From patchwork Thu Oct 24 07:46:47 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Peter Lieven X-Patchwork-Id: 285799 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 3834D2C0090 for ; Thu, 24 Oct 2013 18:52:07 +1100 (EST) Received: from localhost ([::1]:53029 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VZFi9-00033R-2u for incoming@patchwork.ozlabs.org; Thu, 24 Oct 2013 03:52:05 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:49908) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VZFf5-0007Bc-Me for qemu-devel@nongnu.org; Thu, 24 Oct 2013 03:49:01 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1VZFew-0004Yn-Si for qemu-devel@nongnu.org; Thu, 24 Oct 2013 03:48:55 -0400 Received: from mx.ipv6.kamp.de ([2a02:248:0:51::16]:59096 helo=mx01.kamp.de) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VZFew-0004YS-Ha for qemu-devel@nongnu.org; Thu, 24 Oct 2013 03:48:46 -0400 Received: (qmail 22804 invoked by uid 89); 24 Oct 2013 07:48:45 -0000 Received: from [82.141.1.145] by client-16-kamp (envelope-from , uid 89) with qmail-scanner-2010/03/19-MF (clamdscan: 0.98/18001. hbedv: 8.2.12.132/7.11.109.62. spamassassin: 3.3.1. 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X-Received-From: 2a02:248:0:51::16 Cc: kwolf@redhat.com, stefanha@redhat.com, Peter Lieven , ronniesahlberg@gmail.com, pbonzini@redhat.com Subject: [Qemu-devel] [PATCHv6 13/17] block: introduce bdrv_make_zero 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 sped 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 sped 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 | 37 +++++++++++++++++++++++++++++++++++++ include/block/block.h | 1 + 2 files changed, 38 insertions(+) diff --git a/block.c b/block.c index b28dd42..21a992a 100644 --- a/block.c +++ b/block.c @@ -2391,6 +2391,43 @@ int bdrv_write_zeroes(BlockDriverState *bs, int64_t sector_num, BDRV_REQ_ZERO_WRITE | flags); } +/* + * Completely zero out a block device with the help of bdrv_write_zeroes. + * The operation is sped up by checking the block status and only writing + * zeroes to the device if they currently do not return zeroes. Optional + * flags are passed through to bdrv_write_zeroes (e.g. BDRV_REQ_MAY_UNMAP). + * + * Returns < 0 on error, 0 on success. For error codes see bdrv_write(). + */ +int bdrv_make_zero(BlockDriverState *bs, BdrvRequestFlags flags) +{ + int64_t target_size = bdrv_getlength(bs) / BDRV_SECTOR_SIZE; + int64_t ret, nb_sectors, sector_num = 0; + int n; + + 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; + } + ret = bdrv_write_zeroes(bs, sector_num, n, flags); + if (ret < 0) { + error_report("error writing zeroes at sector %" PRId64 ": %s", + sector_num, strerror(-ret)); + return ret; + } + sector_num += n; + } +} + 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 803c5ca..4d9e67c 100644 --- a/include/block/block.h +++ b/include/block/block.h @@ -216,6 +216,7 @@ 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_make_zero(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);