Make union mounting more sensible and robust.

...except that they're broken! But we're getting to that.

diff --git a/scripts/live b/scripts/live
index 08d6d74..d774284 100755 (executable)
--- a/scripts/live
+++ b/scripts/live
@@ -1485,7 +1485,8 @@ setup_unionfs ()
        then
                if [ -n "${PERSISTENT_READONLY}" ]
                then
-                       root_backing="/${rootmnt}/live/persistent/$(basename ${cowdevice})-root"
+                       mount -t tmpfs -o rw,noatime,mode=755 tmpfs "/cow"
+                       root_backing="${rootmnt}/live/persistent/$(basename ${cowdevice})-root"
                        mkdir -p ${root_backing}
                else
                        root_backing="/cow"
@@ -1505,6 +1506,7 @@ setup_unionfs ()
 
        rofscount=$(echo ${rofslist} |wc -w)
 
+       # XXX: we now ensure that there can only be one read-only filesystem. Should this be inside the EXPOSED_ROOT if?
        if [ ${rofscount} -ne 1 ]
        then
                panic "only one RO file system supported with exposedroot: ${rofslist}"
@@ -1532,21 +1534,25 @@ setup_unionfs ()
                #panic "unionmount does not support subunions (${cow_dirs})."
        fi
 
-       unionmountopts=""
-       unionmountpoint=""
-
        for dir in ${cow_dirs}; do
-               unionrw="/cow${dir}"
-               unionro="${rofs}${dir}"
                unionmountpoint="${rootmnt}${dir}"
-               mkdir -p ${unionrw}
+               mkdir -p ${unionmountpoint}
                if [ "${UNIONTYPE}" = "unionmount" ]
                then
                        # FIXME: handle PERSISTENT_READONLY
                        unionmountopts="-t ${cow_fstype} -o noatime,union,${cow_mountopt} ${cowdevice}"
                        mount_full $unionmountopts "${unionmountpoint}"
                else
-                       do_union ${root_backing} ${unionrw} ${unionro} ${unionmountpoint}
+                       cow_dir="/cow${dir}"
+                       rofs_dir="${rofs}${dir}"
+                       mkdir -p ${cow_dir}
+                       if [ -n "${PERSISTENT_READONLY}" ] && [ "${cowdevice}" != "tmpfs" ]
+                       then
+                               #mount -t tmpfs -o rw,noatime,mode=755 tmpfs "${cow_dir}"
+                               do_union ${unionmountpoint} ${cow_dir} ${root_backing} ${rofs_dir}
+                       else
+                               do_union ${unionmountpoint} ${cow_dir} ${rofs_dir}
+                       fi
                fi || panic "mount ${UNIONTYPE} on ${unionmountpoint} failed with option ${unionmountopts}"
        done
 
@@ -1743,10 +1749,10 @@ setup_unionfs ()
                                        dest="$(mktemp -d ${persistent_backing}/links_source-XXXXXX)"
                                        links_source="${dest}"
                                fi
-                               unionrw="$(echo ${dest} | sed -e "s|${rootmnt}|/cow/|")"
-                               mkdir -p ${unionrw}
-                               unionmountopts="noatime,${noxino_opt}dirs=${unionrw}=rw:${source}=${roopt}"
-                               do_union ${root_backing} ${unionrw} ${source} ${dest}
+                               cow_dir="$(echo ${dest} | sed -e "s|${rootmnt}|/cow/|")"
+                               mkdir -p ${cow_dir}
+                               # XXX: broken! will be fixed in the next few commits...
+                               do_union ${dest} ${cow_dir} ${source}
                        fi
 
                        if [ -n "${opt_linkfiles}" ]

diff --git a/scripts/live-helpers b/scripts/live-helpers
index 3de16e5..e7fef47 100644 (file)
--- a/scripts/live-helpers
+++ b/scripts/live-helpers
@@ -607,16 +607,16 @@ link_files ()
 }
 
 do_union () {
-       root_backing="${1}"
-       unionrw="${2}"
-       unionro="${3}"
-       unionmountpoint="${4}"
+       local unionmountpoint="${1}"    # directory where the union is mounted
+       local unionrw="${2}"            # branch where the union changes are stored
+       local unionro1="${3}"           # first underlying read-only branch (optional)
+       local unionro2="${4}"           # second underlying read-only branch (optional)
 
        if [ "${UNIONTYPE}" = "aufs" ]
        then
                rw_opt="rw"
                ro_opt="rr+wh"
-               noxino_opt="noxino,"
+               noxino_opt="noxino"
        elif [ "${UNIONTYPE}" = "unionfs-fuse" ]
        then
                rw_opt="RW"
@@ -628,9 +628,16 @@ do_union () {
 
        case "${UNIONTYPE}" in
                unionfs-fuse)
-                       # FIXME: handle PERSISTENT_READONLY
                        unionmountopts="-o cow -o noinitgroups -o default_permissions -o allow_other -o use_ino -o suid"
-                       unionmountopts="${unionmountopts} ${unionrw}=${rw_opt}:${unionro}=${ro_opt}"
+                       unionmountopts="${unionmountopts} ${unionrw}=${rw_opt}"
+                       if [ -n "${unionro1}" ]
+                       then
+                               unionmountopts="${unionmountopts}:${unionro1}=${ro_opt}"
+                       fi
+                       if [ -n "${unionro2}" ]
+                       then
+                               unionmountopts="${unionmountopts}:${unionro2}=${ro_opt}"
+                       fi
                        ( sysctl -w fs.file-max=391524 ; ulimit -HSn 16384
                        unionfs-fuse ${unionmountopts} "${unionmountpoint}" ) && \
                        ( mkdir -p /run/sendsigs.omit.d
@@ -638,18 +645,21 @@ do_union () {
                        ;;
 
                overlayfs)
-                       # FIXME: is PERSISTENT_READONLY possible? (overlayfs only handles two dirs, but perhaps they can be chained?)
-                       unionmountopts="-o noatime,lowerdir=${unionro},upperdir=${unionrw}"
+                       # XXX: can unionro2 be used? (overlayfs only handles two dirs, but perhaps they can be chained?)
+                       # XXX: and can unionro1 be optional? i.e. can overlayfs skip lowerdir?
+                       unionmountopts="-o noatime,lowerdir=${unionro1},upperdir=${unionrw}"
                        mount -t ${UNIONTYPE} ${unionmountopts} ${UNIONTYPE} "${unionmountpoint}"
                        ;;
 
                *)
-                       if [ -n "${PERSISTENT_READONLY}" ]
+                       unionmountopts="-o noatime,${noxino_opt},dirs=${unionrw}=${rw_opt}"
+                       if [ -n "${unionro1}" ]
                        then
-                               mount -t tmpfs -o rw,noatime,mode=755 tmpfs "${unionrw}"
-                               unionmountopts="-o noatime,${noxino_opt}dirs=${unionrw}=${rw_opt}:${root_backing}=${ro_opt}:${unionro}=${ro_opt}"
-                       else
-                               unionmountopts="-o noatime,${noxino_opt}dirs=${unionrw}=${rw_opt}:${unionro}=${ro_opt}"
+                               unionmountopts="${unionmountopts}:${unionro1}=${ro_opt}"
+                       fi
+                       if [ -n "${unionro2}" ]
+                       then
+                               unionmountopts="${unionmountopts}:${unionro2}=${ro_opt}"
                        fi
                        mount -t ${UNIONTYPE} ${unionmountopts} ${UNIONTYPE} "${unionmountpoint}"
                        ;;