[Gluster-devel] Simulating some kind of "virtual file"

[David Spisla]

Dear Gluster Devels,

at the moment I do some Xlator stuff and I want to know if there is a way
to simulate the existing of a file to the client. It should be a kind of
"virtual file". Here are more details.

1. Client lookup for a file e.g. "apple.test". This file does not exist in
the backend
$ ls -l apple.test
ls: cannot access apple.test: No such file or directory

Normally the system will not find that file

2. In the backend I have a real file called  e.g. "apple". Now there is a
Xlator which manipulates the lookup request and is looking for the file
"apple" instead of "apple.test". Gluster finds the file "apple" and the
client will get a message from gluster that there is a file called
"apple.test" with the attributes of the file "apple" (maybe we can
manipulate that attributes too).

$ ls -l apple.test
-rw-r--r-- 1 davids davids 0 Jan  5 15:42 apple.test

My first idea is, to have a special lookup and lookup_cbk in some Xlator in
the server stack. Or it is better to have this Xlator in the Client Stack?
The lookup function has a parameter called "loc_t *loc". In a first test I
tried to manipulate loc->name and loc-path. If I manipulate loc->path I got
an error and my volume crashed.

Any hints?

Regards
David Spisla
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