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=-8.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,USER_AGENT_MUTT autolearn=unavailable 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 36782C10F11 for ; Wed, 24 Apr 2019 13:58:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0B5522077C for ; Wed, 24 Apr 2019 13:58:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730398AbfDXN6z (ORCPT ); Wed, 24 Apr 2019 09:58:55 -0400 Received: from fieldses.org ([173.255.197.46]:48982 "EHLO fieldses.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727435AbfDXN6z (ORCPT ); Wed, 24 Apr 2019 09:58:55 -0400 Received: by fieldses.org (Postfix, from userid 2815) id 989B81C9D; Wed, 24 Apr 2019 09:58:54 -0400 (EDT) Date: Wed, 24 Apr 2019 09:58:54 -0400 From: "J. Bruce Fields" To: NeilBrown Cc: Jeff Layton , slawek1211@gmail.com, linux-nfs@vger.kernel.org, linux-cifs@vger.kernel.org, Steve French Subject: Re: [PATCH v2 1/2] nfsd: wake waiters blocked on file_lock before deleting it Message-ID: <20190424135854.GB20542@fieldses.org> References: <20190422163424.19402-1-jlayton@kernel.org> <20190422163424.19402-2-jlayton@kernel.org> <87wojl61s5.fsf@notabene.neil.brown.name> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87wojl61s5.fsf@notabene.neil.brown.name> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-nfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org Steve, see Neil's comment, is there a cifs bug here? --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