[PATCH v2] Write to `/var/lib/kdump` if $KDUMP_BOOTDIR not writable

[Kelvin Fan]

The /boot directory on some operating systems might be read-only.
If we cannot write to $KDUMP_BOOTDIR when generating the kdump
initrd, attempt to place the generated initrd at `/var/lib/kdump`
instead.

Signed-off by: Kelvin Fan <kfan(a)redhat.com&gt;
---
 60-kdump.install | 14 ++++++++++----
 kdump-lib.sh     | 24 +++++++++++++++++-------
 kdumpctl         |  4 ++--
 kexec-tools.spec |  2 ++
 4 files changed, 31 insertions(+), 13 deletions(-)

diff --git a/60-kdump.install b/60-kdump.install
index 0a3b40e..7221e56 100755
--- a/60-kdump.install
+++ b/60-kdump.install
@@ -2,17 +2,23 @@
 
 COMMAND="$1"
 KERNEL_VERSION="$2"
-BOOT_DIR_ABS="$3"
+KDUMP_INITRD_DIR_ABS="$3"
 KERNEL_IMAGE="$4"
 
 if ! [[ ${KERNEL_INSTALL_MACHINE_ID-x} ]]; then
     exit 0
 fi
 
-if [[ -d "$BOOT_DIR_ABS" ]]; then
+if [[ -d "$KDUMP_INITRD_DIR_ABS" ]]; then
     KDUMP_INITRD="initrdkdump"
 else
-    BOOT_DIR_ABS="/boot"
+    # If `KDUMP_BOOTDIR` is not writable, then the kdump
+    # initrd must have been placed at `/var/lib/kdump`
+    if [[ ! -w "$KDUMP_BOOTDIR" ]]; then
+        KDUMP_INITRD_DIR_ABS="/var/lib/kdump"
+    else
+        KDUMP_INITRD_DIR_ABS="/boot"
+    fi
     KDUMP_INITRD="initramfs-${KERNEL_VERSION}kdump.img"
 fi
 
@@ -23,7 +29,7 @@ case "$COMMAND" in
         # and managed by kdump service
         ;;
     remove)
-        rm -f -- "$BOOT_DIR_ABS/$KDUMP_INITRD"
+        rm -f -- "$KDUMP_INITRD_DIR_ABS/$KDUMP_INITRD"
         ret=$?
         ;;
 esac
diff --git a/kdump-lib.sh b/kdump-lib.sh
index 21271cf..5f53a8a 100755
--- a/kdump-lib.sh
+++ b/kdump-lib.sh
@@ -733,20 +733,30 @@ prepare_kdump_bootinfo()
     boot_initrdlist="initramfs-$KDUMP_KERNELVER.img initrd"
     for initrd in $boot_initrdlist; do
         if [ -f "$KDUMP_BOOTDIR/$initrd" ]; then
-            DEFAULT_INITRD="$KDUMP_BOOTDIR/$initrd"
+            defaut_initrd_base="$initrd"
+            DEFAULT_INITRD="$KDUMP_BOOTDIR/$defaut_initrd_base"
             break
         fi
     done
 
-    # Get kdump initrd from default initrd filename
+    # Create kdump initrd basename from default initrd basename
     # initramfs-5.7.9-200.fc32.x86_64.img => initramfs-5.7.9-200.fc32.x86_64kdump.img
     # initrd => initrdkdump
-    if [[ -z "$DEFAULT_INITRD" ]]; then
-        KDUMP_INITRD=${KDUMP_BOOTDIR}/initramfs-${KDUMP_KERNELVER}kdump.img
-    elif [[ $(basename $DEFAULT_INITRD) == *.* ]]; then
-        KDUMP_INITRD=${DEFAULT_INITRD%.*}kdump.${DEFAULT_INITRD##*.}
+    if [[ -z "$defaut_initrd_base" ]]; then
+        kdump_initrd_base=initramfs-${KDUMP_KERNELVER}kdump.img
+    elif [[ $defaut_initrd_base == *.* ]]; then
+        kdump_initrd_base=${defaut_initrd_base%.*}kdump.${DEFAULT_INITRD##*.}
     else
-        KDUMP_INITRD=${DEFAULT_INITRD}kdump
+        kdump_initrd_base=${defaut_initrd_base}kdump
+    fi
+
+    # Place kdump initrd in `/var/lib/kdump` if `KDUMP_BOOTDIR` not writable
+    if [[ ! -w "$KDUMP_BOOTDIR" ]];then
+        var_target_initrd_dir="/var/lib/kdump"
+        mkdir -p "$var_target_initrd_dir"
+        KDUMP_INITRD="$var_target_initrd_dir/$kdump_initrd_base"
+    else
+        KDUMP_INITRD="$KDUMP_BOOTDIR/$kdump_initrd_base"
     fi
 }
 
diff --git a/kdumpctl b/kdumpctl
index c3311ad..b0846fa 100755
--- a/kdumpctl
+++ b/kdumpctl
@@ -151,8 +151,8 @@ rebuild_kdump_initrd()
 
 rebuild_initrd()
 {
-	if [[ ! -w "$KDUMP_BOOTDIR" ]];then
-		derror "$KDUMP_BOOTDIR does not have write permission. Can not rebuild
$TARGET_INITRD"
+	if [[ ! -w $(dirname $TARGET_INITRD) ]];then
+		derror "$(dirname $TARGET_INITRD) does not have write permission. Cannot rebuild
$TARGET_INITRD"
 		return 1
 	fi
 
diff --git a/kexec-tools.spec b/kexec-tools.spec
index 24c6b36..74b7877 100644
--- a/kexec-tools.spec
+++ b/kexec-tools.spec
@@ -170,6 +170,7 @@ mkdir -p $RPM_BUILD_ROOT%{_unitdir}
 mkdir -p -m755 $RPM_BUILD_ROOT%{_bindir}
 mkdir -p -m755 $RPM_BUILD_ROOT%{_libdir}
 mkdir -p -m755 $RPM_BUILD_ROOT%{_prefix}/lib/kdump
+mkdir -p -m755 $RPM_BUILD_ROOT%{_sharedstatedir}/kdump
 install -m 755 %{SOURCE1} $RPM_BUILD_ROOT%{_bindir}/kdumpctl
 
 install -m 755 build/sbin/kexec $RPM_BUILD_ROOT/usr/sbin/kexec
@@ -335,6 +336,7 @@ done
 %dir %{_sysconfdir}/kdump
 %dir %{_sysconfdir}/kdump/pre.d
 %dir %{_sysconfdir}/kdump/post.d
+%dir %{_sharedstatedir}/kdump
 %{_mandir}/man8/kdumpctl.8.gz
 %{_mandir}/man8/kexec.8.gz
 %ifarch %{ix86} x86_64 ppc64 s390x ppc64le aarch64
-- 
2.29.2