Re: stop using ioctl_by_bdev in the s390 DASD driver

From: Christian Borntraeger
Date: Tue Apr 21 2020 - 06:43:14 EST




On 21.04.20 12:32, Cornelia Huck wrote:
> On Tue, 21 Apr 2020 11:58:31 +0200
> Christian Borntraeger <borntraeger@xxxxxxxxxx> wrote:
>
>> On 21.04.20 08:12, Christoph Hellwig wrote:
>>> Hi Jens and DASD maintainers,
>>>
>>> can you take a look at this series, which stops the DASD driver from
>>> issuing ioctls from kernel space, in preparation of removing
>>> ioctl_by_bdev. I don't really like the new s390-only method, but short
>>> of forcing the dasd driver to be built into the kernel I can't think of
>>> anything better. But maybe the s390 maintainers are fine with forcing
>>> the DASD driver to be built in, in which case we could go down that
>>> route?
>>
>> Hmm the defconfig results in dasd built-in anyway. But distros really like
>> to keep it modular.
>>
>> Hmm, we do have
>>
>> obj-$(CONFIG_DASD) += dasd_mod.o
>> obj-$(CONFIG_DASD_DIAG) += dasd_diag_mod.o
>> obj-$(CONFIG_DASD_ECKD) += dasd_eckd_mod.o
>> obj-$(CONFIG_DASD_FBA) += dasd_fba_mod.o
>>
>> Would it work to make CONFIG_DASD built-in only and keep the other 3 as modules?
>> Not sure about the implications.
>>
>
> I don't think non-eckd dasd drivers are really useful outside of z/VM
> guests, so keeping at least the disciplines modular would be good.
>
> Also, what about special purpose environments like the zfcp dumper?
> Would be good to be able to keep these small.
>
> How big is the dasd code in the end?


File: drivers/s390/block/dasd_diag_mod.ko
Size: 519976 Blocks: 1016 IO Block: 4096 regular file
--
File: drivers/s390/block/dasd_eckd_mod.ko
Size: 2125976 Blocks: 4160 IO Block: 4096 regular file
--
File: drivers/s390/block/dasd_fba_mod.ko
Size: 524256 Blocks: 1024 IO Block: 4096 regular file
--
File: drivers/s390/block/dasd_mod.ko
Size: 3273464 Blocks: 6400 IO Block: 4096 regular file


So 3 MB seems quite a lot for special purpose Linuxes like the zfcp dumper.