[LTP] [PATCH] block: add BLK_FEAT_LBS to check for PAGE_SIZE limit

[Luis Chamberlain]

On Wed, Mar 12, 2025 at 06:21:55AM +0100, Christoph Hellwig wrote:
> On Tue, Mar 11, 2025 at 10:00:28PM -0700, Luis Chamberlain wrote:
> > We should take time to validate each block driver before enabling
> > support for larger logical block sizes, so that those that didn't
> > have support stay that way and don't need modifications.
> > 
> > Li Wang reported this as a regression on LTP via:
> > 
> > testcases/kernel/syscalls/ioctl/ioctl_loop06
> > 
> > Which uses the loopback driver to enable larger logical block sizes
> > first with LOOP_CONFIGURE and then LOOP_SET_BLOCK_SIZE. While
> > I see no reason why the loopback block driver can't support
> > larger logical block sizes than PAGE_SIZE, leave this validation
> > step as a secondary effort for each block driver.
> 
> This doesn't really make sense.  We don't want a flag that caps driver
> controlled values at a arbitrary value (and then not used it at all in
> the patch).
> 
> If you need extra per-driver validatation, do it in the driver.

Are you suggesting we just move back the PAGE_SIZE check, or to keep
the checks for the block driver limits into each driver?

  Luis