Re: [PATCH] common: Add infrastructure for syncfs syscall tests

[Chengguang Xu <cgxu@mykernel.net>]

> 在 2017年12月1日，下午12:13，Eryu Guan <eguan@redhat.com> 写道：
> 
> On Fri, Dec 01, 2017 at 12:04:44PM +0800, Chengguang Xu wrote:
>> Hi Eryu,
>> 
>> Actually, in my another test case generic/470 will need to check whether fs supports syncfs or not. 
>> I make shared infrastructure for checking that, and because it is common component 
>> I post as an individual patch instead of including in the case of generic/470.
> 
> I think "_require_xfs_io_command syncfs" should be fine, there's no need
> & not encouraged to add new binary & usage like this. If you want to run
> syncfs(2) to make sure the kernel actually supports it, you can add a
> new 'syncfs' switch case in _require_xfs_io_command.
> 

Failure of _require_xfs_io_command check leads to notrun, if we have several
sync patterns(combination of fsync/fdatasync/syncfs/sync) in an actual test case, 
the case will lose downward compatibility for old kernel.
In this situation, we have to split test case though they look similar.

Thanks，
Chengguang.