kdump: Introduce 'force_no_rebuild' option

This patch introduces the 'force_no_rebuild' option
inside the 'kdump.conf' and its handling inside the 'kdumpctl'
script.

There might be several use cases, where a system admin
decides that he doesn't need to rebuild the kdump initrd
and wants to use an existing version of the same. In such cases,
he can set the 'force_no_rebuild' option inside 'kdump.conf'
to 1, to force the 'kdumpctl' script not to rebuild the kdump
initrd.

Signed-off-by: Bhupesh Sharma <bhsharma@redhat.com>
Acked-by: Xunlei Pang <xlpang@redhat.com>
Acked-by: Dave Young <dyoung@redhat.com>

kdump.conf

@@ -115,6 +115,13 @@
 #             Specify 1 to force rebuilding kdump initrd every time when kdump
 #             service starts.
 #
+# force_no_rebuild <0 | 1>
+#           - By default, kdump initrd will be rebuilt when necessary.
+#             Specify 1 to bypass rebuilding of kdump initrd.
+#
+#             force_no_rebuild and force_rebuild options are mutually
+#             exclusive and they should not be set to 1 simultaneously.
+#
 # override_resettable <0 | 1>
 #           - Usually an unresettable block device can't be a dump target.
 #             Specifying 1 when you want to dump even though the block
@@ -150,6 +157,7 @@ core_collector makedumpfile -l --message-level 1 -d 31
 #extra_modules gfs2
 #default shell
 #force_rebuild 1
+#force_no_rebuild 1
 #dracut_args --omit-drivers "cfg80211 snd" --add-drivers "ext2 ext3"
 #fence_kdump_args -p 7410 -f auto -c 0 -i 10
 #fence_kdump_nodes node1 node2

kdump.conf.5

@@ -166,6 +166,16 @@ By default, kdump initrd will only be rebuilt when necessary.
 Specify 1 to force rebuilding kdump initrd every time when kdump service starts.
 .RE
 
+.B force_no_rebuild <0 | 1>
+.RS
+By default, kdump initrd will be rebuilt when necessary.
+Specify 1 to bypass rebuilding of kdump initrd.
+
+.PP
+force_no_rebuild and force_rebuild options are mutually exclusive and
+they should not be set to 1 simultaneously.
+.RE
+
 .B override_resettable <0 | 1>
 .RS
 Usually an unresettable block device can't be a dump target. Specifying 1 means

kdumpctl

@@ -367,7 +367,7 @@ check_config()
 		case "$config_opt" in
 		\#* | "")
 			;;
-		raw|ext2|ext3|ext4|minix|btrfs|xfs|nfs|ssh|sshkey|path|core_collector|kdump_post|kdump_pre|extra_bins|extra_modules|default|force_rebuild|dracut_args|fence_kdump_args|fence_kdump_nodes)
+		raw|ext2|ext3|ext4|minix|btrfs|xfs|nfs|ssh|sshkey|path|core_collector|kdump_post|kdump_pre|extra_bins|extra_modules|default|force_rebuild|force_no_rebuild|dracut_args|fence_kdump_args|fence_kdump_nodes)
 			[ -z "$config_val" ] && {
 				echo "Invalid kdump config value for option $config_opt."
 				return 1;
@@ -627,6 +627,7 @@ check_rebuild()
 {
 	local extra_modules
 	local _force_rebuild force_rebuild="0"
+	local _force_no_rebuild force_no_rebuild="0"
 	local ret system_modified="0"
 
 	check_boot_dir
@@ -643,6 +644,15 @@ check_rebuild()
 		return 1
 	fi
 
+	_force_no_rebuild=`grep ^force_no_rebuild $KDUMP_CONFIG_FILE 2>/dev/null`
+	if [ $? -eq 0 ]; then
+		force_no_rebuild=`echo $_force_no_rebuild | cut -d' '  -f2`
+		if [ "$force_no_rebuild" != "0" ] && [ "$force_no_rebuild" != "1" ];then
+			echo "Error: force_no_rebuild value is invalid"
+			return 1
+		fi
+	fi
+
 	_force_rebuild=`grep ^force_rebuild $KDUMP_CONFIG_FILE 2>/dev/null`
 	if [ $? -eq 0 ]; then
 		force_rebuild=`echo $_force_rebuild | cut -d' '  -f2`
@@ -652,6 +662,16 @@ check_rebuild()
 		fi
 	fi
 
+	if [[ "$force_no_rebuild" == "1" && "$force_rebuild" == "1" ]]; then
+		echo "Error: force_rebuild and force_no_rebuild are enabled simultaneously in kdump.conf"
+		return 1
+	fi
+
+	# Will not rebuild kdump initrd
+	if [ "$force_no_rebuild" == "1" ]; then
+		return 0
+	fi
+
 	#will rebuild every time if extra_modules are specified
 	extra_modules=`grep ^extra_modules $KDUMP_CONFIG_FILE`
 	[ -n "$extra_modules" ] && force_rebuild="1"