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.
