FILE_ALLOCATION_INFORMATION - NtDoc

Native API online documentation, based on the System Informer (formerly Process Hacker) phnt headers
#ifndef _NTIOAPI_H

typedef struct _FILE_ALLOCATION_INFORMATION
{
    LARGE_INTEGER AllocationSize;
} FILE_ALLOCATION_INFORMATION, *PFILE_ALLOCATION_INFORMATION;

#endif

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This structure is documented in Windows Driver Kit.