revert(lvm): remove snapshot feature

The feature of managing lvm snapshots has no known
recent usage.  It is unknown if it works.  The lvm
developers do not wish to maintain or support it.

modules.d/90lvm/lvm_scan.sh

@@ -7,8 +7,6 @@ type getarg > /dev/null 2>&1 || . /lib/dracut-lib.sh
 
 VGS=$(getargs rd.lvm.vg -d rd_LVM_VG=)
 LVS=$(getargs rd.lvm.lv -d rd_LVM_LV=)
-SNAPSHOT=$(getargs rd.lvm.snapshot -d rd_LVM_SNAPSHOT=)
-SNAPSIZE=$(getargs rd.lvm.snapsize -d rd_LVM_SNAPSIZE=)
 
 # shellcheck disable=SC2174
 [ -d /etc/lvm ] || mkdir -m 0755 -p /etc/lvm
@@ -31,17 +29,10 @@ if [ ! -e /etc/lvm/lvm.conf ]; then
         echo '}'
 
         # establish LVM locking
-        if [ -n "$SNAPSHOT" ]; then
-            echo 'global {'
-            echo '    locking_type = 1'
-            echo '    use_lvmetad = 0'
-            echo '}'
-        else
-            echo 'global {'
-            echo '    locking_type = 4'
-            echo '    use_lvmetad = 0'
-            echo '}'
-        fi
+        echo 'global {'
+        echo '    locking_type = 4'
+        echo '    use_lvmetad = 0'
+        echo '}'
     } > /etc/lvm/lvm.conf
     lvmwritten=1
 fi
@@ -90,28 +81,6 @@ unset extraargs
 
 export LVM_SUPPRESS_LOCKING_FAILURE_MESSAGES=1
 
-if [ -n "$SNAPSHOT" ]; then
-    # HACK - this should probably be done elsewhere or turned into a function
-    # Enable read-write LVM locking
-    sed -i -e 's/\(^[[:space:]]*\)locking_type[[:space:]]*=[[:space:]]*[[:digit:]]/\1locking_type =  1/' /etc/lvm/lvm.conf
-
-    # Expected SNAPSHOT format "<orig lv name>:<snap lv name>"
-    ORIG_LV=${SNAPSHOT%%:*}
-    SNAP_LV=${SNAPSHOT##*:}
-
-    info "Removing existing LVM snapshot $SNAP_LV"
-    lvm lvremove --force "$SNAP_LV" 2>&1 | vinfo
-
-    # Determine snapshot size
-    if [ -z "$SNAPSIZE" ]; then
-        SNAPSIZE=$(lvm lvs --noheadings --units m --options lv_size "$ORIG_LV")
-        info "No LVM snapshot size provided, using size of $ORIG_LV ($SNAPSIZE)"
-    fi
-
-    info "Creating LVM snapshot $SNAP_LV ($SNAPSIZE)"
-    lvm lvcreate -s -n "$SNAP_LV" -L "$SNAPSIZE" "$ORIG_LV" 2>&1 | vinfo
-fi
-
 if [ -n "$LVS" ]; then
     info "Scanning devices $lvmdevs for LVM logical volumes $LVS"
     lvm lvscan $lvm_ignorelockingfailure 2>&1 | vinfo