From patchwork Fri Sep 13 10:25:04 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Peter Lieven X-Patchwork-Id: 274712 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [IPv6:2001:4830:134:3::11]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id 038D42C0134 for ; Fri, 13 Sep 2013 20:29:08 +1000 (EST) Received: from localhost ([::1]:45876 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VKQcb-0000S6-97 for incoming@patchwork.ozlabs.org; Fri, 13 Sep 2013 06:29:05 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:53974) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VKQb1-000761-2s for qemu-devel@nongnu.org; Fri, 13 Sep 2013 06:27:32 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1VKQas-0003Sj-O8 for qemu-devel@nongnu.org; Fri, 13 Sep 2013 06:27:27 -0400 Received: from mx.ipv6.kamp.de ([2a02:248:0:51::16]:40957 helo=mx01.kamp.de) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VKQas-0003Rp-9Y for qemu-devel@nongnu.org; Fri, 13 Sep 2013 06:27:18 -0400 Received: (qmail 3030 invoked by uid 89); 13 Sep 2013 10:27:17 -0000 Received: from [82.141.1.145] by client-16-kamp (envelope-from , uid 89) with qmail-scanner-2010/03/19-MF (clamdscan: 0.97.8/17847. hbedv: 8.2.12.118/7.11.102.86. spamassassin: 3.3.1. 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X-Received-From: 2a02:248:0:51::16 Cc: kwolf@redhat.com, ronniesahlberg@gmail.com, Peter Lieven , stefanha@redhat.com, anthony@codemonkey.ws, pbonzini@redhat.com Subject: [Qemu-devel] [PATCH 07/12] block: introduce bdrv_zeroize X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org this patch adds a call to completely zero out a block device. the operation is speed up by checking the block status and only writing zeroes to the device if they currently do not return zeroes. optionally the zero writing can be speed up by setting the flag BDRV_REQ_MAY_UNMAP to emulate the zero write by unmapping if the driver supports it. Signed-off-by: Peter Lieven --- block.c | 45 +++++++++++++++++++++++++++++++++++++++++++++ include/block/block.h | 1 + 2 files changed, 46 insertions(+) diff --git a/block.c b/block.c index 6f498fc..76a6621 100644 --- a/block.c +++ b/block.c @@ -2342,6 +2342,51 @@ int bdrv_write_zeroes(BlockDriverState *bs, int64_t sector_num, BDRV_REQ_ZERO_WRITE | flags); } +int bdrv_zeroize(BlockDriverState *bs, BdrvRequestFlags flags) +{ + BlockDriverInfo bdi; + int64_t target_size = bdrv_getlength(bs) / BDRV_SECTOR_SIZE; + int64_t ret, nb_sectors, sector_num = 0; + int n; + /* split the write requests into 1MB chunks if the driver + * does not return a maximal size via bdi */ + int max_write_zeroes = 1 << (20 - BDRV_SECTOR_BITS); + if (bdrv_get_info(bs, &bdi) == 0 && + bdi.max_write_zeroes > 0) { + max_write_zeroes = bdi.max_write_zeroes; + } + for (;;) { + nb_sectors = target_size - sector_num; + if (nb_sectors <= 0) { + return 0; + } + if (nb_sectors > INT_MAX) { + nb_sectors = INT_MAX; + } + ret = bdrv_get_block_status(bs, sector_num, nb_sectors, &n); + if (ret & BDRV_BLOCK_ZERO) { + sector_num += n; + continue; + } + while (n > 0) { + nb_sectors = n; + if (nb_sectors > max_write_zeroes) { + nb_sectors = max_write_zeroes; + } + ret = bdrv_write_zeroes(bs, sector_num, nb_sectors, + flags & BDRV_REQ_MAY_UNMAP); + if (ret < 0) { + error_report("error writing zeroes at sector %" PRId64 ": %s", + sector_num, strerror(-ret)); + return -EIO; + } + sector_num += nb_sectors; + n -= nb_sectors; + } + } +} + + int bdrv_pread(BlockDriverState *bs, int64_t offset, void *buf, int count1) { diff --git a/include/block/block.h b/include/block/block.h index ee17048..71e9fa1 100644 --- a/include/block/block.h +++ b/include/block/block.h @@ -198,6 +198,7 @@ int bdrv_write(BlockDriverState *bs, int64_t sector_num, const uint8_t *buf, int nb_sectors); int bdrv_write_zeroes(BlockDriverState *bs, int64_t sector_num, int nb_sectors, BdrvRequestFlags flags); +int bdrv_zeroize(BlockDriverState *bs, BdrvRequestFlags flags); int bdrv_writev(BlockDriverState *bs, int64_t sector_num, QEMUIOVector *qiov); int bdrv_pread(BlockDriverState *bs, int64_t offset, void *buf, int count);