From mboxrd@z Thu Jan 1 00:00:00 1970 From: Al Viro Subject: Re: [RFC][PATCHSET v3] non-recursive pathname resolution & RCU symlinks Date: Sat, 16 May 2015 02:55:40 +0100 Message-ID: <20150516015540.GP7232@ZenIV.linux.org.uk> References: <20150513222533.GA24192@ZenIV.linux.org.uk> <20150514033040.GF7232@ZenIV.linux.org.uk> <20150514112304.GT15721@dastard> <20150516093022.51e1464e@notabene.brown> <20150516112503.2f970573@notabene.brown> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: NeilBrown , Andreas Dilger , Dave Chinner , Linux Kernel Mailing List , linux-fsdevel , Christoph Hellwig To: Linus Torvalds Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org On Fri, May 15, 2015 at 06:47:04PM -0700, Linus Torvalds wrote: > Now, maybe we could solve it with a new sleeping lock in the dentry > itself. Maybe we could allocate the new dentry early, add it to the > directory the usual way, but mark it as being "not ready" (so that > d_lookup() wouldn't use it). And have the sleeping lock be a new > sleeping lock in the dentry. See upthread. It might be doable (provided that we turn ->i_mutex into rwsem, to keep the exclusion with directory _modifiers_), but it'll need a really non-trivial code review of a bunch of filesystems, especially ones that want to play with the list of children like ceph does. And things like sillyrename and dcache-populating readdir instances, albeit not as scary as ceph. And then there's lustre...