From: Christoph Hellwig <hch@lst.de>
To: Minwoo Im <minwoo.im.dev@gmail.com>
Cc: Jens Axboe <axboe@fb.com>, Sagi Grimberg <sagi@grimberg.me>,
linux-nvme@lists.infradead.org, linux-block@vger.kernel.org,
Keith Busch <kbusch@kernel.org>, Christoph Hellwig <hch@lst.de>
Subject: Re: [RFC] nvme: set block size during namespace validation
Date: Wed, 23 Dec 2020 17:27:37 +0100 [thread overview]
Message-ID: <20201223162737.GA8688@lst.de> (raw)
In-Reply-To: <20201223161650.GA13354@localhost.localdomain>
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.
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.
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next prev parent reply other threads:[~2020-12-23 16:27 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 [this message]
2020-12-23 18:31 ` Minwoo Im
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