From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:34201) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VnUFz-00006e-BD for qemu-devel@nongnu.org; Mon, 02 Dec 2013 09:13:57 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1VnUFt-0005SD-AY for qemu-devel@nongnu.org; Mon, 02 Dec 2013 09:13:51 -0500 Received: from mx1.redhat.com ([209.132.183.28]:38137) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VnUFt-0005S6-2R for qemu-devel@nongnu.org; Mon, 02 Dec 2013 09:13:45 -0500 Date: Mon, 2 Dec 2013 15:13:36 +0100 From: Stefan Hajnoczi Message-ID: <20131202141336.GC28132@stefanha-thinkpad.redhat.com> References: <1385131710-8978-1-git-send-email-pl@kamp.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1385131710-8978-1-git-send-email-pl@kamp.de> Subject: Re: [Qemu-devel] [RFC][PATCH] qemu-img: add support for skipping zeroes in input during convert List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Peter Lieven Cc: kwolf@redhat.com, pbonzini@redhat.com, qemu-devel@nongnu.org On Fri, Nov 22, 2013 at 03:48:30PM +0100, Peter Lieven wrote: > - /* If the output image is being created as a copy on write image, > - assume that sectors which are unallocated in the input image > - are present in both the output's and input's base images (no > - need to copy them). */ > - if (out_baseimg) { > - ret = bdrv_is_allocated(bs[bs_i], sector_num - bs_offset, > - n, &n1); int coroutine_fn bdrv_is_allocated(BlockDriverState *bs, int64_t sector_num, int nb_sectors, int *pnum) { int64_t ret = bdrv_get_block_status(bs, sector_num, nb_sectors, pnum); if (ret < 0) { return ret; } return (ret & BDRV_BLOCK_DATA) || ((ret & BDRV_BLOCK_ZERO) && !bdrv_has_zero_init(bs)); } bdrv_has_zero_init() returns false when bs->backing_hd != NULL. > + if (out_baseimg || has_zero_init) { > + n = nb_sectors > INT_MAX ? INT_MAX : nb_sectors; > + ret = bdrv_get_block_status(bs[bs_i], sector_num - bs_offset, > + n, &n1); > if (ret < 0) { > - error_report("error while reading metadata for sector " > - "%" PRId64 ": %s", > + error_report("error while reading block status of sector %" PRId64 ": %s", > sector_num - bs_offset, strerror(-ret)); > goto out; > } > - if (!ret) { > + /* If the output image is zero initialized, we are not working > + * on a shared base and the input is zero we can skip the next > + * n1 bytes */ > + if (!out_baseimg && has_zero_init && ret & BDRV_BLOCK_ZERO) { > + sector_num += n1; > + continue; > + } > + /* If the output image is being created as a copy on write image, > + assume that sectors which are unallocated in the input image > + are present in both the output's and input's base images (no > + need to copy them). */ > + if (out_baseimg && !(ret & BDRV_BLOCK_DATA)) { > sector_num += n1; > continue; > } How are these two if statements different from bdrv_is_allocated()? Stefan