change restore mechanism on btrfs filesystem.

Use subvolumes instead of cp to restore files, this will speedup
restore and reduce local memory requirements.

After update system will have ROOTFS subvolume located at root volume.
/ -- root volume
/ROOTFS -- subvolume with actual data.

ROOTFS subvolume is set as default one, so it will be transparent to
system after update because mount will mount it at /.

Change-Id: Ie2d47962bab01537fdcbe1430dff3e3465fb7c09
Signed-off-by: Ernest Borowski <e.borowski@samsung.com>

diff --git a/scripts/fota-init.sh b/scripts/fota-init.sh
index 1c81da427b9f4b5828d2520f56bb89e91fc3d0ad..c9553bca7a83a3ccd2a36afabd7386404b563267 100755 (executable)
--- a/scripts/fota-init.sh
+++ b/scripts/fota-init.sh
@@ -75,36 +75,99 @@ delete_btrfs_snapshot() {
        PART="$1"
        MNT_POINT="$2"
        log "[Info] Deleting btrfs snapshot"
-       "$MOUNT" -o remount,rw "${MNT_POINT}"
+       # we have to delete /fota/RO_update subvolume form root volume
+       # so ensure that root volume is mounted
+       if ! "$UMOUNT" "$MNT_POINT"; then
+               log "[Error] Unable to umount $MNT_POINT"
+               return 1
+       fi
+       if ! "$MOUNT" -o subvolid=5,rw "$PART" "$MNT_POINT"; then
+               log "[Error] Unable to mount $PART root subvolume to: $MNT_POINT"
+               return 1
+       fi
+       # delete subvolume /fota/RO_update containing checkpoint data
        "$BTRFS" subvolume delete "$MNT_POINT/fota/RO_update"
+       # delete /fota directory, as it is no longer needed
+       # because data was already restored
        rm -rf -- "$MNT_POINT/fota"
+       if ! "$UMOUNT" "$MNT_POINT"; then
+               log "[Error] Unable to umount $MNT_POINT"
+               return 1
+       fi
+       # mount default volume
+       if ! "$MOUNT" "$PART" "$MNT_POINT"; then
+               log "[Error] Unable to mount default subvolume $PART to $MNT_POINT"
+               return 1
+       fi
 }
 
 restore_btrfs_snapshot() {
        PART="$1"
        MNT_POINT="$2"
-       if [ ! -d "$MNT_POINT/fota/RO_update" ]; then
-               log "[Info] btrfs snapshot not found"
-               return
-       fi
-       if "$BTRFS" subvolume list "$MNT_POINT/fota/RO_update"; then
+       DEST_DIR="$MNT_POINT/ROOTFS"
+
+       if [ -d "$MNT_POINT/fota/RO_update" ] && "$BTRFS" subvolume list "$MNT_POINT/fota/RO_update"; then
+               # There is snapshot form previously failed update
+               # Use snapshot as source data.
                log "[Info] Got previous snapshot."
-               # remove files from mountpoint because they will be restored from snapshot
-               # it is necessary otherwise files created during os-upgrade will be still there
-               for var in $(ls "$MNT_POINT" | grep -vE 'fota'); do
-                       rm -rf -- "$MNT_POINT/$var"
-               done
-               # remove special directories /dev /proc /sys content
-               # it is needed because "btrfs subvolume snapshot" copies some fies from this directories
-               rm -rf -- "$MNT_POINT/fota/RO_update/dev/"* "$MNT_POINT/fota/RO_update/proc/"* "$MNT_POINT/fota/RO_update/sys/"*
-               # restore files from snapshot
-               cp -a -- "$MNT_POINT/fota/RO_update/"* "$MNT_POINT"
-               delete_btrfs_snapshot "$PART" "$MNT_POINT"
+               SOURCE_DIR="$MNT_POINT/fota/RO_update"
+               # root volume 5 has to be set as default otherwise /ROOTFS subvolume can not be deleted
+               # as it is default subvolume
+               if ! "$BTRFS" subvolume set-default "$MNT_POINT"; then
+                       log "[Error] Unable to set $DEST_DIR as default subvolume"
+                       return 1
+               fi
+               "$BTRFS" subvolume delete "$DEST_DIR"
+               rm -rf "$DEST_DIR"
+       elif [ ! -d "$MNT_POINT/ROOTFS" ]; then
+               # There is no /ROOTFS subvolume, create it and set is as default one.
+               # This will execute during first update when data on root volume 5 exist.
+               # After this update /ROOTFS will be default subvolume. Automatically mounted by mount.
+               # Use / (root volume 5) as source data.
+               log '[Info] Create initial /ROOTFS subvolume'
+               SOURCE_DIR="$MNT_POINT"
        else
+               # There is no data to restore because there was not previous update attempts.
+               # Howether data is stored in /ROOTFS instead off inside root volume 5 /
+               # Therefore there is no need to restore anything so remove any leftover data
+               # and proceed with the update.
                log "[Info] Removing leftover data from previous snapshot."
                rm -rf -- "$MNT_POINT/fota"
+               return 0
+       fi
+       if ! "$BTRFS" subvolume snapshot "$SOURCE_DIR" "$DEST_DIR"; then
+               log "[Error] Unable to create snapshot from: $SOURCE_DIR to $DEST_DIR"
+               return 1
        fi
 
+       # Remove special directories /dev /proc /sys content
+       # it is required because "btrfs subvolume snapshot" copies some files from this directories
+       rm -rf -- "$DEST_DIR/proc/"* "$DEST_DIR/sys/"*
+
+       # Make $DEST_DIR (/ROOTFS) as new root (/).
+       # From now on it will become new default filesystem mounted by mount command.
+       if ! "$BTRFS" subvolume set-default "$DEST_DIR"; then
+               log "[Error] Unable to set $DEST_DIR as default subvolume"
+               return 1
+       fi
+       if [ -d "$MNT_POINT/fota" ]; then
+               delete_btrfs_snapshot "$PART" "$MNT_POINT"
+               # Remount root volume 5 because delete_btrfs_snapshot will mount default subvolume
+               # which is /ROOTFS.
+               if ! "$UMOUNT" "$MNT_POINT"; then
+                       log "[Error] Unable to umount $MNT_POINT"
+                       return 1
+               fi
+               if ! "$MOUNT" -o subvolid=5,rw "$PART" "$MNT_POINT"; then
+                       log "[Error] Unable to mount $PART root subvolume to: $MNT_POINT"
+                       return 1
+               fi
+       fi
+       # delete all files in root volume except new rootfs /ROOTFS
+       for var in "$MNT_POINT"/* "$MNT_POINT"/.[!.]*; do
+               test "$var" = "$MNT_POINT/ROOTFS" && continue
+               rm -rf -- "$var"
+       done
 }
 
 
@@ -165,14 +228,11 @@ mount_btrfs_partition() {
        LABEL=${1}
        PARTITION=${2}
        DIRECTORY=${3}
-       if ! "${MOUNT}" -o rw "${PARTITION}" "${DIRECTORY}"; then
+       # mount btrfs root subvolume
+       if ! "${MOUNT}" -o rw,subvolid=5 "${PARTITION}" "${DIRECTORY}"; then
                log "[Error] Cannot mount ${PARTITION} into ${DIRECTORY}"
                return 1
        fi
-       if ! "$MKDIR" -p "${DIRECTORY}/fota"; then
-               log "[Error] Cannot create directory for btrfs snapshot"
-               return 1
-       fi
        log "[Debug] Mounted ${PARTITION} as btrfs" "${INT_LOG_FILE}"
 }
 
@@ -198,9 +258,25 @@ restore_mount_checkpoint_partition() {
                        return 1
                fi
                restore_checkpoint "${PARTITION}" "${DIRECTORY}"
-               # restore deletes snapshot directory
-               "$MKDIR" -p "$DIRECTORY/fota"
-               "$BTRFS" subvolume snapshot "$DIRECTORY" "$DIRECTORY/fota/RO_update"
+               # Create new checkpoint
+               if ! "$MKDIR" -p "$DIRECTORY/fota"; then
+                       log "[Error] Unable to create $DIRECTORY/fota dir."
+                       return 1
+               fi
+               if ! "$BTRFS" subvolume snapshot "$DIRECTORY/ROOTFS" "$DIRECTORY/fota/RO_update"; then
+                       log "[Error] Unable to create snapshot from $DIRECTORY/ROOTFS to $DIRECTORY/fota/RO_update"
+                       retun 1
+               fi
+               # mount /ROOTFS partition instead of root volume
+               if ! "$UMOUNT" "${PARTITION}"; then
+                       log "[Error] Cannot umount ${PARTITION}"
+                       return 1
+               fi
+               if ! "$MOUNT" "${PARTITION}" "${DIRECTORY}"; then
+                       log "[Error] Cannot mount ${PARTITION} into ${DIRECTORY}"
+                       return 1
+               fi
+
        else
                "${MOUNT}" "${PARTITION}" "${DIRECTORY}"
                log "[Info] Unsupported filesystem ${FSTYPE} on ${PARTITION}" "${INT_LOG_FILE}"