On Wed, Apr 23, 2014 at 9:00 PM, Alfred M. Szmidt <ams@xxxxxxx> wrote: > > Likewise. You infact write that it does get the lock information > > later in the document wrt. F_OFD_GETLK. > > Sorry, I disagree here...GETLK is really a misnomer, IMO. TESTLK > would have been a better name. I'm inclined to agree. > GETLK are used is to "get the first lock". > > It's a way to test whether a particular lock can be applied, and to > return information about a conflicting lock if it can't. If, for > instance there is no conflicting lock, then you don't "get" any > lock information back (l_type just gets reset to F_UNLCK). > > While I kinda see your point, it isn't what GETLK does; it really does > get you information about the first lock -- you're not testing > anything. It is also the terminology used in the POSIX standard. The POSIX wording is a little confused. For example, what does "first" mean in this context? F_GETLK returns information about one (arbitrarily selected) lock that blocks a lock you would like to place. So, I'm inclined to agree with Jeff -- this really is a "test" (or "can I lock it") operation. Of course, the operation has no reliable use: by the time it returns the information might already be out of date. I suspect that it was designed to solve the problem: "My F_GETLK operation failed. Who's blocking me?" Cheers, Michael -- Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Linux/UNIX System Programming Training: http://man7.org/training/ -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
