BTRFS: Reimplement TreeIterator, add some error checks and remove redundancies.

Add BTree::Path as a attribute so enhance performance, so that everytime we iterate through items it wont search all the root to leaf
again. The Iterator is initialized without rewinding to make more flexible.

Signed-off-by: Augustin Cavalier <[email protected]>

src/add-ons/kernel/file_systems/btrfs/AttributeIterator.cpp

@@ -22,9 +22,10 @@ AttributeIterator::AttributeIterator(Inode* inode)
 	fInode(inode),
 	fIterator(NULL)
 {
-	struct btrfs_key key;
+	btrfs_key key;
 	key.SetType(BTRFS_KEY_TYPE_XATTR_ITEM);
 	key.SetObjectID(inode->ID());
+	key.SetOffset(BTREE_BEGIN);
 	fIterator = new(std::nothrow) TreeIterator(inode->GetVolume()->FSTree(),
 		key);
 }
@@ -33,6 +34,7 @@ AttributeIterator::AttributeIterator(Inode* inode)
 AttributeIterator::~AttributeIterator()
 {
 	delete fIterator;
+	fIterator = NULL;
 }
 
 
@@ -46,10 +48,9 @@ AttributeIterator::InitCheck()
 status_t
 AttributeIterator::GetNext(char* name, size_t* _nameLength)
 {
-	btrfs_key key;
 	btrfs_dir_entry* entries;
 	uint32 entries_length;
-	status_t status = fIterator->GetPreviousEntry(key, (void**)&entries,
+	status_t status = fIterator->GetPreviousEntry((void**)&entries,
 		&entries_length);
 	if (status != B_OK)
 		return status;

src/add-ons/kernel/file_systems/btrfs/BTree.cpp

@@ -519,13 +519,16 @@ BTree::_RemoveIterator(TreeIterator* iterator)
 //	#pragma mark -
 
 
-TreeIterator::TreeIterator(BTree* tree, btrfs_key& key)
+TreeIterator::TreeIterator(BTree* tree, const btrfs_key& key)
 	:
 	fTree(tree),
-	fCurrentKey(key)
+	fKey(key),
+	fIteratorStatus(B_NO_INIT)
 {
-	Rewind();
 	tree->_AddIterator(this);
+	fPath = new(std::nothrow) BTree::Path(tree);
+	if (fPath == NULL)
+		fIteratorStatus = B_NO_MEMORY;
 }
 
 
@@ -533,26 +536,72 @@ TreeIterator::~TreeIterator()
 {
 	if (fTree)
 		fTree->_RemoveIterator(this);
+
+	delete fPath;
+	fPath = NULL;
+}
+
+
+void
+TreeIterator::Rewind(bool inverse)
+{
+	if (inverse)
+		fKey.SetOffset(BTREE_END);
+	else
+		fKey.SetOffset(BTREE_BEGIN);
+	fIteratorStatus = B_NO_INIT;
 }
 
 
 /*!	Iterates through the tree in the specified direction.
 */
 status_t
-TreeIterator::Traverse(btree_traversing direction, btrfs_key& key,
-	void** value, uint32* size)
+TreeIterator::_Traverse(btree_traversing direction)
 {
-	if (fTree == NULL)
-		return B_INTERRUPTED;
-
-	fCurrentKey.SetOffset(fCurrentKey.Offset() + direction);
-	BTree::Path path(fTree);
-	status_t status = fTree->_Find(&path, fCurrentKey, value, size, direction);
-	if (status != B_OK) {
-		TRACE("TreeIterator::Traverse() Find failed\n");
-		return B_ENTRY_NOT_FOUND;
+	status_t status = fTree->Traverse(direction, fPath, fKey);
+	if (status < B_OK) {
+		ERROR("TreeIterator::Traverse() Find failed\n");
+		return status;
 	}
 
+	return (fIteratorStatus = B_OK);
+}
+
+
+// Like GetEntry in BTree::Path but here we check the type and moving.
+status_t
+TreeIterator::_GetEntry(btree_traversing type, void** _value, uint32* _size,
+	uint32* _offset)
+{
+	status_t status;
+	if (fIteratorStatus == B_NO_INIT) {
+		status = _Traverse(type);
+		if (status != B_OK)
+			return status;
+		type = BTREE_EXACT;
+	}
+
+	if (fIteratorStatus != B_OK)
+		return fIteratorStatus;
+
+	int move = fPath->Move(0, type);
+	if (move > 0)
+		status = fTree->NextLeaf(fPath);
+	else if (move < 0)
+		status = fTree->PreviousLeaf(fPath);
+	if (status != B_OK)
+		return status;
+
+	btrfs_key found;
+	status = fPath->GetCurrentEntry(&found, _value, _size, _offset);
+	if (status != B_OK)
+		return status;
+
+	fKey.SetObjectID(found.ObjectID());
+	fKey.SetOffset(found.Offset());
+	if (fKey.Type() != found.Type() && fKey.Type() != BTRFS_KEY_TYPE_ANY)
+		return B_ENTRY_NOT_FOUND;
+
 	return B_OK;
 }
 
@@ -560,11 +609,13 @@ TreeIterator::Traverse(btree_traversing direction, btrfs_key& key,
 /*!	just sets the current key in the iterator.
 */
 status_t
-TreeIterator::Find(btrfs_key& key)
+TreeIterator::Find(const btrfs_key& key)
 {
-	if (fTree == NULL)
-		return B_INTERRUPTED;
-	fCurrentKey = key;
+	if (fIteratorStatus == B_INTERRUPTED)
+		return fIteratorStatus;
+
+	fKey = key;
+	fIteratorStatus = B_NO_INIT;
 	return B_OK;
 }
 
@@ -573,4 +624,5 @@ void
 TreeIterator::Stop()
 {
 	fTree = NULL;
+	fIteratorStatus = B_INTERRUPTED;
 }

src/add-ons/kernel/file_systems/btrfs/BTree.h

@@ -176,31 +176,37 @@ public:
 
 class TreeIterator : public SinglyLinkedListLinkImpl<TreeIterator> {
 public:
-								TreeIterator(BTree* tree, btrfs_key& key);
+								TreeIterator(BTree* tree, const btrfs_key& key);
 								~TreeIterator();
 
-			status_t			Traverse(btree_traversing direction,
-									btrfs_key& key, void** value,
-									uint32* size = NULL);
-			status_t			Find(btrfs_key& key);
+			void				Rewind(bool inverse = false);
+			status_t			Find(const btrfs_key& key);
+			status_t			GetNextEntry(void** _value,
+									uint32* _size = NULL,
+									uint32* _offset = NULL);
+			status_t			GetPreviousEntry(void** _value,
+									uint32* _size = NULL,
+									uint32* _offset = NULL);
 
-			status_t			Rewind();
-			status_t			GetNextEntry(btrfs_key& key, void** value,
-									uint32* size = NULL);
-			status_t			GetPreviousEntry(btrfs_key& key, void** value,
-									uint32* size = NULL);
-
-			BTree*			Tree() const { return fTree; }
+			BTree*				Tree() const { return fTree; }
+			btrfs_key			Key() const { return fKey; }
 
 private:
 			friend class BTree;
 
+			status_t			_Traverse(btree_traversing direction);
+			status_t			_Find(btree_traversing type, btrfs_key& key,
+									void** _value);
+			status_t			_GetEntry(btree_traversing type, void** _value,
+									uint32* _size, uint32* _offset);
 			// called by BTree
 			void				Stop();
 
 private:
 			BTree*			fTree;
-			btrfs_key	fCurrentKey;
+			BTree::Path*	fPath;
+			btrfs_key		fKey;
+			status_t		fIteratorStatus;
 };
 
 
@@ -219,25 +225,16 @@ BTree::Path::GetCurrentEntry(btrfs_key* _key, void** _value, uint32* _size,
 
 
 inline status_t
-TreeIterator::Rewind()
+TreeIterator::GetNextEntry(void** _value, uint32* _size, uint32* _offset)
 {
-	fCurrentKey.SetOffset(BTREE_BEGIN);
-	return B_OK;
+	return _GetEntry(BTREE_FORWARD, _value, _size, _offset);
 }
 
 
 inline status_t
-TreeIterator::GetNextEntry(btrfs_key& key, void** value, uint32* size)
+TreeIterator::GetPreviousEntry(void** _value, uint32* _size, uint32* _offset)
 {
-	return Traverse(BTREE_FORWARD, key, value, size);
-}
-
-
-inline status_t
-TreeIterator::GetPreviousEntry(btrfs_key& key, void** value,
-	uint32* size)
-{
-	return Traverse(BTREE_BACKWARD, key, value, size);
+	return _GetEntry(BTREE_BACKWARD, _value, _size, _offset);
 }
 
 

src/add-ons/kernel/file_systems/btrfs/DirectoryIterator.cpp

@@ -26,6 +26,7 @@ DirectoryIterator::DirectoryIterator(Inode* inode)
 	btrfs_key key;
 	key.SetType(BTRFS_KEY_TYPE_DIR_INDEX);
 	key.SetObjectID(inode->ID());
+	key.SetOffset(BTREE_BEGIN);
 	fIterator = new(std::nothrow) TreeIterator(inode->GetVolume()->FSTree(),
 		key);
 }
@@ -33,8 +34,8 @@ DirectoryIterator::DirectoryIterator(Inode* inode)
 
 DirectoryIterator::~DirectoryIterator()
 {
-	if (fIterator != NULL)
-		delete fIterator;
+	delete fIterator;
+	fIterator = NULL;
 }
 
 
@@ -69,11 +70,9 @@ DirectoryIterator::GetNext(char* name, size_t* _nameLength, ino_t* _id)
 		return fInode->FindParent(_id);
 	}
 
-	btrfs_key key;
 	btrfs_dir_entry* entries;
 	uint32 entries_length;
-	status_t status = fIterator->GetNextEntry(key, (void**)&entries,
-		&entries_length);
+	status_t status = fIterator->GetNextEntry((void**)&entries, &entries_length);
 	if (status != B_OK)
 		return status;