Hi, > -----Original Message----- > From: linux-raid-owner@xxxxxxxxxxxxxxx [mailto:linux-raid- > owner@xxxxxxxxxxxxxxx] On Behalf Of Neil Brown > Sent: Monday, November 22, 2010 6:02 AM > To: Hawrylewicz Czarnowski, Przemyslaw > Cc: linux-raid@xxxxxxxxxxxxxxx; Neubauer, Wojciech; Williams, Dan J; > Ciechanowski, Ed; Labun, Marcin; Czarnowska, Anna > Subject: Re: Autorebuild, new dynamic udev rules for hot-plugs > > On Fri, 19 Nov 2010 15:12:19 +0000 > "Hawrylewicz Czarnowski, Przemyslaw" > <przemyslaw.hawrylewicz.czarnowski@xxxxxxxxx> wrote: > > > Hi, > > > > I would like to present another patch for our autorebuild tree (it should > be applied on the top of Autorebuild series, as devel-3.2 is not stable > yet). Dan Williams proposed to reduce overhead associated with passing each > hot-plugged block device to mdadm, using just the devices described in > policies via mdadm.conf file. > > See patch below for details, comments are as always very welcome. > > I am in general in favour of this approach. > It has the benefit that it can very easily be not-used if there turn out to > be problems with it. > > Four comments. > > 1/ I wouldn't write a file in /lib/udev/rules.d/ > I think it should be written to "/dev/.udev/rules.d/" > which is referred to as the "temporary rules directory" > in the udev documentation. I am not sure if it is what we are looking for. Temporary means they disappear after reboot. It is OK as cold-plug does not need support for bare disks (or maybe I am wrong?). But in such case, one who wants to use autorebuild should invoke mdadm --activate-domains for example in /etc/init.d/local.boot or somewhere else. Second idea here is to use ActivateDomain() when one starts monitor with autorebuild enabled. Which one? I would prefer to leave it as it was written initially (considering comment #4). Then, if one removes policies from config, invoking --activate-domains should reset/remove rules (but see #3) > > 2/ I would be good to process the type=disk or type=part part of the > policy into the rules file as well. OK > > 3/ I'm not very comfortable with hard-coding the name of the > file to be created in the rules.d directory. Maybe usage could be > --activate-domains=63-md-whatever Good idea, but only if we store our rules in /dev/.udev/rules.d. Otherwise it would be difficult to maintain all generated rules and remove the old ones... I would leave default if not given by user, but one can pass any file name. > > 4/ I don't think it is good to have an incomplete file in rules.d that udev > might accidentally read. We should create the file with a name with a > leading '.' (assuming udev ignores those, I haven't checked) and then > rename it after it has been completely written. You're right. In theory, such partial udev rules are excluded when udev can't interpret them properly. I have looked into udev's sources and found that it looks for "*.rules" files. All other file extensions are ignored. Files with leading dots are also omitted. I would prefer to create <name>.temp file and then rename it into <name>.rules. > > Other than that, it looks pretty good. Great > > Thanks, > NeilBrown > > > > > Date: Thu, 18 Nov 2010 01:19:52 +0100 > > Subject: [PATCH] New dynamic hot-plug udev rules for policies > > > > When introducing policies, new hot-plug rules were added to support > > bare disks. Mdadm was started for each hot plugged block device > > to determine if it could be used as spare or as a replacement member for > > degraded array. > > This patch introduces limitation of range of devices that are handled > > by mdadm. It limits them to the ones specified in domains associated > > with the actions: spare-same-port, spare and spare-force. > > In order to enable hot-plug for bare disks one must update udev rules > > with command > > > > mdadm --activate-domains > > > > After mdadm.conf is changed one is obliged to re-run > > "mdadm --activate-domains" command in order to bring the system > > configuration up to date. > > All hot-plugged disks containing metadata are still handled by existing > > rules. > > > > Note: this patch is just a proposition to minimize overhead of using > mdadm for > > each plugged block device. If accepted, it will be incorporated in > > previous implementation of hot-plug for bare disks. > > > > Signed-off-by: Przemyslaw Czarnowski > <przemyslaw.hawrylewicz.czarnowski@xxxxxxxxx> > > --- > > Makefile | 2 + > > ReadMe.c | 1 + > > mdadm.c | 4 ++ > > mdadm.h | 9 +++- > > policy.c | 137 > ++++++++++++++++++++++++++++++++++++++++++++++++++++ > > udev-md-raid.rules | 5 +- > > 6 files changed, 154 insertions(+), 4 deletions(-) > > [cut] -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
