Re: [Xen-devel] [PATCH OSSTEST] Debian: Wait for udev devices to settle in erase-other-disks

[Ian Campbell <ian.campbell@xxxxxxxxxx>]

On Wed, 2015-09-23 at 16:59 +0100, Ian Jackson wrote:
> Ian Campbell writes ("[PATCH OSSTEST] Debian: Wait for udev devices to
> settle in erase-other-disks"):
> > Otherwise we, apparently, have a race between the "test -b" + dd
> > against the sda1 device node being removed and end up creating a file
> > called /dev/sda1 containing 32K of zeroes, which will later render
> > mke2fs very confused.
> > 
> > For some reason we seem to reliably loose the race on Jessie i386 host
> > installs, but not on Wheezy or other arches on Jessie.
> > 
> > This was tricky to diagnose because the Debian installer main-menu
> > process appears to buffer the output of things it runs before logging
> > them to /var/log/syslog, which means the output of "set -x" and the
> > actual affect of the commands (e.g. in the kernel messages) can be
> > presented in very confusing orders. Hence this patch also adds
> > extensive use of logger(1) to record what it is actually doing at the
> > time it does it. These logs include the pid of the command too  since
> > main-menu only logs its own pid, not that of the subcommand which
> > gneerated the output.
> > 
> > Lastly this patch adds an explicit test that each device it touches is
> > actually still a block device afterwards.
> > 
> > Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
> 
> Acked-by: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
> 
> Although
> 
> > +    logger -t osstest-erase-other-disks-\$\$ "Already ran, exiting"
> > +logger -t osstest-erase-other-disks-\$\$ "Running..."
> > +        logger -t osstest-erase-other-disks-\$\$ "Erasing \$dev"
> > +            logger -t osstest-erase-other-disks-\$\$ "\$dev is no
> > longer a block device!"
> > +        logger -t osstest-erase-other-disks-\$\$ "\$dev does not exist
> > or is not a block device."
> 
> maybe
> 
>   logmsg () { logger -t osstest-erase-other-disks-\$\$ "\$@" }
> 
> ?

I wasn't confident in getting the shell-in-perl backticks correct, or
rather I was too lazy to do the inevitable extra two rounds of testing it
would have needed.

I can do that if you want though.

Ian.

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel