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SubjectRe: [NFS] [PATCH] Re: grow_inodes: inode-max limit reached - how to find/fix the inode leak?
On Fri, Sep 01, 2000 at 12:37:21AM +0200, Trond Myklebust wrote:
> >>>>> " " == Michael Riepe <michael@stud.uni-hannover.de> writes:
>
> > On Thu, Aug 31, 2000 at 03:23:43PM +0200, Trond Myklebust
> > wrote:
> >> Your patch does not seem correct to me. IMO you should rather
> >> be calling nlm_release_file() in both cases where you applied
> >> 'put_file()'.
>
> > No. In the first of two cases, lockd will call
> > nlm_release_file() on its own when the function returns. In
>
> The call in nlmsvc_unshare_file() is in order to clear the f_count
> from nlmsvc_share_file().

Yes. That one was missing.

> That in nlmsvc_proc_unshare() clears the f_count from
> nlmsvc_retrieve_args().

Correct. The calling sequence is

nlmsvc_retrieve_args() /* increments */
nlmsvc_unshare_file() /* decrements if share is removed */
nlm_release_file() /* decrements */

so f_count will be at least 2 when nlmsvc_unshare_file() finds a share
to remove. In nlmsvc_traverse_shares(), the surrounding retrieve/release
calls are missing, so the minimum f_count is 1.

> > the second case, we're being called from inside
> > nlm_traverse_files(), which holds a lock on the file table --
> > nlm_release_file() would wait forever.
>
> Ugh. In that case, my personal preference would be to make
> nlm_release_file() grab the semaphore, then call another routine to do
> f_count-- and possible file cleanup which could also be called by
> nlmsvc_traverse_shares(). Call it nlm_put_file() if you like 8-).

nlm_release_file() *does* grab the semaphore. That's the problem.

> However, the test for min_count is wrong. In both cases you are trying
> to clear the f_count that was incremented in
> nlmsvc_share_file(). Since shares and locks are invisible to one
> another, I'm quite free to have an ordinary block on the same file
> thus screwing up your f_count test.

Adding or removing blocks or locks does not affect f_count at all.
There ist one function that changes f_count when it removes a block,
but it is never called, at least not in 2.2.x.

The min_count test is irrelevant (TM) anyway. In fact, I could have used
a simple `file->f_count--;' instead of `put_file();' (feel free to
do that yourself), but I'm paranoid and wanted lockd to complain if
something goes wrong. The min_count values are correct, however.

--
Michael "Tired" Riepe <Michael.Riepe@stud.uni-hannover.de>
"All I wanna do is have a little fun before I die"
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