From mboxrd@z Thu Jan  1 00:00:00 1970
From: Malahal Naineni <malahal@us.ibm.com>
Subject: Re: Doubt regarding dm-raid1
Date: Fri, 28 Jan 2011 11:38:41 -0800
Message-ID: <20110128193841.GA4616@us.ibm.com>
References: <AANLkTi=ryfEU9VOBE7qBaecWnJ93h9tdYt0cNb388vXC@mail.gmail.com>
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nishant mungse [nishantmungse@gmail.com] wrote:
>    Hi Malahal
> 
>     Thanks for reply. I am not able to understand what  this
>     "INIT_WORK(&ms->kmirrord_work, do_mirror)" function does. It  is written
>     in mirror_ctr of dm-raid1. What i think is whenever a bio comes dm_mirror
>     will be called if that is case then why this is written in mirror_ctr.

INIT_WORK just initializes the work structure. When it is queued by calling
queue_work() (e.g. from wakeup_mirrord) the actual function do_mirror() gets
called. It is called in a different thread context though!

The following article is a bit outdated, but it gives what a work queue
is and its API:

http://lwn.net/Articles/23634/

Hope that helps,
Malahal.