Re: [PATCH] nbd: don't update block size after device is started

[lining <lining2020x@163.com>]

Tested on Ubuntu 20.04.1 LTS with kernel 5.10.0-rc1+, it works fine.

Tested-by: lining <lining2020x@163.com>

在 2020/10/28 15:24, Ming Lei 写道:
> Mounted NBD device can be resized, one use case is rbd-nbd.
> 
> Fix the issue by setting up default block size, then not touch it
> in nbd_size_update() any more. This kind of usage is aligned with loop
> which has same use case too.
> 
> Reported-by: lining <lining2020x@163.com>
> Cc: Josef Bacik <josef@toxicpanda.com>
> Cc: Jan Kara <jack@suse.cz>
> Signed-off-by: Ming Lei <ming.lei@redhat.com>
> ---
>   drivers/block/nbd.c | 9 +++++----
>   1 file changed, 5 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
> index 3c9485acdd81..e13ce0f75f80 100644
> --- a/drivers/block/nbd.c
> +++ b/drivers/block/nbd.c
> @@ -296,7 +296,7 @@ static void nbd_size_clear(struct nbd_device *nbd)
>   	}
>   }
>   
> -static void nbd_size_update(struct nbd_device *nbd)
> +static void nbd_size_update(struct nbd_device *nbd, bool start)
>   {
>   	struct nbd_config *config = nbd->config;
>   	struct block_device *bdev = bdget_disk(nbd->disk, 0);
> @@ -313,7 +313,8 @@ static void nbd_size_update(struct nbd_device *nbd)
>   	if (bdev) {
>   		if (bdev->bd_disk) {
>   			bd_set_nr_sectors(bdev, nr_sectors);
> -			set_blocksize(bdev, config->blksize);
> +			if (start)
> +				set_blocksize(bdev, config->blksize);
>   		} else
>   			set_bit(GD_NEED_PART_SCAN, &nbd->disk->state);
>   		bdput(bdev);
> @@ -328,7 +329,7 @@ static void nbd_size_set(struct nbd_device *nbd, loff_t blocksize,
>   	config->blksize = blocksize;
>   	config->bytesize = blocksize * nr_blocks;
>   	if (nbd->task_recv != NULL)
> -		nbd_size_update(nbd);
> +		nbd_size_update(nbd, false);
>   }
>   
>   static void nbd_complete_rq(struct request *req)
> @@ -1308,7 +1309,7 @@ static int nbd_start_device(struct nbd_device *nbd)
>   		args->index = i;
>   		queue_work(nbd->recv_workq, &args->work);
>   	}
> -	nbd_size_update(nbd);
> +	nbd_size_update(nbd, true);
>   	return error;
>   }
>   
>