From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from bombadil.infradead.org ([65.50.211.133]:50080 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756757AbdLTW4O (ORCPT ); Wed, 20 Dec 2017 17:56:14 -0500 Date: Wed, 20 Dec 2017 14:56:04 -0800 From: Matthew Wilcox To: NeilBrown Cc: Al Viro , Linus Torvalds , "J. Bruce Fields" , Trond Myklebust , Anna Schumaker , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Linux NFS Mailing List Subject: Re: [PATCH/RFC] VFS: don't keep disconnected dentries on d_anon Message-ID: <20171220225604.GA2980@bombadil.infradead.org> References: <87y3lxj9wr.fsf@notabene.neil.brown.name> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87y3lxj9wr.fsf@notabene.neil.brown.name> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Thu, Dec 21, 2017 at 09:45:40AM +1100, NeilBrown wrote: > -c/ Helper routines to allocate anonymous dentries, and to help attach > + prefix. If the refcount on a dentry with this flag set > + becomes zero, the dentry is immediately discarded, rather than being > + kept in the dcache. If a dentry that is not already in the dcache > + is repeatedly accessed by filehandle (as NFSD might do), an new dentry > + will be a allocated for each access, and discarded at the end of s/a // > + the access. As there is no parent, children, or name in the dentry > + is it unlikely that there will be any useful information to lose, > + and allocating a new dentry should normally be fast. How about: As the dentry is completely unattached, there is little information to lose, and allocating a new dentry is normally fast.