From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nick Piggin Subject: Re: [PATCH 11/18] fs: Introduce per-bucket inode hash locks Date: Sun, 17 Oct 2010 04:12:13 +1100 Message-ID: <20101016171213.GC3240@amd> References: <1286515292-15882-1-git-send-email-david@fromorbit.com> <1286515292-15882-12-git-send-email-david@fromorbit.com> <20101008185409.GA29251@infradead.org> <20101016075703.GO19147@amd> <20101016161642.GC16861@infradead.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Nick Piggin , Dave Chinner , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org To: Christoph Hellwig Return-path: Content-Disposition: inline In-Reply-To: <20101016161642.GC16861@infradead.org> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org On Sat, Oct 16, 2010 at 12:16:42PM -0400, Christoph Hellwig wrote: > On Sat, Oct 16, 2010 at 06:57:03PM +1100, Nick Piggin wrote: > > > duplicating these helpers in the dcache code aswell. IMHO they > > > should simple operate directly on the hlist_bl_head, as that's > > > what it was designed for. I also don't really see any point in > > > wrapping the hlist_bl_head as inode_hash_bucket. If the bucket naming > > > is important we could rename the hlist_bl stuff to bl_hash, and the > > > hlist_bl_head could become bl_hash_bucket. > > > > It was done because someone, like -rt, might want more than one bit of > > memory to implement a lock. They would have to make a few other > > changes, granted, but this helps reduce a lot of churn. > > > > I didn't see the point of a layer of dumb wrappers for hlist_bl_head > > locking. Just reproducing bit spin and wait locks in wrappers when we > > already have good functions for them. > > With the changes Dave implemented based on my suggestions we now have > an abstract locked hash list data type. It has the normal hash list > operations plus lock/unlock operations. That's ugly. It just hides the locking. If a bit of casting bothers you then put it in a function where it is used like I did. > So if e.g. the -rt folks need > real locks in there there is one single place they need to touch > instead of every user. Similarly if we want to add lockdep support > there is just one place to touch. It's unnecessary.