From mboxrd@z Thu Jan  1 00:00:00 1970
From: NeilBrown <neilb@suse.com>
Subject: Re: [PATCH] udev rules: introduce rules for cluster-md to confirm device
Date: Tue, 01 Aug 2017 14:40:12 +1000
Message-ID: <87o9rzvr2r.fsf@notabene.neil.brown.name>
References: <20170801031504.8452-1-gqjiang@suse.com>
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To: linux-raid@vger.kernel.org
Cc: jes.sorensen@gmail.com, Guoqing Jiang <gqjiang@suse.com>
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On Tue, Aug 01 2017, Guoqing Jiang wrote:

> For cluster scenario, add device is different with native raid.
> When a node issues adds a device, then the node will broadcast
> a message with UUID to other nodes in the cluster. If receiving
> node can find the device with the specific UUID, it must confirm
> the device, otherwise reports it is missing.
>
> Signed-off-by: Guoqing Jiang <gqjiang@suse.com>
> ---
>  Makefile                               |  6 ++++--
>  udev-md-clustered-confirm-device.rules | 20 ++++++++++++++++++++
>  2 files changed, 24 insertions(+), 2 deletions(-)
>  create mode 100644 udev-md-clustered-confirm-device.rules
>
> diff --git a/Makefile b/Makefile
> index 021d3ad..0977f27 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -256,8 +256,10 @@ install-man: mdadm.8 md.4 mdadm.conf.5 mdmon.8
>  	$(INSTALL) -D -m 644 md.4 $(DESTDIR)$(MAN4DIR)/md.4
>  	$(INSTALL) -D -m 644 mdadm.conf.5 $(DESTDIR)$(MAN5DIR)/mdadm.conf.5
>=20=20
> -install-udev: udev-md-raid-arrays.rules udev-md-raid-assembly.rules udev=
-md-raid-creating.rules
> -	@for file in 01-md-raid-creating.rules 63-md-raid-arrays.rules 64-md-ra=
id-assembly.rules ; \
> +install-udev: udev-md-raid-arrays.rules udev-md-raid-assembly.rules udev=
-md-raid-creating.rules \
> +		udev-md-clustered-confirm-device.rules=20
> +	@for file in 01-md-raid-creating.rules 63-md-raid-arrays.rules 64-md-ra=
id-assembly.rules \
> +		69-md-clustered-confirm-device.rules ; \
>  	do sed -e 's,BINDIR,$(BINDIR),g' udev-$${file#??-} > .install.tmp.1 && \
>  	   $(ECHO) $(INSTALL) -D -m 644 udev-$${file#??-} $(DESTDIR)$(UDEVDIR)/=
rules.d/$$file ; \
>  	   $(INSTALL) -D -m 644 .install.tmp.1 $(DESTDIR)$(UDEVDIR)/rules.d/$$f=
ile ; \
> diff --git a/udev-md-clustered-confirm-device.rules b/udev-md-clustered-c=
onfirm-device.rules
> new file mode 100644
> index 0000000..d763e27
> --- /dev/null
> +++ b/udev-md-clustered-confirm-device.rules
> @@ -0,0 +1,20 @@
> +# do not edit this file, it will be overwritten on update
> +
> +SUBSYSTEM!=3D"block", GOTO=3D"clustermd_end"
> +
> +# handle md arrays
> +KERNEL!=3D"md*", GOTO=3D"clustermd_end"
> +ENV{DEVTYPE}!=3D"disk", GOTO=3D"clustermd_end"
> +
> +# Based on the received UUID, node confirms the device if
> +# it is found by blkid, otherwise the node reports it is
> +# missing.
> +ACTION=3D=3D"change", ENV{EVENT}=3D=3D"ADD_DEVICE", ENV{DEVICE_UUID}=3D=
=3D"?*", ENV{RAID_DISK}=3D=3D"?*", \
> +PROGRAM=3D"BINDIR/blkid -o device -t UUID_SUB=3D$env{DEVICE_UUID}", RESU=
LT!=3D"", \
> +RUN+=3D"BINDIR/mdadm --manage $env{DEVNAME} --cluster-confirm $env{RAID_=
DISK}:$result"
> +
> +ACTION=3D=3D"change", ENV{EVENT}=3D=3D"ADD_DEVICE", ENV{DEVICE_UUID}=3D=
=3D"?*", ENV{RAID_DISK}=3D=3D"?*", \
> +PROGRAM=3D"BINDIR/blkid -o device -t UUID_SUB=3D$env{DEVICE_UUID}", RESU=
LT=3D=3D"", \
> +RUN+=3D"BINDIR/mdadm --manage $env{DEVNAME} --cluster-confirm $env{RAID_=
DISK}:missing"
> +
> +LABEL=3D"clustermd_end"
> --=20
> 2.10.0

This can run "blkid" twice, which seems wasteful.
I think it would be best to skip to the end if ACTION !=3D "change" and if
event !=3D ADD_DEVICE etc.
Then
 PROGRAM=3D"BINDIR/blkid -o device -t UUID_SUB=3D$env{DEVICE_UUID}", ENV{".=
mdadm.blkid"} =3D "$result"

Then have two rules which tests ENV{".mdadm.blkid"} and run one of the
two mdadm commands.

NeilBrown

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