Merge commit 'v2.6.28-rc2' into x86/pci-ioapic-boot-irq-quirks

1 files changed, 381 insertions, 247 deletions

diff --git a/fs/dcache.c b/fs/dcache.c
index 6068c25b393c..a1d86c7f3e66 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -61,7 +61,6 @@ static struct kmem_cache *dentry_cache __read_mostly;
 static unsigned int d_hash_mask __read_mostly;
 static unsigned int d_hash_shift __read_mostly;
 static struct hlist_head *dentry_hashtable __read_mostly;
-static LIST_HEAD(dentry_unused);
 
 /* Statistics gathering. */
 struct dentry_stat_t dentry_stat = {
@@ -70,6 +69,7 @@ struct dentry_stat_t dentry_stat = {
 
 static void __d_free(struct dentry *dentry)
 {
+	WARN_ON(!list_empty(&dentry->d_alias));
 	if (dname_external(dentry))
 		kfree(dentry->d_name.name);
 	kmem_cache_free(dentry_cache, dentry); 
@@ -96,14 +96,6 @@ static void d_free(struct dentry *dentry)
 		call_rcu(&dentry->d_u.d_rcu, d_callback);
 }
 
-static void dentry_lru_remove(struct dentry *dentry)
-{
-	if (!list_empty(&dentry->d_lru)) {
-		list_del_init(&dentry->d_lru);
-		dentry_stat.nr_unused--;
-	}
-}
-
 /*
  * Release the dentry's inode, using the filesystem
  * d_iput() operation if defined.
@@ -130,6 +122,41 @@ static void dentry_iput(struct dentry * dentry)
 	}
 }
 
+/*
+ * dentry_lru_(add|add_tail|del|del_init) must be called with dcache_lock held.
+ */
+static void dentry_lru_add(struct dentry *dentry)
+{
+	list_add(&dentry->d_lru, &dentry->d_sb->s_dentry_lru);
+	dentry->d_sb->s_nr_dentry_unused++;
+	dentry_stat.nr_unused++;
+}
+
+static void dentry_lru_add_tail(struct dentry *dentry)
+{
+	list_add_tail(&dentry->d_lru, &dentry->d_sb->s_dentry_lru);
+	dentry->d_sb->s_nr_dentry_unused++;
+	dentry_stat.nr_unused++;
+}
+
+static void dentry_lru_del(struct dentry *dentry)
+{
+	if (!list_empty(&dentry->d_lru)) {
+		list_del(&dentry->d_lru);
+		dentry->d_sb->s_nr_dentry_unused--;
+		dentry_stat.nr_unused--;
+	}
+}
+
+static void dentry_lru_del_init(struct dentry *dentry)
+{
+	if (likely(!list_empty(&dentry->d_lru))) {
+		list_del_init(&dentry->d_lru);
+		dentry->d_sb->s_nr_dentry_unused--;
+		dentry_stat.nr_unused--;
+	}
+}
+
 /**
  * d_kill - kill dentry and return parent
  * @dentry: dentry to kill
@@ -148,9 +175,12 @@ static struct dentry *d_kill(struct dentry *dentry)
 	dentry_stat.nr_dentry--;	/* For d_free, below */
 	/*drops the locks, at that point nobody can reach this dentry */
 	dentry_iput(dentry);
-	parent = dentry->d_parent;
+	if (IS_ROOT(dentry))
+		parent = NULL;
+	else
+		parent = dentry->d_parent;
 	d_free(dentry);
-	return dentry == parent ? NULL : parent;
+	return parent;
 }
 
 /* 
@@ -212,8 +242,7 @@ repeat:
 		goto kill_it;
   	if (list_empty(&dentry->d_lru)) {
   		dentry->d_flags |= DCACHE_REFERENCED;
-  		list_add(&dentry->d_lru, &dentry_unused);
-  		dentry_stat.nr_unused++;
+		dentry_lru_add(dentry);
   	}
  	spin_unlock(&dentry->d_lock);
 	spin_unlock(&dcache_lock);
@@ -222,7 +251,8 @@ repeat:
 unhash_it:
 	__d_drop(dentry);
 kill_it:
-	dentry_lru_remove(dentry);
+	/* if dentry was on the d_lru list delete it from there */
+	dentry_lru_del(dentry);
 	dentry = d_kill(dentry);
 	if (dentry)
 		goto repeat;
@@ -290,7 +320,7 @@ int d_invalidate(struct dentry * dentry)
 static inline struct dentry * __dget_locked(struct dentry *dentry)
 {
 	atomic_inc(&dentry->d_count);
-	dentry_lru_remove(dentry);
+	dentry_lru_del_init(dentry);
 	return dentry;
 }
 
@@ -406,133 +436,168 @@ static void prune_one_dentry(struct dentry * dentry)
 
 		if (dentry->d_op && dentry->d_op->d_delete)
 			dentry->d_op->d_delete(dentry);
-		dentry_lru_remove(dentry);
+		dentry_lru_del_init(dentry);
 		__d_drop(dentry);
 		dentry = d_kill(dentry);
 		spin_lock(&dcache_lock);
 	}
 }
 
-/**
- * prune_dcache - shrink the dcache
- * @count: number of entries to try and free
- * @sb: if given, ignore dentries for other superblocks
- *         which are being unmounted.
- *
- * Shrink the dcache. This is done when we need
- * more memory, or simply when we need to unmount
- * something (at which point we need to unuse
- * all dentries).
- *
- * This function may fail to free any resources if
- * all the dentries are in use.
+/*
+ * Shrink the dentry LRU on a given superblock.
+ * @sb   : superblock to shrink dentry LRU.
+ * @count: If count is NULL, we prune all dentries on superblock.
+ * @flags: If flags is non-zero, we need to do special processing based on
+ * which flags are set. This means we don't need to maintain multiple
+ * similar copies of this loop.
  */
- 
-static void prune_dcache(int count, struct super_block *sb)
+static void __shrink_dcache_sb(struct super_block *sb, int *count, int flags)
 {
-	spin_lock(&dcache_lock);
-	for (; count ; count--) {
-		struct dentry *dentry;
-		struct list_head *tmp;
-		struct rw_semaphore *s_umount;
-
-		cond_resched_lock(&dcache_lock);
+	LIST_HEAD(referenced);
+	LIST_HEAD(tmp);
+	struct dentry *dentry;
+	int cnt = 0;
 
-		tmp = dentry_unused.prev;
-		if (sb) {
-			/* Try to find a dentry for this sb, but don't try
-			 * too hard, if they aren't near the tail they will
-			 * be moved down again soon
+	BUG_ON(!sb);
+	BUG_ON((flags & DCACHE_REFERENCED) && count == NULL);
+	spin_lock(&dcache_lock);
+	if (count != NULL)
+		/* called from prune_dcache() and shrink_dcache_parent() */
+		cnt = *count;
+restart:
+	if (count == NULL)
+		list_splice_init(&sb->s_dentry_lru, &tmp);
+	else {
+		while (!list_empty(&sb->s_dentry_lru)) {
+			dentry = list_entry(sb->s_dentry_lru.prev,
+					struct dentry, d_lru);
+			BUG_ON(dentry->d_sb != sb);
+
+			spin_lock(&dentry->d_lock);
+			/*
+			 * If we are honouring the DCACHE_REFERENCED flag and
+			 * the dentry has this flag set, don't free it. Clear
+			 * the flag and put it back on the LRU.
 			 */
-			int skip = count;
-			while (skip && tmp != &dentry_unused &&
-			    list_entry(tmp, struct dentry, d_lru)->d_sb != sb) {
-				skip--;
-				tmp = tmp->prev;
+			if ((flags & DCACHE_REFERENCED)
+				&& (dentry->d_flags & DCACHE_REFERENCED)) {
+				dentry->d_flags &= ~DCACHE_REFERENCED;
+				list_move_tail(&dentry->d_lru, &referenced);
+				spin_unlock(&dentry->d_lock);
+			} else {
+				list_move_tail(&dentry->d_lru, &tmp);
+				spin_unlock(&dentry->d_lock);
+				cnt--;
+				if (!cnt)
+					break;
 			}
+			cond_resched_lock(&dcache_lock);
 		}
-		if (tmp == &dentry_unused)
-			break;
-		list_del_init(tmp);
-		prefetch(dentry_unused.prev);
- 		dentry_stat.nr_unused--;
-		dentry = list_entry(tmp, struct dentry, d_lru);
-
- 		spin_lock(&dentry->d_lock);
+	}
+	while (!list_empty(&tmp)) {
+		dentry = list_entry(tmp.prev, struct dentry, d_lru);
+		dentry_lru_del_init(dentry);
+		spin_lock(&dentry->d_lock);
 		/*
 		 * We found an inuse dentry which was not removed from
-		 * dentry_unused because of laziness during lookup.  Do not free
-		 * it - just keep it off the dentry_unused list.
+		 * the LRU because of laziness during lookup.  Do not free
+		 * it - just keep it off the LRU list.
 		 */
- 		if (atomic_read(&dentry->d_count)) {
- 			spin_unlock(&dentry->d_lock);
+		if (atomic_read(&dentry->d_count)) {
+			spin_unlock(&dentry->d_lock);
 			continue;
 		}
-		/* If the dentry was recently referenced, don't free it. */
-		if (dentry->d_flags & DCACHE_REFERENCED) {
-			dentry->d_flags &= ~DCACHE_REFERENCED;
- 			list_add(&dentry->d_lru, &dentry_unused);
- 			dentry_stat.nr_unused++;
- 			spin_unlock(&dentry->d_lock);
+		prune_one_dentry(dentry);
+		/* dentry->d_lock was dropped in prune_one_dentry() */
+		cond_resched_lock(&dcache_lock);
+	}
+	if (count == NULL && !list_empty(&sb->s_dentry_lru))
+		goto restart;
+	if (count != NULL)
+		*count = cnt;
+	if (!list_empty(&referenced))
+		list_splice(&referenced, &sb->s_dentry_lru);
+	spin_unlock(&dcache_lock);
+}
+
+/**
+ * prune_dcache - shrink the dcache
+ * @count: number of entries to try to free
+ *
+ * Shrink the dcache. This is done when we need more memory, or simply when we
+ * need to unmount something (at which point we need to unuse all dentries).
+ *
+ * This function may fail to free any resources if all the dentries are in use.
+ */
+static void prune_dcache(int count)
+{
+	struct super_block *sb;
+	int w_count;
+	int unused = dentry_stat.nr_unused;
+	int prune_ratio;
+	int pruned;
+
+	if (unused == 0 || count == 0)
+		return;
+	spin_lock(&dcache_lock);
+restart:
+	if (count >= unused)
+		prune_ratio = 1;
+	else
+		prune_ratio = unused / count;
+	spin_lock(&sb_lock);
+	list_for_each_entry(sb, &super_blocks, s_list) {
+		if (sb->s_nr_dentry_unused == 0)
 			continue;
-		}
-		/*
-		 * If the dentry is not DCACHED_REFERENCED, it is time
-		 * to remove it from the dcache, provided the super block is
-		 * NULL (which means we are trying to reclaim memory)
-		 * or this dentry belongs to the same super block that
-		 * we want to shrink.
-		 */
-		/*
-		 * If this dentry is for "my" filesystem, then I can prune it
-		 * without taking the s_umount lock (I already hold it).
+		sb->s_count++;
+		/* Now, we reclaim unused dentrins with fairness.
+		 * We reclaim them same percentage from each superblock.
+		 * We calculate number of dentries to scan on this sb
+		 * as follows, but the implementation is arranged to avoid
+		 * overflows:
+		 * number of dentries to scan on this sb =
+		 * count * (number of dentries on this sb /
+		 * number of dentries in the machine)
 		 */
-		if (sb && dentry->d_sb == sb) {
-			prune_one_dentry(dentry);
-			continue;
-		}
+		spin_unlock(&sb_lock);
+		if (prune_ratio != 1)
+			w_count = (sb->s_nr_dentry_unused / prune_ratio) + 1;
+		else
+			w_count = sb->s_nr_dentry_unused;
+		pruned = w_count;
 		/*
-		 * ...otherwise we need to be sure this filesystem isn't being
-		 * unmounted, otherwise we could race with
-		 * generic_shutdown_super(), and end up holding a reference to
-		 * an inode while the filesystem is unmounted.
-		 * So we try to get s_umount, and make sure s_root isn't NULL.
-		 * (Take a local copy of s_umount to avoid a use-after-free of
-		 * `dentry').
+		 * We need to be sure this filesystem isn't being unmounted,
+		 * otherwise we could race with generic_shutdown_super(), and
+		 * end up holding a reference to an inode while the filesystem
+		 * is unmounted.  So we try to get s_umount, and make sure
+		 * s_root isn't NULL.
 		 */
-		s_umount = &dentry->d_sb->s_umount;
-		if (down_read_trylock(s_umount)) {
-			if (dentry->d_sb->s_root != NULL) {
-				prune_one_dentry(dentry);
-				up_read(s_umount);
-				continue;
+		if (down_read_trylock(&sb->s_umount)) {
+			if ((sb->s_root != NULL) &&
+			    (!list_empty(&sb->s_dentry_lru))) {
+				spin_unlock(&dcache_lock);
+				__shrink_dcache_sb(sb, &w_count,
+						DCACHE_REFERENCED);
+				pruned -= w_count;
+				spin_lock(&dcache_lock);
 			}
-			up_read(s_umount);
+			up_read(&sb->s_umount);
 		}
-		spin_unlock(&dentry->d_lock);
+		spin_lock(&sb_lock);
+		count -= pruned;
 		/*
-		 * Insert dentry at the head of the list as inserting at the
-		 * tail leads to a cycle.
+		 * restart only when sb is no longer on the list and
+		 * we have more work to do.
 		 */
- 		list_add(&dentry->d_lru, &dentry_unused);
-		dentry_stat.nr_unused++;
+		if (__put_super_and_need_restart(sb) && count > 0) {
+			spin_unlock(&sb_lock);
+			goto restart;
+		}
 	}
+	spin_unlock(&sb_lock);
 	spin_unlock(&dcache_lock);
 }
 
-/*
- * Shrink the dcache for the specified super block.
- * This allows us to unmount a device without disturbing
- * the dcache for the other devices.
- *
- * This implementation makes just two traversals of the
- * unused list.  On the first pass we move the selected
- * dentries to the most recent end, and on the second
- * pass we free them.  The second pass must restart after
- * each dput(), but since the target dentries are all at
- * the end, it's really just a single traversal.
- */
-
 /**
  * shrink_dcache_sb - shrink dcache for a superblock
  * @sb: superblock
@@ -541,44 +606,9 @@ static void prune_dcache(int count, struct super_block *sb)
  * is used to free the dcache before unmounting a file
  * system
  */
-
 void shrink_dcache_sb(struct super_block * sb)
 {
-	struct list_head *tmp, *next;
-	struct dentry *dentry;
-
-	/*
-	 * Pass one ... move the dentries for the specified
-	 * superblock to the most recent end of the unused list.
-	 */
-	spin_lock(&dcache_lock);
-	list_for_each_prev_safe(tmp, next, &dentry_unused) {
-		dentry = list_entry(tmp, struct dentry, d_lru);
-		if (dentry->d_sb != sb)
-			continue;
-		list_move_tail(tmp, &dentry_unused);
-	}
-
-	/*
-	 * Pass two ... free the dentries for this superblock.
-	 */
-repeat:
-	list_for_each_prev_safe(tmp, next, &dentry_unused) {
-		dentry = list_entry(tmp, struct dentry, d_lru);
-		if (dentry->d_sb != sb)
-			continue;
-		dentry_stat.nr_unused--;
-		list_del_init(tmp);
-		spin_lock(&dentry->d_lock);
-		if (atomic_read(&dentry->d_count)) {
-			spin_unlock(&dentry->d_lock);
-			continue;
-		}
-		prune_one_dentry(dentry);
-		cond_resched_lock(&dcache_lock);
-		goto repeat;
-	}
-	spin_unlock(&dcache_lock);
+	__shrink_dcache_sb(sb, NULL, 0);
 }
 
 /*
@@ -595,7 +625,7 @@ static void shrink_dcache_for_umount_subtree(struct dentry *dentry)
 
 	/* detach this root from the system */
 	spin_lock(&dcache_lock);
-	dentry_lru_remove(dentry);
+	dentry_lru_del_init(dentry);
 	__d_drop(dentry);
 	spin_unlock(&dcache_lock);
 
@@ -609,7 +639,7 @@ static void shrink_dcache_for_umount_subtree(struct dentry *dentry)
 			spin_lock(&dcache_lock);
 			list_for_each_entry(loop, &dentry->d_subdirs,
 					    d_u.d_child) {
-				dentry_lru_remove(loop);
+				dentry_lru_del_init(loop);
 				__d_drop(loop);
 				cond_resched_lock(&dcache_lock);
 			}
@@ -640,11 +670,12 @@ static void shrink_dcache_for_umount_subtree(struct dentry *dentry)
 				BUG();
 			}
 
-			parent = dentry->d_parent;
-			if (parent == dentry)
+			if (IS_ROOT(dentry))
 				parent = NULL;
-			else
+			else {
+				parent = dentry->d_parent;
 				atomic_dec(&parent->d_count);
+			}
 
 			list_del(&dentry->d_u.d_child);
 			detached++;
@@ -791,14 +822,13 @@ resume:
 		struct dentry *dentry = list_entry(tmp, struct dentry, d_u.d_child);
 		next = tmp->next;
 
-		dentry_lru_remove(dentry);
+		dentry_lru_del_init(dentry);
 		/* 
 		 * move only zero ref count dentries to the end 
 		 * of the unused list for prune_dcache
 		 */
 		if (!atomic_read(&dentry->d_count)) {
-			list_add_tail(&dentry->d_lru, &dentry_unused);
-			dentry_stat.nr_unused++;
+			dentry_lru_add_tail(dentry);
 			found++;
 		}
 
@@ -840,10 +870,11 @@ out:
  
 void shrink_dcache_parent(struct dentry * parent)
 {
+	struct super_block *sb = parent->d_sb;
 	int found;
 
 	while ((found = select_parent(parent)) != 0)
-		prune_dcache(found, parent->d_sb);
+		__shrink_dcache_sb(sb, &found, 0);
 }
 
 /*
@@ -863,7 +894,7 @@ static int shrink_dcache_memory(int nr, gfp_t gfp_mask)
 	if (nr) {
 		if (!(gfp_mask & __GFP_FS))
 			return -1;
-		prune_dcache(nr, NULL);
+		prune_dcache(nr);
 	}
 	return (dentry_stat.nr_unused / 100) * sysctl_vfs_cache_pressure;
 }
@@ -951,6 +982,15 @@ struct dentry *d_alloc_name(struct dentry *parent, const char *name)
 	return d_alloc(parent, &q);
 }
 
+/* the caller must hold dcache_lock */
+static void __d_instantiate(struct dentry *dentry, struct inode *inode)
+{
+	if (inode)
+		list_add(&dentry->d_alias, &inode->i_dentry);
+	dentry->d_inode = inode;
+	fsnotify_d_instantiate(dentry, inode);
+}
+
 /**
  * d_instantiate - fill in inode information for a dentry
  * @entry: dentry to complete
@@ -970,10 +1010,7 @@ void d_instantiate(struct dentry *entry, struct inode * inode)
 {
 	BUG_ON(!list_empty(&entry->d_alias));
 	spin_lock(&dcache_lock);
-	if (inode)
-		list_add(&entry->d_alias, &inode->i_dentry);
-	entry->d_inode = inode;
-	fsnotify_d_instantiate(entry, inode);
+	__d_instantiate(entry, inode);
 	spin_unlock(&dcache_lock);
 	security_d_instantiate(entry, inode);
 }
@@ -1003,7 +1040,7 @@ static struct dentry *__d_instantiate_unique(struct dentry *entry,
 	unsigned int hash = entry->d_name.hash;
 
 	if (!inode) {
-		entry->d_inode = NULL;
+		__d_instantiate(entry, NULL);
 		return NULL;
 	}
 
@@ -1022,9 +1059,7 @@ static struct dentry *__d_instantiate_unique(struct dentry *entry,
 		return alias;
 	}
 
-	list_add(&entry->d_alias, &inode->i_dentry);
-	entry->d_inode = inode;
-	fsnotify_d_instantiate(entry, inode);
+	__d_instantiate(entry, inode);
 	return NULL;
 }
 
@@ -1085,69 +1120,71 @@ static inline struct hlist_head *d_hash(struct dentry *parent,
 }
 
 /**
- * d_alloc_anon - allocate an anonymous dentry
+ * d_obtain_alias - find or allocate a dentry for a given inode
  * @inode: inode to allocate the dentry for
  *
- * This is similar to d_alloc_root.  It is used by filesystems when
- * creating a dentry for a given inode, often in the process of 
- * mapping a filehandle to a dentry.  The returned dentry may be
- * anonymous, or may have a full name (if the inode was already
- * in the cache).  The file system may need to make further
- * efforts to connect this dentry into the dcache properly.
+ * Obtain a dentry for an inode resulting from NFS filehandle conversion or
+ * similar open by handle operations.  The returned dentry may be anonymous,
+ * or may have a full name (if the inode was already in the cache).
  *
- * When called on a directory inode, we must ensure that
- * the inode only ever has one dentry.  If a dentry is
- * found, that is returned instead of allocating a new one.
+ * When called on a directory inode, we must ensure that the inode only ever
+ * has one dentry.  If a dentry is found, that is returned instead of
+ * allocating a new one.
  *
  * On successful return, the reference to the inode has been transferred
- * to the dentry.  If %NULL is returned (indicating kmalloc failure),
- * the reference on the inode has not been released.
+ * to the dentry.  In case of an error the reference on the inode is released.
+ * To make it easier to use in export operations a %NULL or IS_ERR inode may
+ * be passed in and will be the error will be propagate to the return value,
+ * with a %NULL @inode replaced by ERR_PTR(-ESTALE).
  */
-
-struct dentry * d_alloc_anon(struct inode *inode)
+struct dentry *d_obtain_alias(struct inode *inode)
 {
 	static const struct qstr anonstring = { .name = "" };
 	struct dentry *tmp;
 	struct dentry *res;
 
-	if ((res = d_find_alias(inode))) {
-		iput(inode);
-		return res;
-	}
+	if (!inode)
+		return ERR_PTR(-ESTALE);
+	if (IS_ERR(inode))
+		return ERR_CAST(inode);
 
-	tmp = d_alloc(NULL, &anonstring);
-	if (!tmp)
-		return NULL;
+	res = d_find_alias(inode);
+	if (res)
+		goto out_iput;
 
+	tmp = d_alloc(NULL, &anonstring);
+	if (!tmp) {
+		res = ERR_PTR(-ENOMEM);
+		goto out_iput;
+	}
 	tmp->d_parent = tmp; /* make sure dput doesn't croak */
-	
+
 	spin_lock(&dcache_lock);
 	res = __d_find_alias(inode, 0);
-	if (!res) {
-		/* attach a disconnected dentry */
-		res = tmp;
-		tmp = NULL;
-		spin_lock(&res->d_lock);
-		res->d_sb = inode->i_sb;
-		res->d_parent = res;
-		res->d_inode = inode;
-		res->d_flags |= DCACHE_DISCONNECTED;
-		res->d_flags &= ~DCACHE_UNHASHED;
-		list_add(&res->d_alias, &inode->i_dentry);
-		hlist_add_head(&res->d_hash, &inode->i_sb->s_anon);
-		spin_unlock(&res->d_lock);
-
-		inode = NULL; /* don't drop reference */
+	if (res) {
+		spin_unlock(&dcache_lock);
+		dput(tmp);
+		goto out_iput;
 	}
+
+	/* attach a disconnected dentry */
+	spin_lock(&tmp->d_lock);
+	tmp->d_sb = inode->i_sb;
+	tmp->d_inode = inode;
+	tmp->d_flags |= DCACHE_DISCONNECTED;
+	tmp->d_flags &= ~DCACHE_UNHASHED;
+	list_add(&tmp->d_alias, &inode->i_dentry);
+	hlist_add_head(&tmp->d_hash, &inode->i_sb->s_anon);
+	spin_unlock(&tmp->d_lock);
+
 	spin_unlock(&dcache_lock);
+	return tmp;
 
-	if (inode)
-		iput(inode);
-	if (tmp)
-		dput(tmp);
+ out_iput:
+	iput(inode);
 	return res;
 }
-
+EXPORT_SYMBOL_GPL(d_obtain_alias);
 
 /**
  * d_splice_alias - splice a disconnected dentry into the tree if one exists
@@ -1174,17 +1211,14 @@ struct dentry *d_splice_alias(struct inode *inode, struct dentry *dentry)
 		new = __d_find_alias(inode, 1);
 		if (new) {
 			BUG_ON(!(new->d_flags & DCACHE_DISCONNECTED));
-			fsnotify_d_instantiate(new, inode);
 			spin_unlock(&dcache_lock);
 			security_d_instantiate(new, inode);
 			d_rehash(dentry);
 			d_move(new, dentry);
 			iput(inode);
 		} else {
-			/* d_instantiate takes dcache_lock, so we do it by hand */
-			list_add(&dentry->d_alias, &inode->i_dentry);
-			dentry->d_inode = inode;
-			fsnotify_d_instantiate(dentry, inode);
+			/* already taking dcache_lock, so d_add() by hand */
+			__d_instantiate(dentry, inode);
 			spin_unlock(&dcache_lock);
 			security_d_instantiate(dentry, inode);
 			d_rehash(dentry);
@@ -1194,6 +1228,106 @@ struct dentry *d_splice_alias(struct inode *inode, struct dentry *dentry)
 	return new;
 }
 
+/**
+ * d_add_ci - lookup or allocate new dentry with case-exact name
+ * @inode:  the inode case-insensitive lookup has found
+ * @dentry: the negative dentry that was passed to the parent's lookup func
+ * @name:   the case-exact name to be associated with the returned dentry
+ *
+ * This is to avoid filling the dcache with case-insensitive names to the
+ * same inode, only the actual correct case is stored in the dcache for
+ * case-insensitive filesystems.
+ *
+ * For a case-insensitive lookup match and if the the case-exact dentry
+ * already exists in in the dcache, use it and return it.
+ *
+ * If no entry exists with the exact case name, allocate new dentry with
+ * the exact case, and return the spliced entry.
+ */
+struct dentry *d_add_ci(struct dentry *dentry, struct inode *inode,
+			struct qstr *name)
+{
+	int error;
+	struct dentry *found;
+	struct dentry *new;
+
+	/* Does a dentry matching the name exist already? */
+	found = d_hash_and_lookup(dentry->d_parent, name);
+	/* If not, create it now and return */
+	if (!found) {
+		new = d_alloc(dentry->d_parent, name);
+		if (!new) {
+			error = -ENOMEM;
+			goto err_out;
+		}
+		found = d_splice_alias(inode, new);
+		if (found) {
+			dput(new);
+			return found;
+		}
+		return new;
+	}
+	/* Matching dentry exists, check if it is negative. */
+	if (found->d_inode) {
+		if (unlikely(found->d_inode != inode)) {
+			/* This can't happen because bad inodes are unhashed. */
+			BUG_ON(!is_bad_inode(inode));
+			BUG_ON(!is_bad_inode(found->d_inode));
+		}
+		/*
+		 * Already have the inode and the dentry attached, decrement
+		 * the reference count to balance the iget() done
+		 * earlier on.  We found the dentry using d_lookup() so it
+		 * cannot be disconnected and thus we do not need to worry
+		 * about any NFS/disconnectedness issues here.
+		 */
+		iput(inode);
+		return found;
+	}
+	/*
+	 * Negative dentry: instantiate it unless the inode is a directory and
+	 * has a 'disconnected' dentry (i.e. IS_ROOT and DCACHE_DISCONNECTED),
+	 * in which case d_move() that in place of the found dentry.
+	 */
+	if (!S_ISDIR(inode->i_mode)) {
+		/* Not a directory; everything is easy. */
+		d_instantiate(found, inode);
+		return found;
+	}
+	spin_lock(&dcache_lock);
+	if (list_empty(&inode->i_dentry)) {
+		/*
+		 * Directory without a 'disconnected' dentry; we need to do
+		 * d_instantiate() by hand because it takes dcache_lock which
+		 * we already hold.
+		 */
+		__d_instantiate(found, inode);
+		spin_unlock(&dcache_lock);
+		security_d_instantiate(found, inode);
+		return found;
+	}
+	/*
+	 * Directory with a 'disconnected' dentry; get a reference to the
+	 * 'disconnected' dentry.
+	 */
+	new = list_entry(inode->i_dentry.next, struct dentry, d_alias);
+	dget_locked(new);
+	spin_unlock(&dcache_lock);
+	/* Do security vodoo. */
+	security_d_instantiate(found, inode);
+	/* Move new in place of found. */
+	d_move(new, found);
+	/* Balance the iget() we did above. */
+	iput(inode);
+	/* Throw away found. */
+	dput(found);
+	/* Use new as the actual dentry. */
+	return new;
+
+err_out:
+	iput(inode);
+	return ERR_PTR(error);
+}
 
 /**
  * d_lookup - search for a dentry
@@ -1215,7 +1349,7 @@ struct dentry *d_splice_alias(struct inode *inode, struct dentry *dentry)
  * rcu_read_lock() and rcu_read_unlock() are used to disable preemption while
  * lookup is going on.
  *
- * dentry_unused list is not updated even if lookup finds the required dentry
+ * The dentry unused LRU is not updated even if lookup finds the required dentry
  * in there. It is updated in places such as prune_dcache, shrink_dcache_sb,
  * select_parent and __dget_locked. This laziness saves lookup from dcache_lock
  * acquisition.
@@ -1268,6 +1402,10 @@ struct dentry * __d_lookup(struct dentry * parent, struct qstr * name)
 		if (dentry->d_parent != parent)
 			goto next;
 
+		/* non-existing due to RCU? */
+		if (d_unhashed(dentry))
+			goto next;
+
 		/*
 		 * It is safe to compare names since d_move() cannot
 		 * change the qstr (protected by d_lock).
@@ -1283,10 +1421,8 @@ struct dentry * __d_lookup(struct dentry * parent, struct qstr * name)
 				goto next;
 		}
 
-		if (!d_unhashed(dentry)) {
-			atomic_inc(&dentry->d_count);
-			found = dentry;
-		}
+		atomic_inc(&dentry->d_count);
+		found = dentry;
 		spin_unlock(&dentry->d_lock);
 		break;
 next:
@@ -1327,8 +1463,6 @@ out:
  * d_validate - verify dentry provided from insecure source
  * @dentry: The dentry alleged to be valid child of @dparent
  * @dparent: The parent dentry (known to be valid)
- * @hash: Hash of the dentry
- * @len: Length of the name
  *
  * An insecure source has sent us a dentry, here we verify it and dget() it.
  * This is used by ncpfs in its readdir implementation.
@@ -1585,18 +1719,23 @@ void d_move(struct dentry * dentry, struct dentry * target)
 	spin_unlock(&dcache_lock);
 }
 
-/*
- * Helper that returns 1 if p1 is a parent of p2, else 0
+/**
+ * d_ancestor - search for an ancestor
+ * @p1: ancestor dentry
+ * @p2: child dentry
+ *
+ * Returns the ancestor dentry of p2 which is a child of p1, if p1 is
+ * an ancestor of p2, else NULL.
  */
-static int d_isparent(struct dentry *p1, struct dentry *p2)
+struct dentry *d_ancestor(struct dentry *p1, struct dentry *p2)
 {
 	struct dentry *p;
 
-	for (p = p2; p->d_parent != p; p = p->d_parent) {
+	for (p = p2; !IS_ROOT(p); p = p->d_parent) {
 		if (p->d_parent == p1)
-			return 1;
+			return p;
 	}
-	return 0;
+	return NULL;
 }
 
 /*
@@ -1620,7 +1759,7 @@ static struct dentry *__d_unalias(struct dentry *dentry, struct dentry *alias)
 
 	/* Check for loops */
 	ret = ERR_PTR(-ELOOP);
-	if (d_isparent(alias, dentry))
+	if (d_ancestor(alias, dentry))
 		goto out_err;
 
 	/* See lock_rename() */
@@ -1693,7 +1832,7 @@ struct dentry *d_materialise_unique(struct dentry *dentry, struct inode *inode)
 
 	if (!inode) {
 		actual = dentry;
-		dentry->d_inode = NULL;
+		__d_instantiate(dentry, NULL);
 		goto found_lock;
 	}
 
@@ -2020,32 +2159,27 @@ out:
  * Caller must ensure that "new_dentry" is pinned before calling is_subdir()
  */
   
-int is_subdir(struct dentry * new_dentry, struct dentry * old_dentry)
+int is_subdir(struct dentry *new_dentry, struct dentry *old_dentry)
 {
 	int result;
-	struct dentry * saved = new_dentry;
 	unsigned long seq;
 
-	/* need rcu_readlock to protect against the d_parent trashing due to
-	 * d_move
+	/* FIXME: This is old behavior, needed? Please check callers. */
+	if (new_dentry == old_dentry)
+		return 1;
+
+	/*
+	 * Need rcu_readlock to protect against the d_parent trashing
+	 * due to d_move
 	 */
 	rcu_read_lock();
-        do {
+	do {
 		/* for restarting inner loop in case of seq retry */
-		new_dentry = saved;
-		result = 0;
 		seq = read_seqbegin(&rename_lock);
-		for (;;) {
-			if (new_dentry != old_dentry) {
-				struct dentry * parent = new_dentry->d_parent;
-				if (parent == new_dentry)
-					break;
-				new_dentry = parent;
-				continue;
-			}
+		if (d_ancestor(old_dentry, new_dentry))
 			result = 1;
-			break;
-		}
+		else
+			result = 0;
 	} while (read_seqretry(&rename_lock, seq));
 	rcu_read_unlock();
 
@@ -2215,7 +2349,6 @@ void __init vfs_caches_init(unsigned long mempages)
 }
 
 EXPORT_SYMBOL(d_alloc);
-EXPORT_SYMBOL(d_alloc_anon);
 EXPORT_SYMBOL(d_alloc_root);
 EXPORT_SYMBOL(d_delete);
 EXPORT_SYMBOL(d_find_alias);
@@ -2228,6 +2361,7 @@ EXPORT_SYMBOL(d_path);
 EXPORT_SYMBOL(d_prune_aliases);
 EXPORT_SYMBOL(d_rehash);
 EXPORT_SYMBOL(d_splice_alias);
+EXPORT_SYMBOL(d_add_ci);
 EXPORT_SYMBOL(d_validate);
 EXPORT_SYMBOL(dget_locked);
 EXPORT_SYMBOL(dput);