[PATCH 3/3 v2] dracut-module-setup: Enhance kdump to support the bind mounted feature in Atomic

[Minfei Huang]

The kdump will dump the core in incorrect target directory, if the
target is bind mounted.

The kdump cann't parse the bind mounted path, if we specifies the vale
"path /var/crash" in the /etc/kdump.conf.

To correct dumping target, we can construct the real dumping path in
Atomic, which contains two part, one bind mounted path, the other
specified dump target.

Following is an example:
    -bash-4.2# cat /etc/kdump.conf | grep ^path
    path /var/crash

    -bash-4.2# findmnt /var | tail -n 1 | awk '{print $2}'
    /dev/mapper/atomicos-root[/ostree/deploy/rhel-atomic-host/var]

    -bash-4.2# findmnt -v /var | tail -n 1 | awk '{print $2}'
    /dev/mapper/atomicos-root

Then we can found it that the real path of dumping core is
/ostree/deploy/rhel-atomic-host/var/crash.

Signed-off-by: Minfei Huang <mhuang(a)redhat.com&gt;
---
 dracut-module-setup.sh | 39 ++++++++++++++++++++++++++++++++++-----
 kdump-lib.sh           |  5 +++++
 mkdumprd               | 24 +++++++++++++++++++++++-
 3 files changed, 62 insertions(+), 6 deletions(-)

diff --git a/dracut-module-setup.sh b/dracut-module-setup.sh
index 477ede1..7915b82 100755
--- a/dracut-module-setup.sh
+++ b/dracut-module-setup.sh
@@ -311,8 +311,7 @@ kdump_install_net() {
 default_dump_target_install_conf()
 {
     local _target _fstype
-    local _mntpoint
-    local _save_path
+    local _mntpoint _save_path
 
     is_user_configured_dump_target && return
 
@@ -321,6 +320,17 @@ default_dump_target_install_conf()
 
     _mntpoint=$(get_mntpoint_from_path $_save_path)
     _target=$(get_target_from_path $_save_path)
+
+    if is_atomic && is_bind_mount $_mntpoint; then
+        _save_path=$(cut_out_substring $_save_path $_mntpoint)
+        # the real dump path in the 2nd kernel, if the mount point is bind mounted.
+        _save_path=$(get_bind_mount_directory $_mntpoint)/$_save_path
+        _mntpoint=$(get_mntpoint_from_target $_target)
+
+        # the absolute path in the 1st kernel
+        _save_path=$_mntpoint/$_save_path
+    fi
+
     if [ "$_mntpoint" != "/" ]; then
         _fstype=$(get_fs_type_from_target $_target)
 
@@ -332,14 +342,30 @@ default_dump_target_install_conf()
         fi
 
         echo "$_fstype $_target" >> ${initdir}/tmp/$$-kdump.conf
-
         _save_path=$(cut_out_substring $_save_path $_mntpoint)
+    fi
+
+    sed -i "/^path/d" ${initdir}/tmp/$$-kdump.conf
+    echo "path $_save_path" >> ${initdir}/tmp/$$-kdump.conf
+}
+
+adjust_bind_mount_path()
+{
+    local _target=$1
+    local _save_path=$(get_option_value "path")
+    [ -z "$_save_path" ] && _save_path=$DEFAULT_PATH
+
+    local _absolute_save_path=$(get_mntpoint_from_target $_target)/$_save_path
+    local _mntpoint=$(get_mntpoint_from_path $_absolute_save_path)
+
+    if is_bind_mount $_mntpoint; then
+        _save_path=$(cut_out_substring $_absolute_save_path $_mntpoint)
+        # the real dump path in the 2nd kernel, if the mount point is bind mounted.
+        _save_path=$(get_bind_mount_directory $_mntpoint)/$_save_path
 
-        #erase the old path line, then insert the parsed path
         sed -i "/^path/d" ${initdir}/tmp/$$-kdump.conf
         echo "path $_save_path" >> ${initdir}/tmp/$$-kdump.conf
     fi
-
 }
 
 #install kdump.conf and what user specifies in kdump.conf
@@ -353,6 +379,9 @@ kdump_install_conf() {
         case "$config_opt" in
         ext[234]|xfs|btrfs|minix|raw)
             sed -i -e "s#^$config_opt[[:space:]]\+$config_val#$config_opt
$(kdump_to_udev_name $config_val)#" ${initdir}/tmp/$$-kdump.conf
+            if is_atomic; then
+                adjust_bind_mount_path "$config_val"
+            fi
             ;;
         ssh|nfs)
             kdump_install_net "$config_val"
diff --git a/kdump-lib.sh b/kdump-lib.sh
index 75d7673..8aa0da4 100755
--- a/kdump-lib.sh
+++ b/kdump-lib.sh
@@ -237,3 +237,8 @@ cut_out_substring()
     local _sub_str=$(echo $2|sed "s#/\{1,\}#/#g")
     echo ${_main_str#*"$_sub_str"}
 }
+
+is_atomic()
+{
+    grep -q "ostree" /proc/cmdline
+}
diff --git a/mkdumprd b/mkdumprd
index 7fdcebf..d7d006f 100644
--- a/mkdumprd
+++ b/mkdumprd
@@ -359,6 +359,17 @@ handle_default_dump_target()
 
     _mntpoint=$(get_mntpoint_from_path $SAVE_PATH)
     _target=$(get_target_from_path $SAVE_PATH)
+
+    if is_atomic && is_bind_mount $_mntpoint; then
+        SAVE_PATH=$(cut_out_substring $SAVE_PATH $_mntpoint)
+        # the real dump path in the 2nd kernel, if the mount point is bind mounted.
+        SAVE_PATH=$(get_bind_mount_directory $_mntpoint)/$SAVE_PATH
+        _mntpoint=$(get_mntpoint_from_target $_target)
+
+        # the absolute path in the 1st kernel
+        SAVE_PATH=$_mntpoint/$SAVE_PATH
+    fi
+
     if [ "$_mntpoint" != "/" ]; then
         SAVE_PATH=$(cut_out_substring $SAVE_PATH $_mntpoint)
         _fstype=$(get_fs_type_from_target $_target)
@@ -530,8 +541,19 @@ do
         if [ "$config_opt" = "nfs" ]; then
             add_dracut_module "nfs"
         fi
+
+        _absolute_save_path=$(make_absolute_save_path $config_val)
+        if is_atomic; then
+            _mntpoint=$(get_mntpoint_from_path $_absolute_save_path)
+            if is_bind_mount $_mntpoint; then
+                SAVE_PATH=$(cut_out_substring $_absolute_save_path $_mntpoint)
+                # the real dump path in the 2nd kernel, if the mount point is bind
mounted.
+                SAVE_PATH=$(get_bind_mount_directory $_mntpoint)/$SAVE_PATH
+            fi
+        fi
+
         add_mount "$config_val"
-        check_save_path_fs $(make_absolute_save_path $config_val)
+        check_save_path_fs $_absolute_save_path
         check_size fs $config_val
         ;;
     raw)
-- 
1.9.3