From: Minwoo Im <minwoo.im.dev@gmail.com>
To: Christoph Hellwig <hch@lst.de>
Cc: linux-block@vger.kernel.org, Keith Busch <kbusch@kernel.org>,
Jens Axboe <axboe@fb.com>,
linux-nvme@lists.infradead.org, Sagi Grimberg <sagi@grimberg.me>
Subject: Re: [RFC] nvme: set block size during namespace validation
Date: Thu, 24 Dec 2020 03:31:43 +0900 [thread overview]
Message-ID: <20201223183143.GB13354@localhost.localdomain> (raw)
In-Reply-To: <20201223162737.GA8688@lst.de>
On 20-12-23 17:27:37, Christoph Hellwig wrote:
> On Thu, Dec 24, 2020 at 01:16:50AM +0900, Minwoo Im wrote:
> > Hello,
> >
> > On 20-12-23 16:49:04, Christoph Hellwig wrote:
> > > set_blocksize just sets the block sise used for buffer heads and should
> > > not be called by the driver. blkdev_get updates the block size, so
> > > you must already have the fd re-reading the partition table open?
> > > I'm not entirely sure how we can work around this except by avoiding
> > > buffer head I/O in the partition reread code. Note that this affects
> > > all block drivers where the block size could change at runtime.
> >
> > Thank you Christoph for your comment on this.
> >
> > Agreed. BLKRRPART leads us to block_read_full_page which takes buffer
> > heads for I/O.
> >
> > Yes, __blkdev_get() sets i_blkbits of block device inode via
> > set_init_blocksize. And Yes again as nvme-cli already opened the block
> > device fd and requests the BLKRRPART with that fd. Also, __bdev_get()
> > only updates the i_blkbits(blocksize) in case bdev->bd_openers == 0 which
> > is the first time to open this block device.
> >
> > Then, how about having NVMe driver prevent underflow case for the
> > request->__data_len is smaller than the logical block size like:
>
> Not sure this helps. I think we need to fix this proper and in the
> block layer. The long term fix is to stop messing with i_blksize
> at all, but that is going to take very long.
Agreed.
>
> I think for now the only thing we can do is to set a flag in the
> gendisk when the block size changes and then reject all I/O until
> the next first open that sets the blocksize.
Let me prepare work around patch for this issue soon.
Thanks!
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prev parent reply other threads:[~2020-12-23 18:31 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-23 15:01 [RFC] nvme: set block size during namespace validation Minwoo Im
2020-12-23 15:49 ` Christoph Hellwig
2020-12-23 16:16 ` Minwoo Im
2020-12-23 16:27 ` Christoph Hellwig
2020-12-23 18:31 ` Minwoo Im [this message]
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