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[[!meta copyright="Copyright © 2008, 2009 Free Software Foundation, Inc."]]
[[!meta license="""[[!toggle id="license" text="GFDL 1.2+"]][[!toggleable
id="license" text="Permission is granted to copy, distribute and/or modify this
document under the terms of the GNU Free Documentation License, Version 1.2 or
any later version published by the Free Software Foundation; with no Invariant
Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license
is included in the section entitled
[[GNU Free Documentation License|/fdl]]."]]"""]]
Sergiu Ivanov
Mail: <mailto:unlimitedscolobb@gmail.com>
# Google Summer of Code: 2009 Project
**Unionmount**: The goal of this project is to make it possible to set
translators in unionmount mode, which means that the filesystem
published by the mounted translator will get merged with the directory
tree of the node the translator is mounted onto.
For documentation, see [[hurd/translator/unionmount]].
---
## Roadmap
### DONE
* **Make `unionfs` build.** For reasons unknown to me, `unionfs`
Makefile was configured to search for include files from under
`$(prefix)/include`, while `$(prefix)` was never defined. Setting
`$(prefix)` to `/usr` solved the problem.
* **Change the command line parsing in `unionfs` to comply with the
requirements of `unionmount`.** Although the core functionality of
`unionmount` heavily relies on `unionfs`, the command line interface
of these two programs is completely different: `unionfs` operates on
directories, the list of which is explicitly specified, while
`unionmount` *always* merges the underlying filesystem and the
filesystem published by the mountee. Therefore, options like
`--add`, `--remove`, `--underlying` (specific to `unionfs`) make
little sense in `unionmount` context. These options have been
removed. Also, `unionmount` must be able to pass some switches to
the mountee, which means that it should stop parsing the command
line arguments immediately after having encountered the path to the
mountee (very similar to how `settrans` works). This functionality
has also been implemented.
* **Make `unionmount` capable of starting the mountee.** The idea
behind implementation of this goal is that `unionmount` should
provide a proxy node on which to set the mountee. The main issue
about this goal was the fact that the mountee *cannot* be started
during the initialization of `unionmount`, because in this phase
`unionmount` is not capable of responding to RPCs, while many
translators try to `io_stat` their underlying node or do other
interesting things on startup. The solution to this problem is,
obviously, *lazy* startup, i.e. the mountee is started at the first
attempt to access (via `dir_lookup` or `dir_readdir`) the merged
filesystem published by `unionmount`.
* **Include the filesystem published by the mountee in the list of
merged filesystems.** `unionfs` operates on a list of ports to the
underlying filesystems, therefore, to finish the unionmount
functionality, I had to include the port to the mountee in this
list.
* **Learn Texinfo.** In order to produce canonical documentation I had
to learn the Texinfo documentation format.
* **Write documentation for `unionmount`.** The basic unionmount
functionality being finished, it has to be documented properly, lest
it should lag behind and remain unfinished eventually.
* **Write documentation for `unionfs`.** `unionfs` is not exactly
well-documented at the moment, the only help being provided by the
comments in the sources. The goal is to write a more coherent
documentation.
### TODO
(Dates in brackets show the approximate deadline)
* **Implement merging rules.** *(25 Jul)* Some details are still
awaiting discovery by me.
* **Wrap up the project for upstream inclusion.** *(1 Aug)*
`unionmount` is intended to be included upstream, therefore it
should be mostly complete and polished by the end of GSoC.
* **Decide as to location of unionmount.** *(1 Aug)* Presently,
`unionmount` is a (local) branch in `unionfs` git repository. The
first step of publishing it is planned to be pushing it to the
Savannah `unionfs` repository. Some agree that there should also be
a second step consisting in splitting `unionmount` in a separate git
repository, since the destinations of `unionfs` and `unionmount` are
*similar*, and not identical.
* **Employ `unionmount` in eth-multiplexer.** *(10 Aug)* I still have
to scrounge for details.
* **Use a different (better?) implementation idea.** *(17 Aug)* It has
been pointed out several times that `unionmount` could be
implemented not by forking off `unionfs`, but by keeping the merging
functionality in a stand-alone module (which could then be used by
`unionfs` as well). Different implementation ideas with their own
specific advantages may also arise in the future.
---
# Google Summer of Code: 2008 Project: Namespace-based translator selection
---
## Current Task
Write the filesystem proxy for namespace-based translator selection (*nsmux*).
The code is at <http://github.com/scolobb/nsmux/tree/master>.
---
###Did this week
* Modified the node cache so that it maintains shadow nodes alive.
###Plans for the next week
* Implement the shutting down of translator stacks when *nsmux* is asked to go away (in case **antrik** considers that necessary).
* Make *nsmux* provide the access to the translator stack of the real node, in case a translator (mainly, a filter) should ask for its underlying node to be opened in O_NOTRANS mode.
---
###Current Status
####DONE:
* The skeleton which mirrors the filesystem.
* Provide proxy nodes (modify the standard version of netfs_S_dir_lookup).
####TODO:
* Create the generic filtering translator.
* Create the translator '0' (providing the untranslated version of the
node).
* Create the "recursive wrappers" for one-node translators.
* Create special translators for the main proxy so that its functionality
should be complete.
* Implement sharing of dynamic translator stacks where possible.
* Make dynamic translators go away as soon as they are not required.
* Refine the skeleton in several places so that it should become faster
and more reliable.
* Kill bugs.
* Integrate nsmux upstream.
* Solve the libtrivfs stacking issue.
* Patch libnetfs (it does not support file_get_translator_cntl, for
instance).
---
###Progress
####8: Fri Sep 19:
> Modified the ncache so that it now maintains shadow nodes (and directory nodes too, it is a side effect at the moment) alive.
####7: Sat Aug 30 - Fri Sep 5:
> Added the code for shutting down dynamic translator stacks.
####6: Mon Aug 4 - Fri Aug 29:
> Implemented the proxy nodes.
####5: Thu Jul 24 - Thu Jul 24:
> Created a *libnetfs*-based one-node translator, working exactly like the *libtrivfs*-based translator I had written before; the former, however, can be included in a translator stack.
####4: Tue Jul 22 - Thu Jul 24:
> Attempted to make a *libtrivfs*-based translator to be able to be stacked upon itself (to be able to receive a translator on top of itself, more exactly); attempted to borrow some code from *libnetfs* but this didn't bring any results.
####3: Sun Jul 20 - Tue Jul 22:
> Implemented the possibility to propagate a translator on all files belonging to a directory 'dir' in the request of the type 'dir,,x/'.
####2: Thu Jul 17 - Fri Jul 18:
> Extended the lookup code in *nsmux* to allow for looking up nodes like 'file,,x' and added the possibility to escape the double-comma in the following way: ',,,'.
####1: Mon Jul 12 - Tue Jul 13:
> Implemented a simple *libtrivfs*-based translator to test the lookup code for *nsmux*.
####0: Sat Jul 12 - Sat Jul 12:
> Made small changes to the code of *filterfs* to fit the needs of *nsmux*.
---
## Completed Tasks
####2: Sat May 3 - Fri Jul 17:
> Write a translator that should filter the contents of the directory it is set on according to some property. The property can be an arbitrary command.
> The code is at <http://github.com/scolobb/filterfs/tree/master>.
####1: Mon Apr 28 - Wed Apr 30:
> Wrote a Python extension module in C for retreiving the uptime. The module is based on the code of *w*.
####0: Sun Apr 27:
> Followed the code of *dmesgd* (<http://www.bddebian.com/junk/dmesgd/>) kindly offered by **bddebian** and rewrote it from scratch as a tutorial.
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