From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752796AbaBPBW4 (ORCPT ); Sat, 15 Feb 2014 20:22:56 -0500 Received: from out03.mta.xmission.com ([166.70.13.233]:34100 "EHLO out03.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752586AbaBPBWy (ORCPT ); Sat, 15 Feb 2014 20:22:54 -0500 From: ebiederm@xmission.com (Eric W. Biederman) To: Linus Torvalds Cc: Al Viro , "Serge E. Hallyn" , Linux-Fsdevel , Kernel Mailing List , Andy Lutomirski , Rob Landley , Miklos Szeredi , Christoph Hellwig , Karel Zak , "J. Bruce Fields" References: <87a9kkax0j.fsf@xmission.com> <8761v7h2pt.fsf@tw-ebiederman.twitter.com> <87li281wx6.fsf_-_@xmission.com> <87ob28kqks.fsf_-_@xmission.com> <87bny8kqik.fsf_-_@xmission.com> <87a9ds55av.fsf@xmission.com> Date: Sat, 15 Feb 2014 17:22:41 -0800 In-Reply-To: (Linus Torvalds's message of "Sat, 15 Feb 2014 16:03:53 -0800") Message-ID: <878utb3l7i.fsf@xmission.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-XM-AID: U2FsdGVkX1+sghsv6k1JftPEnjF2r/9nCM1yWPDPPRc= X-SA-Exim-Connect-IP: 98.207.154.105 X-SA-Exim-Mail-From: ebiederm@xmission.com X-Spam-Report: * -1.0 ALL_TRUSTED Passed through trusted hosts only via SMTP * 0.0 KHOP_BIG_TO_CC Sent to 10+ recipients instaed of Bcc or a list * 1.5 XMNoVowels Alpha-numberic number with no vowels * 0.0 T_TM2_M_HEADER_IN_MSG BODY: T_TM2_M_HEADER_IN_MSG * -3.0 BAYES_00 BODY: Bayes spam probability is 0 to 1% * [score: 0.0000] * -0.0 DCC_CHECK_NEGATIVE Not listed in DCC * [sa06 1397; Body=1 Fuz1=1 Fuz2=1] * 0.0 T_TooManySym_01 4+ unique symbols in subject * 1.0 T_XMDrugObfuBody_08 obfuscated drug references X-Spam-DCC: XMission; sa06 1397; Body=1 Fuz1=1 Fuz2=1 X-Spam-Combo: ;Linus Torvalds X-Spam-Relay-Country: Subject: Re: [PATCH 02/11] vfs: More precise tests in d_invalidate X-Spam-Flag: No X-SA-Exim-Version: 4.2.1 (built Wed, 14 Nov 2012 14:26:46 -0700) X-SA-Exim-Scanned: Yes (on in02.mta.xmission.com) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Linus Torvalds writes: > On Sat, Feb 15, 2014 at 3:23 PM, Eric W. Biederman > wrote: >> >> Except that today d_invalidate drops the dcache lock and >> calls shrink_dcache_parent. Which gets you into exactly the same >> complex "walk parents and check all siblings" code. > > Hmm. It only does that for directories that have sub-entries, though. > > I think you may care just about directories (because that's what your > series is about), but d_invalidate() is used for other cases too, > notably d_revalidate() (ie things like stale NFS lookups of normal > files). > > That said, I'll have to think about this more. If d_subdir is empty, I > guess d_walk() will be fairly cheap. It's very different, but maybe > not as disastrous as I thought. Thank you for taking the time to look. It is also very true that I have been mostly focusing on the semantics and correctness rather than on the performance of these changes. I did keep a weather eye on the performance impact of these changes though and as long as we can stand a slow down in the rare case where mount points are present my changes should be fine. Eric