On Mon, Mar 06, 2023 at 01:01:26PM +0100, Hannes Reinecke wrote:
> Use an arbitrary limit of 32M for the maximal blocksize so as not
> to overflow the page cache.
>
> Signed-off-by: Hannes Reinecke <hare@xxxxxxx>
> ---
> drivers/block/brd.c | 16 ++++++++--------
> 1 file changed, 8 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/block/brd.c b/drivers/block/brd.c
> index 11bac3c3f1b6..1ed114cd5cb0 100644
> --- a/drivers/block/brd.c
> +++ b/drivers/block/brd.c
> @@ -348,6 +348,7 @@ static int max_part = 1;
> module_param(max_part, int, 0444);
> MODULE_PARM_DESC(max_part, "Num Minors to reserve between devices");
>
> +#define RD_MAX_SECTOR_SIZE 65536
> static unsigned int rd_blksize = PAGE_SIZE;
> module_param(rd_blksize, uint, 0444);
> MODULE_PARM_DESC(rd_blksize, "Blocksize of each RAM disk in bytes.");
> @@ -410,15 +411,14 @@ static int brd_alloc(int i)
> disk->private_data = brd;
> strscpy(disk->disk_name, buf, DISK_NAME_LEN);
> set_capacity(disk, rd_size * 2);
> -
> - /*
> - * This is so fdisk will align partitions on 4k, because of
> - * direct_access API needing 4k alignment, returning a PFN
> - * (This is only a problem on very small devices <= 4M,
> - * otherwise fdisk will align on 1M. Regardless this call
> - * is harmless)
> - */
> +
> + if (rd_blksize > RD_MAX_SECTOR_SIZE) {
rd_blkside is in bytes, but the above is ccomapring it to something in units of
SECTOR_SIZE.
> + /* Arbitrary limit maximum block size to 32M */
> + err = -EINVAL;
> + goto out_cleanup_disk;
> + }
rd_blksize also needs to be >= 512, and a power of 2.
> blk_queue_physical_block_size(disk->queue, rd_blksize);
> + blk_queue_max_hw_sectors(disk->queue, RD_MAX_SECTOR_SIZE);
>
> /* Tell the block layer that this is not a rotational device */
> blk_queue_flag_set(QUEUE_FLAG_NONROT, disk->queue);
