cvs commit: src/sys/fs/smbfs smbfs.h smbfs_node.c smbfs_vfsops.c

[Robert Watson]

On Sun, 2 Mar 2008, Yar Tikhiy wrote:

> On Sun, Mar 2, 2008 at 9:56 PM, Robert Watson <rwatson at freebsd.org> wrote:
>> rwatson 2008-03-02 18:56:14 UTC
>>
>>   FreeBSD src repository
>>
>>   Modified files:
>>     sys/fs/smbfs smbfs.h smbfs_node.c smbfs_vfsops.c
>>   Log:
>>   Replace lockmgr lock protecting smbfs node hash table with sx lock.
>
> This commit message is a textbook example of how not to write commit 
> messages: It accurately re-tells what was obvious from the diff anyway but 
> provides no pointers to the background for the change. Sorry for my 
> bitching, but I just couldn't resist... :-)

This change, the the similar change in nwfs, are part of a longer running 
effort to move towards using our SMPng locks rather than the less 
well-optimized and generally less pretty pre-SMPng primitives.  I wouldn't 
expect any noticeable improvement in performance, and ideally no change in 
behavior, but it does reduce the number of unnecessary lockmgr consumers.  In 
this context, my definition of "necessary" is where a consumer relies on 
specific semantics of lockmgr to function, such as LK_DRAIN, LK_UPGRADE, etc, 
which don't have comparable behavior with the newer primitives.

Robert N M Watson
Computer Laboratory
University of Cambridge