feature #3782: live snapshots for qcow2

src/datastore_mad/remotes/fs/snap_flatten

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/bin/bash -ex
 
 # -------------------------------------------------------------------------- #
 # Copyright 2002-2015, OpenNebula Project (OpenNebula.org), C12G Labs        #
@@ -62,7 +62,7 @@ SNAP_PATH="${SNAP_DIR}/${SNAP_ID}"
 SNAP_PATH_RELATIVE=$(basename ${SNAP_PATH})
 CURRENT_PATH=${DISK_PATH}
 
-rm ${DISK_PATH}
-qemu-img convert -O qcow2 ${SNAP_PATH} ${CURRENT_PATH}
+qemu-img convert -O qcow2 ${SNAP_PATH} ${CURRENT_PATH}.tmp
+mv "${CURRENT_PATH}.tmp" "${CURRENT_PATH}"
 rm -rf ${SNAP_DIR}
 

src/tm_mad/qcow2/clone

@@ -96,9 +96,11 @@ http://*)
        RESIZE_CMD="; qemu-img resize ${DST_PATH} ${SIZE}M"
     fi
 
-    CLONE_CMD="cd $DST_DIR; \
-        rm -f $DST_PATH; $QEMU_IMG create -b $SRC_PATH -f qcow2 $DST_PATH \
+    CLONE_CMD="cd $DST_DIR; rm -f $DST_PATH; \
+        $QEMU_IMG create -b $SRC_PATH -f qcow2 ${DST_PATH}.orig; \
+        ln -s ${DST_PATH}.orig ${DST_PATH}; \
         ${RESIZE_CMD}"
+
     ssh_exec_and_log "$DST_HOST" "$CLONE_CMD" "Error copying $SRC to $DST"
     ;;
 esac

src/tm_mad/qcow2/snap_create

@@ -52,27 +52,89 @@ while IFS= read -r -d '' element; do
     XPATH_ELEMENTS[i++]="$element"
 done < <(onevm show -x $VMID| $XPATH \
                     /VM/TEMPLATE/DISK[DISK_ID=$DISK_ID]/SOURCE \
-                    /VM/TEMPLATE/DISK[DISK_ID=$DISK_ID]/CLONE)
+                    /VM/TEMPLATE/DISK[DISK_ID=$DISK_ID]/CLONE \
+                    /VM/TEMPLATE/DISK[DISK_ID=$DISK_ID]/TARGET \
+                    "/VM/SNAPSHOTS[DISK_ID=$DISK_ID]/SNAPSHOT[last()]/ID" \
+                    /VM/HISTORY_RECORDS/HISTORY/VMMMAD \
+                    /VM/STATE \
+                    /VM/LCM_STATE \
+                    '%m%/VM/TEMPLATE/DISK/TARGET')
 
 DISK_SRC="${XPATH_ELEMENTS[j++]}"
 CLONE="${XPATH_ELEMENTS[j++]}"
+TARGET="${XPATH_ELEMENTS[j++]}"
+LAST_SNAP_ID="${XPATH_ELEMENTS[j++]}"
+VMMAD="${XPATH_ELEMENTS[j++]}"
+STATE="${XPATH_ELEMENTS[j++]}"
+LCM_STATE="${XPATH_ELEMENTS[j++]}"
+ALL_DISKS="${XPATH_ELEMENTS[j++]}"
+
+if [ -z "$LAST_SNAP_ID" ]; then
+    LAST_SNAP_ID=0
+fi
 
 
 SYSTEM_DS_PATH=$(dirname ${SRC_PATH})
 IMAGE_DS_PATH=$(dirname ${DISK_SRC})
 
+SYSTEM_DS_DISK_PATH="${SYSTEM_DS_PATH}/disk.${DISK_ID}"
 
 if [ "$CLONE" = "YES" ]; then
-    DISK_PATH="${SYSTEM_DS_PATH}/disk.${DISK_ID}"
+    DISK_PATH="${SYSTEM_DS_DISK_PATH}"
+    DISK_PATH_ORIG="${DISK_PATH}.orig"
 else
     DISK_PATH=$DISK_SRC
+    DISK_PATH_ORIG=$DISK_PATH
 fi
 
+SNAP_ID=$(( $LAST_SNAP_ID + 1 ))
+
 SNAP_DIR="${DISK_PATH}.snap"
 SNAP_PATH="${SNAP_DIR}/${SNAP_ID}"
+LAST_SNAP_PATH="${SNAP_DIR}/${LAST_SNAP_ID}"
 SNAP_PATH_RELATIVE=$(basename ${SNAP_PATH})
 CURRENT_PATH=${DISK_PATH}
 
+# virsh snapshot-create by default creates snapshots for all the disks that
+# are not read only. To be able to make a snapshot in only one of the disks
+# an xml must be created describing all of the disks and setting the value
+# snapshot='no' to the disks that are not going to be snapshotted.
+
+# <domainsnapshot>
+#   <name>1</name>
+#   <description>snap 1</description>
+#   <disks>
+#     <disk name='vda' snapshot='no'/>
+#     <disk name='vdb'>
+#       <source file='/var/lib/one/datastores/1/09eec196c67b38dea41048a628978600.snap/1'/>
+#     </disk>
+#     <disk name='vdc' snapshot='no'/>
+#   </disks>
+# </domainsnapshot>
+
+
+DOC="
+<domainsnapshot>
+  <name>${SNAP_ID}</name>
+  <description>snap ${SNAP_ID}</description>
+  <disks>"
+
+for disk in $ALL_DISKS; do
+    if [ "$disk" = "$TARGET" ]; then
+        DOC="$DOC
+    <disk name='$disk' snapshot='external'>
+      <source file='$SNAP_PATH'/>
+    </disk>"
+    else
+        DOC="$DOC
+    <disk name='$disk' snapshot='no'/>"
+    fi
+done
+
+DOC="$DOC
+  </disks>
+</domainsnapshot>"
+
 CMD=$(cat <<EOT
 set -ex
 
@@ -80,28 +142,43 @@ if [ ! -d "${SNAP_DIR}" ]; then
     mkdir "${SNAP_DIR}"
 fi
 
-# Move save current snapshot and create a new one. The snapshot uses
-# absolute path name as the qemu-img has problems with relative backing
-# file paths and symlinks
-mv "${CURRENT_PATH}" "${SNAP_PATH}"
-qemu-img create -f qcow2 -b "${SNAP_PATH}" "${CURRENT_PATH}"
+# 57 is DISK_SNAPSHOT. When the snapshot is done with the VM in running state
+if [ "$LCM_STATE" = "57" ] && [ "$VMMMAD" = "kvm" ] ; then
+    # The file must be created beforehand or libvirt complains with
+    # "permission denied"
+    touch $SNAP_PATH
 
-# TODO: Check that the new snapshot can be created. Roll back in case
-# of error
+    # Temporary xml file
+    FILENAME="/tmp/snapshot-\$(date +%s)"
+    echo -e "$DOC" > \$FILENAME
 
-# Convert backing file absolute path to relative path so it works outside
-# the system directory. Do not do this for snapshot one as:
-# * It could be a non backed file (persistent)
-# * The backing file is in images directory, is not relative
-if [ "$SNAP_ID" != "0" ]; then
-    BACKING_FILE=\$(qemu-img info ${SNAP_PATH} | grep '^backing file:' | \
-        cut -d: -f2 | sed 's/^ //')
+    virsh -c qemu:///system snapshot-create one-$VMID --disk-only --atomic \
+        --xmlfile \$FILENAME --quiesce
 
-    if [ -n "\$BACKING_FILE" ]; then
-        RELATIVE_BACKING_FILE="\$(basename \${BACKING_FILE})"
+    ln -sf $SNAP_PATH $SYSTEM_DS_DISK_PATH
 
-        qemu-img rebase -u -b "\${RELATIVE_BACKING_FILE}" "${SNAP_PATH}"
+    rm \$FILENAME
+else
+    if [ "$SNAP_ID" = "1" ]; then
+        ORIG="$DISK_PATH_ORIG"
+    else
+        ORIG="$LAST_SNAP_PATH"
     fi
+
+    qemu-img create -f qcow2 -b "\${ORIG}" "${SNAP_PATH}"
+    ln -sf $SNAP_PATH $SYSTEM_DS_DISK_PATH
+fi
+
+if [ "$SNAP_ID" = "1" ] && [ "$CLONE" != "YES" ]; then
+    ln -sf "${DISK_PATH_ORIG}" "${SNAP_DIR}/0"
+fi
+
+BACKING_FILE=\$(qemu-img info ${SNAP_PATH} | grep '^backing file:' | \
+    cut -d: -f2 | sed 's/^ //')
+
+if [ "\${BACKING_FILE}" = "${SYSTEM_DS_DISK_PATH}" ]; then
+    REAL_BACKING_FILE="${DISK_PATH_ORIG}"
+    qemu-img rebase -u -b "\${REAL_BACKING_FILE}" "${SNAP_PATH}"
 fi
 EOT
 )

src/tm_mad/qcow2/snap_revert

@@ -67,13 +67,16 @@ else
     DISK_PATH=$DISK_SRC
 fi
 
+NEXT_ID=$(( $SNAP_ID + 1 ))
 SNAP_DIR="${DISK_PATH}.snap"
 SNAP_PATH="${SNAP_DIR}/${SNAP_ID}"
+SNAP_PATH_NEXT="${SNAP_DIR}/${NEXT_ID}"
 SNAP_PATH_RELATIVE=$(basename ${SNAP_PATH})
 CURRENT_PATH=${DISK_PATH}
 
-CMD="rm \"${CURRENT_PATH}\" ; \
-qemu-img create -f qcow2 -b \"${SNAP_PATH}\" \"${CURRENT_PATH}\""
+CMD="set -ex ; \
+qemu-img create -f qcow2 -b \"${SNAP_PATH}\" \"${CURRENT_PATH}\"; \
+"
 
 ssh_exec_and_log "${SRC_HOST}" "${CMD}" \
                  "Error reverting snapshot to ${SNAP_PATH}"

src/tm_mad/shared/ln

@@ -63,8 +63,21 @@ ssh_make_path $DST_HOST $DST_DIR
 #-------------------------------------------------------------------------------
 log "Linking $SRC_PATH in $DST"
 
-ssh_exec_and_log $DST_HOST \
-                "cd $DST_DIR; rm -f $DST_PATH ; ln -s $SRC_PATH $DST_PATH" \
-                "Error linking $SRC to $DST"
+CMD=$(cat <<EOT
+set -ex
 
+SRC="$SRC_PATH"
+SNAP_DIR="${SRC_PATH}.snap"
+
+if [ -d "\${SNAP_DIR}" ]; then
+    SNAP="\$(ls \${SNAP_DIR} | sort -n | tail -n 1)"
+    SRC="\${SNAP_DIR}/\${SNAP}"
+fi
+
+ln -sf "\$SRC" "$DST_PATH"
+EOT
+)
+
+ssh_exec_and_log $DST_HOST "$CMD" \
+                "Error linking $SRC to $DST"
 exit 0