linux-kernel - Re: [PATCH v4 2/2] s390/dasd: remove ioctl_by

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Message-ID: <ca1bad1e-6d4b-7e86-4a98-b9ba12e2bef2@de.ibm.com>
Date:   Wed, 7 Oct 2020 12:44:55 +0200
From:   Christian Borntraeger <borntraeger@...ibm.com>
To:     Christoph Hellwig <hch@....de>
Cc:     Stefan Haberland <sth@...ux.ibm.com>, axboe@...nel.dk,
        hoeppner@...ux.ibm.com, linux-s390@...r.kernel.org,
        heiko.carstens@...ibm.com, gor@...ux.ibm.com,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 2/2] s390/dasd: remove ioctl_by_bdev calls



On 07.10.20 12:39, Christoph Hellwig wrote:
> On Wed, Oct 07, 2020 at 11:34:17AM +0200, Christian Borntraeger wrote:
>>
>> On 19.05.20 16:22, Stefan Haberland wrote:
>>> The IBM partition parser requires device type specific information only
>>> available to the DASD driver to correctly register partitions. The
>>> current approach of using ioctl_by_bdev with a fake user space pointer
>>> is discouraged.
>>>
>>> Fix this by replacing IOCTL calls with direct in-kernel function calls.
>>>
>>> Suggested-by: Christoph Hellwig <hch@....de>
>>> Signed-off-by: Stefan Haberland <sth@...ux.ibm.com>
>>> Reviewed-by: Jan Hoeppner <hoeppner@...ux.ibm.com>
>>> Reviewed-by: Peter Oberparleiter <oberpar@...ux.ibm.com>
>>
>> FWIW, this broken the ibm-partition code for virtio-blk, when CONFIG_DASD=m.
> 
> What are the symptoms?

During boot I normally have
 
[    0.930231] virtio_blk virtio1: [vda] 5409180 4096-byte logical blocks (22.2 GB/20.6 GiB)
[    0.930233] vda: detected capacity change from 0 to 22156001280
[    0.932806]  vda:VOL1/  0X3333: vda1 vda2 vda3

With this change, the last line is no longer there (if CONFIG_DASD=m) and this also 
reflects itself in /proc/partitions. The partitions are no longer detected.