From patchwork Thu Jan 23 11:58:22 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: "Dr. David Alan Gilbert" X-Patchwork-Id: 1228084 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=nongnu.org (client-ip=209.51.188.17; helo=lists.gnu.org; envelope-from=qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org; receiver=) Authentication-Results: ozlabs.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: ozlabs.org; dkim=pass (1024-bit key; unprotected) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=dfBRTvcB; dkim-atps=neutral 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 ozlabs.org (Postfix) with ESMTPS id 483Q3S2yqxz9sR1 for ; Fri, 24 Jan 2020 01:42:27 +1100 (AEDT) Received: from localhost ([::1]:58288 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iudge-0007N6-R2 for incoming@patchwork.ozlabs.org; Thu, 23 Jan 2020 09:42:24 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:41582) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iubAY-0004A1-J0 for qemu-devel@nongnu.org; Thu, 23 Jan 2020 07:01:07 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1iubAX-0006TI-4t for qemu-devel@nongnu.org; Thu, 23 Jan 2020 07:01:06 -0500 Received: from us-smtp-delivery-1.mimecast.com ([207.211.31.120]:57295 helo=us-smtp-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1iubAX-0006Sv-0r for qemu-devel@nongnu.org; Thu, 23 Jan 2020 07:01:05 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1579780864; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=xFiJzCmw9nQ6WRZGQBVDeKp8kTLzMnMMVpVQq0q8ohM=; b=dfBRTvcBPJ3SWBRMhWSE5HOyQyU4hQEzyEWaaPczk7zpGDEw47mSQA6SH3el/jwY8NwNCH 5qHduEb/bNjenW6EMDzjYTfUOTbxxWVkD4qCmZp4qm+1zPHPxGGmz9ufuUPckJQY3yVvDA rxDQd/4pph9z5s8XcIWbLWd24Gq2mTA= 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-133-tLkrQp-LPweE3eMeWBv--w-1; Thu, 23 Jan 2020 07:01:02 -0500 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 6005118A6EC6 for ; Thu, 23 Jan 2020 12:01:00 +0000 (UTC) Received: from dgilbert-t580.localhost (unknown [10.36.118.0]) by smtp.corp.redhat.com (Postfix) with ESMTP id AC7F385750; Thu, 23 Jan 2020 12:00:59 +0000 (UTC) From: "Dr. David Alan Gilbert (git)" To: qemu-devel@nongnu.org, stefanha@redhat.com Subject: [PULL 092/111] virtiofsd: rename inode->refcount to inode->nlookup Date: Thu, 23 Jan 2020 11:58:22 +0000 Message-Id: <20200123115841.138849-93-dgilbert@redhat.com> In-Reply-To: <20200123115841.138849-1-dgilbert@redhat.com> References: <20200123115841.138849-1-dgilbert@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-MC-Unique: tLkrQp-LPweE3eMeWBv--w-1 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 207.211.31.120 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: , Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: "Qemu-devel" From: Stefan Hajnoczi 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 Reviewed-by: Philippe Mathieu-Daudé Signed-off-by: Dr. David Alan Gilbert --- tools/virtiofsd/passthrough_ll.c | 37 +++++++++++++++++++++----------- 1 file changed, 25 insertions(+), 12 deletions(-) diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c index 2d703b57e5..c819b5f782 100644 --- a/tools/virtiofsd/passthrough_ll.c +++ b/tools/virtiofsd/passthrough_ll.c @@ -99,7 +99,20 @@ 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; + fuse_ino_t fuse_ino; pthread_mutex_t plock_mutex; GHashTable *posix_locks; /* protected by lo_inode->plock_mutex */ @@ -568,7 +581,7 @@ retry: if (last == path) { p = &lo->root; pthread_mutex_lock(&lo->mutex); - p->refcount++; + p->nlookup++; pthread_mutex_unlock(&lo->mutex); } else { *last = '\0'; @@ -786,8 +799,8 @@ static struct lo_inode *lo_find(struct lo_data *lo, struct stat *st) pthread_mutex_lock(&lo->mutex); p = 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); @@ -855,7 +868,7 @@ static int lo_do_lookup(fuse_req_t req, fuse_ino_t parent, const char *name, } inode->is_symlink = S_ISLNK(e->attr.st_mode); - inode->refcount = 1; + inode->nlookup = 1; inode->fd = newfd; newfd = -1; inode->key.ino = e->attr.st_ino; @@ -1112,7 +1125,7 @@ static void lo_link(fuse_req_t req, fuse_ino_t ino, fuse_ino_t parent, } pthread_mutex_lock(&lo->mutex); - inode->refcount++; + inode->nlookup++; pthread_mutex_unlock(&lo->mutex); e.ino = inode->fuse_ino; @@ -1193,9 +1206,9 @@ static void unref_inode_lolocked(struct lo_data *lo, struct lo_inode *inode, } pthread_mutex_lock(&lo->mutex); - assert(inode->refcount >= n); - inode->refcount -= n; - if (!inode->refcount) { + assert(inode->nlookup >= n); + inode->nlookup -= 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)) { @@ -1216,7 +1229,7 @@ static int unref_all_inodes_cb(gpointer key, gpointer value, gpointer user_data) struct lo_inode *inode = value; struct lo_data *lo = user_data; - inode->refcount = 0; + inode->nlookup = 0; lo_map_remove(&lo->ino_map, inode->fuse_ino); close(inode->fd); @@ -1241,7 +1254,7 @@ static void lo_forget_one(fuse_req_t req, fuse_ino_t ino, uint64_t nlookup) } fuse_log(FUSE_LOG_DEBUG, " forget %lli %lli -%lli\n", - (unsigned long long)ino, (unsigned long long)inode->refcount, + (unsigned long long)ino, (unsigned long long)inode->nlookup, (unsigned long long)nlookup); unref_inode_lolocked(lo, inode, nlookup); @@ -2609,7 +2622,7 @@ static void setup_root(struct lo_data *lo, struct lo_inode *root) root->fd = fd; root->key.ino = stat.st_ino; root->key.dev = stat.st_dev; - root->refcount = 2; + root->nlookup = 2; } static guint lo_key_hash(gconstpointer key)