[ros-diffs] [tkreuzer] 53983: [FREELDR] Implement directory buffer caching for FAT

Author: tkreuzer
Date: Mon Oct  3 23:35:27 2011
New Revision: 53983

URL: http://svn.reactos.org/svn/reactos?rev=53983&view=rev
Log:
[FREELDR]
Implement directory buffer caching for FAT

Modified:
    trunk/reactos/boot/freeldr/freeldr/fs/fat.c

Modified: trunk/reactos/boot/freeldr/freeldr/fs/fat.c
URL: http://svn.reactos.org/svn/reactos/trunk/reactos/boot/freeldr/freeldr/fs/fat...
==============================================================================
--- trunk/reactos/boot/freeldr/freeldr/fs/fat.c [iso-8859-1] (original)
+++ trunk/reactos/boot/freeldr/freeldr/fs/fat.c [iso-8859-1] Mon Oct  3 23:35:27 2011
@@ -370,9 +370,21 @@
    }
 }

+typedef struct _DIRECTORY_BUFFER
+{
+	LIST_ENTRY Link;
+	PVOID Volume;
+	ULONG DirectoryStartCluster;
+	ULONG DirectorySize;
+	UCHAR Data[];
+} DIRECTORY_BUFFER, *PDIRECTORY_BUFFER;
+
+LIST_ENTRY DirectoryBufferListHead = {&DirectoryBufferListHead, &DirectoryBufferListHead};
+
 PVOID FatBufferDirectory(PFAT_VOLUME_INFO Volume, ULONG DirectoryStartCluster, ULONG *DirectorySize, BOOLEAN RootDirectory)
 {
-	PVOID	DirectoryBuffer;
+	PDIRECTORY_BUFFER DirectoryBuffer;
+	PLIST_ENTRY Entry;

TRACE("FatBufferDirectory() DirectoryStartCluster = %d RootDirectory = %s\n", DirectoryStartCluster, (RootDirectory ? "TRUE" : "FALSE"));

@@ -386,6 +398,23 @@
    	RootDirectory = FALSE;
    }

+	/* Search the list for a match */
+	for (Entry = DirectoryBufferListHead.Flink;
+	     Entry != &DirectoryBufferListHead;
+	     Entry = Entry->Flink)
+	{
+		DirectoryBuffer = CONTAINING_RECORD(Entry, DIRECTORY_BUFFER, Link);
+
+		/* Check if it matches */
+		if ((DirectoryBuffer->Volume == Volume) &&
+		    (DirectoryBuffer->DirectoryStartCluster == DirectoryStartCluster))
+		{
+			TRACE("Found cached buffer\n");
+			*DirectorySize = DirectoryBuffer->DirectorySize;
+			return DirectoryBuffer->Data;
+		}
+	}
+
    //
    // Calculate the size of the directory
    //
@@ -402,7 +431,7 @@
    // Attempt to allocate memory for directory buffer
    //
    TRACE("Trying to allocate (DirectorySize) %d bytes.\n", *DirectorySize);
-	DirectoryBuffer = MmHeapAlloc(*DirectorySize);
+	DirectoryBuffer = MmHeapAlloc(*DirectorySize + sizeof(DIRECTORY_BUFFER));

if (DirectoryBuffer == NULL)
    {
@@ -414,7 +443,7 @@
    //
    if (RootDirectory)
    {
-		if (!FatReadVolumeSectors(Volume, Volume->RootDirSectorStart, Volume->RootDirSectors, DirectoryBuffer))
+		if (!FatReadVolumeSectors(Volume, Volume->RootDirSectorStart, Volume->RootDirSectors, DirectoryBuffer->Data))
    	{
    		MmHeapFree(DirectoryBuffer);
    		return NULL;
@@ -422,14 +451,20 @@
    }
    else
    {
-		if (!FatReadClusterChain(Volume, DirectoryStartCluster, 0xFFFFFFFF, DirectoryBuffer))
+		if (!FatReadClusterChain(Volume, DirectoryStartCluster, 0xFFFFFFFF, DirectoryBuffer->Data))
    	{
    		MmHeapFree(DirectoryBuffer);
    		return NULL;
    	}
    }

-	return DirectoryBuffer;
+	/* Enqueue it in the list */
+	DirectoryBuffer->Volume = Volume;
+	DirectoryBuffer->DirectoryStartCluster = DirectoryStartCluster;
+	DirectoryBuffer->DirectorySize = *DirectorySize;
+	InsertTailList(&DirectoryBufferListHead, &DirectoryBuffer->Link);
+
+	return DirectoryBuffer->Data;
 }

BOOLEAN FatSearchDirectoryBufferForFile(PFAT_VOLUME_INFO Volume, PVOID DirectoryBuffer, ULONG DirectorySize, PCHAR FileName, PFAT_FILE_INFO FatFileInfoPointer)
@@ -774,7 +809,6 @@
    	{
    		if (!FatXSearchDirectoryBufferForFile(Volume, DirectoryBuffer, DirectorySize, PathPart, &FatFileInfo))
    		{
-				MmHeapFree(DirectoryBuffer);
    			return ENOENT;
    		}
    	}
@@ -782,12 +816,9 @@
    	{
    		if (!FatSearchDirectoryBufferForFile(Volume, DirectoryBuffer, DirectorySize, PathPart, &FatFileInfo))
    		{
-				MmHeapFree(DirectoryBuffer);
    			return ENOENT;
    		}
    	}
-
-		MmHeapFree(DirectoryBuffer);

//
    	// If we have another sub-directory to go then