[fuse-devel] Questions ( hard links )

[Leandro F. <leo...@gm...>]

Hi all,

I am having a couple of problems and I would like to know if someone
has an interesting idea to solve them ( as you always do :) ).

 1. The ugliest one: I have a FS that enforces quotas. The idea is
simple, when I write to a file I increase the "used" variable and when
I delete a file I decrease the variable (a bit more than that but is
not really difficult).

However, I have a tricky scenario where things get messy and I end up
with negative used space.

  - create file "test"
  - truncate(test,10)              used=3D=3D10
  - link(test, link_to_test)       used=3D=3D20
  - truncate(link_to_test,20)  used=3D=3D30    (here both increase !!!)
  - unlink(test)                      used=3D=3D10    (Will say "test" is
20 not 10 !!!)
  - unlink(link_to_test)           used=3D=3D-10   !!!!!!!!!


I only know the basics about hard links and I dont see how to solve
the problem in a simple way... :/


2. Very ugly: The same idea than the last one but with directories....

    When there are too many files in a directory it will increase (in
size),   and I dont know a way to track it... so we get a negative
"used" space when we delete it.


3. Not so ugly but seems to be a fuse bug:

   - mkdir("dir")
   - open("dir/file", O_CREAT)
   - unlink("dir/file")
   - rmdir("dir")                             !!!! Error, directory not emp=
ty
   - close("dir/file");                      the .fuse is deleted here

   I saw it using fsstress and apart from that I don't know if it
could be dangerous... I suppose the error comes from the .fuse_hidden
file so I dont think it will be easy to solve....


All the comments are welcome and thanks a lot for the great work

Leandro Franco