Re: fcntl(F_GETLEASE) semantics??

[Peter Chubb <peterc@gelato.unsw.edu.au>]

>>>>> "Trond" == Trond Myklebust <trond.myklebust@fys.uio.no> writes:

Trond> to den 11.08.2005 Klokka 09:48 (+1000) skreiv Peter Chubb:
>> Hi, The LTP test fcntl23 is failing.  It does, in essence, fd =
>> open(xxx, O_RDWR|O_CREAT, 0777); if (fcntl(fd, F_SETLEASE, F_RDLCK)
>> == -1) fail;
>> 
>> fcntl always returns EAGAIN here.  The manual page says that a read
>> lease causes notification when `another process' opens the file for
>> writing or truncates it.  The kernel implements `any process'
>> (including the current one).
>> 
>> Which semantics are correct?  Personally I think that what the
>> kernel implements is correct (you can't get a read lease unsless
>> there are no writers _at_ _all_)

Trond> A read lease should mean that there are no writers at all.

Trond> If we were to allow the current process to open for write, then
Trond> that would still mean that nobody else can get a lease. In
Trond> effect you have been granted a lease with exclusive semantics
Trond> (i.e. a write lease). You might as well request that instead of
Trond> pretending it is a read lease.

So the manual page is wrong.  Fine.


-- 
Dr Peter Chubb  http://www.gelato.unsw.edu.au  peterc AT gelato.unsw.edu.au
The technical we do immediately,  the political takes *forever*
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