pass mount info to dracut when default target is a separate disk

When user does not specify dump target explicitly, it's better to
dump to the "path" specified. That means after dump user enter into
1st kernel, can find vmcore in the "path". If that path is in root
fs, vmcore is stored in root fs. If separate disk is mounted on
any tier of "path", we just dump vmcore into the left path on the
left separate disk.

E.g in kdump.conf
path /mnt/nfs

in mount info,
/dev/vdb on /mnt type ext4 (rw,relatime,seclabel,data=ordered)

Then vmcore will be saved in /nfs of /dev/vdb.

In this patch, pass mount info to dracut in this case if separate
disk is mounted on any tier of "path".

Meanwhile introduce a function in kdump-lib.sh to check if any
target is specified.

v4->v5:
    Per Vivek's comment, add a helper function is_fs_dump_target.
    Then is_user_configured_dump_target is rewrite with these helper
    functions.

v5->v7:
    No v6 for this patch. Just use newly introduced function
    is_fs_type_nfs in handle_default_dump_target.

Signed-off-by: Baoquan He <bhe@redhat.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>

kdump-lib.sh

@@ -29,6 +29,16 @@ is_fs_type_nfs()
     return 1
 }
 
+is_fs_dump_target()
+{
+    egrep -q "^ext[234]|^xfs|^btrfs|^minix" /etc/kdump.conf
+}
+
+is_user_configured_dump_target()
+{
+    return $(is_ssh_dump_target || is_nfs_dump_target || is_raw_dump_target || is_fs_dump_target)
+}
+
 strip_comments()
 {
     echo $@ | sed -e 's/\(.*\)#.*/\1/'
@@ -67,20 +77,6 @@ get_user_configured_dump_disk()
     return
 }
 
-is_user_configured_dump_target()
-{
-    local _target
-
-    if is_ssh_dump_target || is_nfs_dump_target; then
-        return 0
-    fi
-
-    _target=$(egrep "^ext[234]|^xfs|^btrfs|^minix|^raw" /etc/kdump.conf 2>/dev/null |awk '{print $2}')
-    [ -n "$_target" ] && return 0
-
-    return 1
-}
-
 get_root_fs_device()
 {
     local _target

mkdumprd

@@ -325,24 +325,29 @@ get_block_dump_target()
     [ -b "$_target" ] && echo $(to_dev_name $_target)
 }
 
-# If no dump disk is specified make sure /var/crash is not mounted on a
-# separate disk.
-check_block_dump_target()
+#handle the case user does not specify the dump target explicitly
+handle_default_dump_target()
 {
     local _target
     local _mntpoint
+    local _fstype
 
     is_user_configured_dump_target && return
 
-    _target=$(get_root_fs_device)
-    if [ -b "$_target" ]; then
-        mkdir -p $SAVE_PATH
-        _mntpoint=`df $SAVE_PATH | tail -1 |  awk '{print $NF}'`
-        if [ "$_mntpoint" != "/" ]; then
-            perror "No dump target specified. Default dump target is rootfs block device."
-            perror "But dump path $SAVE_PATH is not backed by rootfs block device. "
-            perror_exit "Either explicitly specify a dump target or specify a dump path backed by rootfs block device"
+    check_save_path_fs $SAVE_PATH
+
+    _mntpoint=$(get_mntpoint_from_path $SAVE_PATH)
+    _target=$(get_target_from_path $SAVE_PATH)
+    if [ "$_mntpoint" != "/" ]; then
+        SAVE_PATH=${SAVE_PATH##"$_mntpoint"}
+        _fstype=$(get_fs_type_from_target $_target)
+
+        if $(is_fs_type_nfs $_fstype); then
+            add_dracut_module "nfs"
         fi
+
+        add_mount "$_target"
+        check_size fs $_target
     fi
 }
 
@@ -469,8 +474,6 @@ check_crypt()
     return 1
 }
 
-check_block_dump_target
-
 if ! check_resettable; then
     exit 1
 fi
@@ -548,6 +551,8 @@ do
     esac
 done < $conf_file
 
+handle_default_dump_target
+
 if [ -n "$extra_modules" ]
 then
     add_dracut_arg "--add-drivers" "$extra_modules"