From mboxrd@z Thu Jan 1 00:00:00 1970 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 lists.gnu.org (lists.gnu.org [209.51.188.17]) (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 E1F0AC369AB for ; Fri, 25 Apr 2025 00:56:56 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1u87LX-0006bS-KE; Thu, 24 Apr 2025 20:55:15 -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 1u87LS-0006V1-HP for qemu-devel@nongnu.org; Thu, 24 Apr 2025 20:55:10 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1u87LQ-0000i4-0E for qemu-devel@nongnu.org; Thu, 24 Apr 2025 20:55:10 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1745542506; 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=mp8jz+1BcXAdMIlc1C2i9pFAxzOJBCrZpHHsY/LwbF8=; b=M+NUYap5YEQHZgFqV2En2aJAIAVQ3aYshSzVGTRJHf4x27nK396TskAz99CuFSYoGZbxNK MNqlRNJ/l7ds/bc7eL3++ALl5QvkN8VZZEkJpPHYt3zATwfzJJxsBWhpsuJaKKdtPnoVn9 QTEr2J4Yw91PYPWOchG8AjGRIXgvcXA= 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-119-JjXkulD3OyCak1KbLUJlng-1; Thu, 24 Apr 2025 20:55:04 -0400 X-MC-Unique: JjXkulD3OyCak1KbLUJlng-1 X-Mimecast-MFC-AGG-ID: JjXkulD3OyCak1KbLUJlng_1745542503 Received: from mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.93]) (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 3B4DB1956088; Fri, 25 Apr 2025 00:55:03 +0000 (UTC) Received: from green.redhat.com (unknown [10.2.16.59]) by mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 5A40E1800378; Fri, 25 Apr 2025 00:55:01 +0000 (UTC) From: Eric Blake To: qemu-devel@nongnu.org Cc: qemu-block@nongnu.org, vsementsov@yandex-team.ru, stefanha@redhat.com, Fam Zheng , Kevin Wolf , Hanna Reitz Subject: [PATCH v3 03/11] block: Let bdrv_co_is_zero_fast consolidate adjacent extents Date: Thu, 24 Apr 2025 19:52:03 -0500 Message-ID: <20250425005439.2252467-16-eblake@redhat.com> In-Reply-To: <20250425005439.2252467-13-eblake@redhat.com> References: <20250425005439.2252467-13-eblake@redhat.com> MIME-Version: 1.0 Content-type: text/plain Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.93 Received-SPF: pass client-ip=170.10.129.124; envelope-from=eblake@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -28 X-Spam_score: -2.9 X-Spam_bar: -- X-Spam_report: (-2.9 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.84, 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_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Some BDS drivers have a cap on how much block status they can supply in one query (for example, NBD talking to an older server cannot inspect more than 4G per query; and qcow2 tends to cap its answers rather than cross a cluster boundary of an L1 table). Although the existing callers of bdrv_co_is_zero_fast are not passing in that large of a 'bytes' parameter, an upcoming caller wants to query the entire image at once, and will thus benefit from being able to treat adjacent zero regions in a coalesced manner, rather than claiming the region is non-zero merely because pnum was truncated and didn't match the incoming bytes. While refactoring this into a loop, note that there is no need to assign pnum prior to calling bdrv_co_common_block_status_above() (it is guaranteed to be assigned deeper in the callstack). Signed-off-by: Eric Blake --- v3: also tweak function comment --- block/io.c | 29 ++++++++++++++++------------- 1 file changed, 16 insertions(+), 13 deletions(-) diff --git a/block/io.c b/block/io.c index 056af8198bc..d3bd1211acf 100644 --- a/block/io.c +++ b/block/io.c @@ -2751,28 +2751,31 @@ int coroutine_fn bdrv_co_block_status(BlockDriverState *bs, int64_t offset, * by @offset and @bytes is known to read as zeroes. * Return 1 if that is the case, 0 otherwise and -errno on error. * This test is meant to be fast rather than accurate so returning 0 - * does not guarantee non-zero data. + * does not guarantee non-zero data; but a return of 1 is reliable. */ int coroutine_fn bdrv_co_is_zero_fast(BlockDriverState *bs, int64_t offset, int64_t bytes) { int ret; - int64_t pnum = bytes; + int64_t pnum; IO_CODE(); - if (!bytes) { - return 1; + while (bytes) { + ret = bdrv_co_common_block_status_above(bs, NULL, false, + BDRV_WANT_ZERO, offset, bytes, + &pnum, NULL, NULL, NULL); + + if (ret < 0) { + return ret; + } + if (!(ret & BDRV_BLOCK_ZERO)) { + return 0; + } + offset += pnum; + bytes -= pnum; } - ret = bdrv_co_common_block_status_above(bs, NULL, false, BDRV_WANT_ZERO, - offset, bytes, &pnum, NULL, NULL, - NULL); - - if (ret < 0) { - return ret; - } - - return (pnum == bytes) && (ret & BDRV_BLOCK_ZERO); + return 1; } int coroutine_fn bdrv_co_is_allocated(BlockDriverState *bs, int64_t offset, -- 2.49.0