linux-kernel - Re: [PATCH] null_blk: allow teardown on request timeout

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Date:   Mon, 17 Oct 2022 09:30:47 +0000
From:   Chaitanya Kulkarni <chaitanyak@...dia.com>
To:     Ming Lei <ming.lei@...hat.com>,
        Chaitanya Kulkarni <chaitanyak@...dia.com>
CC:     "linux-block@...r.kernel.org" <linux-block@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "axboe@...nel.dk" <axboe@...nel.dk>,
        "damien.lemoal@...nsource.wdc.com" <damien.lemoal@...nsource.wdc.com>,
        "johannes.thumshirn@....com" <johannes.thumshirn@....com>,
        "bvanassche@....org" <bvanassche@....org>,
        "shinichiro.kawasaki@....com" <shinichiro.kawasaki@....com>,
        "vincent.fu@...sung.com" <vincent.fu@...sung.com>,
        "yukuai3@...wei.com" <yukuai3@...wei.com>
Subject: Re: [PATCH] null_blk: allow teardown on request timeout


>> +	/*
>> +	 * Unblock any pending dispatch I/Os before we destroy the device.
>> +	 * From null_destroy_dev()->del_gendisk() will set GD_DEAD flag
>> +	 * causing any new I/O from __bio_queue_enter() to fail with -ENODEV.
>> +	 */
>> +	blk_mq_unquiesce_queue(nullb->q);
>> +
>> +	null_destroy_dev(nullb);
> 
> destroying device is never good cleanup for handling timeout/abort, and it
> should have been the last straw any time.
> 

That is exactly why I've added the rq_abort_limit, so until the limit
is not reached null_abort_work() will not get scheduled and device is
not destroyed.

-ck