[sheepdog] [PATCH v3 3/6] md: add hot-plug and hot-unplug support

[Liu Yuan]

On 04/03/2013 04:21 PM, MORITA Kazutaka wrote:
> At Wed,  3 Apr 2013 14:27:44 +0800,
> Liu Yuan wrote:
>>
>>  static void md_do_recover(struct work *work)
>>  {
>>  	struct md_work *mw = container_of(work, struct md_work, work);
>> @@ -383,7 +408,10 @@ static void md_do_recover(struct work *work)
>>  	if (idx < 0)
>>  		/* Just ignore the duplicate EIO of the same path */
>>  		goto out;
>> -	unplug_disk(idx);
>> +	remove_disk(idx);
>> +	sys->disk_space = md_init_space();
> 
> tests/055 emulates disk failure by removing the md direcotry, but
> md_init_space() creates a new directory if it doesn't exist.  So, if
> simultaneous two disk failures happen, the first md_do_recover() will
> create a new md directory for the second disk and the second disk
> failure will be cancelled (objects in the directory will be removed
> though).
> 
> This might not be a problem because the md directory is a mount point
> in the actual use cases.  However, it is cleaner to call mkdir() only
> when starting sheepdog, I think.

But md plug also need mkdir. Maybe we can try to mkdir at collie side.
Then we can move mkdir out of md_init_space().

Thanks,
Yuan