From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from cuda.sgi.com (cuda2.sgi.com [192.48.176.25]) by oss.sgi.com (8.14.3/8.14.3/SuSE Linux 0.8) with ESMTP id o4T9ltmQ021026 for ; Sat, 29 May 2010 04:47:56 -0500 Date: Sat, 29 May 2010 05:50:19 -0400 From: Christoph Hellwig Subject: Re: [PATCH] xfs: improve xfs_isilocked Message-ID: <20100529095019.GA18859@infradead.org> References: <20100527190533.GB16102@infradead.org> <1275075653.2302.38.camel@doink> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <1275075653.2302.38.camel@doink> List-Id: XFS Filesystem from SGI List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: xfs-bounces@oss.sgi.com Errors-To: xfs-bounces@oss.sgi.com To: Alex Elder Cc: Christoph Hellwig , xfs@oss.sgi.com On Fri, May 28, 2010 at 02:40:53PM -0500, Alex Elder wrote: > On Thu, 2010-05-27 at 15:05 -0400, Christoph Hellwig wrote: > > Use rwsem_is_locked to make the assertations for shared locks work. > > So you're changing it so it answers "yes it's locked" > even it it's only a read lock now, right? If XFS_ILOCK_SHARED/XFS_IOLOCK_SHARED are in the flags we'll answer yes it's locked for a read lock now, indeed. > Previously it was basically (once each for ilock and > iolock): "If the exclusive flag is set, but there is no > writer, then it is not locked; otherwise it is." Yes. > Now it's "If the exclusive flag is set, but no writer, > it's not locked. Otherwise if the shared flag is > set it's locked if rwsem_is_locked() says we are. > Otherwise (ASSERT(0) and) it is not locked." Not exactly. Now it's: - if excl is set but shared isn't return true if mr_writer is set, else false - if shared is set either alone or together with excl return if it is locked in any way (rwsem_is_locked). Note that xfs_isilocked can be called like: ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL|XFS_ILOCK_SHARED)); which means that either excl or shared is fine. - if either one or both of excl and shared are set and it's > That last part is wrong I think. It should be OK to > call xfs_isilocked() with neither flag set, in which > case the result should be 0. We can argue about removing the assert, but we currently don't and should't call xfs_isilocked wit ha 0 argument - it's rather pointless to do so. > And if the exclusive > flag is set, and there *is* a writer, it *is* locked, > so it should return 1. We do that right now. _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs