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

[Harald Hoyer <harald-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>]

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* ??

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