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Fri, 15 Nov 2019 13:47:47 +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 9448A60138; Fri, 15 Nov 2019 13:47:45 +0000 (UTC) Subject: [PATCH 2/2 V2] fs: call fsnotify_sb_delete after evict_inodes From: Eric Sandeen To: linux-fsdevel@vger.kernel.org Cc: viro@zeniv.linux.org.uk References: <1573159954-27846-1-git-send-email-sandeen@redhat.com> <1573159954-27846-3-git-send-email-sandeen@redhat.com> 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 Message-ID: Date: Fri, 15 Nov 2019 07:47:44 -0600 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:68.0) Gecko/20100101 Thunderbird/68.2.2 MIME-Version: 1.0 In-Reply-To: <1573159954-27846-3-git-send-email-sandeen@redhat.com> Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-MC-Unique: qk_3XNMLOVGm9V4V669n0Q-1 X-Mimecast-Spam-Score: 0 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 looking for any inodes with watches. This is inefficient and can lead to livelocks as it iterates over many unwatched inodes. At this point, SB_ACTIVE is gone and dropping refcount to zero kicks the inode out out immediately, so anything processed by fsnotify_sb_delete / fsnotify_unmount_inodes gets evicted in that loop. After that, the call to evict_inodes will evict everything else with a zero refcount. This should speed things up overall, and avoid livelocks in fsnotify_unmount_inodes(). Signed-off-by: Eric Sandeen Reviewed-by: Jan Kara --- V2: Update changelog fs/notify/fsnotify.c | 3 +++ fs/super.c | 4 +++- 2 files changed, 6 insertions(+), 1 deletion(-) diff --git a/fs/notify/fsnotify.c b/fs/notify/fsnotify.c index ac9eb27..f44e39c 100644 --- a/fs/notify/fsnotify.c +++ b/fs/notify/fsnotify.c @@ -57,6 +57,9 @@ 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 cfadab2..cd35253 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);