Well, I think I will take your suggestions. I am sending another version
of the patch.

Thanks,
-Tao

-----Original Message-----
From: shlikernel@gmail.com [mailto:shlikernel@gmail.com] On Behalf Of
Shaohua Li
Sent: Wednesday, June 06, 2012 10:07 AM
To: Guo, Tao
Cc: glorioustao@gmail.com; linux-kernel@vger.kernel.org; neilb@suse.de;
axboe@kernel.dk; stable@vger.kernel.org; akpm@linux-foundation.org
Subject: Re: [PATCH 1/2] block: Move general unplug callback function
from md/raid to blk-core

2012/6/5  [off-list ref]:

quoted

If you ever tried to implement unplug function in umem, you would

find the code was almost identical as in dm/raid driver.

quoted

For other components which also need such unplug mechanism, it will

much more convenient to have such facilities.
It's just several lines of code and your usage actually doesn't need
the counter.
It's unclear to me your usage requires to move the callback to list
head.

quoted

PS: What's your specific concern about blk_plug_cb handles each

request_queue?
the blk_plug_cb stores request_queue, which is incorrect to me. Why
can't
one plug cb unplug two or more request_queues?