[dm-devel] [PATCH 01/17] multipathd: use /run instead of /var/run

[Benjamin Marzinski]

On Tue, Mar 29, 2016 at 09:57:25AM -0400, John Stoffel wrote:
> 
> Benjamin> /var/run is now usually a symlink to /run.  If /var is on a separate
> Benjamin> filesytem, when multipathd starts up, it might end up writing to
> Benjamin> /var/run before the /var filesytem is mounted and thus not have its
> Benjamin> pidfile accessible at /var/run afterwards.  On most distrubutions /run
> Benjamin> is now a tmpfs and should always be available before multipathd is
> Benjamin> started, so multipath should just write there directly, instead of
> Benjamin> through the symlink.
> 
> I'm not sure I agree with this, it really smells more like a
> distribution problem, than a multipathd problem.  If multipathd starts
> up in an initramfs, how does it get reset to the proper /var/run or
> /run directory then?

Huh? /run is a tmpfs on almost all distros now. It gets remounted
when you switch the root from the initramfs, but it doesn't go away. So
there isn't a "proper" /run that appears later. /var/run just gets
symlinked to it. 

> And especially if it's a symlink, we shouldn't care at all either.

But /var/run isn't a symlink before /var is mounted.  That's the problem
that this is supposed to fix.

> What distros are using /run instead of /var/run these days?

Debian, Suse, Ubuntu, Fedora and some others. Pretty much everyone who
is using systemd made or is planning to make this switch. See
https://lists.fedoraproject.org/pipermail/devel/2011-March/150031.html

We could call it a distribution problem, but it will be a problem that
almost all distributions will face. To turn your question around, which
distribution do you think will be negatively impacted by this?

-Ben

> 
> John
> 
> 
> Benjamin> If /var/run is not a symlink, continue using it.
> 
> Benjamin> Signed-off-by: Benjamin Marzinski <bmarzins at redhat.com>
> Benjamin> ---
> Benjamin>  Makefile.inc                    | 10 +++++++++-
> Benjamin>  libmultipath/defaults.h         |  2 +-
> Benjamin>  multipathd/multipathd.init.suse |  2 +-
> Benjamin>  3 files changed, 11 insertions(+), 3 deletions(-)
> 
> Benjamin> diff --git a/Makefile.inc b/Makefile.inc
> Benjamin> index c3ed73f..357dd33 100644
> Benjamin> --- a/Makefile.inc
> Benjamin> +++ b/Makefile.inc
> Benjamin> @@ -21,6 +21,14 @@ ifndef LIB
> Benjamin>  	endif
> Benjamin>  endif
>  
> Benjamin> +ifndef RUN
> Benjamin> +	ifeq ($(shell test -L /var/run -o ! -d /var/run && echo 1),1)
> Benjamin> +		RUN=run
> Benjamin> +	else
> Benjamin> +		RUN=var/run
> Benjamin> +	endif
> Benjamin> +endif
> Benjamin> +
> Benjamin>  ifndef SYSTEMD
> Benjamin>  	ifeq ($(shell systemctl --version > /dev/null 2>&1 && echo 1), 1)
> Benjamin>  		SYSTEMD = $(shell systemctl --version 2> /dev/null |  sed -n 's/systemd \([0-9]*\)/\1/p')
> Benjamin> @@ -54,7 +62,7 @@ ifndef RPM_OPT_FLAGS
> Benjamin>  endif
>  
> Benjamin>  OPTFLAGS     = $(RPM_OPT_FLAGS) -Wunused -Wstrict-prototypes
> Benjamin> -CFLAGS	     = $(OPTFLAGS) -fPIC -DLIB_STRING=\"${LIB}\"
> Benjamin> +CFLAGS	     = $(OPTFLAGS) -fPIC -DLIB_STRING=\"${LIB}\" -DRUN_DIR=\"${RUN}\"
> Benjamin>  SHARED_FLAGS = -shared
>  
> Benjamin>  %.o:	%.c
> Benjamin> diff --git a/libmultipath/defaults.h b/libmultipath/defaults.h
> Benjamin> index 8902f40..cf1d5be 100644
> Benjamin> --- a/libmultipath/defaults.h
> Benjamin> +++ b/libmultipath/defaults.h
> Benjamin> @@ -26,7 +26,7 @@
> Benjamin>  #define MAX_CHECKINT(a)		(a << 2)
>  
> Benjamin>  #define MAX_DEV_LOSS_TMO	0x7FFFFFFF
> Benjamin> -#define DEFAULT_PIDFILE		"/var/run/multipathd.pid"
> Benjamin> +#define DEFAULT_PIDFILE		"/" RUN_DIR "/multipathd.pid"
> Benjamin>  #define DEFAULT_SOCKET		"/org/kernel/linux/storage/multipathd"
> Benjamin>  #define DEFAULT_CONFIGFILE	"/etc/multipath.conf"
> Benjamin>  #define DEFAULT_BINDINGS_FILE	"/etc/multipath/bindings"
> Benjamin> diff --git a/multipathd/multipathd.init.suse b/multipathd/multipathd.init.suse
> Benjamin> index d1319b1..ed699fa 100644
> Benjamin> --- a/multipathd/multipathd.init.suse
> Benjamin> +++ b/multipathd/multipathd.init.suse
> Benjamin> @@ -17,7 +17,7 @@
>  
> Benjamin>  PATH=/bin:/usr/bin:/sbin:/usr/sbin
> Benjamin>  DAEMON=/sbin/multipathd
> Benjamin> -PIDFILE=/var/run/multipathd.pid
> Benjamin> +PIDFILE=/run/multipathd.pid
> Benjamin>  MPATH_INIT_TIMEOUT=10
> Benjamin>  ARGS=""
>  
> Benjamin> -- 
> Benjamin> 1.8.3.1
> 
> Benjamin> --
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