From mboxrd@z Thu Jan  1 00:00:00 1970
From: NeilBrown <neilb@suse.de>
Subject: Re: Catching a RAID error in a process
Date: Thu, 19 Jul 2012 09:00:45 +1000
Message-ID: <20120719090045.361edaef@notabene.brown>
References: <50071D3B.3090309@tmr.com>
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To: Bill Davidsen <davidsen@tmr.com>
Cc: Linux RAID <linux-raid@vger.kernel.org>
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On Wed, 18 Jul 2012 16:31:55 -0400 Bill Davidsen <davidsen@tmr.com> wrote:

> Can someone point me to the docs to have a process run or notified when a=
 RAID=20
> event triggers? I've been playing with some recovery ideas, but polling s=
tates=20
> and status is not the proper way to do this, and I want to test with a us=
er=20
> program before I start putting patches in the kernel.
>=20

I guess you don't mean "run mdadm --monitor --program /bin/myscript" ??

Do you want "just any event" or some specific set of events?

See mdstat_wait in mdstat.c in the mdadm sources.  It waits for any event by
using 'select' on /proc/mdstat.

void mdstat_wait(int seconds)
{
	fd_set fds;
	struct timeval tm;
	int maxfd =3D 0;
	FD_ZERO(&fds);
	if (mdstat_fd >=3D 0) {
		FD_SET(mdstat_fd, &fds);
		maxfd =3D mdstat_fd;
	}
	tm.tv_sec =3D seconds;
	tm.tv_usec =3D 0;
	select(maxfd + 1, NULL, NULL, &fds, &tm);
}


mdstat_fd is a global variable=20
    mdstat_fd =3D open("/proc/mdstat", O_RDONLY);

NeilBrown

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