Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 09AF3C282CE for ; Wed, 24 Apr 2019 15:30:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DCB8321904 for ; Wed, 24 Apr 2019 15:30:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731217AbfDXPaC (ORCPT ); Wed, 24 Apr 2019 11:30:02 -0400 Received: from mx1.redhat.com ([209.132.183.28]:39052 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730534AbfDXPaB (ORCPT ); Wed, 24 Apr 2019 11:30:01 -0400 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 25447C7CAE; Wed, 24 Apr 2019 15:30:01 +0000 (UTC) Received: from madhat.boston.devel.redhat.com (madhat.boston.devel.redhat.com [10.19.60.33]) by smtp.corp.redhat.com (Postfix) with ESMTP id 138601A92D; Wed, 24 Apr 2019 15:29:59 +0000 (UTC) Subject: Re: [PATCH v2 1/2] nfsd: wake waiters blocked on file_lock before deleting it To: "J. Bruce Fields" , NeilBrown Cc: Jeff Layton , slawek1211@gmail.com, linux-nfs@vger.kernel.org, linux-cifs@vger.kernel.org, Steve French References: <20190422163424.19402-1-jlayton@kernel.org> <20190422163424.19402-2-jlayton@kernel.org> <87wojl61s5.fsf@notabene.neil.brown.name> <20190424135854.GB20542@fieldses.org> From: Steve Dickson Message-ID: <2b131f18-1df4-790c-a548-3155a0677c34@RedHat.com> Date: Wed, 24 Apr 2019 11:29:59 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: <20190424135854.GB20542@fieldses.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.39]); Wed, 24 Apr 2019 15:30:01 +0000 (UTC) Sender: linux-nfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org On 4/24/19 9:58 AM, J. Bruce Fields wrote: > Steve, see Neil's comment, is there a cifs bug here? Looking into it... steved. > > --b. > > On Tue, Apr 23, 2019 at 09:47:06AM +1000, NeilBrown wrote: >> On Mon, Apr 22 2019, Jeff Layton wrote: >> >>> After a blocked nfsd file_lock request is deleted, knfsd will send a >>> callback to the client and then free the request. Commit 16306a61d3b7 >>> ("fs/locks: always delete_block after waiting.") changed it such that >>> locks_delete_block is always called on a request after it is awoken, >>> but that patch missed fixing up blocked nfsd request handling. >>> >>> Call locks_delete_block on the block to wake up any locks still blocked >>> on the nfsd lock request before freeing it. Some of its callers already >>> do this however, so just remove those calls. >>> >>> URL: https://bugzilla.kernel.org/show_bug.cgi?id=203363 >>> Fixes: 16306a61d3b7 ("fs/locks: always delete_block after waiting.") >>> Reported-by: Slawomir Pryczek >>> Cc: Neil Brown >>> Cc: stable@vger.kernel.org >>> Signed-off-by: Jeff Layton >>> --- >>> fs/nfsd/nfs4state.c | 3 +-- >>> 1 file changed, 1 insertion(+), 2 deletions(-) >>> >>> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c >>> index 6a45fb00c5fc..e87e15df2044 100644 >>> --- a/fs/nfsd/nfs4state.c >>> +++ b/fs/nfsd/nfs4state.c >>> @@ -265,6 +265,7 @@ find_or_allocate_block(struct nfs4_lockowner *lo, struct knfsd_fh *fh, >>> static void >>> free_blocked_lock(struct nfsd4_blocked_lock *nbl) >>> { >>> + locks_delete_block(&nbl->nbl_lock); >>> locks_release_private(&nbl->nbl_lock); >> >> Thanks for tracking this down. >> >> An implication of this bug and fix is that we need to be particularly >> careful to make sure locks_delete_block() is called on all relevant >> paths. >> Can we make that easier? My first thought was to include the call in >> locks_release_private, but lockd calls the two quite separately and it >> certainly seems appropriate that locks_delete_block should be called >> asap, but locks_release_private() can be delayed. >> >> Also cifs calls locks_delete_block, but never calls >> locks_release_private, so it wouldn't help there. >> >> Looking at cifs, I think there is a call missing there too. >> cifs_posix_lock_set() *doesn't* always call locks_delete_block() after >> waiting. In particular, if ->can_cache_brlcks becomes true while >> waiting then I don't think the behaviour is right.... though I'm not >> sure it is right for other reasons. It looks like the return value >> should be 1 in that case, but it'll be zero. >> >> But back to my question about making it easier, move the BUG_ON() >> calls from locks_free_lock() into locks_release_private(). >> >> ?? >> >> Thanks, >> NeilBrown >> >> >>> kfree(nbl); >>> } >>> @@ -293,7 +294,6 @@ remove_blocked_locks(struct nfs4_lockowner *lo) >>> nbl = list_first_entry(&reaplist, struct nfsd4_blocked_lock, >>> nbl_lru); >>> list_del_init(&nbl->nbl_lru); >>> - locks_delete_block(&nbl->nbl_lock); >>> free_blocked_lock(nbl); >>> } >>> } >>> @@ -4863,7 +4863,6 @@ nfs4_laundromat(struct nfsd_net *nn) >>> nbl = list_first_entry(&reaplist, >>> struct nfsd4_blocked_lock, nbl_lru); >>> list_del_init(&nbl->nbl_lru); >>> - locks_delete_block(&nbl->nbl_lock); >>> free_blocked_lock(nbl); >>> } >>> out: >>> -- >>> 2.20.1 > >