[Merge] lp:~xnox/ubuntu/trusty/mountall/remount into lp:ubuntu/mountall

[Dmitrijs Ledkovs]

Dmitrijs Ledkovs has proposed merging lp:~xnox/ubuntu/trusty/mountall/remount into lp:ubuntu/mountall.

Requested reviews:
  Upstart Reviewers (upstart-reviewers)
Related bugs:
  Bug #1039887 in mountall (Ubuntu): "fstab does not honor /proc mount options"
  https://bugs.launchpad.net/ubuntu/+source/mountall/+bug/1039887

For more details, see:
https://code.launchpad.net/~xnox/ubuntu/trusty/mountall/remount/+merge/197840

This is one way to implement/fix "fstab does not honor /proc mount options".

The actual problem is: mount-points are remounted, only if currently mounted "ro" and "ro was not requested.

Implementation is to convert current/requested mount options from character array, to NihHash and then compare the two sets of mount options. I don't like this approach as it is buggy in many subtle ways:
- "complement" options are not parsed properly, e.g. -orw,ro,rw are stored as RW and RO keys.
- ordering of the options is no longer preserved
- requested options, are not necessarily the same after successful mount, e.g. "defaults" get expanded, no-op options are dropped (tmpfs gid=0), relative options expanded (size=10%) etc.

What I think a better approach is to:
- when mountall starts mark up all mountpoints that we didn't mount
- remount them once

That should be a more simple and more robust approach.

I'm leaving code here for now, in case someone wants to pick it up / review. There are other useful changes in this branch (e.g. test-cases and general clean-up).
-- 
The attached diff has been truncated due to its size.
https://code.launchpad.net/~xnox/ubuntu/trusty/mountall/remount/+merge/197840
Your team Upstart Reviewers is requested to review the proposed merge of lp:~xnox/ubuntu/trusty/mountall/remount into lp:ubuntu/mountall.
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