Function Ext2SupersedeOrOverWriteFile

Ext4Fsd/create.c:2139–2197

NTSTATUS
Ext2SupersedeOrOverWriteFile(
    IN PEXT2_IRP_CONTEXT IrpContext,
    IN PFILE_OBJECT      FileObject,
    IN PEXT2_VCB         Vcb,
    IN PEXT2_FCB         Fcb,
    IN PLARGE_INTEGER    AllocationSize,
    IN ULONG             Disposition
)
{
    LARGE_INTEGER   CurrentTime;
    LARGE_INTEGER   Size;

    KeQuerySystemTime(&CurrentTime);

    Size.QuadPart = 0;
    if (!MmCanFileBeTruncated(&(Fcb->SectionObject), &(Size))) {
        return STATUS_USER_MAPPED_FILE;
    }

    /* purge all file cache and shrink cache windows size */
    CcPurgeCacheSection(&Fcb->SectionObject, NULL, 0, FALSE);
    Fcb->Header.AllocationSize.QuadPart =
        Fcb->Header.FileSize.QuadPart =
            Fcb->Header.ValidDataLength.QuadPart = 0;
    CcSetFileSizes(FileObject,
                   (PCC_FILE_SIZES)&Fcb->Header.AllocationSize);

    Size.QuadPart = CEILING_ALIGNED(ULONGLONG,
                                    (ULONGLONG)AllocationSize->QuadPart,
                                    (ULONGLONG)BLOCK_SIZE);

    if ((loff_t)Size.QuadPart > Fcb->Inode->i_size) {
        Ext2ExpandFile(IrpContext, Vcb, Fcb->Mcb, &Size);
    } else {
        Ext2TruncateFile(IrpContext, Vcb, Fcb->Mcb, &Size);
    }

    Fcb->Header.AllocationSize = Size;
    if (Fcb->Header.AllocationSize.QuadPart > 0) {
        SetLongFlag(Fcb->Flags, FCB_ALLOC_IN_CREATE);
        CcSetFileSizes(FileObject,
                       (PCC_FILE_SIZES)&Fcb->Header.AllocationSize );
    }

    /* remove all extent mappings */
    DEBUG(DL_EXT, ("Ext2SuperSede ...: %wZ\n", &Fcb->Mcb->FullName));
    Fcb->Inode->i_size = 0;

    if (Disposition == FILE_SUPERSEDE) {
        Fcb->Inode->i_ctime = Ext2LinuxTime(CurrentTime);
    }
    Fcb->Inode->i_atime =
        Fcb->Inode->i_mtime = Ext2LinuxTime(CurrentTime);
    Ext2SaveInode(IrpContext, Vcb, Fcb->Inode);

    // See if we need to overwrite EA of the file
    return Ext2OverwriteEa(IrpContext, Vcb, Fcb, &IrpContext->Irp->IoStatus);