Re: [PATCH] 90multipath: add hostonly multipath.conf in case hostonly mode

[Dave Young <dyoung-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>]

On 07/06/15 at 12:03pm, Harald Hoyer wrote:
> On 06.07.2015 09:31, Dave Young wrote:
> > For large machine, suppose there's a lot of multipath devices, multipath layer
> > will use a lot of memory. For kdump kernel memory is very limited thus it causes
> > oom. To avoid oom, we only add necessary multipath devices in kdump kernel
> > multipath.conf.
> > 
> > This is done by use mpathconf --allow, a new option which is like whitelist.
> > 
> > Signed-off-by: Dave Young <dyoung-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
> > ---
> >  modules.d/90multipath/module-setup.sh | 42 ++++++++++++++++++++++++++++-------
> >  1 file changed, 34 insertions(+), 8 deletions(-)
> > 
> > diff --git a/modules.d/90multipath/module-setup.sh b/modules.d/90multipath/module-setup.sh
> > index 29643d4..321f13e 100755
> > --- a/modules.d/90multipath/module-setup.sh
> > +++ b/modules.d/90multipath/module-setup.sh
> > @@ -1,18 +1,28 @@
> >  #!/bin/bash
> >  
> > +is_mpath() {
> > +    local _dev=$1
> > +    [ -e /sys/dev/block/$_dev/dm/uuid ] || return 1
> > +    [[ $(cat /sys/dev/block/$_dev/dm/uuid) =~ mpath- ]] && return 0
> > +    return 1
> > +}
> > +
> > +majmin_to_mpath_dev() {
> > +    local _dev
> > +    for i in `ls -1 /dev/mapper/mpath*`; do
> > +        dev=$(get_maj_min $i)
> > +        if [ "$dev" = "$1" ]; then
> > +            echo $i
> > +            return
> > +        fi
> > +    done
> > +}
> >  # called by dracut
> >  check() {
> >      local _rootdev
> >      # if there's no multipath binary, no go.
> >      require_binaries multipath || return 1
> >  
> > -    is_mpath() {
> > -        local _dev=$1
> > -        [ -e /sys/dev/block/$_dev/dm/uuid ] || return 1
> > -        [[ $(cat /sys/dev/block/$_dev/dm/uuid) =~ mpath- ]] && return 0
> > -        return 1
> > -    }
> > -
> >      [[ $hostonly ]] || [[ $mount_needs ]] && {
> >          for_each_host_dev_and_slaves is_mpath || return 255
> >      }
> > @@ -79,7 +89,18 @@ installkernel() {
> >  
> >  # called by dracut
> >  install() {
> > -    local _f
> > +    local _f _allow
> > +    add_hostonly_mpath_conf() {
> > +        is_mpath $1 && {
> > +            local _dev
> > +
> > +            _dev=$(majmin_to_mpath_dev $1)
> > +            [ -z "$_dev" ] && return
> > +            strstr "$_allow" "$_dev" && return
> > +            _allow="$_allow --allow $_dev"
> > +        }
> > +    }
> > +
> >      inst_multiple -o  \
> >          dmsetup \
> >          kpartx \
> > @@ -93,6 +114,11 @@ install() {
> >          /etc/multipath.conf \
> >          /etc/multipath/*
> >  
> > +    [[ $hostonly ]] && {
> > +        for_each_host_dev_and_slaves_all add_hostonly_mpath_conf
> 
> don't we have to just check all $host_devs if it is a /dev/mapper/mpath* ??

Harald, I worry about stacked devices, host_devs are the top level devices,
if slave deivces are multipath we should use for_each_host_dev_and_slaves,
right?

> 
> > +        [ -n "$_allow" ] && mpathconf $_allow --outfile ${initdir}/etc/multipath.conf
> > +    }
> > +
> >      inst $(command -v partx) /sbin/partx
> >  
> >      inst_libdir_file "libmultipath*" "multipath/*"
> > 
>