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 X-Spam-Level: X-Spam-Status: No, score=-17.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 76C4AC43460 for ; Wed, 12 May 2021 14:50:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3D371613AF for ; Wed, 12 May 2021 14:50:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231697AbhELOvq (ORCPT ); Wed, 12 May 2021 10:51:46 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:51337 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231440AbhELOvF (ORCPT ); Wed, 12 May 2021 10:51:05 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1620830996; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=/g/HcRWJK0OnvZH6C7dQC3u45Y7+3wQdH9PWZ/XlGkA=; b=VE3pEQu1YSTRvyy6eixs2nIgbiuMEuhbtahJnobTmZgAYPENe01+Za09wCOr52D8GY5icA dAE5fxQ8pnx4mDvLl6yrRu/P0Cy9/mLfarKyhxfHH6vMus3JlZ123FnPLtJyWOUBPShPED BXDMyP758V1g1Lg0yS37x6s134//XWU= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-43-QQ8YxaF4PgCqJW1Ti-ivgA-1; Wed, 12 May 2021 10:49:52 -0400 X-MC-Unique: QQ8YxaF4PgCqJW1Ti-ivgA-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 088C91074657; Wed, 12 May 2021 14:49:51 +0000 (UTC) Received: from localhost (ovpn-114-114.ams2.redhat.com [10.36.114.114]) by smtp.corp.redhat.com (Postfix) with ESMTP id B41C660657; Wed, 12 May 2021 14:49:45 +0000 (UTC) Date: Wed, 12 May 2021 15:49:44 +0100 From: "Richard W.M. Jones" To: Shachar Sharon Cc: miklos@szeredi.hu, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, eblake@redhat.com, libguestfs@redhat.com Subject: Re: [PATCH v2] fuse: Allow fallocate(FALLOC_FL_ZERO_RANGE) Message-ID: <20210512144944.GY26415@redhat.com> References: <20210512103704.3505086-1-rjones@redhat.com> <20210512103704.3505086-2-rjones@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Wed, May 12, 2021 at 05:27:22PM +0300, Shachar Sharon wrote: > On Wed, May 12, 2021 at 11:37:04AM +0100, Richard W.M. Jones wrote: > >libnbd's nbdfuse utility would like to translate fallocate zero > >requests into NBD_CMD_WRITE_ZEROES. Currently the fuse module filters > >these out, returning -EOPNOTSUPP. This commit treats these almost the > >same way as FALLOC_FL_PUNCH_HOLE except not calling > >truncate_pagecache_range. > > > Why don't you call 'truncate_pagecache_range' ? Very good point. I just assumed that it would only be useful when hole-punching, but now I actually read the description of the function I see we need it. Also looking at other filesystems that also support FALLOC_FL_ZERO_RANGE: ext4_zero_range -> calls truncate_pagecache_range f2fs_zero_range -> calls it xfs -> calls it indirectly btrfs_zero_range -> does not call it (?) I'll add this, and retest everything. > >A way to test this is with the following script: In my next version I'll also address this script which is rather long-winded. I think there's an easier way for people to test this: > >-------------------- > > #!/bin/bash > > # Requires fuse >= 3, nbdkit >= 1.8, and latest nbdfuse from > > # https://gitlab.com/nbdkit/libnbd/-/tree/master/fuse > > set -e > > set -x > > > > export output=$PWD/output > > rm -f test.img $output > > > > # Create an nbdkit instance that prints the NBD requests seen. > > nbdkit sh - <<'EOF' > > case "$1" in > > get_size) echo 1M ;; > > can_write|can_trim|can_zero|can_fast_zero) ;; > > pread) echo "$@" >>$output; dd if=/dev/zero count=$3 iflag=count_bytes ;; > > pwrite) echo "$@" >>$output; cat >/dev/null ;; > > trim|zero) echo "$@" >>$output ;; > > *) exit 2 ;; > > esac [etc] > >diff --git a/fs/fuse/file.c b/fs/fuse/file.c > >index 09ef2a4d25ed..22e8e88c78d4 100644 > >--- a/fs/fuse/file.c > >+++ b/fs/fuse/file.c > >@@ -2907,11 +2907,13 @@ static long fuse_file_fallocate(struct file *file, int mode, loff_t offset, > > }; > > int err; > > bool lock_inode = !(mode & FALLOC_FL_KEEP_SIZE) || > >- (mode & FALLOC_FL_PUNCH_HOLE); > >+ (mode & FALLOC_FL_PUNCH_HOLE) || > >+ (mode & FALLOC_FL_ZERO_RANGE); > To stay aligned with existing code style, consider: > - (mode & FALLOC_FL_PUNCH_HOLE); > +» » » (mode & (FALLOC_FL_PUNCH_HOLE | > +» » » » FALLOC_FL_ZERO_RANGE)); Good idea. Thanks for the quick review. Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com libguestfs lets you edit virtual machines. Supports shell scripting, bindings from many languages. http://libguestfs.org