# Re: \[PATCH\] locks: Ability to test for flock presence on fd

- From: J. Bruce Fields \<hidden\>
- Date: 2014-09-09 16:18:21 
- List: linux-api
- Page: https://ratatoskr.run/linux-api/2014/09/87752
- Thread: https://ratatoskr.run/linux-api/2014/09/87752/t.md

```text
On Tue, Sep 02, 2014 at 11:07:14PM +0400, Pavel Emelyanov wrote:
> > Would it make sense to return the lock type held instead, so you could
> > do one flock(fd, LOCK_TEST) instead of flock(fd, LOCK_TEST|LOCK_SH) and
> > flock(fd, LOCK_TEST|LOCK_EX) ?
> 
> Well, in our case we parse /proc/locks anyway to see what
> files at least to test for being locked. But what you propose
> looks even better. I'll look what can be done here.

Actually I think I prefer your version.  It seems cleaner to define
LOCK_TEST as returning the same result as you'd get if you actually
tried the lock, just without applying the lock.  It avoids having a
different return-value convention for this one command.  It might avoid
some ambiguity in cases where the flock might be denied for reasons
other than a conflicting flock (e.g. on NFS where flocks and fcntl locks
conflict).  It's closer to what GETLK does in the fcntl case.

--b.
```