/** @file
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Block group related routines
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Copyright (c) 2021 Pedro Falcato All rights reserved.
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Copyright (c) 2007 - 2018, Intel Corporation. All rights reserved.<BR>
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SPDX-License-Identifier: BSD-2-Clause-Patent
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**/
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#include "Ext4Dxe.h"
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/**
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Retrieves a block group descriptor of the ext4 filesystem.
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@param[in] Partition Pointer to the opened ext4 partition.
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@param[in] BlockGroup Block group number.
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@return A pointer to the block group descriptor.
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**/
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EXT4_BLOCK_GROUP_DESC *
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Ext4GetBlockGroupDesc (
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IN EXT4_PARTITION *Partition,
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IN UINT32 BlockGroup
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)
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{
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// Maybe assert that the block group nr isn't a nonsense number?
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return (EXT4_BLOCK_GROUP_DESC *)((CHAR8 *)Partition->BlockGroups + BlockGroup * Partition->DescSize);
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}
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/**
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Reads an inode from disk.
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@param[in] Partition Pointer to the opened partition.
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@param[in] InodeNum Number of the desired Inode
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@param[out] OutIno Pointer to where it will be stored a pointer to the read inode.
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@return Status of the inode read.
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**/
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EFI_STATUS
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Ext4ReadInode (
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IN EXT4_PARTITION *Partition,
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IN EXT4_INO_NR InodeNum,
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OUT EXT4_INODE **OutIno
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)
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{
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UINT64 InodeOffset;
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UINT32 BlockGroupNumber;
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EXT4_INODE *Inode;
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EXT4_BLOCK_GROUP_DESC *BlockGroup;
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EXT4_BLOCK_NR InodeTableStart;
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EFI_STATUS Status;
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BlockGroupNumber = (UINT32)DivU64x64Remainder (
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InodeNum - 1,
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Partition->SuperBlock.s_inodes_per_group,
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&InodeOffset
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);
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// Check for the block group number's correctness
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if (BlockGroupNumber >= Partition->NumberBlockGroups) {
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return EFI_VOLUME_CORRUPTED;
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}
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Inode = Ext4AllocateInode (Partition);
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if (Inode == NULL) {
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return EFI_OUT_OF_RESOURCES;
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}
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BlockGroup = Ext4GetBlockGroupDesc (Partition, BlockGroupNumber);
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// Note: We'll need to check INODE_UNINIT and friends when/if we add write support
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InodeTableStart = EXT4_BLOCK_NR_FROM_HALFS (
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Partition,
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BlockGroup->bg_inode_table_lo,
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BlockGroup->bg_inode_table_hi
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);
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Status = Ext4ReadDiskIo (
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Partition,
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Inode,
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Partition->InodeSize,
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EXT4_BLOCK_TO_BYTES (Partition, InodeTableStart) + MultU64x32 (InodeOffset, Partition->InodeSize)
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);
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if (EFI_ERROR (Status)) {
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DEBUG ((
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DEBUG_ERROR,
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"[ext4] Error reading inode: status %x; inode offset %lx"
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" inode table start %lu block group %lu\n",
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Status,
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InodeOffset,
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InodeTableStart,
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BlockGroupNumber
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));
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FreePool (Inode);
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return Status;
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}
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if (!Ext4CheckInodeChecksum (Partition, Inode, InodeNum)) {
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DEBUG ((
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DEBUG_ERROR,
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"[ext4] Inode %llu has invalid checksum (calculated %x)\n",
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InodeNum,
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Ext4CalculateInodeChecksum (Partition, Inode, InodeNum)
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));
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FreePool (Inode);
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return EFI_VOLUME_CORRUPTED;
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}
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*OutIno = Inode;
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return EFI_SUCCESS;
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}
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/**
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Calculates the checksum of the block group descriptor for METADATA_CSUM enabled filesystems.
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@param[in] Partition Pointer to the opened EXT4 partition.
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@param[in] BlockGroupDesc Pointer to the block group descriptor.
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@param[in] BlockGroupNum Number of the block group.
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@return The checksum.
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**/
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STATIC
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UINT16
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Ext4CalculateBlockGroupDescChecksumMetadataCsum (
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IN CONST EXT4_PARTITION *Partition,
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IN CONST EXT4_BLOCK_GROUP_DESC *BlockGroupDesc,
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IN UINT32 BlockGroupNum
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)
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{
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UINT32 Csum;
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UINT16 Dummy;
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Dummy = 0;
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Csum = Ext4CalculateChecksum (Partition, &BlockGroupNum, sizeof (BlockGroupNum), Partition->InitialSeed);
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Csum = Ext4CalculateChecksum (Partition, BlockGroupDesc, OFFSET_OF (EXT4_BLOCK_GROUP_DESC, bg_checksum), Csum);
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Csum = Ext4CalculateChecksum (Partition, &Dummy, sizeof (Dummy), Csum);
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Csum =
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Ext4CalculateChecksum (
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Partition,
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&BlockGroupDesc->bg_block_bitmap_hi,
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Partition->DescSize - OFFSET_OF (EXT4_BLOCK_GROUP_DESC, bg_block_bitmap_hi),
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Csum
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);
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return (UINT16)Csum;
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}
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/**
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Calculates the checksum of the block group descriptor for GDT_CSUM enabled filesystems.
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@param[in] Partition Pointer to the opened EXT4 partition.
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@param[in] BlockGroupDesc Pointer to the block group descriptor.
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@param[in] BlockGroupNum Number of the block group.
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@return The checksum.
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**/
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STATIC
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UINT16
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Ext4CalculateBlockGroupDescChecksumGdtCsum (
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IN CONST EXT4_PARTITION *Partition,
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IN CONST EXT4_BLOCK_GROUP_DESC *BlockGroupDesc,
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IN UINT32 BlockGroupNum
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)
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{
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UINT16 Csum;
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UINT16 Dummy;
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Dummy = 0;
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Csum = CalculateCrc16 (Partition->SuperBlock.s_uuid, 16, 0);
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Csum = CalculateCrc16 (&BlockGroupNum, sizeof (BlockGroupNum), Csum);
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Csum = CalculateCrc16 (BlockGroupDesc, OFFSET_OF (EXT4_BLOCK_GROUP_DESC, bg_checksum), Csum);
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Csum = CalculateCrc16 (&Dummy, sizeof (Dummy), Csum);
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Csum =
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CalculateCrc16 (
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&BlockGroupDesc->bg_block_bitmap_hi,
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Partition->DescSize - OFFSET_OF (EXT4_BLOCK_GROUP_DESC, bg_block_bitmap_hi),
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Csum
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);
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return Csum;
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}
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/**
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Checks if the checksum of the block group descriptor is correct.
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@param[in] Partition Pointer to the opened EXT4 partition.
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@param[in] BlockGroupDesc Pointer to the block group descriptor.
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@param[in] BlockGroupNum Number of the block group.
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@return TRUE if checksum is correct, FALSE if there is corruption.
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**/
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BOOLEAN
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Ext4VerifyBlockGroupDescChecksum (
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IN CONST EXT4_PARTITION *Partition,
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IN CONST EXT4_BLOCK_GROUP_DESC *BlockGroupDesc,
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IN UINT32 BlockGroupNum
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)
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{
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if (!EXT4_HAS_METADATA_CSUM (Partition) && !EXT4_HAS_GDT_CSUM (Partition)) {
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return TRUE;
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}
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return Ext4CalculateBlockGroupDescChecksum (Partition, BlockGroupDesc, BlockGroupNum) == BlockGroupDesc->bg_checksum;
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}
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/**
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Calculates the checksum of the block group descriptor.
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@param[in] Partition Pointer to the opened EXT4 partition.
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@param[in] BlockGroupDesc Pointer to the block group descriptor.
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@param[in] BlockGroupNum Number of the block group.
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@return The checksum.
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**/
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UINT16
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Ext4CalculateBlockGroupDescChecksum (
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IN CONST EXT4_PARTITION *Partition,
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IN CONST EXT4_BLOCK_GROUP_DESC *BlockGroupDesc,
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IN UINT32 BlockGroupNum
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)
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{
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if (Partition->FeaturesRoCompat & EXT4_FEATURE_RO_COMPAT_METADATA_CSUM) {
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return Ext4CalculateBlockGroupDescChecksumMetadataCsum (Partition, BlockGroupDesc, BlockGroupNum);
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} else if (Partition->FeaturesRoCompat & EXT4_FEATURE_RO_COMPAT_GDT_CSUM) {
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return Ext4CalculateBlockGroupDescChecksumGdtCsum (Partition, BlockGroupDesc, BlockGroupNum);
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}
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return 0;
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}
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