This is only one line, but it takes a lot to untangle ... basically
the current "correct" path is:
---
mk_build_dir()
-> sets trap trap_cleanup EXIT
... stuff ..
mount_proc_dev_sys
-> mounts $TMP_MOUNT_PATH/<proc,dev.sysfs>
pre-finalise.d
finalise.d
unmount_image $TMP_BUILD_DIR/mnt # nb == $TMP_MOUNT_PATH
-> unmount_dir()
-> recursive unmount everything inside TMP_MOUNT_PATH
TMP_IMAGE_PATH=$(dib-block-device getval image-path)
export TMP_IMAGE_PATH
dib-block-device umount
dib-block-device cleanup
... actually cleanup directories ...
---
Our current failure exit trap does:
---
dib-block-device umount
unmount_image
...
---
Note this is the *opposite* of what is done in the correct exit path.
In the failure case, if a script fails in the finalise stages it leads
to /proc, /sys, /dev etc. still being mounted inside the image; the
"dib-block-device umount" call doesn't know anything about these
mounts and tries to unmount the parent directory, and we get a hard
failure with a busy mount, and all the mounts are subsequently leaked.
Note that "unmount_dir", which is ultimately called by
"unmount_image", already knows to skip those mounts that
"dib-block-device umount" manages (this is the DIB_MOUNTPOINTS list).
This is further evidence it should be called *before* the
dib-block-device umount.
Change-Id: Ibef3ce9d1167b9c4ff3d5717b113cd3ed374f5e3
5284564071