[PATCH 3/5] block/bdev: lift restrictions on supported blocksize

[Luis Chamberlain]

On Fri, May 10, 2024 at 12:29:04PM +0200, hare at kernel.org wrote:
> From: Hannes Reinecke <hare at suse.de>
> 
> We now can support blocksizes larger than PAGE_SIZE, so lift
> the restriction.
> 
> Signed-off-by: Hannes Reinecke <hare at suse.de>
> ---
>  block/bdev.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/block/bdev.c b/block/bdev.c
> index b8e32d933a63..d37aa51b99ed 100644
> --- a/block/bdev.c
> +++ b/block/bdev.c
> @@ -146,8 +146,8 @@ static void set_init_blocksize(struct block_device *bdev)
>  
>  int set_blocksize(struct block_device *bdev, int size)
>  {
> -	/* Size must be a power of two, and between 512 and PAGE_SIZE */
> -	if (size > PAGE_SIZE || size < 512 || !is_power_of_2(size))
> +	/* Size must be a power of two, and larger than 512 */
> +	if (size < 512 || !is_power_of_2(size))

That needs to just be replaced with:

1 << (PAGE_SHIFT + MAX_PAGECACHE_ORDER)

We're not magically shooting to the sky all of a sudden. The large folio
world still has a limit. While that's 2 MiB today, yes, we can go higher
later, but even then, we still have a cap.

  Luis