG_ON(dentry->d_count);
+	BUG_ON(dentry->d_lockref.count);
 	this_cpu_dec(nr_dentry);
 	if (dentry->d_op && dentry->d_op->d_release)
 		dentry->d_op->d_release(dentry);
@@ -467,12 +467,12 @@ relock:
 	}
 
 	if (ref)
-		dentry->d_count--;
+		dentry->d_lockref.count--;
 	/*
 	 * inform the fs via d_prune that this dentry is about to be
 	 * unhashed and destroyed.
 	 */
-	if (dentry->d_flags & DCACHE_OP_PRUNE)
+	if ((dentry->d_flags & DCACHE_OP_PRUNE) && !d_unhashed(dentry))
 		dentry->d_op->d_prune(dentry);
 
 	dentry_lru_del(dentry);
@@ -513,15 +513,10 @@ void dput(struct dentry *dentry)
 		return;
 
 repeat:
-	if (dentry->d_count == 1)
+	if (dentry->d_lockref.count == 1)
 		might_sleep();
-	spin_lock(&dentry->d_lock);
-	BUG_ON(!dentry->d_count);
-	if (dentry->d_count > 1) {
-		dentry->d_count--;
-		spin_unlock(&dentry->d_lock);
+	if (lockref_put_or_lock(&dentry->d_lockref))
 		return;
-	}
 
 	if (dentry->d_flags & DCACHE_OP_DELETE) {
 		if (dentry->d_op->d_delete(dentry))
@@ -535,7 +530,7 @@ repeat:
 	dentry->d_flags |= DCACHE_REFERENCED;
 	dentry_lru_add(dentry);
 
-	dentry->d_count--;
+	dentry->d_lockref.count--;
 	spin_unlock(&dentry->d_lock);
 	return;
 
@@ -590,7 +585,7 @@ int d_invalidate(struct dentry * dentry)
 	 * We also need to leave mountpoints alone,
 	 * directory or not.
 	 */
-	if (dentry->d_count > 1 && dentry->d_inode) {
+	if (dentry->d_lockref.count > 1 && dentry->d_inode) {
 		if (S_ISDIR(dentry->d_inode->i_mode) || d_mountpoint(dentry)) {
 			spin_unlock(&dentry->d_lock);
 			return -EBUSY;
@@ -606,20 +601,33 @@ EXPORT_SYMBOL(d_invalidate);
 /* This must be called with d_lock held */
 static inline void __dget_dlock(struct dentry *dentry)
 {
-	dentry->d_count++;
+	dentry->d_lockref.count++;
 }
 
 static inline void __dget(struct dentry *dentry)
 {
-	spin_lock(&dentry->d_lock);
-	__dget_dlock(dentry);
-	spin_unlock(&dentry->d_lock);
+	lockref_get(&dentry->d_lockref);
 }
 
 struct dentry *dget_parent(struct dentry *dentry)
 {
+	int gotref;
 	struct dentry *ret;
 
+	/*
+	 * Do optimistic parent lookup without any
+	 * locking.
+	 */
+	rcu_read_lock();
+	ret = ACCESS_ONCE(dentry->d_parent);
+	gotref = lockref_get_not_zero(&ret->d_lockref);
+	rcu_read_unlock();
+	if (likely(gotref)) {
+		if (likely(ret == ACCESS_ONCE(dentry->d_parent)))
+			return ret;
+		dput(ret);
+	}
+
 repeat:
 	/*
 	 * Don't need rcu_dereference because we re-check it was correct under
@@ -634,8 +642,8 @@ repeat:
 		goto repeat;
 	}
 	rcu_read_unlock();
-	BUG_ON(!ret->d_count);
-	ret->d_count++;
+	BUG_ON(!ret->d_lockref.count);
+	ret->d_lockref.count++;
 	spin_unlock(&ret->d_lock);
 	return ret;
 }
@@ -718,7 +726,15 @@ restart:
 	spin_lock(&inode->i_lock);
 	hlist_for_each_entry(dentry, &inode->i_dentry, d_alias) {
 		spin_lock(&dentry->d_lock);
-		if (!dentry->d_count) {
+		if (!dentry->d_lockref.count) {
+			/*
+			 * inform the fs via d_prune that this dentry
+			 * is about to be unhashed and destroyed.
+			 */
+			if ((dentry->d_flags & DCACHE_OP_PRUNE) &&
+			    !d_unhashed(dentry))
+				dentry->d_op->d_prune(dentry);
+
 			__dget_dlock(dentry);
 			__d_drop(dentry);
 			spin_unlock(&dentry->d_lock);
@@ -763,12 +779,8 @@ static void try_prune_one_dentry(struct dentry *dentry)
 	/* Prune ancestors. */
 	dentry = parent;
 	while (dentry) {
-		spin_lock(&dentry->d_lock);
-		if (dentry->d_count > 1) {
-			dentry->d_count--;
-			spin_unlock(&dentry->d_lock);
+		if (lockref_put_or_lock(&dentry->d_lockref))
 			return;
-		}
 		dentry = dentry_kill(dentry, 1);
 	}
 }
@@ -793,7 +805,7 @@ static void shrink_dentry_list(struct list_head *list)
 		 * the LRU because of laziness during lookup.  Do not free
 		 * it - just keep it off the LRU list.
 		 */
-		if (dentry->d_count) {
+		if (dentry->d_lockref.count) {
 			dentry_lru_del(dentry);
 			spin_unlock(&dentry->d_lock);
 			continue;
@@ -907,13 +919,14 @@ static void shrink_dcache_for_umount_subtree(struct dentry *dentry)
 			 * inform the fs that this dentry is about to be
 			 * unhashed and destroyed.
 			 */
-			if (dentry->d_flags & DCACHE_OP_PRUNE)
+			if ((dentry->d_flags & DCACHE_OP_PRUNE) &&
+			    !d_unhashed(dentry))
 				dentry->d_op->d_prune(dentry);
 
 			dentry_lru_del(dentry);
 			__d_shrink(dentry);
 
-			if (dentry->d_count != 0) {
+			if (dentry->d_lockref.count != 0) {
 				printk(KERN_ERR
 				       "BUG: Dentry %p{i=%lx,n=%s}"
 				       " still in use (%d)"
@@ -922,7 +935,7 @@ static void shrink_dcache_for_umount_subtree(struct dentry *dentry)
 				       dentry->d_inode ?
 				       dentry->d_inode->i_ino : 0UL,
 				       dentry->d_name.name,
-				       dentry->d_count,
+				       dentry->d_lockref.count,
 				       dentry->d_sb->s_type->name,
 				       dentry->d_sb->s_id);
 				BUG();
@@ -933,7 +946,7 @@ static void shrink_dcache_for_umount_subtree(struct dentry *dentry)
 				list_del(&dentry->d_u.d_child);
 			} else {
 				parent = dentry->d_parent;
-				parent->d_count--;
+				parent->d_lockref.count--;
 				list_del(&dentry->d_u.d_child);
 			}
 
@@ -981,7 +994,7 @@ void shrink_dcache_for_umount(struct super_block *sb)
 
 	dentry = sb->s_root;
 	sb->s_root = NULL;
-	dentry->d_count--;
+	dentry->d_lockref.count--;
 	shrink_dcache_for_umount_subtree(dentry);
 
 	while (!hlist_bl_empty(&sb->s_anon)) {
@@ -1147,7 +1160,7 @@ resume:
 		 * loop in shrink_dcache_parent() might not make any progress
 		 * and loop forever.
 		 */
-		if (dentry->d_count) {
+		if (dentry->d_lockref.count) {
 			dentry_lru_del(dentry);
 		} else if (!(dentry->d_flags & DCACHE_SHRINK_LIST)) {
 			dentry_lru_move_list(dentry, dispose);
@@ -1269,7 +1282,7 @@ struct dentry *__d_alloc(struct super_block *sb, const struct qstr *name)
 	smp_wmb();
 	dentry->d_name.name = dname;
 
-	dentry->d_count = 1;
+	dentry->d_lockref.count = 1;
 	dentry->d_flags = 0;
 	spin_lock_init(&dentry->d_lock);
 	seqcount_init(&dentry->d_seq);
@@ -1782,7 +1795,7 @@ static noinline enum slow_d_compare slow_dentry_cmp(
  * without taking d_lock and checking d_seq sequence count against @seq
  * returned here.
  *
- * A refcount may be taken on the found dentry with the __d_rcu_to_refcount
+ * A refcount may be taken on the found dentry with the d_rcu_to_refcount
  * function.
  *
  * Alternatively, __d_lookup_rcu may be called again to look up the child of
@@ -1970,7 +1983,7 @@ struct dentry *__d_lookup(const struct dentry *parent, const struct qstr *name)
 				goto next;
 		}
 
-		dentry->d_count++;
+		dentry->d_lockref.count++;
 		found = dentry;
 		spin_unlock(&dentry->d_lock);
 		break;
@@ -2069,7 +2082,7 @@ again:
 	spin_lock(&dentry->d_lock);
 	inode = dentry->d_inode;
 	isdir = S_ISDIR(inode->i_mode);
-	if (dentry->d_count == 1) {
+	if (dentry->d_lockref.count == 1) {
 		if (!spin_trylock(&inode->i_lock)) {
 			spin_unlock(&dentry->d_lock);
 			cpu_relax();
@@ -2724,6 +2737,17 @@ char *dynamic_dname(struct dentry *dentry, char *buffer, int buflen,
 	return memcpy(buffer, temp, sz);
 }
 
+char *simple_dname(struct dentry *dentry, char *buffer, int buflen)
+{
+	char *end = buffer + buflen;
+	/* these dentries are never renamed, so d_lock is not needed */
+	if (prepend(&end, &buflen, " (deleted)", 11) ||
+	    prepend_name(&end, &buflen, &dentry->d_name) ||
+	    prepend(&end, &buflen, "/", 1))  
+		end = ERR_PTR(-ENAMETOOLONG);
+	return end;  
+}
+
 /*
  * Write full pathname from the root of the filesystem into the buffer.
  */
@@ -2937,7 +2961,7 @@ resume:
 		}
 		if (!(dentry->d_flags & DCACHE_GENOCIDE)) {
 			dentry->d_flags |= DCACHE_GENOCIDE;
-			dentry->d_count--;
+			dentry->d_lockref.count--;
 		}
 		spin_unlock(&dentry->d_lock);
 	}
@@ -2945,7 +2969,7 @@ resume:
 		struct dentry *child = this_parent;
 		if (!(this_parent->d_flags & DCACHE_GENOCIDE)) {
 			this_parent->d_flags |= DCACHE_GENOCIDE;
-			this_parent->d_count--;
+			this_parent->d_lockref.count--;
 		}
 		this_parent = try_to_ascend(this_parent, locked, seq);
 		if (!this_parent)