380 lines
8.7 KiB
C
380 lines
8.7 KiB
C
/*++
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Copyright (c) 1990 Microsoft Corporation
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Module Name:
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LogPgSup.c
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Abstract:
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This module implements support for manipulating log pages.
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Author:
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Brian Andrew [BrianAn] 20-June-1991
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Revision History:
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--*/
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#include "lfsprocs.h"
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// The debug trace level
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#define Dbg (DEBUG_TRACE_LOG_PAGE_SUP)
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#undef MODULE_POOL_TAG
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#define MODULE_POOL_TAG ('PsfL')
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#ifdef ALLOC_PRAGMA
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#pragma alloc_text(PAGE, LfsAllocateSpanningBuffer)
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#pragma alloc_text(PAGE, LfsFreeSpanningBuffer)
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#pragma alloc_text(PAGE, LfsNextLogPageOffset)
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#endif
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VOID
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LfsNextLogPageOffset (
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IN PLFCB Lfcb,
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IN LONGLONG CurrentLogPageOffset,
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OUT PLONGLONG NextLogPageOffset,
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OUT PBOOLEAN Wrapped
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)
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/*++
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Routine Description:
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This routine will compute the offset in the log file of the next log
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page.
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Arguments:
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Lfcb - This is the file control block for the log file.
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CurrentLogPageOffset - This is the file offset of the current log page.
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NextLogPageOffset - Address to store the next log page to use.
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Wrapped - This is a pointer to a boolean variable that, if present,
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we use to indicate whether we wrapped in the log file.
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Return Value:
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None.
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--*/
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{
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PAGED_CODE();
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DebugTrace( +1, Dbg, "LfsNextLogPageOffset: Entered\n", 0 );
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DebugTrace( 0, Dbg, "Lfcb -> %08lx\n", Lfcb );
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DebugTrace( 0, Dbg, "CurrentLogPageOffset (Low) -> %08lx\n", CurrentLogPageOffset.LowPart );
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DebugTrace( 0, Dbg, "CurrentLogPageOffset (High) -> %08lx\n", CurrentLogPageOffset.HighPart );
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DebugTrace( 0, Dbg, "Wrapped -> %08lx\n", Wrapped );
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// We add the log page size to the current log offset.
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LfsTruncateOffsetToLogPage( Lfcb, CurrentLogPageOffset, &CurrentLogPageOffset );
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*NextLogPageOffset = CurrentLogPageOffset + Lfcb->LogPageSize; //**** xxAdd( CurrentLogPageOffset, Lfcb->LogPageSize );
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// If the result is larger than the file, we use the first page offset
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// in the file.
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if ( *NextLogPageOffset >= Lfcb->FileSize ) { //**** xxGeq( *NextLogPageOffset, Lfcb->FileSize )
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*NextLogPageOffset = Lfcb->FirstLogPage;
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*Wrapped = TRUE;
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} else {
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*Wrapped = FALSE;
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}
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DebugTrace( 0, Dbg, "NextLogPageOffset (Low) -> %08lx\n", NextLogPageOffset->LowPart );
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DebugTrace( 0, Dbg, "NextLogPageOffset (High) -> %08lx\n", NextLogPageOffset->HighPart );
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DebugTrace( 0, Dbg, "Wrapped -> %08x\n", *Wrapped );
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DebugTrace( -1, Dbg, "LfsNextLogPageOffset: Exit\n", 0 );
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return;
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}
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PVOID
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LfsAllocateSpanningBuffer (
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IN PLFCB Lfcb,
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IN ULONG Length
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)
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/*++
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Routine Description:
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This routine is called to allocate a spare buffer to read a file record
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which spans a log page. We will first try to allocate one. If that
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fails we will use one of the existing spare buffers. If that fails then
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we will raise.
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Arguments:
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Lfcb - This is the file control block for the log file.
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Length - Length of the buffer required.
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Return Value:
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PVOID - Pointer to the buffer to use for reading the log record.
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May be either from pool or from the auxilary buffer pool.
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--*/
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{
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PVOID NewBuffer = NULL;
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ERESOURCE_THREAD Thread;
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BOOLEAN Wait = FALSE;
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PAGED_CODE();
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DebugTrace( +1, Dbg, "LfsAllocateSpanningBuffer: Entered\n", 0 );
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// Loop while we don't have a buffer. First try to get our reserved buffer
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// without waiting. Then try to allocate a buffer. Finally wait for the reserved
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// buffer as the final alternative.
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do {
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// Skip the reserved buffer if the request is larger than we can read into it.
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if (Length <= LFS_BUFFER_SIZE) {
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// If this thread already owns one buffer it can get the second directly.
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Thread = ExGetCurrentResourceThread();
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if (Thread == LfsData.BufferOwner) {
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if (!FlagOn( LfsData.BufferFlags, LFS_BUFFER1_OWNED )) {
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SetFlag( LfsData.BufferFlags, LFS_BUFFER1_OWNED );
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NewBuffer = LfsData.Buffer1;
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break;
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} else if (!FlagOn( LfsData.BufferFlags, LFS_BUFFER2_OWNED )) {
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SetFlag( LfsData.BufferFlags, LFS_BUFFER2_OWNED );
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NewBuffer = LfsData.Buffer2;
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break;
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} else if (Wait) {
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// This shouldn't happen but handle anyway.
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DebugTrace( -1, Dbg, "LfsAllocateSpanningBuffer: Exit\n", 0 );
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ExRaiseStatus( STATUS_INSUFFICIENT_RESOURCES );
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}
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// Otherwise acquire the buffer lock and check the state of the buffers.
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} else {
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BOOLEAN LfcbOwned = TRUE;
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while (TRUE) {
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LfsAcquireBufferLock();
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// Check to see if the buffers are available. No
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// need to drop the Lfcb in the typical case.
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if (LfsData.BufferOwner == (ERESOURCE_THREAD) NULL) {
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ASSERT( !FlagOn( LfsData.BufferFlags, LFS_BUFFER1_OWNED | LFS_BUFFER2_OWNED ));
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NewBuffer = LfsData.Buffer1;
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LfsData.BufferOwner = Thread;
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SetFlag( LfsData.BufferFlags, LFS_BUFFER1_OWNED );
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LfsBlockBufferWaiters();
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// Reacquire the Lfcb if needed.
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if (!LfcbOwned) {
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LfsAcquireLfcb( Lfcb );
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}
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// Break out.
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LfsReleaseBufferLock();
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break;
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}
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// Release the Lfcb and wait on the notification for the buffers.
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if (Wait) {
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if (LfcbOwned) {
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LfsReleaseLfcb( Lfcb );
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LfcbOwned = FALSE;
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}
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LfsReleaseBufferLock();
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LfsWaitForBufferNotification();
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} else {
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// Go ahead and try to allocate a buffer from pool next.
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LfsReleaseBufferLock();
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break;
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}
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}
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}
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// Raise if we already tried the allocate path.
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} else if (Wait) {
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DebugTrace( -1, Dbg, "LfsAllocateSpanningBuffer: Exit\n", 0 );
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ExRaiseStatus( STATUS_INSUFFICIENT_RESOURCES );
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}
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// Try pool if we didn't get a buffer above.
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if (NewBuffer == NULL) {
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// Try pool next but don't let this fail on pool allocation.
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NewBuffer = LfsAllocatePoolNoRaise( PagedPool, Length );
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}
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// Wait on the next pass through the loop.
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Wait = TRUE;
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} while (NewBuffer == NULL);
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DebugTrace( -1, Dbg, "LfsAllocateSpanningBuffer: Exit\n", 0 );
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return NewBuffer;
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}
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VOID
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LfsFreeSpanningBuffer (
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IN PVOID Buffer
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)
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/*++
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Routine Description:
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This routine is called to free a buffer used to read a log record
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which spans pages. We will check if it is one of our special buffers
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and deal with synchronization in that case.
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Arguments:
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Buffer - Buffer to free.
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Return Value:
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None.
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--*/
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{
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ERESOURCE_THREAD Thread;
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PAGED_CODE();
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DebugTrace( +1, Dbg, "LfsFreeSpanningBuffer: Entered\n", 0 );
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// Do an unsafe test of the buffer flags. If we own a buffer then they must be non-zero.
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// Otherwise do the correct check of the resource thread.
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if (!FlagOn( LfsData.BufferFlags, LFS_BUFFER1_OWNED | LFS_BUFFER2_OWNED ) ||
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(LfsData.BufferOwner != ExGetCurrentResourceThread())) {
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LfsFreePool( Buffer );
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} else {
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// Acquire the lock for synchronization.
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LfsAcquireBufferLock();
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// Check which buffer it is.
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if (Buffer == LfsData.Buffer1) {
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ClearFlag( LfsData.BufferFlags, LFS_BUFFER1_OWNED );
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} else {
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// It better be buffer2
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ASSERT( FlagOn( LfsData.BufferFlags, LFS_BUFFER2_OWNED ));
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ClearFlag( LfsData.BufferFlags, LFS_BUFFER2_OWNED );
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}
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// If no buffers owned then signal the waiters.
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if (!FlagOn( LfsData.BufferFlags, LFS_BUFFER1_OWNED | LFS_BUFFER2_OWNED )) {
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LfsData.BufferOwner = (ERESOURCE_THREAD) NULL;
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LfsNotifyBufferWaiters();
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}
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LfsReleaseBufferLock();
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}
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DebugTrace( -1, Dbg, "LfsFreeSpanningBuffer: Exit\n", 0 );
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return;
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}
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