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

[Li Wang]

On Wed, Mar 12, 2025 at 9:59 PM Christoph Hellwig <hch@lst.de> wrote:

> On Wed, Mar 12, 2025 at 05:19:36PM +0800, Li Wang wrote:
> > Well, does that patch for ioctl_loop06 still make sense?
> > Or any other workaround?
> > https://lists.linux.it/pipermail/ltp/2025-March/042599.html
>
> The real question is what block sizes we want to support for the
> loop driver.  Because if it is larger than the physical block size
> it can lead to torn writes.  But I guess no one cared about those
> on loop so far, so why care about this now..
>

That's because the kernel test-robot reports a LTP/ioctl_loop06 test
fail in kernel commit:
  47dd67532303803  ("block/bdev: lift block size restrictions to 64k")

The ioctl_loop06 is a boundary testing and always fail with
LOOP_SET_BLOCK_SIZE set a value larger than PAGE_SIZE.
But now it's set successfully unexpectedly.

If you all believe the boundary test for loopback driver is redundant,
I can help remove that from LTP code.



> But if we don't want any limit on the block size that patch looks
> right.
>

Yes, it highly depends on the kernel behavior.


-- 
Regards,
Li Wang