B #2217: Zero LVM space

src/tm_mad/fs_lvm/clone

@@ -82,6 +82,21 @@ if [ $FILE_SIZE -gt $SIZE ]; then
     SIZE="$FILE_SIZE"
 fi
 
+# Compute the seek start for zeroing of the new LV as the smaller
+# number of ONE or file image virtual size. We start to zero from
+# 1 MiB before the end of image size prior to the copying.
+if [ "${FILE_SIZE}" -lt "${SIZE}" ]; then
+	ZERO_SEEK_BYTES=$FILE_SIZE
+else
+	ZERO_SEEK_BYTES=$SIZE
+fi
+
+if [ "${ZERO_SEEK_BYTES}" -gt 0 ]; then
+	ZERO_SEEK_BYTES=$(( (ZERO_SEEK_BYTES-1) * 1024 * 1024 ))
+else
+	ZERO_SEEK_BYTES=0
+fi
+
 #-------------------------------------------------------------------------------
 # Create the snapshot and link it
 #-------------------------------------------------------------------------------
@@ -109,6 +124,12 @@ CLONE_CMD=$(cat <<EOF
 
     hostname -f >"${DST_DIR}/.host" || :
 
+    # zero trailing space
+    LVSIZE=\$(${SUDO} ${LVS} --nosuffix --noheadings --units B -o lv_size "${DEV}" | tr -d '[:blank:]')
+    ${DD} if=/dev/zero of="${DEV}" bs=64k \
+        oflag=seek_bytes iflag=count_bytes \
+        seek="${ZERO_SEEK_BYTES}" count="\$(( LVSIZE - ${ZERO_SEEK_BYTES} ))"
+
     $QEMU_IMG convert -O raw "$SRC_PATH" "$DEV"
     rm -f "$DST_PATH"
     ln -s "$DEV" "$DST_PATH"

src/tm_mad/fs_lvm/delete

@@ -41,6 +41,17 @@ DST_HOST=`arg_host $DST`
 
 DS_SYS_ID=$(echo $DST_PATH | grep -E '\/disk\.[[:digit:]]+$' | $AWK -F '/' '{print $(NF-2)}')
 
+# Zero space
+ZERO_CMD=$(cat <<EOF
+    set -x
+    DEV=\$(readlink $DST_PATH)
+
+    if echo "\$DEV" | grep "^/dev/" &>/dev/null; then
+        ${DD} if=/dev/zero of="\${DEV}" bs=64k || :
+    fi
+EOF
+)
+
 # Delete the device if it's a clone (LVM snapshot)
 DELETE_CMD=$(cat <<EOF
     set -x
@@ -63,6 +74,9 @@ EOF
 )
 
 if [ -n "${DS_SYS_ID}" ]; then
+    ssh_exec_and_log "$DST_HOST" "$ZERO_CMD" \
+        "Error cleaning $DST_PATH"
+
     LOCK="tm-fs_lvm-${DS_SYS_ID}.lock"
     exclusive "${LOCK}" 120 ssh_exec_and_log "$DST_HOST" "$DELETE_CMD" \
         "Error deleting $DST_PATH"

src/tm_mad/fs_lvm/resize

@@ -57,6 +57,22 @@ LV_NAME="lv-one-$VM_ID-$DISK_ID"
 VG_NAME="vg-one-$DS_SYS_ID"
 DEV="/dev/${VG_NAME}/${LV_NAME}"
 
+# Get current LV size
+LVSIZE_CMD=$(cat <<EOF
+    set -e -o pipefail
+    ${SUDO} ${LVS} --nosuffix --noheadings --units B -o lv_size "${DEV}" | \
+        tr -d '[:blank:]'
+EOF
+)
+
+LVSIZE_OLD=$(ssh_monitor_and_log "$SRC_HOST" "$LVSIZE_CMD" \
+        "Failed to get current LV size")
+
+if [ $? -ne 0 ] || [ -z "${LVSIZE_OLD}" ]; then
+    error_message "$script_name: Could not detect current size of LV ${LV_NAME}"
+    exit 1
+fi
+
 # Execute lvextend with a lock in the frontend
 RESIZE_CMD=$(cat <<EOF
     set -e -o pipefail
@@ -69,4 +85,21 @@ EOF
 LOCK="tm-fs_lvm-${DS_SYS_ID}.lock"
 exclusive "${LOCK}" 120 ssh_exec_and_log "$SRC_HOST" "$RESIZE_CMD" \
         "Error resizing LV named $LV_NAME"
+
+# Zero additional space
+ZERO_CMD=$(cat <<EOF
+    set -e -o pipefail
+
+    LVSIZE_NEW=\$(${SUDO} ${LVS} --nosuffix --noheadings --units B -o lv_size "${DEV}" | \
+        tr -d '[:blank:]')
+
+    ${DD} if=/dev/zero of="${DEV}" bs=64k \
+        oflag=seek_bytes iflag=count_bytes \
+        seek="${LVSIZE_OLD}" count="\$(( LVSIZE_NEW - ${LVSIZE_OLD} ))"
+EOF
+)
+
+ssh_exec_and_log "$SRC_HOST" "$ZERO_CMD" \
+        "Error preparing additional space on LV $LV_NAME"
+
 exit 0