On 7/31/19 1:29 AM, Coly Li wrote:
> When people assemble a md raid device with a large number of
> component deivces (e.g. 1500 DASD disks), the raid device detail
> information generated by 'mdadm --detail --export $devnode' is very
> large. It is because the detail information contains information of
> all the component disks (even the missing/failed ones).
>
> In such condition, when udev-md-raid-arrays.rules is triggered and
> internally calls "mdadm --detail --no-devices --export $devnode",
> user may observe systemd error message ""invalid message length". It
> is because the following on-stack raw message buffer in systemd code
> is not big enough,
> systemd/src/libudev/libudev-monitor.c
> _public_ struct udev_device *udev_monito ...
> struct ucred *cred;
> union {
> struct udev_monitor_netlink_header nlh;
> char raw[8192];
> } buf;
> Even change size of raw[] from 8KB to larger size, it may still be not
> enough for detail message of a md raid device with much larger number of
> component devices.
>
> To fix this problem, an extra option '--no-devices' is added (the
> original idea is proposed by Neil Brown). When printing detailed
> information of a md raid device, if '--no-devices' is specified, then
> all component devices information will not be printed, then the output
> message size can be restricted to a small number, even with the systemd
> only has 8KB on-disk raw buffer, the md raid array udev rules can work
> correctly without failure message.
>
> Signed-off-by: Coly Li <colyli@xxxxxxx>
> Reviewed-by: NeilBrown <neilb@xxxxxxxx>
Applied!
Thanks,
Jes
