Some filesystem tests are failing when their image is prepared with
guestmount, but succeeding if loop mounts are used instead. The reason
seems to be a race condition the guestmount(1) manual page explains:
When guestunmount(1)/fusermount(1) exits, guestmount may still be
running and cleaning up the mountpoint. The disk image will not be
fully finalized.
This means that scripts like the following have a nasty race condition:
guestmount -a disk.img -i /mnt
# copy things into /mnt
guestunmount /mnt
# immediately try to use 'disk.img' ** UNSAFE **
The solution is to use the --pid-file option to write the guestmount
PID to a file, then after guestunmount spin waiting for this PID to
exit.
The Python standard library has an os.waitpid() function for waiting a
child to terminate, but it cannot wait on non-child processes. Implement
a utility function that can do this by polling the process repeatedly
for a given duration, optionally killing the process if it won't
terminate on its own. Apply the suggested solution with this utility
function, which makes the failing tests succeed again.
Signed-off-by: Alper Nebi Yasak <alpernebiyasak@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
85d775a193