[Ocfs2-devel] [PATCH] ocfs2: add trimfs dlm lock

[alex chen]

Hi Gang,

On 2017/12/8 8:35, Gang He wrote:
> Hello Andrew and All,
> 
>>>> Andrew Morton <akpm at linux-foundation.org> 12/08/17 7:34 AM >>>
> On Thu,  7 Dec 2017 21:21:58 +0800 Gang He <ghe at suse.com> wrote:
> 
>> As you know, ocfs2 has support trim the underlying disk via
>> fstrim command. But there is a problem, ocfs2 is a shared storage
>> cluster file system, if the user configures a scheduled fstrim
>> job on each file system node, this will trigger multiple nodes
>> trim a shared disk simultaneously, it is very wasteful for CPU
>> and IO consumption.
>> Then, we introduce a trimfs dlm lock, which will make only one
>> fstrim command is running on the shared disk among the cluster,
>> the other fstrim command should be returned with -EBUSY errno.
> 
> Newly returning -EBUSY sounds a bit rude.  And non-backward-compatible. 
> Would it be better for the other fstrim callers to wait until the
> operation has completed then return success?
> Gang: OK, that means, if multiple nodes trim a shared disk simultaneously,
> only one node (get the lock first) do the real trimming operation, 
> the other nodes will wait until that node finishes trimming, then return zero.
> Does anyone has more comments? If not, I will do this change in v2.
> 

IMO, it is better for the other fstrim callers to wait until this node finishes trimming.

Thanks,
Alex
> Thanks
> Gang 
> 
> 
> 
> 
> 
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