[PATCH 3/8] kdump-lib.sh: introduce a helper to get underlying crypt device

[Kairui Song]

Signed-off-by: Kairui Song <kasong(a)redhat.com&gt;
---
 kdump-lib.sh | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/kdump-lib.sh b/kdump-lib.sh
index a7b9cba..5a37f4c 100755
--- a/kdump-lib.sh
+++ b/kdump-lib.sh
@@ -933,3 +933,20 @@ append_initramfs()
 
     (cd "$2"; find . -print0 | cpio -R $cpio_owner --null -H newc -o --quiet
>> "$1")
 }
+
+# Print all underlying crypt devices of a block device
+# print nothing if device is not on top of a crypt device
+# $1: the block device to be checked in maj:min format
+get_luks_crypt_dev()
+{
+    [[ -b /dev/block/$1 ]] || return 1
+
+    local _type=$(eval "$(blkid -u filesystem,crypto -o export -- /dev/block/$1);
echo \$TYPE")
+    [[ $_type == "crypto_LUKS" ]] && echo $1
+
+    for _x in /sys/dev/block/$1/slaves/*; do
+        [[ -f $_x/dev ]] || continue
+        [[ $_x/subsystem -ef /sys/class/block ]] || continue
+        get_luks_crypt_dev "$(< "$_x/dev")"
+    done
+}
-- 
2.30.2