Re: [PATCH 4/8] aio: add aio_read_pages and aio_write_pages

[Jeff Moyer <jmoyer@redhat.com>]

Jeff Moyer <jmoyer@redhat.com> writes:

> Zach Brown <zach.brown@oracle.com> writes:
>
>> This adds read and write file operations which specify memory with an array of
>> page pointers, offsets, and lengths.  AIO commands are added which call these
>> methods.  Fields are added to the iocb to specify the pages which are passed to
>> the methods.
>>
>> This is intended to be used by callers in the kernel.
>>
>> Signed-off-by: Zach Brown <zach.brown@oracle.com>
>> diff --git a/include/linux/aio_abi.h b/include/linux/aio_abi.h
>> index 2c87316..5b67ed6 100644
>> --- a/include/linux/aio_abi.h
>> +++ b/include/linux/aio_abi.h
>> @@ -44,6 +44,8 @@ enum {
>>  	IOCB_CMD_NOOP = 6,
>>  	IOCB_CMD_PREADV = 7,
>>  	IOCB_CMD_PWRITEV = 8,
>> +	IOCB_CMD_PREADP = 9,
>> +	IOCB_CMD_PWRITEP = 10,
>
> I question the merits of adding commands to the aio_abi that cannot be
> called from userspace.  However, I don't know how else you would keep
> things consistent.  I guess we live with it.

Actually, I didn't see code in the patch to prevent userspace from
issuing such commands.  Shouldn't we check for that and spit an error?
It sounds like a security risk if we don't.

Cheers,
Jeff