{"id":2197754,"url":"http://patchwork.ozlabs.org/api/1.0/patches/2197754/?format=json","project":{"id":14,"url":"http://patchwork.ozlabs.org/api/1.0/projects/14/?format=json","name":"QEMU Development","link_name":"qemu-devel","list_id":"qemu-devel.nongnu.org","list_email":"qemu-devel@nongnu.org","web_url":"","scm_url":"","webscm_url":""},"msgid":"<20260218132633.29748-22-hreitz@redhat.com>","date":"2026-02-18T13:26:30","name":"[v4,21/24] fuse: Make shared export state atomic","commit_ref":null,"pull_url":null,"state":"new","archived":false,"hash":"fcd7f985180502f685ccdf62b4baa6bd8c74578e","submitter":{"id":82279,"url":"http://patchwork.ozlabs.org/api/1.0/people/82279/?format=json","name":"Hanna Czenczek","email":"hreitz@redhat.com"},"delegate":null,"mbox":"http://patchwork.ozlabs.org/project/qemu-devel/patch/20260218132633.29748-22-hreitz@redhat.com/mbox/","series":[{"id":492547,"url":"http://patchwork.ozlabs.org/api/1.0/series/492547/?format=json","date":"2026-02-18T13:26:09","name":"export/fuse: Use coroutines and multi-threading","version":4,"mbox":"http://patchwork.ozlabs.org/series/492547/mbox/"}],"check":"pending","checks":"http://patchwork.ozlabs.org/api/patches/2197754/checks/","tags":{},"headers":{"Return-Path":"","X-Original-To":"incoming@patchwork.ozlabs.org","Delivered-To":"patchwork-incoming@legolas.ozlabs.org","Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (1024-bit key;\n unprotected) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256\n header.s=mimecast20190719 header.b=OlGT7XtU;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256\n header.s=google header.b=stytBGEO;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=nongnu.org\n (client-ip=209.51.188.17; helo=lists.gnu.org;\n envelope-from=qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org;\n receiver=patchwork.ozlabs.org)"],"Received":["from lists.gnu.org (lists.gnu.org [209.51.188.17])\n\t(using TLSv1.2 with cipher ECDHE-ECDSA-AES256-GCM-SHA384 (256/256 bits))\n\t(No client certificate requested)\n\tby legolas.ozlabs.org (Postfix) with ESMTPS id 4fGHZR1nFfz1xwr\n\tfor ; Thu, 19 Feb 2026 00:35:27 +1100 (AEDT)","from localhost ([::1] helo=lists1p.gnu.org)\n\tby lists.gnu.org with esmtp (Exim 4.90_1)\n\t(envelope-from )\n\tid 1vshfl-0004Od-Kx; Wed, 18 Feb 2026 08:32:57 -0500","from eggs.gnu.org ([2001:470:142:3::10])\n by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256)\n (Exim 4.90_1) (envelope-from ) id 1vshfh-0004Hw-3E\n for qemu-devel@nongnu.org; Wed, 18 Feb 2026 08:32:53 -0500","from us-smtp-delivery-124.mimecast.com ([170.10.129.124])\n by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256)\n (Exim 4.90_1) (envelope-from ) id 1vshfa-00064w-0p\n for qemu-devel@nongnu.org; Wed, 18 Feb 2026 08:32:52 -0500","from mail-wm1-f72.google.com (mail-wm1-f72.google.com\n [209.85.128.72]) by relay.mimecast.com with ESMTP with STARTTLS\n (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id\n us-mta-590-A9ZZAotrOOORghMIuIAPWA-1; Wed, 18 Feb 2026 08:27:38 -0500","by mail-wm1-f72.google.com with SMTP id\n 5b1f17b1804b1-4837f288194so42109955e9.2\n for ; Wed, 18 Feb 2026 05:27:37 -0800 (PST)","from localhost\n (p200300cfd737d029edef7b8da7441ac2.dip0.t-ipconnect.de.\n [2003:cf:d737:d029:edef:7b8d:a744:1ac2])\n by smtp.gmail.com with ESMTPSA id\n 5b1f17b1804b1-48370ac3564sm362444415e9.5.2026.02.18.05.27.34\n (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256);\n Wed, 18 Feb 2026 05:27:34 -0800 (PST)"],"DKIM-Signature":["v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com;\n s=mimecast20190719; t=1771421565;\n h=from:from:reply-to:subject:subject:date:date:message-id:message-id:\n to:to:cc:cc:mime-version:mime-version:content-type:content-type:\n content-transfer-encoding:content-transfer-encoding:\n in-reply-to:in-reply-to:references:references;\n bh=eC1GpsxsI4aDAAkTkGGQOGTuPmmj07fAx5eTswWosPE=;\n b=OlGT7XtUsRNEtvKfd2F/5rDRX1GO+rdKGkh/q9p2VesNCjAMc8wiBMcZQQQn/gRsnHZRVH\n TO9OaW5ozcS1FcjwLatoPUn06bgJQOxouoT4gIDSZDmUWMDTVyiHv5H7XKUfxaWbQIGTqR\n ELNZHakvs2XXRX+1KylXBFG2zwmZkiw=","v=1; a=rsa-sha256; c=relaxed/relaxed;\n d=redhat.com; s=google; t=1771421257; x=1772026057; darn=nongnu.org;\n h=content-transfer-encoding:mime-version:references:in-reply-to\n :message-id:date:subject:cc:to:from:from:to:cc:subject:date\n :message-id:reply-to;\n bh=eC1GpsxsI4aDAAkTkGGQOGTuPmmj07fAx5eTswWosPE=;\n b=stytBGEO65PwvMt2foNCp+nVnTiADfmkjdav+su3jB0OdCqoumzr0/u7KeDaMvMHwf\n 3l2+FitUfbDdrsjewzkmqPjs7/YdffnP9Ao76YcQSBpXeAa0BaWTCZDi+n8AzFa9NKYA\n YmhGq/OxhUnc2phke2h5MwwdVirRCi1Q2KcIRLTkqXcbBE7d+H6N6enVrqa0GEGx8C5U\n kWsFiFhqC75ys9k47qJeuSbagHdnDdkIIiiJHG/UA6IgazGBA1uhojIlR39bbxvtBcp5\n GCUYQyCT86SGE0txYuOIgW9WdfWkOMS3wuiSr3airaOy0vtStoKwZeC3BwV6OFQSXOf9\n R6oA=="],"X-MC-Unique":"A9ZZAotrOOORghMIuIAPWA-1","X-Mimecast-MFC-AGG-ID":"A9ZZAotrOOORghMIuIAPWA_1771421257","X-Google-DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/relaxed;\n d=1e100.net; s=20230601; t=1771421257; x=1772026057;\n h=content-transfer-encoding:mime-version:references:in-reply-to\n :message-id:date:subject:cc:to:from:x-gm-gg:x-gm-message-state:from\n :to:cc:subject:date:message-id:reply-to;\n bh=eC1GpsxsI4aDAAkTkGGQOGTuPmmj07fAx5eTswWosPE=;\n b=LUkSGu3wYBknwMF6g79GpfVeFZCG9uky/ha1CDN1XrgI7wSsYX8ofpxQl9mzw96SRC\n sVZXaokm3L4cdl8Du4ktOUaiE7QRAH6FQJGD+TGnaxNaa+7ZotFD/WKP3l9TN/7ovjaz\n MiEoVimrrS1JV/HumXrlGHASEeYiKohnIN/HhGYL95dTXnm4gQ3dKf5HBmq/YEjmHB/f\n IGqS8xccs0Uq1Vaa+BjVUB/bbc9UIHzpqGmvuvWjnaSKSjfuQ7KlqLTMKQRflo2Bqz+q\n 3c6TOZ5o2oZObQUheXuoxJkVmZt7jxh3LDvAGt3IYCrtRjrlNgEeW2bqgR1+wIJQWVep\n EX3g==","X-Gm-Message-State":"AOJu0YxtjjTfp8g87JsK4/tNW4/Nr9E7j5YT3UOmaV/Cd+O8vYT8ZPjF\n Ghnf7MaD9jLIOv27NFqwY8XlT0sCmVfsTebrttaGBs8aC0AbRTWL38pWDfnwRYIiuYwvbJxPlYa\n zMULVwx99MQE3923v7OQh4kO5WZJICeeWEzGV2UzQVaAIJqtCY8TbmNiS","X-Gm-Gg":"AZuq6aKyGW8g+crMaCSXj1uLih6jwhGNjYTHCHwiITjdzaN1hVXSBvaK4hseMYo6oVT\n rQbRPfYP1C5gkjlwIza9Jemd0p4g06JHzFdguqx1ORdfqFLWqaFS6VQFk/1uhfNKA81EQvpqvB6\n wQ0TbjNe2LgmsJADgJL8tGVW17qNqwB3Nax+a12vix3wTKPluxly2HbxP1VoQnGfwOs5B9BKWI5\n SDkEfIYw/WnsoN02v8NN7obuLnTwyU9J1W8ilwz7WG8vzhebdXe0IeceuXBEuRshsDDbtxeZiQX\n EVuZH/1kBDQG08JL6ILX1umnUTSELbvezjfeRswr15JjpgHKtdkYOZcKzqZk5Q4jmUIZpTMNkb+\n xdK6wzbfOhHb+9k0SQcCjPSUrl0rxndMPvLMw1xWIAk9whmkBt7L41mSq1W8B07rr9eVJVVG1Ao\n ZaKG7N","X-Received":["by 2002:a05:600c:620d:b0:480:3bba:1cac with SMTP id\n 5b1f17b1804b1-48371043046mr263552445e9.6.1771421256833;\n Wed, 18 Feb 2026 05:27:36 -0800 (PST)","by 2002:a05:600c:620d:b0:480:3bba:1cac with SMTP id\n 5b1f17b1804b1-48371043046mr263552055e9.6.1771421256341;\n Wed, 18 Feb 2026 05:27:36 -0800 (PST)"],"From":"Hanna Czenczek ","To":"qemu-block@nongnu.org","Cc":"qemu-devel@nongnu.org, Hanna Czenczek ,\n Kevin Wolf , Brian Song ","Subject":"[PATCH v4 21/24] fuse: Make shared export state atomic","Date":"Wed, 18 Feb 2026 14:26:30 +0100","Message-ID":"<20260218132633.29748-22-hreitz@redhat.com>","X-Mailer":"git-send-email 2.53.0","In-Reply-To":"<20260218132633.29748-1-hreitz@redhat.com>","References":"<20260218132633.29748-1-hreitz@redhat.com>","MIME-Version":"1.0","Content-Type":"text/plain; charset=UTF-8","Content-Transfer-Encoding":"8bit","Received-SPF":"pass client-ip=170.10.129.124; envelope-from=hreitz@redhat.com;\n helo=us-smtp-delivery-124.mimecast.com","X-Spam_score_int":"-20","X-Spam_score":"-2.1","X-Spam_bar":"--","X-Spam_report":"(-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.043,\n DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1,\n RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001,\n RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001,\n SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no","X-Spam_action":"no action","X-BeenThere":"qemu-devel@nongnu.org","X-Mailman-Version":"2.1.29","Precedence":"list","List-Id":"qemu development ","List-Unsubscribe":",\n ","List-Archive":"","List-Post":"","List-Help":"","List-Subscribe":",\n ","Errors-To":"qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org","Sender":"qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org"},"content":"The next commit is going to allow multi-threaded access to a FUSE\nexport. In order to allow safe concurrent SETATTR operations that\ncan modify the shared st_mode, st_uid, and st_gid, make any access to\nthose fields atomic operations.\n\nSigned-off-by: Hanna Czenczek \n---\n block/export/fuse.c | 23 +++++++++++++----------\n 1 file changed, 13 insertions(+), 10 deletions(-)","diff":"diff --git a/block/export/fuse.c b/block/export/fuse.c\nindex aa4f1c0307..162cbdacfc 100644\n--- a/block/export/fuse.c\n+++ b/block/export/fuse.c\n@@ -157,6 +157,7 @@ typedef struct FuseExport {\n /* Whether allow_other was used as a mount option or not */\n bool allow_other;\n \n+ /* All atomic */\n mode_t st_mode;\n uid_t st_uid;\n gid_t st_gid;\n@@ -267,6 +268,7 @@ static int fuse_export_create(BlockExport *blk_exp,\n ERRP_GUARD(); /* ensure clean-up even with error_fatal */\n FuseExport *exp = container_of(blk_exp, FuseExport, common);\n BlockExportOptionsFuse *args = &blk_exp_args->u.fuse;\n+ uint32_t st_mode;\n int ret;\n \n assert(blk_exp_args->type == BLOCK_EXPORT_TYPE_FUSE);\n@@ -335,12 +337,13 @@ static int fuse_export_create(BlockExport *blk_exp,\n args->allow_other = FUSE_EXPORT_ALLOW_OTHER_AUTO;\n }\n \n- exp->st_mode = S_IFREG | S_IRUSR;\n+ st_mode = S_IFREG | S_IRUSR;\n if (exp->writable) {\n- exp->st_mode |= S_IWUSR;\n+ st_mode |= S_IWUSR;\n }\n- exp->st_uid = getuid();\n- exp->st_gid = getgid();\n+ qatomic_set(&exp->st_mode, st_mode);\n+ qatomic_set(&exp->st_uid, getuid());\n+ qatomic_set(&exp->st_gid, getgid());\n \n if (args->allow_other == FUSE_EXPORT_ALLOW_OTHER_AUTO) {\n /* Try allow_other == true first, ignore errors */\n@@ -818,10 +821,10 @@ fuse_co_getattr(FuseExport *exp, struct fuse_attr_out *out)\n .attr_valid = 1,\n .attr = {\n .ino = 1,\n- .mode = exp->st_mode,\n+ .mode = qatomic_read(&exp->st_mode),\n .nlink = 1,\n- .uid = exp->st_uid,\n- .gid = exp->st_gid,\n+ .uid = qatomic_read(&exp->st_uid),\n+ .gid = qatomic_read(&exp->st_gid),\n .size = length,\n .blksize = blk_bs(exp->common.blk)->bl.request_alignment,\n .blocks = allocated_blocks,\n@@ -934,15 +937,15 @@ fuse_co_setattr(FuseExport *exp, struct fuse_attr_out *out, uint32_t to_set,\n \n if (to_set & FATTR_MODE) {\n /* Ignore FUSE-supplied file type, only change the mode */\n- exp->st_mode = (mode & 07777) | S_IFREG;\n+ qatomic_set(&exp->st_mode, (mode & 07777) | S_IFREG);\n }\n \n if (to_set & FATTR_UID) {\n- exp->st_uid = uid;\n+ qatomic_set(&exp->st_uid, uid);\n }\n \n if (to_set & FATTR_GID) {\n- exp->st_gid = gid;\n+ qatomic_set(&exp->st_gid, gid);\n }\n \n return fuse_co_getattr(exp, out);\n","prefixes":["v4","21/24"]}