* Some preparations to be able to split transactions if they become too large

for the log.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@31860 a95241bf-73f2-0310-859d-f6bbb57e9c96

src/add-ons/kernel/file_systems/bfs/Journal.cpp

@@ -599,6 +599,26 @@ Journal::ReplayLog()
 }
 
 
+size_t
+Journal::CurrentTransactionSize() const
+{
+	if (_HasSubTransaction()) {
+		return cache_blocks_in_sub_transaction(fVolume->BlockCache(),
+			fTransactionID);
+	}
+
+	return cache_blocks_in_main_transaction(fVolume->BlockCache(),
+		fTransactionID);
+}
+
+
+bool
+Journal::CurrentTransactionTooLarge() const
+{
+	return CurrentTransactionSize() > fLogSize;
+}
+
+
 /*!	This is a callback function that is called by the cache, whenever
 	all blocks of a transaction have been flushed to disk.
 	This lets us keep track of completed transactions, and update

src/add-ons/kernel/file_systems/bfs/Journal.h

@@ -32,6 +32,8 @@ public:
 			status_t		ReplayLog();
 
 			Transaction*	CurrentTransaction() const { return fOwner; }
+			size_t			CurrentTransactionSize() const;
+			bool			CurrentTransactionTooLarge() const;
 
 			status_t		FlushLogAndBlocks();
 			Volume*			GetVolume() const { return fVolume; }
@@ -44,7 +46,9 @@ public:
 #endif
 
 private:
-			bool			_HasSubTransaction() { return fHasSubtransaction; }
+			bool			_HasSubTransaction() const
+								{ return fHasSubtransaction; }
+
 			status_t		_FlushLog(bool canWait, bool flushBlocks);
 			uint32			_TransactionSize() const;
 			status_t		_WriteTransactionToLog();
@@ -127,7 +131,7 @@ public:
 		return status;
 	}
 
-	bool HasParent()
+	bool HasParent() const
 	{
 		if (fJournal != NULL)
 			return fJournal->CurrentTransaction() == this;
@@ -135,6 +139,11 @@ public:
 		return false;
 	}
 
+	bool IsTooLarge() const
+	{
+		return fJournal->CurrentTransactionTooLarge();
+	}
+
 	status_t WriteBlocks(off_t blockNumber, const uint8* buffer,
 		size_t numBlocks = 1)
 	{
@@ -159,7 +168,13 @@ public:
 		return B_OK;
 	}
 
-	Volume	*GetVolume()
+	void Split()
+	{
+		cache_start_sub_transaction(fJournal->GetVolume()->BlockCache(),
+			fJournal->TransactionID());
+	}
+
+	Volume* GetVolume() const
 		{ return fJournal != NULL ? fJournal->GetVolume() : NULL; }
 	int32 ID() const
 		{ return fJournal->TransactionID(); }