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

[Dave Young <dyoung@xxxxxxxxxx>]

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@xxxxxxxxxx>
---
 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/*
 
+    [[ $hostonly ]] && {
+        for_each_host_dev_and_slaves_all add_hostonly_mpath_conf
+        [ -n "$_allow" ] && mpathconf $_allow --outfile ${initdir}/etc/multipath.conf
+    }
+
     inst $(command -v partx) /sbin/partx
 
     inst_libdir_file "libmultipath*" "multipath/*"
-- 
1.8.3.1

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