From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:58925) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VKQun-0007kd-DI for qemu-devel@nongnu.org; Fri, 13 Sep 2013 06:47:58 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1VKQuh-0001LX-RZ for qemu-devel@nongnu.org; Fri, 13 Sep 2013 06:47:53 -0400 Received: from mx.ipv6.kamp.de ([2a02:248:0:51::16]:55535 helo=mx01.kamp.de) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VKQuh-0001Jy-Fv for qemu-devel@nongnu.org; Fri, 13 Sep 2013 06:47:47 -0400 Message-ID: <5232ED48.2030102@kamp.de> Date: Fri, 13 Sep 2013 12:47:36 +0200 From: Peter Lieven MIME-Version: 1.0 References: <1379067909-22984-1-git-send-email-pl@kamp.de> <1379067909-22984-8-git-send-email-pl@kamp.de> In-Reply-To: <1379067909-22984-8-git-send-email-pl@kamp.de> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH 07/12] block: introduce bdrv_zeroize List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Peter Lieven Cc: kwolf@redhat.com, stefanha@redhat.com, qemu-devel@nongnu.org, ronniesahlberg@gmail.com, anthony@codemonkey.ws, pbonzini@redhat.com On 13.09.2013 12:25, Peter Lieven wrote: > 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); forgot to check for ret < 0 here. Peter