Merge lp:~binli/ubuntu/trusty/casper/overlayfs into lp:ubuntu/trusty/casper

[Bin Li]

Support newer overlayfs in newer kernel.(LP: #1401620, LP: #1412411)

=== modified file 'debian/changelog'
--- debian/changelog	2014-04-09 18:47:09 +0000
+++ debian/changelog	2015-04-14 09:00:51 +0000
@@ -1,3 +1,17 @@
+casper (1.341) UNRELEASED; urgency=medium
+
+  [Andy Whitcroft]
+  * scripts/casper: switch up to overlayfs V2 format (overlay filesystem
+    type) when available.  (LP: #1412411)
+
+  * scripts/casper: move union content into a subdirectory of the /cow
+    device, to allow us to create a workdir where that is needed for
+    overlayfs.  Also attempt to mount overlayfs with and without the
+    workdir= to cope with the semantic change in newer kernels.
+    (LP: #1401620)
+
+ -- Bin Li <[e-mail]>  Tue, 14 Apr 2015 16:49:31 +0800
+
 casper (1.340) trusty; urgency=medium
 
   * Remove 23etc_modules which does more harm than good (LP: #1296386)

=== modified file 'scripts/casper'
--- scripts/casper	2014-03-19 14:22:36 +0000
+++ scripts/casper	2015-04-14 09:00:51 +0000
@@ -380,7 +380,7 @@
     rootmnt="$2"
 
     if [ "${UNIONFS}" = 'DEFAULT' ]; then
-        for union in 'overlayfs' 'aufs' 'unionfs'
+        for union in 'overlay' 'overlayfs' 'aufs' 'unionfs'
         do
             modprobe "${MP_QUIET}" -b ${union} || true
             if cut -f2 /proc/filesystems | grep -q "^${union}\$"; then
@@ -461,17 +461,18 @@
     fi
 
     mount -t ${cow_fstype} -o ${cow_mountopt} ${cowdevice} /cow || panic "Can not mount $cowdevice on /cow"
+    mkdir -p /cow/upper /cow/work
 
     case ${UNIONFS} in
         unionfs-fuse)
-            (ulimit -n 16384; unionfs-fuse -o cow -o noinitgroups -o default_permissions -o allow_other -o use_ino -o suid /cow=RW:$rofsstring "$rootmnt" || panic "${UNIONFS} mount failed")
+            (ulimit -n 16384; unionfs-fuse -o cow -o noinitgroups -o default_permissions -o allow_other -o use_ino -o suid /cow/upper=RW:$rofsstring "$rootmnt" || panic "${UNIONFS} mount failed")
             mkdir -p /dev/.initramfs/varrun
             pidof unionfs-fuse >> /dev/.initramfs/varrun/sendsigs.omit || true
             ;;
         aufs|unionfs)
-            mount -t ${UNIONFS} -o noatime,dirs=/cow=rw:$rofsstring ${UNIONFS} "$rootmnt" || panic "${UNIONFS} mount failed"
+            mount -t ${UNIONFS} -o noatime,dirs=/cow/upper=rw:$rofsstring ${UNIONFS} "$rootmnt" || panic "${UNIONFS} mount failed"
             ;;
-        overlayfs)
+        overlay|overlayfs)
             # Mount the layers pairwise from the bottom onto rootmnt,
             # for the second and later layers rootmnt forms the lower layer.
             mounts=""
@@ -486,8 +487,10 @@
                     lower="$mount"
                     continue
                 fi
-                mount -t overlayfs -o "upperdir=$mount,lowerdir=$lower" \
-                    "$mount" "$rootmnt"
+                mount -t ${UNIONFS} -o "upperdir=$mount/upper,lowerdir=$lower,workdir=$mount/work" \
+                    "$mount" "$rootmnt" || \
+                  mount -t ${UNIONFS} -o "upperdir=$mount/upper,lowerdir=$lower" \
+                      "$mount" "$rootmnt"
                 lower="$rootmnt"
             done
             ;;