Re: [PATCH v2] loop: avoid EAGAIN, if offset or block_size are changed

[Bart Van Assche]

On 11/25/19 11:22 AM, Jaegeuk Kim wrote:
> On 11/25, Bart Van Assche wrote:
> > Thank you for the additional and very helpful clarification. Can you have a look at the (totally untested) patch below? I prefer that version because it prevents concurrent processing of requests and syncing/killing the bdev.
>
> Yeah, I thought this was much cleaner way, but wasn't sure it could be doable
> to sync|kill block device after freezing the queue. Is it okay?

Hi Jaegeuk,

That patch was based on an incorrect interpretation of the meaning of 
lo_device. After having taken another loop at the block driver, I don't 
think that calling sync after freezing the queue is OK. How about using 
the following call sequence:
* sync_blockdev()
* blk_mq_freeze_queue()
* kill_bdev()

Thanks,

Bart.