Refactor mounting of persistent storage media.

This also fixes a bug where for home-rw image files: they were mounted
in ${rootmnt}/live before ${rootmnt} was mounted, hence "hiding" the
mount point.

diff --git a/scripts/live-helpers b/scripts/live-helpers
index b2aa125..88a3861 100644 (file)
--- a/scripts/live-helpers
+++ b/scripts/live-helpers
@@ -514,12 +514,19 @@ get_fstype ()
 where_is_mounted ()
 {
        device=${1}
+       # return first found
+       grep -m1 "^${device} " /proc/mounts | cut -f2 -d ' '
+}
 
-       if grep -q "^${device} " /proc/mounts
-       then
-               # return the first found
-               grep -m1 "^${device} " /proc/mounts | cut -f2 -d ' '
-       fi
+trim_path () {
+    # remove all unnecessary /:s in the path, including last
+    echo ${1} | sed 's|//|/|g' | sed 's|/$||'
+}
+
+what_is_mounted_on ()
+{
+       local dir="$(trim_path ${1})"
+       grep -m1 "^[^ ]\+ ${dir} " /proc/mounts | cut -d' ' -f1
 }
 
 lastline ()
@@ -711,6 +718,52 @@ try_mount ()
        fi
 }
 
+mount_persistent_media ()
+{
+       local device=${1}
+       local backing=""
+
+       # We can't mount into ${rootmnt}/live before ${rootmnt} has been
+       # mounted since that would cover our mountpoint.
+       if [ -n "${rootmnt}" ] && [ -z "$(what_is_mounted_on ${rootmnt})" ]
+       then
+               backing="/$(basename ${device})-backing"
+       else
+               backing="${rootmnt}/live/persistent/$(basename ${device})"
+       fi
+
+       mkdir -p "${backing}"
+       local old_backing="$(where_is_mounted ${device})"
+       if [ -z "${old_backing}" ]
+       then
+               local fstype="$(get_fstype ${device})"
+               local mount_opts="rw,noatime"
+               if [ -n "${PERSISTENT_READONLY}" ]
+               then
+                       mount_opts="ro,noatime"
+               fi
+               if mount -t "${fstype}" -o "${mount_opts}" "${device}" "${backing}" >/dev/null
+               then
+                       echo ${backing}
+                       return 0
+               else
+                       log_warning_msg "Failed to mount persistent media ${device}"
+                       return 1
+               fi
+       elif [ "${backing}" != "${old_backing}" ]
+       then
+               if mount --move ${old_backing} ${backing} >/dev/null
+               then
+                       echo ${backing}
+                       return 0
+               else
+                       log_warning_msg "Failed to move persistent media ${device}"
+                       return 1
+               fi
+       fi
+       return 0
+}
+
 open_luks_device ()
 {
        dev="${1}"
@@ -815,39 +868,39 @@ probe_for_file_name ()
        local snapshots="${2}"
        local dev="${3}"
 
-       local devfstype="$(get_fstype ${dev})"
-       local backing="${rootmnt}/live/persistent/$(basename ${dev})"
        local ret=""
-       if is_supported_fs ${devfstype} && mkdir -p "${backing}" && \
-          try_mount "${dev}" "${backing}" "rw" "${devfstype}"
+       local backing="$(mount_persistent_media ${dev})"
+       if [ -z "${backing}" ]
        then
-               for label in ${overlays}
+           return
+       fi
+
+       for label in ${overlays}
+       do
+               path=${backing}/${PERSISTENT_PATH}${label}
+               if [ -f "${path}" ]
+               then
+                       local loopdev=$(setup_loop "${path}" "loop" "/sys/block/loop*")
+                       ret="${ret} ${label}=${loopdev}"
+               fi
+       done
+       for label in ${snapshots}
+       do
+               for ext in squashfs cpio.gz ext2 ext3 ext4 jffs2
                do
-                       path=${backing}/${PERSISTENT_PATH}${label}
-                       if [ -f "${path}" ]
+                       path="${PERSISTENT_PATH}${label}.${ext}"
+                       if [ -f "${backing}/${path}" ]
                        then
-                               local loopdev=$(setup_loop "${path}" "loop" "/sys/block/loop*")
-                               ret="${ret} ${label}=${loopdev}"
+                               ret="${ret} ${label}=${dev}:${backing}:${path}"
                        fi
                done
-               for label in ${snapshots}
-               do
-                       for ext in squashfs cpio.gz ext2 ext3 ext4 jffs2
-                       do
-                               path="${PERSISTENT_PATH}${label}.${ext}"
-                               if [ -f "${backing}/${path}" ]
-                               then
-                                       ret="${ret} ${label}=${dev}:${backing}:${path}"
-                               fi
-                       done
-               done
+       done
 
-               if [ -n "${ret}" ]
-               then
-                       echo ${ret}
-               else
-                       umount ${backing} > /dev/null 2>&1 || true
-               fi
+       if [ -n "${ret}" ]
+       then
+               echo ${ret}
+       else
+               umount ${backing} > /dev/null 2>&1 || true
        fi
 }
 
@@ -1180,7 +1233,6 @@ get_custom_mounts ()
        local bindings="/bindings.list"
        local links="/links.list"
        rm -rf ${bindings} ${links} 2> /dev/null
-       local persistent_backing="${rootmnt}/live/persistent"
 
        for device in ${devices}
        do
@@ -1191,26 +1243,12 @@ get_custom_mounts ()
 
                local device_name="$(basename ${device})"
                local device_used=""
-               # $device may already have been mounted by
-               # probe_for_file_name() in find_persistent_media() ...
-               local backing=$(where_is_mounted ${device})
+               local backing=$(mount_persistent_media ${device})
                if [ -z "${backing}" ]
                then
-                       # ... otherwise we mount it now
-                       backing="${persistent_backing}/${device_name}"
-                       mkdir -p "${backing}"
-                       local device_fstype="$(get_fstype ${device})"
-                       if [ -z "${PERSISTENT_READONLY}" ]
-                       then
-                               device_mount_opts="rw,noatime"
-                       else
-                               device_mount_opts="ro,noatime"
-                       fi
-                       if ! mount -t "${device_fstype}" -o "${device_mount_opts}" "${device}" "${backing}" >/dev/null 2>&1
-                       then
-                               log_warning_msg "Could not mount persistent media ${device} (${device_fstype})"
-                       fi
+                       continue
                fi
+
                local include_list="${backing}/${persistence_list}"
                if [ ! -r "${include_list}" ]
                then
@@ -1223,7 +1261,11 @@ get_custom_mounts ()
                        continue
                fi
 
-               [ "${DEBUG}" = "Yes" ] && cp ${include_list} ${persistent_backing}/${persistence_list}.${device_name}
+               if [ -n "${DEBUG}" ] && [ -e "${include_list}" ]
+               then
+                       cp ${include_list} ${rootmnt}/live/persistent/${persistence_list}.${device_name}
+               fi
+
                while read source dest options # < ${include_list}
                do
                        if echo ${source} | grep -qe "^[[:space:]]*\(#.*\)\?$"
@@ -1321,9 +1363,9 @@ do_custom_mounts ()
                        esac
                done
 
-               if mountpoint -q "${dest}";
+               if [ -n "$(what_is_mounted_on "${dest}")" ]
                then
-                       log_warning_msg "Skipping custom mount ${source} on ${dest}: destination is already a mount point"
+                       log_warning_msg "Skipping custom mount ${source} on ${dest}: $(what_is_mounted_on "${dest}") is already mounted there"
                        continue
                fi
 
@@ -1442,15 +1484,9 @@ fix_home_rw_compatibility ()
                return
        fi
 
-       local backing="$(where_is_mounted ${device})"
+       local backing="$(mount_persistent_media ${device})"
        if [ -z "${backing}" ]
        then
-               backing="${rootmnt}/live/persistent/$(basename ${device})"
-               mkdir -p "${backing}"
-               local device_fstype="$(get_fstype ${device})"
-       local device_mount_opts="rw,noatime"
-       if ! mount -t "${device_fstype}" -o "${device_mount_opts}" "${device}" "${backing}" >/dev/null 2>&1
-       then
                return
        fi