[9fans] semi-synthetic file system

[9fans] semi-synthetic file system

[Ronald G Minnich]

I'd like to make a file system that reflects /proc from a linux node, 
but that adds plan9-style proc support, e.g. text commands for ctl, and 
so on. (note we're adding plan9 style ctl etc. to linux /proc, here, but 
don't know if the linux core will buy it).

What I'm thinking to do is tag /proc in some way, when walk()ing to it, 
in the QID, then track  children of /proc, and tag them in some way, and 
then make it so that walk will allow people to walk to the mythical ctl 
file This directory won't exist in linux, only in my semi-synthetic file 
server.

I'm wondering if something like this has not already been done, or if 
there is some better way to do it. Has anyone done a mixed sort of file 
server like this? I would most prefer just to hack u9fs, for a number of 
reasons, but I'm open to better ideas.

thanks

ron

Re: [9fans] semi-synthetic file system

[Steve Simon]

I have a hack I did in cifs/ncpfs which adds a few files in
the root of the mounted directory additional to those from
the remote server. These could easily be a directory heirarchy
like /proc however I am not sure how relevant it would be in u9fs
(I am using lib9p).

If you plan to access this from Plan9 I would suggest a file
server which mounts its own /proc before of the remote
linux /proc and does the translation - fairly straigntforward.
If you want to do this using u9fs and v9fs (as I suspect) then this
doesn't help.

Havn't helped much, sorry.

-Steve

Re: [9fans] semi-synthetic file system

[rog]

> I would most prefer just to hack u9fs, for a number of reasons

if you really wish to mirror the linux /proc exactly but with ctl
files, this wouldn't be hard.  i'd be tempted to do things lexically.
the path string is already held in the fid.  just check if the fid's
path matches "/proc/[0-9]+" - if so, then allow userwalk and useropen of
"ctl", and amend rread() to add the extra entry in this case.  there
should be enough space in the 64-bit qid path to have a uniquely
separate identifier for ctl files without impinging on linux inode
space.