From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1B4C5C433FE for ; Fri, 30 Sep 2022 19:47:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231837AbiI3TrN (ORCPT ); Fri, 30 Sep 2022 15:47:13 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42126 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229522AbiI3TrL (ORCPT ); Fri, 30 Sep 2022 15:47:11 -0400 Received: from mail.hallyn.com (mail.hallyn.com [178.63.66.53]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D1EE6F534E for ; Fri, 30 Sep 2022 12:47:08 -0700 (PDT) Received: by mail.hallyn.com (Postfix, from userid 1001) id 3A17F1ED7; Fri, 30 Sep 2022 14:47:07 -0500 (CDT) Date: Fri, 30 Sep 2022 14:47:07 -0500 From: "Serge E. Hallyn" To: Miklos Szeredi Cc: Tycho Andersen , Eric Biederman , linux-kernel@vger.kernel.org, fuse-devel@lists.sourceforge.net, "Serge E. Hallyn" Subject: Re: [PATCH] fuse: In fuse_flush only wait if someone wants the return code Message-ID: <20220930194707.GA12456@mail.hallyn.com> References: <20220901140647.1125079-1-tycho@tycho.pizza> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.9.4 (2018-02-28) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Sep 27, 2022 at 11:46:44AM +0200, Miklos Szeredi wrote: > On Thu, 1 Sept 2022 at 16:07, Tycho Andersen wrote: > > > > From: "Eric W. Biederman" > > > > In my very light testing this resolves a hang where a thread of the > > fuse server was accessing the fuse filesystem (the fuse server is > > serving up), when the fuse server is killed. > > > > The practical problem is that the fuse server file descriptor was > > being closed after the file descriptor into the fuse filesystem so > > that the fuse filesystem operations were being blocked for instead of > > being aborted. Simply skipping the unnecessary wait resolves this > > issue. > > > > This is just a proof of concept and someone should look to see if the > > fuse max_background limit could cause a problem with this approach. > > Maybe you missed my comments here: > > https://lore.kernel.org/all/CAJfpegsTmiO-sKaBLgoVT4WxDXBkRES=HF1YmQN1ES7gfJEJ+w@mail.gmail.com/ That's odd - fwiw I too had completely missed that reply, sorry. > I'm generally okay with this, but please write a proper changelog for > the patch, also mentioning the issues related to posix locks. > > > --- a/fs/fuse/file.c > > +++ b/fs/fuse/file.c > > @@ -464,6 +464,67 @@ static void fuse_sync_writes(struct inode *inode) > > fuse_release_nowrite(inode); > > } > > > > +struct fuse_flush_args { > > + struct fuse_args args; > > + struct fuse_flush_in inarg; > > + struct inode *inode; > > + struct fuse_file *ff; > > +}; > > + > > +static void fuse_flush_end(struct fuse_mount *fm, struct fuse_args *args, int err) > > +{ > > + struct fuse_flush_args *fa = container_of(args, typeof(*fa), args); > > + > > + if (err == -ENOSYS) { > > + fm->fc->no_flush = 1; > > + err = 0; > > + } > > + > > + /* > > + * In memory i_blocks is not maintained by fuse, if writeback cache is > > + * enabled, i_blocks from cached attr may not be accurate. > > + */ > > + if (!err && fm->fc->writeback_cache) > > + fuse_invalidate_attr_mask(fa->inode, STATX_BLOCKS); > > + > > + > > + iput(fa->inode); > > + fuse_file_put(fa->ff, false, false); > > + kfree(fa); > > +} > > + > > +static int fuse_flush_async(struct file *file, fl_owner_t id) > > +{ > > + struct inode *inode = file_inode(file); > > + struct fuse_mount *fm = get_fuse_mount(inode); > > + struct fuse_file *ff = file->private_data; > > + struct fuse_flush_args *fa; > > + int err; > > + > > + fa = kzalloc(sizeof(*fa), GFP_KERNEL); > > + if (!fa) > > + return -ENOMEM; > > + > > + fa->inarg.fh = ff->fh; > > + fa->inarg.lock_owner = fuse_lock_owner_id(fm->fc, id); > > + fa->args.opcode = FUSE_FLUSH; > > + fa->args.nodeid = get_node_id(inode); > > + fa->args.in_numargs = 1; > > + fa->args.in_args[0].size = sizeof(fa->inarg); > > + fa->args.in_args[0].value = &fa->inarg; > > + fa->args.force = true; > > + fa->args.nocreds = true; > > + fa->args.end = fuse_flush_end; > > + fa->inode = igrab(inode); > > Grabbing the inode should already taken care of by fuse_file_release(). > > Also please try to reduce duplication in both the above functions. > > Thanks, > Miklos