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Reads of the FAT on FAT32 filesystems go through the cache, writes are
disabled svn path=/trunk/; revision=1604
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parent
076c1c6ac3
commit
b2fe7525bf
1 changed files with 31 additions and 12 deletions
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@ -1,5 +1,5 @@
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/*
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* $Id: fat.c,v 1.16 2001/01/16 23:22:03 dwelch Exp $
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* $Id: fat.c,v 1.17 2001/02/06 00:41:19 dwelch Exp $
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*
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* COPYRIGHT: See COPYING in the top level directory
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* PROJECT: ReactOS kernel
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@ -31,25 +31,41 @@ Fat32GetNextCluster (PDEVICE_EXTENSION DeviceExt,
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* disk read
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*/
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{
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ULONG FATsector;
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ULONG FATeis;
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PULONG Block;
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PVOID BaseAddress;
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BOOLEAN Valid;
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PCACHE_SEGMENT CacheSeg;
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NTSTATUS Status;
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ULONG FATOffset;
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Block = ExAllocatePool (NonPagedPool, 1024);
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FATsector = CurrentCluster / (512 / sizeof (ULONG));
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FATeis = CurrentCluster - (FATsector * (512 / sizeof (ULONG)));
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Status = VfatReadSectors (DeviceExt->StorageDevice,
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(ULONG) (DeviceExt->FATStart + FATsector), 1,
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(UCHAR *) Block);
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FATOffset = (DeviceExt->FATStart * BLOCKSIZE) +
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(CurrentCluster * sizeof(ULONG));
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Status = CcRequestCacheSegment(DeviceExt->StorageBcb,
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PAGE_ROUND_DOWN(FATOffset),
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&BaseAddress,
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&Valid,
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&CacheSeg);
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if (!NT_SUCCESS(Status))
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{
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return(Status);
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}
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CurrentCluster = Block[FATeis];
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if (!Valid)
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{
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Status = VfatReadSectors(DeviceExt->StorageDevice,
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PAGE_ROUND_DOWN(FATOffset) / BLOCKSIZE,
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PAGESIZE / BLOCKSIZE,
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BaseAddress);
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if (!NT_SUCCESS(Status))
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{
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CcReleaseCacheSegment(DeviceExt->StorageBcb, CacheSeg, FALSE);
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return(Status);
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}
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}
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CurrentCluster = *((PUSHORT)BaseAddress + (FATOffset % PAGESIZE));
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if (CurrentCluster >= 0xffffff8 && CurrentCluster <= 0xfffffff)
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CurrentCluster = 0xffffffff;
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ExFreePool (Block);
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CcReleaseCacheSegment(DeviceExt->StorageBcb, CacheSeg, TRUE);
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*NextCluster = CurrentCluster;
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return (STATUS_SUCCESS);
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}
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@ -571,6 +587,7 @@ FAT32WriteCluster (PDEVICE_EXTENSION DeviceExt, ULONG ClusterToWrite,
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* FUNCTION: Writes a cluster to the FAT32 physical tables
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*/
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{
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#if 0
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ULONG FATsector;
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ULONG FATeis;
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PUSHORT Block;
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@ -596,6 +613,8 @@ FAT32WriteCluster (PDEVICE_EXTENSION DeviceExt, ULONG ClusterToWrite,
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Start += pBoot->FATSectors;
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}
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ExFreePool (Block);
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#endif
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KeBugCheck(0);
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}
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NTSTATUS
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