[Linux-cluster] Re: GFS, what's remaining

[Joel Becker]

On Sun, Sep 04, 2005 at 09:37:15AM +0100, Alan Cox wrote:
> I am curious why a lock manager uses open to implement its locking
> semantics rather than using the locking API (POSIX locks etc) however.

	Because it is simple (how do you fcntl(2) from a shell fd?), has no
ranges (what do you do with ranges passed in to fcntl(2) and you don't
support them?), and has a well-known fork(2)/exec(2) pattern.  fcntl(2)
has a known but less intuitive fork(2) pattern.
	The real reason, though, is that we never considered fcntl(2).
We could never think of a case when a process wanted a lock fd open but
not locked.  At least, that's my recollection.  Mark might have more to
comment.

Joel

-- 

"In the room the women come and go
 Talking of Michaelangelo."

Joel Becker
Senior Member of Technical Staff
Oracle
E-mail: joel.becker at oracle.com
Phone: (650) 506-8127