From patchwork Wed Jul 19 20:19:09 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mikulas Patocka X-Patchwork-Id: 13319452 X-Patchwork-Delegate: snitzer@redhat.com Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 82BD9C001DC for ; Wed, 19 Jul 2023 20:20:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1689798035; h=from:from:sender:sender: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:list-id:list-help: list-unsubscribe:list-subscribe:list-post; bh=045tEj1vhBfjQLldLd22FAY7cz/SNVzowk5OaUyaNLc=; b=ZoBQnme+q8tcDF/6q1571v1AQdv0aYV6HekwqZkfVt1akvl33F5Eq6JzRXsrQqnnlYgYgq F7/sBcysxqXg0/wLUX4XuOZJsibVs21ASF3sXo5lcYVcRNyw8GK9HFERr27O1pqU9vfuze FQstbm9dGaNjoV9EIyAXZD9IDPKDSrc= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-317-qZA2K2YnMX-no_grAlB8Rw-1; Wed, 19 Jul 2023 16:20:32 -0400 X-MC-Unique: qZA2K2YnMX-no_grAlB8Rw-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.rdu2.redhat.com [10.11.54.8]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 3ACA28F184A; Wed, 19 Jul 2023 20:20:30 +0000 (UTC) Received: from mm-prod-listman-01.mail-001.prod.us-east-1.aws.redhat.com (unknown [10.30.29.100]) by smtp.corp.redhat.com (Postfix) with ESMTP id 2A2F6C57969; Wed, 19 Jul 2023 20:20:30 +0000 (UTC) Received: from mm-prod-listman-01.mail-001.prod.us-east-1.aws.redhat.com (localhost [IPv6:::1]) by mm-prod-listman-01.mail-001.prod.us-east-1.aws.redhat.com (Postfix) with ESMTP id 07B6219465B9; Wed, 19 Jul 2023 20:20:30 +0000 (UTC) Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.rdu2.redhat.com [10.11.54.1]) by mm-prod-listman-01.mail-001.prod.us-east-1.aws.redhat.com (Postfix) with ESMTP id 2884519465A4 for ; Wed, 19 Jul 2023 20:19:10 +0000 (UTC) Received: by smtp.corp.redhat.com (Postfix) id 129B540C2071; Wed, 19 Jul 2023 20:19:10 +0000 (UTC) Received: from file1-rdu.file-001.prod.rdu2.dc.redhat.com (unknown [10.11.5.21]) by smtp.corp.redhat.com (Postfix) with ESMTPS id F3B1640C206F; Wed, 19 Jul 2023 20:19:09 +0000 (UTC) Received: by file1-rdu.file-001.prod.rdu2.dc.redhat.com (Postfix, from userid 12668) id EDE063096A42; Wed, 19 Jul 2023 20:19:09 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by file1-rdu.file-001.prod.rdu2.dc.redhat.com (Postfix) with ESMTP id ECE523F7CF; Wed, 19 Jul 2023 22:19:09 +0200 (CEST) Date: Wed, 19 Jul 2023 22:19:09 +0200 (CEST) From: Mikulas Patocka To: Jens Axboe Message-ID: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.1 Subject: [dm-devel] [PATCH 1/3] brd: extend the rcu regions to cover read and write X-BeenThere: dm-devel@redhat.com X-Mailman-Version: 2.1.29 Precedence: list List-Id: device-mapper development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Christoph Hellwig , Li Nan , dm-devel@redhat.com, linux-block@vger.kernel.org, Zdenek Kabelac Errors-To: dm-devel-bounces@redhat.com Sender: "dm-devel" X-Scanned-By: MIMEDefang 3.1 on 10.11.54.8 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com This patch extends the rcu regions, so that lookup followed by a read or write of a page is done inside rcu read lock. This is needed for the following patch that enables discard. Signed-off-by: Mikulas Patocka --- drivers/block/brd.c | 8 ++++++++ 1 file changed, 8 insertions(+) -- dm-devel mailing list dm-devel@redhat.com https://listman.redhat.com/mailman/listinfo/dm-devel Index: linux-2.6/drivers/block/brd.c =================================================================== --- linux-2.6.orig/drivers/block/brd.c +++ linux-2.6/drivers/block/brd.c @@ -150,23 +150,27 @@ static void copy_to_brd(struct brd_devic size_t copy; copy = min_t(size_t, n, PAGE_SIZE - offset); + rcu_read_lock(); page = brd_lookup_page(brd, sector); BUG_ON(!page); dst = kmap_atomic(page); memcpy(dst + offset, src, copy); kunmap_atomic(dst); + rcu_read_unlock(); if (copy < n) { src += copy; sector += copy >> SECTOR_SHIFT; copy = n - copy; + rcu_read_lock(); page = brd_lookup_page(brd, sector); BUG_ON(!page); dst = kmap_atomic(page); memcpy(dst, src, copy); kunmap_atomic(dst); + rcu_read_unlock(); } } @@ -182,6 +186,7 @@ static void copy_from_brd(void *dst, str size_t copy; copy = min_t(size_t, n, PAGE_SIZE - offset); + rcu_read_lock(); page = brd_lookup_page(brd, sector); if (page) { src = kmap_atomic(page); @@ -189,11 +194,13 @@ static void copy_from_brd(void *dst, str kunmap_atomic(src); } else memset(dst, 0, copy); + rcu_read_unlock(); if (copy < n) { dst += copy; sector += copy >> SECTOR_SHIFT; copy = n - copy; + rcu_read_lock(); page = brd_lookup_page(brd, sector); if (page) { src = kmap_atomic(page); @@ -201,6 +208,7 @@ static void copy_from_brd(void *dst, str kunmap_atomic(src); } else memset(dst, 0, copy); + rcu_read_unlock(); } }