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Subject: Re: [PATCH v2] fstests: btrfs: Add regression test for reserved space
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References: <1438736914-28147-1-git-send-email-quwenruo@cn.fujitsu.com>
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From: Tsutomu Itoh <t-itoh@jp.fujitsu.com>
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Date: Wed, 5 Aug 2015 11:52:36 +0900
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To: Qu Wenruo <quwenruo@cn.fujitsu.com>
Cc: linux-btrfs@vger.kernel.org, fstests@vger.kernel.org
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On 2015/08/05 10:57, Dave Chinner wrote:
> On Wed, Aug 05, 2015 at 09:39:35AM +0800, Qu Wenruo wrote:
>> Tsutomu Itoh wrote on 2015/08/05 10:26 +0900:
>>> On 2015/08/05 10:08, Qu Wenruo wrote:
>>>> +# As the reserved space freeing happens at commit_transaction time,
>>>> +# without a transaction commit, no reserved space needs freeing and
>>>> +# won't trigger the bug.
>>>> +sync
>>>
>>> Isn't '$BTRFS_UTIL_PROG filesystem sync' better instead of 'sync'?
>>>
>>> Thanks,
>>> Tsutomu
>> Hi, Tsutomu-san,
>>
>> Yes, I did use such method before, but Dave said it's better to use
>> unified interface to sync a filesystem other than the specialized
>> one.
>>
>> So I still use sync as Dave said.
>
> Mainly because "sync" is what users will use to make sure their data
> is safe. filesystem specific tools have a habit of doing "special
> stuff" to sync a filesystem, so it may not reflect the way users
> expect the system to behaviour when they run sync.
>
> The other option is this:
>
> _syncfs()
> {
> 	mntpt=$1
>
> 	$XFS_IO_PROG -c syncfs $mntpt
> }
>
> _sync_test()
> {
> 	_syncfs $TEST_DIR
> }
>
> _sync_scratch()
> {
> 	_syncfs $SCRATCH_MNT
> }
>
> which only runs sync on the filesystem that needs syncing (via the
> syncfs() syscall)

I think that syncfs is better instead of sync because the syncing of
the specified filesystem is necessary.

Thanks,
Tsutomu

>
> Cheers,
>
> Dave.
>