[LTP] [PATCH v4] ioctl_loop06: update loopback block size validation

[Petr Vorel]

Hi Li,

> The kernel commit 47dd6753 ("block/bdev: lift block size restrictions to 64k")
> now supports block sizes larger than PAGE_SIZE, with a new upper limit of
> BLK_MAX_BLOCK_SIZE (64K). But ioctl_loop06 still assumes that PAGE_SIZE is the
> maximum allowed block size, causing failures on newer kernels(>= 6.14):

>   ioctl_loop06.c:74: TINFO: Using LOOP_SET_BLOCK_SIZE with arg > PAGE_SIZE
>   ioctl_loop06.c:57: TFAIL: Set block size succeed unexpectedly
>   ...
>   ioctl_loop06.c:74: TINFO: Using LOOP_CONFIGURE with block_size > PAGE_SIZE
>   ioctl_loop06.c:57: TFAIL: Set block size succeed unexpectedly

> This patch updates ioctl_loop06 to use BLK_MAX_BLOCK_SIZE instead of PAGE_SIZE
> for block size validation.

> And, dynamically sets bs based on BLK_MAX_BLOCK_SIZE, using 1024 bytes if it's
> below 1MB or scaling it otherwise. Ensures tst_fill_file() writes efficiently
> while maintaining compatibility across different kernel versions.

LGTM.
Reviewed-by: Petr Vorel <pvorel@suse.cz>

Kind regards,
Petr