Re: [RFC PATCH V3 1/1] block: reject I/O for same fd if block size changed

From: Minwoo Im <minwoo.im.dev@gmail.com>
To: Christoph Hellwig <hch@lst.de>
Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-fsdevel@vger.kernel.org, Jens Axboe <axboe@kernel.dk>,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	Chaitanya Kulkarni <Chaitanya.Kulkarni@wdc.com>
Subject: Re: [RFC PATCH V3 1/1] block: reject I/O for same fd if block size changed
Date: Tue, 5 Jan 2021 10:04:56 +0900	[thread overview]
Message-ID: <20210105010456.GA6454@localhost.localdomain> (raw)
In-Reply-To: <20210104171141.GB27235@lst.de>

Hello Christoph,

Thanks for your review.

On 21-01-04 18:11:41, Christoph Hellwig wrote:
> On Mon, Jan 04, 2021 at 06:11:08PM +0100, Christoph Hellwig wrote:
> > On Mon, Jan 04, 2021 at 10:06:59PM +0900, Minwoo Im wrote:
> > > +	if (q->backing_dev_info && q->backing_dev_info->owner &&
> > > +			limits->logical_block_size != size) {
> > > +		bdev = blkdev_get_no_open(q->backing_dev_info->owner->devt);
> > > +		bdev->bd_disk->flags |= GENHD_FL_BLOCK_SIZE_CHANGED;
> > > +		blkdev_put_no_open(bdev);
> > > +	}
> > 
> > We really need the backpointer from the queue to the gendisk I've wanted
> > to add for a while.  Can we at least restrict this to a live gendisk?

It was a point that I really would like to ask by RFC whether we can
have backpointer to the gendisk from the request_queue.  And I'd like to
have it to simplify this routine and for future usages also.

I will restrict this one by checking GENHD_FL_UP flag from the gendisk
for the next patch.

> 
> Alternatively we could make this request_queue QUEUE* flag for now.

As this patch rejects I/O from the block layer partition code, can we
have this flag in gendisk rather than request_queue ?

Thanks,