Function Ext2ExpandFile

Ext4Fsd/fileinfo.c:1137–1186

NTSTATUS
Ext2ExpandFile(
    PEXT2_IRP_CONTEXT IrpContext,
    PEXT2_VCB         Vcb,
    PEXT2_MCB         Mcb,
    PLARGE_INTEGER    Size
)
{
    NTSTATUS status = STATUS_SUCCESS;
    ULONG    Start = 0;
    ULONG    End = 0;

    Start = (ULONG)((Mcb->Inode.i_size + BLOCK_SIZE - 1) >> BLOCK_BITS);
    End = (ULONG)((Size->QuadPart + BLOCK_SIZE - 1) >> BLOCK_BITS);

    /* it's a truncate operation, not expanding */
    if (Start >= End) {
        Size->QuadPart = ((LONGLONG) Start) << BLOCK_BITS;
        return STATUS_SUCCESS;
    }

	/* ignore special files */
	if (IsMcbSpecialFile(Mcb)) {
        return STATUS_INVALID_DEVICE_REQUEST;
    }

	/* expandind file extents */ 
    if (INODE_HAS_EXTENT(&Mcb->Inode)) {

        status = Ext2ExpandExtent(IrpContext, Vcb, Mcb, Start, End, Size);

    } else {

        BOOLEAN do_expand;

#if EXT2_PRE_ALLOCATION_SUPPORT
        do_expand = TRUE;
#else
        do_expand = (IrpContext->MajorFunction == IRP_MJ_WRITE) ||
                    IsMcbDirectory(Mcb);
#endif
        if (!do_expand)
            goto errorout;

        status = Ext2ExpandIndirect(IrpContext, Vcb, Mcb, Start, End, Size);
    }

errorout:
    return status;
}


NTSTATUS