From nobody Wed Apr 8 04:26:38 2026 Delivered-To: importer@patchew.org Authentication-Results: mx.zohomail.com; dkim=pass; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=pass(p=quarantine dis=none) header.from=redhat.com ARC-Seal: i=1; a=rsa-sha256; t=1773160154; cv=none; d=zohomail.com; s=zohoarc; b=T5AcNgycbsPqJnqGd9Majnkda7LBY29+r+TQd1xgmWXJrkomZk+K2UnVCMw87yUWIXwfKhuOC1TdUlTbj7XSGDCSI+JiY/wg09UPUQrAVtuWR6xneTxtqbSP7KfrhxJocorN4bejkr/Q+WGw/ifvjEdqxSEC8U/01xmNxtB2PTE= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1773160154; h=Content-Transfer-Encoding:Cc:Cc:Date:Date:From:From:In-Reply-To:List-Subscribe:List-Post:List-Id:List-Archive:List-Help:List-Unsubscribe:MIME-Version:Message-ID:References:Sender:Subject:Subject:To:To:Message-Id:Reply-To; bh=sCdxqzzqW+CcsOoWHKJz2eNl+Nl/2EEfwXKHZ5AnWwM=; b=OOdCA7778vdYK0VZ4UJLn+GGa8x8yBfmGVPTCIy4XnFs1uakj+0ubjYIPVHQhak5xjsDdpEMLHp6MCgEeG8R8n4metqlh+FHZURae9Gd6IgxP1BqpoeyNw2pwuiQj0VAJNSFa2zOEdyZIfrVxpj/uu7xrwm5ZxyHOfU1os9XlgI= ARC-Authentication-Results: i=1; mx.zohomail.com; dkim=pass; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=pass header.from= (p=quarantine dis=none) Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1773160154586656.7651287052076; Tue, 10 Mar 2026 09:29:14 -0700 (PDT) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1vzzvO-0003S6-Jp; Tue, 10 Mar 2026 12:27:14 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1vzzv4-0003Gw-Kx for qemu-devel@nongnu.org; Tue, 10 Mar 2026 12:26:55 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1vzzv2-0000t6-V5 for qemu-devel@nongnu.org; Tue, 10 Mar 2026 12:26:54 -0400 Received: from mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-262-E-Scm9PxPxaos7yX-tk5aQ-1; Tue, 10 Mar 2026 12:26:49 -0400 Received: from mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.12]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 606061956089; Tue, 10 Mar 2026 16:26:48 +0000 (UTC) Received: from merkur.fritz.box (unknown [10.45.224.112]) by mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 1FE7A19560A6; Tue, 10 Mar 2026 16:26:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1773160012; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=sCdxqzzqW+CcsOoWHKJz2eNl+Nl/2EEfwXKHZ5AnWwM=; b=KebrbOXIAa2GgnaNln78tnA2WOTkFH+mvOMgk5a4tthZAarF6xxsXnsWow2KBohUS4AlXT 2xbIvl5VHrOhH1q6XlEhJ6miN+hgPnxRPAa+D1AQ0vxz4/Wg55QvphDEAtSceRymJubq62 M7AUq4nTaFf1njQ7NfLn7o96dsjWR2U= X-MC-Unique: E-Scm9PxPxaos7yX-tk5aQ-1 X-Mimecast-MFC-AGG-ID: E-Scm9PxPxaos7yX-tk5aQ_1773160008 From: Kevin Wolf To: qemu-block@nongnu.org Cc: kwolf@redhat.com, qemu-devel@nongnu.org Subject: [PULL 11/28] fuse: Add halted flag Date: Tue, 10 Mar 2026 17:26:05 +0100 Message-ID: <20260310162622.333137-12-kwolf@redhat.com> In-Reply-To: <20260310162622.333137-1-kwolf@redhat.com> References: <20260310162622.333137-1-kwolf@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=170.10.133.124; envelope-from=kwolf@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -3 X-Spam_score: -0.4 X-Spam_bar: / X-Spam_report: (-0.4 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.819, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.903, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=no 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: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @redhat.com) X-ZM-MESSAGEID: 1773160155180158500 Content-Type: text/plain; charset="utf-8" From: Hanna Czenczek This is a flag that we will want when processing FUSE requests ourselves: When the kernel sends us e.g. a truncated request (i.e. we receive less data than the request's indicated length), we cannot rely on subsequent data to be valid. Then, we are going to set this flag, halting all FUSE request processing. We plan to only use this flag in cases that would effectively be kernel bugs. While not necessary yet, access the flag atomically so that it will be safe to use once we introduce multi-threading. (Right now, the flag is unused because libfuse still does our request processing.) Signed-off-by: Hanna Czenczek Message-ID: <20260309150856.26800-12-hreitz@redhat.com> Reviewed-by: Kevin Wolf Signed-off-by: Kevin Wolf --- block/export/fuse.c | 30 ++++++++++++++++++++++++++++++ 1 file changed, 30 insertions(+) diff --git a/block/export/fuse.c b/block/export/fuse.c index fc75a5e74d9..f6a5f4fa0a0 100644 --- a/block/export/fuse.c +++ b/block/export/fuse.c @@ -53,6 +53,13 @@ typedef struct FuseExport { unsigned int in_flight; /* atomic */ bool mounted, fd_handler_set_up; =20 + /* + * Set when there was an unrecoverable error and no requests should be= read + * from the device anymore (basically only in case of something we wou= ld + * consider a kernel bug). Access atomically. + */ + bool halted; + char *mountpoint; bool writable; bool growable; @@ -69,6 +76,7 @@ static const struct fuse_lowlevel_ops fuse_ops; =20 static void fuse_export_shutdown(BlockExport *exp); static void fuse_export_delete(BlockExport *exp); +static void fuse_export_halt(FuseExport *exp) G_GNUC_UNUSED; =20 static void init_exports_table(void); =20 @@ -99,6 +107,10 @@ static void fuse_dec_in_flight(FuseExport *exp) =20 static void fuse_attach_handlers(FuseExport *exp) { + if (qatomic_read(&exp->halted)) { + return; + } + aio_set_fd_handler(exp->common.ctx, fuse_session_fd(exp->fuse_session), read_from_fuse_export, NULL, NULL, NULL, exp); @@ -322,6 +334,10 @@ static void read_from_fuse_export(void *opaque) FuseExport *exp =3D opaque; int ret; =20 + if (unlikely(qatomic_read(&exp->halted))) { + return; + } + fuse_inc_in_flight(exp); =20 do { @@ -380,6 +396,20 @@ static void fuse_export_delete(BlockExport *blk_exp) g_free(exp->mountpoint); } =20 +/** + * Halt the export: Detach FD handlers, and set exp->halted to true, preve= nting + * fuse_attach_handlers() from re-attaching them, therefore stopping all f= urther + * request processing. + * + * Call this function when an unrecoverable error happens that makes proce= ssing + * all future requests unreliable. + */ +static void fuse_export_halt(FuseExport *exp) +{ + qatomic_set(&exp->halted, true); + fuse_detach_handlers(exp); +} + /** * Check whether @path points to a regular file. If not, put an * appropriate message into *errp. --=20 2.53.0