From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Howells Subject: Re: [PATCH 21/41] CacheFiles: Permit the page lock state to be monitored [ver #48] Date: Sat, 04 Apr 2009 23:13:33 +0100 Message-ID: <951.1238883213@redhat.com> References: <200904050122.42081.nickpiggin@yahoo.com.au> <20090403155436.28714.23368.stgit@warthog.procyon.org.uk> <20090403155624.28714.87176.stgit@warthog.procyon.org.uk> <200904041709.31651.nickpiggin@yahoo.com.au> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: dhowells@redhat.com, linux-fsdevel@vger.kernel.org, Andrew Morton , nfsv4@linux-nfs.org, linux-kernel@vger.kernel.org To: Nick Piggin Return-path: In-Reply-To: <200904050122.42081.nickpiggin@yahoo.com.au> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: nfsv4-bounces@linux-nfs.org Errors-To: nfsv4-bounces@linux-nfs.org List-Id: linux-fsdevel.vger.kernel.org Nick Piggin wrote: > On Saturday 04 April 2009 17:09:31 Nick Piggin wrote: > > On Saturday 04 April 2009 02:56:24 David Howells wrote: > > > Add a function to install a monitor on the page lock waitqueue for a > > > particular page, thus allowing the page being unlocked to be detected. > > > > > > This is used by CacheFiles to detect read completion on a page in the > > > backing filesystem so that it can then copy the data to the waiting > > > netfs page. > > > > This is the only thing I'm still worried about in core code. The extra > > page flag (which is probably unusable for any other fs, due to its > > semantics) is an issue, but Andrew seemed like he was willing to spend > > *2* page flags on this, so I'm sure he's happy with 1. > > Well that is to say it is not a such a bad concept to have... What is not such a bad concept to have? Having an extra page flag? > actually we already have exactly this concept which is what should be used. > Ie. the filesystem's io completion handler. Which filesystem's I/O completion handler? David