From nobody Sat Apr 11 23:03:18 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=1773069192; cv=none; d=zohomail.com; s=zohoarc; b=aEjVPMsmYdr/4wG7l4mp/Zsrgcqb5TFhUKBxVyDMjIJP8YJAcyPPD198wNRml3kX8PJBeWqnfQkfkrK6XX02qplgLV45rhBrvHViGCtRJedc3QPkcshOn17a1L35XpqJ2rDuviRiX8/2o/Us81rMX+3VrSHNVTYp0hoiQbWPZy0= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1773069192; h=Content-Type: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=ri63c0zIoSQgAinKj4Gr9ogtshcXsY80vNDrWEB/NVk=; b=bz5gSoGndi1DFd6H5HZJo8Dljzjd2eEMILPJbxceU8h8x6FqH40YfAWgfCA4ORn2Jftdmbfp3TIXkrippIFHDB+hkCEfhU3r8o26HCMRGHNmeFzVxUbwiq/tCHcc7WUpdmxsOF08U6UWMbAE2ydKdLra73i/Eu9KC3J9DRmwkH8= 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 1773069192583730.0285377737308; Mon, 9 Mar 2026 08:13:12 -0700 (PDT) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1vzcF6-0001Iw-F1; Mon, 09 Mar 2026 11:10:00 -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 1vzcF2-0001DW-Rc for qemu-devel@nongnu.org; Mon, 09 Mar 2026 11:09:56 -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 1vzcEz-0008RT-Ch for qemu-devel@nongnu.org; Mon, 09 Mar 2026 11:09:56 -0400 Received: from mail-wm1-f69.google.com (mail-wm1-f69.google.com [209.85.128.69]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-650-GHRI3WG7PdGx1TGdfMrjGQ-1; Mon, 09 Mar 2026 11:09:51 -0400 Received: by mail-wm1-f69.google.com with SMTP id 5b1f17b1804b1-485355493aeso3417015e9.1 for ; Mon, 09 Mar 2026 08:09:50 -0700 (PDT) Received: from localhost (p200300cfd737d0cf29d515fbd6051d53.dip0.t-ipconnect.de. [2003:cf:d737:d0cf:29d5:15fb:d605:1d53]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-48531818b5asm88131615e9.3.2026.03.09.08.09.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 09 Mar 2026 08:09:47 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1773068992; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=ri63c0zIoSQgAinKj4Gr9ogtshcXsY80vNDrWEB/NVk=; b=GDzP8GyANw7jMf9C9+IUshsW2StizenNk5qFoEDgEQmbI1K//dR+9RLVyRfp9pXRvAJRWp 1/VspIQvZxEMo48bRWK4a8tZa8xKkuPzMkZik1OFFPYuH4QHrEYAPCZR3/dGIXqpEAzzBL ki1RIE8uacHideuNKxj/4v12dI1JEfk= X-MC-Unique: GHRI3WG7PdGx1TGdfMrjGQ-1 X-Mimecast-MFC-AGG-ID: GHRI3WG7PdGx1TGdfMrjGQ_1773068990 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=google; t=1773068990; x=1773673790; darn=nongnu.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=ri63c0zIoSQgAinKj4Gr9ogtshcXsY80vNDrWEB/NVk=; b=gBJINylToqoIein58AZtJD2uY7Mani6ESzz5EDwsObgGBZRt86eazL/z/tmnusRa4r +UgaSI3/H68DwjT/VNTqoX4SAKC0Taf5xCFYe3qpmVoUSx68uDgtpr8SDpjNMBts6eG9 mDUnjcUW0BTCERATb0wmyI6nDFTqHflyKxQbcgjQjGiTQj20+p9C4iMTD7g253TiOhRa xDOWs96TTpbJIL4ppiEJ978zZzqra5a1dO1lXYxOiO9T+vL6IZxewr9wz85bJ+pBwa// R6TQuZo9WCMqPBGNYufp05tUXXzV4ppRKdrkpWW8ZkdLR0fgvrHyct8mhNPNI0TDVKUn 4skQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1773068990; x=1773673790; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to; bh=ri63c0zIoSQgAinKj4Gr9ogtshcXsY80vNDrWEB/NVk=; b=rrj3BfcyJ594HhVG2PXfEPksm3wv2plsRLutpxiGLEVXa8UMFxsB35eXRvm+XhgjQf YFh318b2H70Ix2kUNECKz0D7cX0N6hSaA0YKaLLM5dgUr04UOC8rLjpyBx/NliBEkBg6 muUWg8mbc6SpLEdhZ+9XfjX0NlhoNSurthqhfrVzeAzAoQMnWT9NTv5oAs8ECLrScrGO op0zNtEouL5SgAWq8KHWBs0pHIt93c/cP5J0aw+cvdIXs8ubeF8K77ZxIy4bspumd6OV NLi7ZHcREDzoDWNAHNGWcxvHAFm7J+NC4iihibtBI/kSRuax8IDh9g17dT1sW/2ENWyY iFDQ== X-Gm-Message-State: AOJu0Yx34nwI08I+AjW7wPD2lx/hut01Z66sp3igp7jLCxGESsfvQ9H6 GtDkesqYKb6ZRsH5rx8FZYBA/lHiLDwpReQ7hC++I69oeBC9pZn0x6rMiyUA/jaGqsbssC9VwCk bqSZ1MLiHhVCItuavWon/8L+RI5aKy858npQ2RkUYlaONEoP2aq07mvwz X-Gm-Gg: ATEYQzzsnE5sZUYhwT2G7mZmho1WO5HCaDDZdTEechOjhoUyhZJrQU1iMn2gB1sVziQ z4q4ekIKnTLgquNMP3tgY3tWpIyBHCBlEbclMN+n0wdZUePJ0R433RTs3wR+3r0eICE2CCj54Cs 3JsMHfJrUIknDNj2Xc6yRo3unSJ/A3+ktZAwXLJwXASR4MJr3xPnYeoFJZtkY0lKx7ECVEP6ByE dMeovdcDgSJeNexbN817P/kfJ8y0Kvz/EvJ7TOl2OePx0JTOJa+wju2xBq71EabNxVR8LrQz3Wi kNF2AhWJeuEksz61OX6Qz9t5ssYOyf/CjFZyFP7u6JRG8Lh8cyUvMx4v9oHeoCUqz4Z+x5YVzoM QkVSpnRYPPy2AfZRyuxs8qamBlvc1CUZlAXqrlCY5oGDxYwRqGnfFhQWXvNdeg8yQcr1ireyU/2 zcqoMw X-Received: by 2002:a05:600c:46c4:b0:485:304a:58cd with SMTP id 5b1f17b1804b1-485304a5a00mr136119535e9.4.1773068989701; Mon, 09 Mar 2026 08:09:49 -0700 (PDT) X-Received: by 2002:a05:600c:46c4:b0:485:304a:58cd with SMTP id 5b1f17b1804b1-485304a5a00mr136118845e9.4.1773068989214; Mon, 09 Mar 2026 08:09:49 -0700 (PDT) From: Hanna Czenczek To: qemu-block@nongnu.org Cc: qemu-devel@nongnu.org, Hanna Czenczek , Kevin Wolf , Brian Song Subject: [PATCH v5 18/25] fuse: Reduce max read size Date: Mon, 9 Mar 2026 16:08:49 +0100 Message-ID: <20260309150856.26800-19-hreitz@redhat.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260309150856.26800-1-hreitz@redhat.com> References: <20260309150856.26800-1-hreitz@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable 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=hreitz@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: 1773069193544158500 Content-Type: text/plain; charset="utf-8" We are going to introduce parallel processing via coroutines, a maximum read size of 64 MB may be problematic, allowing users of the export to force us to allocate quite large amounts of memory with just a few requests. At least tone it down to 1 MB, which is still probably far more than enough. (Larger requests are split automatically by the FUSE kernel driver anyway.) (Yes, we inadvertently already had parallel request processing due to nested polling before. Better to fix this late than never.) Reviewed-by: Stefan Hajnoczi Signed-off-by: Hanna Czenczek --- block/export/fuse.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/block/export/fuse.c b/block/export/fuse.c index bd099d1291..f32e74f39d 100644 --- a/block/export/fuse.c +++ b/block/export/fuse.c @@ -45,7 +45,7 @@ #endif =20 /* Prevent overly long bounce buffer allocations */ -#define FUSE_MAX_READ_BYTES (MIN(BDRV_REQUEST_MAX_BYTES, 64 * 1024 * 1024)) +#define FUSE_MAX_READ_BYTES (MIN(BDRV_REQUEST_MAX_BYTES, 1 * 1024 * 1024)) #define FUSE_MAX_WRITE_BYTES (64 * 1024) =20 /* --=20 2.53.0