FsRtlResetLargeMcb function (ntifs.h)

Article
02/22/2024

The FsRtlResetLargeMcb routine truncates a map control block (MCB) structure to contain zero mapping pairs. It does not shrink the mapping pairs array.

Syntax

void FsRtlResetLargeMcb(
  [in] PLARGE_MCB Mcb,
  [in] BOOLEAN    SelfSynchronized
);

Parameters

[in] Mcb

Pointer to the MCB structure to truncate.

[in] SelfSynchronized

Indicates whether the caller is already synchronized with respect to the MCB.

Return value

None

Remarks

FsRtlResetLargeMcb truncates a map control block (MCB) structure. File systems use MCB structures to map virtual block numbers (VBN) for a file to the corresponding logical block numbers (LBN) on disk.

Note The upper 32 bits of the LBN are ignored. Only the lower 32 bits are used.

File systems must call FsRtlInitializeLargeMcb before using any other FsRtl...Mcb... routines on the MCB structure.

If the caller is already synchronized (the SelfSynchronized parameter is set to TRUE), such that no other thread of operation can call an Mcb routine on this MCB during this call, then FsRtlResetLargeMcb just clears out the current mapping pair count. If the SelfSynchronized parameter is set to FALSE, then FsRtlResetLargeMcb will serialize access to the Mcb before clearing the pair count which requires more time.

Requirements

Requirement	Value
Minimum supported client	Windows XP
Target Platform	Universal
Header	ntifs.h (include Ntifs.h)
Library	NtosKrnl.lib
DLL	NtosKrnl.exe
IRQL	<= APC_LEVEL