shutdown: teardown loop devices only after umount

This still isn't really ideal, but attempting to detach loops while
they're still mounted will definitely fail. Ideally, the loop device is
in autoclear mode and dropping its refcount to 0 on umount will cause
the backing file to be detached from the loop.

Of course, this all gets way too complicated for userspace to handle
when dealing with the sort of rat's nest of loop devices that ArchISO
sets up. The kernel doesn't help us out here by populating things like
holders/ and slaves/, but I'm not sure it could.

Maybe there's a better way...

Signed-off-by: Dave Reisner <dreisner@archlinux.org>

1 files changed, 6 insertions, 6 deletions

diff --git a/shutdown b/shutdown
index dc293d4..b0934b7 100644
--- a/shutdown
+++ b/shutdown
@@ -75,12 +75,6 @@ fi
 # chdir, so that we can avoid a lot of path chopping
 cd /sys/class/block
 
-printf '%s\n' 'Detaching loop devices.'
-
-for loop in loop*/loop; do
-    [ -e "$loop" ] && losetup -d "${loop%/loop}"
-done
-
 printf '%s\n' "Unmounting all devices."
 
 # unmount everything in /oldroot
@@ -99,6 +93,12 @@ END {
     umount "$mount"
 done
 
+printf '%s\n' 'Detaching loop devices.'
+
+for loop in loop*/loop; do
+    [ -e "$loop" ] && losetup -d "${loop%/loop}"
+done
+
 printf '%s\n' "Disassembling stacked devices."
 
 # iterate over devices with holders