[LTP] [PATCH] dio_read: fix infinite loop when readsize >= filesize

[Petr Vorel]

Hi Andrea,

> The do_direct_reads() function had exit conditions inside the inner
> for loop. When readsize >= filesize, the for loop condition is never
> true, causing the while(1) loop to spin infinitely without checking
> if writers completed or runtime expired.

> Move the exit condition checks outside the for loop to ensure they
> are evaluated on every iteration, regardless of readsize/filesize
> parameters.

> Signed-off-by: Andrea Cervesato <andrea.cervesato@suse.com>
> ---
> There's a sporadic failure in DOR000 that causes test to loop
> indefinetly under s390x. This patch tries to fix the issue by ensuring
> test will check runtime and if children completed.

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

As a fix for indefinite loop LGTM. But why it happen readsize >= filesize? These
are related to -r and -s values, but we always use -r 512k -w 512k -s 32M.
I wonder why this happen only on s390x? (I'd expect ppc64le which has different
page size.

Also that means that pread() is skipped when this happen.

Kind regards,
Petr