[LTP] [PATCH] mkswap: make the test device size is aligned to pagesize

From: Cyril Hrubis <chrubis@suse.cz>
To: ltp@lists.linux.it
Subject: [LTP] [PATCH] mkswap: make the test device size is aligned to pagesize
Date: Wed, 17 Aug 2016 13:18:41 +0200	[thread overview]
Message-ID: <20160817111841.GA10343@rei.lan> (raw)
In-Reply-To: <20160817033946.GA6430@gmail.com>

Hi!
> > Now that makes sense.
> > 
> > But if that is the case we still have to align down the device size to
> > the page size at the start of the test. Since the device can also be
> > passed down to the runltp script as a parameter and we cannot make any
> > assumptions about its size.
> 
> Hmm, yes, we have to face the problem.
> 
> A simple idea comes to my mind is that the loop device size should be
> customized by specific testcase(mkswap01.sh).
> 
> That would be happy if function "tst_acquire_device() 'NUM'" can get
> 'NUM' MB block device for testing.
> 
> It means we have to modify another path which about tst_acquire_device().

This is a bad idea for two reasons.

Fist one is that the reason the user passed block device to runltp may
be that the kernel does not support loop devices. In this case the test
would be skipped for no good reason.

The second is that there is another patch in flight that aims to add
minimal size parameter to the tst_acquire_device(). Which is much more
useful.

Why cannot we just simply take the size of the device at start of the
test, align it down to be the multiple of $PAGE_SIZE and use that as the
size for testing?

-- 
Cyril Hrubis
chrubis@suse.cz