dummy fs

[Jan Koss <kossjan@gmail.com>]

Hello.

I want implement educational file-system for Linux.
I suppose it would be very simplified UFS (for example,
with such limitations like: size of file <=8K, length of name <20 characters
and so on). The main goal is simplicity, small size of implementation
and space for speedup improvements.

1)May be some one hear about such for Linux 2.6 ?

2)Currently I'm investigating how "truncate" method should works on
the filesystem layer.
Is any description how it should works?
I mean, as I understand first I should truncate page cache
(block_truncate_page?),
what about "buffer_head" which now not belong to my file and may be
used by another process at the same time?

3)As I see sb_find_get_block return "buffer_head", with b_count==2,
(if nobody before use this "buffer_head"),
is it right behavior?
Should I call two time brelse to free "buffer_head",
which I get using sb_find_get_block?

4)Is there set of tests to check work of ordinary Unix file-system?
For example: one process creates files, and another check using
(readdir) is all right,
one open file for writing, another open the same file for reading... etc