From patchwork Tue Dec 3 17:50:29 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ming Hung Tsai X-Patchwork-Id: 13892785 X-Patchwork-Delegate: snitzer@redhat.com Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0E0841FC0E0 for ; Tue, 3 Dec 2024 17:50:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733248244; cv=none; b=nQ0Jx8fZ5oRl60F7Wd3tvf/uKuDZWQAvCOqJMBNwUnX+pTMNMXjdHnee0pyNiaMBbBZ0ubOZwz2EMwDiF7XJflBCZF2maPeNj2rONFLQsqiS3GmFBSVbHm8d5DlV2cAPHMyizJM6PN2FdeY6LFtWGDpBYghvL7lmkFR6M4Ko1/o= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733248244; c=relaxed/simple; bh=zIUHK65kTEHSdpveWrss+ErYIWT+4juOjNkAEt3H8pM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:content-type; b=UogAGxmrgHTSA7xwwXatkMX2RbV43FqA3dyVyG/5G3msftciNIopic5atswnucK3cOCzLwmQJB/uJqlul3vzWnxL80RlBVKZ0mIfYRZ2gAbwPUSPpwSSiPUaOWUsrKCNwiJO2Jl1IonmPolwu9NjFlEDFWBtvW8lmH9kOI4lQj0= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=LIWUKB2L; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="LIWUKB2L" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1733248241; 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=HULijjWGV1+G9zVOYPCMw+7nNRhQ0FBn9s6ocOTMmuQ=; b=LIWUKB2Lw7eVB1A2o0LryeT+Kp41ORe0D4FYDRFkjIEFwgEZXJOQaAzlzqPx6vHPMpWvfF HlS+TelJDtKOAvIZaQ/wu9ktH91OVrhqk1D5I7gE/yEeucEYytS/2vCEITSgbfTVUFhxfZ 3O9xKatv/wCLM1ELdoQCvObOSAN+2gc= Received: from mx-prod-mc-05.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-388-d0TVMtRXNjGZ16s6wdHT0w-1; Tue, 03 Dec 2024 12:50:40 -0500 X-MC-Unique: d0TVMtRXNjGZ16s6wdHT0w-1 X-Mimecast-MFC-AGG-ID: d0TVMtRXNjGZ16s6wdHT0w Received: from mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.17]) (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-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 8EB041955EB3; Tue, 3 Dec 2024 17:50:39 +0000 (UTC) Received: from thinkpad.redhat.com (unknown [10.67.24.41]) by mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 1AD4F1955F2D; Tue, 3 Dec 2024 17:50:35 +0000 (UTC) From: Ming-Hung Tsai To: dm-devel@lists.linux.dev Cc: Mikulas Patocka , Joe Thornber , Heinz Mauelshagen , Mike Snitzer , Ming-Hung Tsai Subject: [PATCH 3/3] dm array: fix cursor index when skipping across block boundaries Date: Wed, 4 Dec 2024 01:50:29 +0800 Message-ID: <20241203175029.1259542-1-mtsai@redhat.com> In-Reply-To: <20241203173756.1257967-1-mtsai@redhat.com> References: <20241203173756.1257967-1-mtsai@redhat.com> Precedence: bulk X-Mailing-List: dm-devel@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.0 on 10.30.177.17 X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: HVmu_dsFYEqv2-QE8QhoK-2Yo1VwP1cDD5OwV7p43_Y_1733248239 X-Mimecast-Originator: redhat.com content-type: text/plain; charset="US-ASCII"; x-default=true dm_array_cursor_skip() seeks to the target position by loading array blocks iteratively until the specified number of entries to skip is reached. When seeking across block boundaries, it uses dm_array_cursor_next() to step into the next block. dm_array_cursor_skip() must first move the cursor index to the end of the current block; otherwise, the cursor position could incorrectly remain in the same block, causing the actual number of skipped entries to be much smaller than expected. This bug affects cache resizing in v2 metadata and could lead to data loss if the fast device is shrunk during the first-time resume. For example: 1. create a cache metadata consists of 32768 blocks, with a dirty block assigned to the second bitmap block. cache_restore v1.0 is required. cat <> cmeta.xml EOF dmsetup create cmeta --table "0 8192 linear /dev/sdc 0" cache_restore -i cmeta.xml -o /dev/mapper/cmeta --metadata-version=2 2. bring up the cache while attempt to discard all the blocks belonging to the second bitmap block (block# 32576 to 32767). The last command is expected to fail, but it actually succeeds. dmsetup create cdata --table "0 2084864 linear /dev/sdc 8192" dmsetup create corig --table "0 65536 linear /dev/sdc 2105344" dmsetup create cache --table "0 65536 cache /dev/mapper/cmeta \ /dev/mapper/cdata /dev/mapper/corig 64 2 metadata2 writeback smq \ 2 migration_threshold 0" Signed-off-by: Ming-Hung Tsai Fixes: 9b696229aa7d ("dm persistent data: add cursor skip functions to the cursor APIs") Reviewed-by: thornber@redhat.com --- drivers/md/persistent-data/dm-array.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/md/persistent-data/dm-array.c b/drivers/md/persistent-data/dm-array.c index 1c3af717ee4f..b293da766fb1 100644 --- a/drivers/md/persistent-data/dm-array.c +++ b/drivers/md/persistent-data/dm-array.c @@ -1004,6 +1004,7 @@ int dm_array_cursor_skip(struct dm_array_cursor *c, uint32_t count) } count -= remaining; + c->index += (remaining - 1); r = dm_array_cursor_next(c); } while (!r);