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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,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 AD413FA3728 for ; Wed, 16 Oct 2019 17:27:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2FEE421835 for ; Wed, 16 Oct 2019 17:27:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731290AbfJPR1j (ORCPT ); Wed, 16 Oct 2019 13:27:39 -0400 Received: from mx1.redhat.com ([209.132.183.28]:40239 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729259AbfJPR1j (ORCPT ); Wed, 16 Oct 2019 13:27:39 -0400 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 mx1.redhat.com (Postfix) with ESMTPS id B94F781F0D; Wed, 16 Oct 2019 17:11:25 +0000 (UTC) Received: from [IPv6:::1] (ovpn04.gateway.prod.ext.phx2.redhat.com [10.5.9.4]) by smtp.corp.redhat.com (Postfix) with ESMTPS id A7E2E60464; Wed, 16 Oct 2019 17:11:24 +0000 (UTC) Subject: [PATCH 2/1] fs: call fsnotify_sb_delete after evict_inodes From: Eric Sandeen To: fsdevel References: Autocrypt: addr=sandeen@redhat.com; prefer-encrypt=mutual; keydata= mQINBE6x99QBEADMR+yNFBc1Y5avoUhzI/sdR9ANwznsNpiCtZlaO4pIWvqQJCjBzp96cpCs nQZV32nqJBYnDpBDITBqTa/EF+IrHx8gKq8TaSBLHUq2ju2gJJLfBoL7V3807PQcI18YzkF+ WL05ODFQ2cemDhx5uLghHEeOxuGj+1AI+kh/FCzMedHc6k87Yu2ZuaWF+Gh1W2ix6hikRJmQ vj5BEeAx7xKkyBhzdbNIbbjV/iGi9b26B/dNcyd5w2My2gxMtxaiP7q5b6GM2rsQklHP8FtW ZiYO7jsg/qIppR1C6Zr5jK1GQlMUIclYFeBbKggJ9mSwXJH7MIftilGQ8KDvNuV5AbkronGC sEEHj2khs7GfVv4pmUUHf1MRIvV0x3WJkpmhuZaYg8AdJlyGKgp+TQ7B+wCjNTdVqMI1vDk2 BS6Rg851ay7AypbCPx2w4d8jIkQEgNjACHVDU89PNKAjScK1aTnW+HNUqg9BliCvuX5g4z2j gJBs57loTWAGe2Ve3cMy3VoQ40Wt3yKK0Eno8jfgzgb48wyycINZgnseMRhxc2c8hd51tftK LKhPj4c7uqjnBjrgOVaVBupGUmvLiePlnW56zJZ51BR5igWnILeOJ1ZIcf7KsaHyE6B1mG+X dmYtjDhjf3NAcoBWJuj8euxMB6TcQN2MrSXy5wSKaw40evooGwARAQABtCRFcmljIFIuIFNh bmRlZW4gPHNhbmRlZW5AcmVkaGF0LmNvbT6JAjgEEwECACIFAk6yrl4CGwMGCwkIBwMCBhUI AgkKCwQWAgMBAh4BAheAAAoJECCuFpLhPd7gh2kP/A6CRmIF2MSttebyBk+6Ppx47ct+Kcmp YokwfI9iahSPiQ+LmmBZE+PMYesE+8+lsSiAvzz6YEXsfWMlGzHiqiE76d2xSOYVPO2rX7xl 4T2J98yZlYrjMDmQ6gpFe0ZBpVl45CFUYkBaeulEMspzaYLH6zGsPjgfVJyYnW94ZXLWcrST ixBPJcDtk4j6jrbY3K8eVFimK+RSq6CqZgUZ+uaDA/wJ4kHrYuvM3QPbsHQr/bYSNkVAFxgl G6a4CSJ4w70/dT9FFb7jzj30nmaBmDFcuC+xzecpcflaLvuFayuBJslMp4ebaL8fglvntWsQ ZM8361Ckjt82upo2JRYiTrlE9XiSEGsxW3EpdFT3vUmIlgY0/Xo5PGv3ySwcFucRUk1Q9j+Z X4gCaX5sHpQM03UTaDx4jFdGqOLnTT1hfrMQZ3EizVbnQW9HN0snm9lD5P6O1dxyKbZpevfW BfwdQ35RXBbIKDmmZnwJGJgYl5Bzh5DlT0J7oMVOzdEVYipWx82wBqHVW4I1tPunygrYO+jN n+BLwRCOYRJm5BANwYx0MvWlm3Mt3OkkW2pbX+C3P5oAcxrflaw3HeEBi/KYkygxovWl93IL TsW03R0aNcI6bSdYR/68pL4ELdx7G/SLbaHf28FzzUFjRvN55nBoMePOFo1O6KtkXXQ4GbXV ebdvuQINBE6x99QBEADQOtSJ9OtdDOrE7xqJA4Lmn1PPbk2n9N+m/Wuh87AvxU8Ey8lfg/mX VXbJ3vQxlFRWCOYLJ0TLEsnobZjIc7YhlMRqNRjRSn5vcSs6kulnCG+BZq2OJ+mPpsFIq4Nd 5OGoV2SmEXmQCaB9UAiRqflLFYrf5LRXYX+jGy0hWIGEyEPAjpexGWdUGgsthwSKXEDYWVFR Lsw5kaZEmRG10YPmShVlIzrFVlBKZ8QFphD9YkEYlB0/L3ieeUBWfeUff43ule81S4IZX63h hS3e0txG4ilgEI5aVztumB4KmzldrR0hmAnwui67o4Enm9VeM/FOWQV1PRLT+56sIbnW7ynq wZEudR4BQaRB8hSoZSNbasdpeBY2/M5XqLe1/1hqJcqXdq8Vo1bWQoGzRPkzVyeVZlRS2XqT TiXPk6Og1j0n9sbJXcNKWRuVdEwrzuIthBKtxXpwXP09GXi9bUsZ9/fFFAeeB43l8/HN7xfk 0TeFv5JLDIxISonGFVNclV9BZZbR1DE/sc3CqY5ZgX/qb7WAr9jaBjeMBCexZOu7hFVNkacr AQ+Y4KlJS+xNFexUeCxYnvSp3TI5KNa6K/hvy+YPf5AWDK8IHE8x0/fGzE3l62F4sw6BHBak ufrI0Wr/G2Cz4QKAb6BHvzJdDIDuIKzm0WzY6sypXmO5IwaafSTElQARAQABiQIfBBgBAgAJ BQJOsffUAhsMAAoJECCuFpLhPd7gErAP/Rk46ZQ05kJI4sAyNnHea1i2NiB9Q0qLSSJg+94a hFZOpuKzxSK0+02sbhfGDMs6KNJ04TNDCR04in9CdmEY2ywx6MKeyW4rQZB35GQVVY2ZxBPv yEF4ZycQwBdkqrtuQgrO9zToYWaQxtf+ACXoOI0a/RQ0Bf7kViH65wIllLICnewD738sqPGd N51fRrKBcDquSlfRjQW83/11+bjv4sartYCoE7JhNTcTr/5nvZtmgb9wbsA0vFw+iiUs6tTj eioWcPxDBw3nrLhV8WPf+MMXYxffG7i/Y6OCVWMwRgdMLE/eanF6wYe6o6K38VH6YXQw/0kZ +PrH5uP/0kwG0JbVtj9o94x08ZMm9eMa05VhuUZmtKNdGfn75S7LfoK+RyuO7OJIMb4kR7Eb FzNbA3ias5BaExPknJv7XwI74JbEl8dpheIsRbt0jUDKcviOOfhbQxKJelYNTD5+wE4+TpqH XQLj5HUlzt3JSwqSwx+++FFfWFMheG2HzkfXrvTpud5NrJkGGVn+ErXy6pNf6zSicb+bUXe9 i92UTina2zWaaLEwXspqM338TlFC2JICu8pNt+wHpPCjgy2Ei4u5/4zSYjiA+X1I+V99YJhU +FpT2jzfLUoVsP/6WHWmM/tsS79i50G/PsXYzKOHj/0ZQCKOsJM14NMMCC8gkONe4tek Cc: Jan Kara , Al Viro , Eric Paris Message-ID: Date: Wed, 16 Oct 2019 12:11:24 -0500 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:68.0) Gecko/20100101 Thunderbird/68.1.2 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.27]); Wed, 16 Oct 2019 17:11:25 +0000 (UTC) Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org When a filesystem is unmounted, we currently call fsnotify_sb_delete() before evict_inodes(), which means that fsnotify_unmount_inodes() must iterate over all inodes on the superblock, even though it will only act on inodes with a refcount. This is inefficient and can lead to livelocks as it iterates over many unrefcounted inodes. However, since fsnotify_sb_delete() and evict_inodes() are working on orthogonal sets of inodes (fsnotify_sb_delete() only cares about nonzero refcount, and evict_inodes() only cares about zero refcount), we can swap the order of the calls. The fsnotify call will then have a much smaller list to walk (any refcounted inodes). This should speed things up overall, and avoid livelocks in fsnotify_unmount_inodes(). Signed-off-by: Eric Sandeen --- I just did basic sanity testing here, but AFAIK there is no *notify test suite, so I'm not sure how to really give this a workout. diff --git a/fs/notify/fsnotify.c b/fs/notify/fsnotify.c index ac9eb273e28c..426f03b6e660 100644 --- a/fs/notify/fsnotify.c +++ b/fs/notify/fsnotify.c @@ -57,6 +57,10 @@ static void fsnotify_unmount_inodes(struct super_block *sb) * doing an __iget/iput with SB_ACTIVE clear would actually * evict all inodes with zero i_count from icache which is * unnecessarily violent and may in fact be illegal to do. + * + * However, we should have been called /after/ evict_inodes + * removed all zero refcount inodes, in any case. Test to + * be sure. */ if (!atomic_read(&inode->i_count)) { spin_unlock(&inode->i_lock); diff --git a/fs/super.c b/fs/super.c index cfadab2cbf35..cd352530eca9 100644 --- a/fs/super.c +++ b/fs/super.c @@ -448,10 +448,12 @@ void generic_shutdown_super(struct super_block *sb) sync_filesystem(sb); sb->s_flags &= ~SB_ACTIVE; - fsnotify_sb_delete(sb); cgroup_writeback_umount(); + /* evict all inodes with zero refcount */ evict_inodes(sb); + /* only nonzero refcount inodes can have marks */ + fsnotify_sb_delete(sb); if (sb->s_dio_done_wq) { destroy_workqueue(sb->s_dio_done_wq);