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=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS 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 071D0C433FF for ; Wed, 31 Jul 2019 16:17:33 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id D4512206A3 for ; Wed, 31 Jul 2019 16:17:32 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D4512206A3 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:42457 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hsrIC-0001pI-4t for qemu-devel@archiver.kernel.org; Wed, 31 Jul 2019 12:17:32 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:41163) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hsrBQ-0006Lg-Pn for qemu-devel@nongnu.org; Wed, 31 Jul 2019 12:10:33 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hsrBP-0001uw-Lw for qemu-devel@nongnu.org; Wed, 31 Jul 2019 12:10:32 -0400 Received: from mx1.redhat.com ([209.132.183.28]:46398) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hsrBP-0001un-ES for qemu-devel@nongnu.org; Wed, 31 Jul 2019 12:10:31 -0400 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id C218B30044CC; Wed, 31 Jul 2019 16:10:30 +0000 (UTC) Received: from localhost (ovpn-117-27.ams2.redhat.com [10.36.117.27]) by smtp.corp.redhat.com (Postfix) with ESMTP id 556C219C5B; Wed, 31 Jul 2019 16:10:30 +0000 (UTC) From: Stefan Hajnoczi To: virtio-fs@redhat.com, qemu-devel@nongnu.org Date: Wed, 31 Jul 2019 17:10:04 +0100 Message-Id: <20190731161006.9447-4-stefanha@redhat.com> In-Reply-To: <20190731161006.9447-1-stefanha@redhat.com> References: <20190731161006.9447-1-stefanha@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.46]); Wed, 31 Jul 2019 16:10:30 +0000 (UTC) Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: [Qemu-devel] [PATCH 3/5] virtiofsd: rename inode->refcount to inode->nlookup X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Liu Bo , "Dr. David Alan Gilbert" , Stefan Hajnoczi Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" This reference counter plays a specific role in the FUSE protocol. It's not a generic object reference counter and the FUSE kernel code calls it "nlookup". Signed-off-by: Stefan Hajnoczi --- contrib/virtiofsd/passthrough_ll.c | 36 ++++++++++++++++++++---------- 1 file changed, 24 insertions(+), 12 deletions(-) diff --git a/contrib/virtiofsd/passthrough_ll.c b/contrib/virtiofsd/passt= hrough_ll.c index e1d729d26b..135123366a 100644 --- a/contrib/virtiofsd/passthrough_ll.c +++ b/contrib/virtiofsd/passthrough_ll.c @@ -97,7 +97,19 @@ struct lo_inode { int fd; bool is_symlink; struct lo_key key; - uint64_t refcount; /* protected by lo->mutex */ + + /* This counter keeps the inode alive during the FUSE session. + * Incremented when the FUSE inode number is sent in a reply + * (FUSE_LOOKUP, FUSE_READDIRPLUS, etc). Decremented when an inode is + * released by requests like FUSE_FORGET, FUSE_RMDIR, FUSE_RENAME, etc. + * + * Note that this value is untrusted because the client can manipulate + * it arbitrarily using FUSE_FORGET requests. + * + * Protected by lo->mutex. + */ + uint64_t nlookup; + uint64_t version_offset; uint64_t ireg_refid; fuse_ino_t fuse_ino; @@ -485,7 +497,7 @@ retry: if (last =3D=3D path) { p =3D &lo->root; pthread_mutex_lock(&lo->mutex); - p->refcount++; + p->nlookup++; pthread_mutex_unlock(&lo->mutex); } else { *last =3D '\0'; @@ -688,8 +700,8 @@ static struct lo_inode *lo_find(struct lo_data *lo, s= truct stat *st) pthread_mutex_lock(&lo->mutex); p =3D g_hash_table_lookup(lo->inodes, &key); if (p) { - assert(p->refcount > 0); - p->refcount++; + assert(p->nlookup > 0); + p->nlookup++; } pthread_mutex_unlock(&lo->mutex); =20 @@ -797,7 +809,7 @@ static int lo_do_lookup(fuse_req_t req, fuse_ino_t pa= rent, const char *name, goto out_err; =20 inode->is_symlink =3D S_ISLNK(e->attr.st_mode); - inode->refcount =3D 1; + inode->nlookup =3D 1; inode->fd =3D newfd; newfd =3D -1; inode->key.ino =3D e->attr.st_ino; @@ -1051,7 +1063,7 @@ static void lo_link(fuse_req_t req, fuse_ino_t ino,= fuse_ino_t parent, goto out_err; =20 pthread_mutex_lock(&lo->mutex); - inode->refcount++; + inode->nlookup++; pthread_mutex_unlock(&lo->mutex); e.ino =3D inode->fuse_ino; update_version(lo, inode); @@ -1200,9 +1212,9 @@ static void unref_inode(struct lo_data *lo, struct = lo_inode *inode, uint64_t n) return; =20 pthread_mutex_lock(&lo->mutex); - assert(inode->refcount >=3D n); - inode->refcount -=3D n; - if (!inode->refcount) { + assert(inode->nlookup >=3D n); + inode->nlookup -=3D n; + if (!inode->nlookup) { lo_map_remove(&lo->ino_map, inode->fuse_ino); g_hash_table_remove(lo->inodes, &inode->key); if (g_hash_table_size(inode->posix_locks)) { @@ -1225,7 +1237,7 @@ static int unref_all_inodes_cb(gpointer key, gpoint= er value, struct lo_inode *inode =3D value; struct lo_data *lo =3D user_data; =20 - inode->refcount =3D 0; + inode->nlookup =3D 0; lo_map_remove(&lo->ino_map, inode->fuse_ino); close(inode->fd); =20 @@ -1252,7 +1264,7 @@ static void lo_forget_one(fuse_req_t req, fuse_ino_= t ino, uint64_t nlookup) if (lo_debug(req)) { fuse_debug(" forget %lli %lli -%lli\n", (unsigned long long) ino, - (unsigned long long) inode->refcount, + (unsigned long long) inode->nlookup, (unsigned long long) nlookup); } =20 @@ -2581,7 +2593,7 @@ static void setup_root(struct lo_data *lo, struct l= o_inode *root) root->fd =3D fd; root->key.ino =3D stat.st_ino; root->key.dev =3D stat.st_dev; - root->refcount =3D 2; + root->nlookup =3D 2; } =20 static void setup_proc_self_fd(struct lo_data *lo) --=20 2.21.0