From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:60168) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VoyQL-0000dt-RX for qemu-devel@nongnu.org; Fri, 06 Dec 2013 11:38:46 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1VoyQG-0003xF-MW for qemu-devel@nongnu.org; Fri, 06 Dec 2013 11:38:41 -0500 Received: from mx1.redhat.com ([209.132.183.28]:22593) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VoyQG-0003x6-EE for qemu-devel@nongnu.org; Fri, 06 Dec 2013 11:38:36 -0500 From: Stefan Hajnoczi Date: Fri, 6 Dec 2013 17:36:42 +0100 Message-Id: <1386347807-27359-44-git-send-email-stefanha@redhat.com> In-Reply-To: <1386347807-27359-1-git-send-email-stefanha@redhat.com> References: <1386347807-27359-1-git-send-email-stefanha@redhat.com> Subject: [Qemu-devel] [PULL 43/48] qemu-img: round down request length to an aligned sector List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Peter Lieven , Stefan Hajnoczi , Anthony Liguori From: Peter Lieven this patch shortens requests to end at an aligned sector so that the next request starts aligned. [Squashed Peter's fix for bdrv_get_info() failure discussed on the mailing list. --Stefan] Reviewed-by: Paolo Bonzini Signed-off-by: Peter Lieven Signed-off-by: Stefan Hajnoczi --- qemu-img.c | 32 ++++++++++++++++++++++++-------- 1 file changed, 24 insertions(+), 8 deletions(-) diff --git a/qemu-img.c b/qemu-img.c index 0725f22..76f05f2 100644 --- a/qemu-img.c +++ b/qemu-img.c @@ -1129,8 +1129,7 @@ out3: static int img_convert(int argc, char **argv) { - int c, n, n1, bs_n, bs_i, compress, cluster_size, - cluster_sectors, skip_create; + int c, n, n1, bs_n, bs_i, compress, cluster_sectors, skip_create; int64_t ret = 0; int progress = 0, flags; const char *fmt, *out_fmt, *cache, *out_baseimg, *out_filename; @@ -1424,19 +1423,23 @@ static int img_convert(int argc, char **argv) } } - if (compress) { - ret = bdrv_get_info(out_bs, &bdi); - if (ret < 0) { + cluster_sectors = 0; + ret = bdrv_get_info(out_bs, &bdi); + if (ret < 0) { + if (compress) { error_report("could not get block driver info"); goto out; } - cluster_size = bdi.cluster_size; - if (cluster_size <= 0 || cluster_size > bufsectors * BDRV_SECTOR_SIZE) { + } else { + cluster_sectors = bdi.cluster_size / BDRV_SECTOR_SIZE; + } + + if (compress) { + if (cluster_sectors <= 0 || cluster_sectors > bufsectors) { error_report("invalid cluster size"); ret = -1; goto out; } - cluster_sectors = cluster_size >> 9; sector_num = 0; nb_sectors = total_sectors; @@ -1569,6 +1572,19 @@ static int img_convert(int argc, char **argv) } n = MIN(nb_sectors, bufsectors); + + /* round down request length to an aligned sector, but + * do not bother doing this on short requests. They happen + * when we found an all-zero area, and the next sector to + * write will not be sector_num + n. */ + if (cluster_sectors > 0 && n >= cluster_sectors) { + int64_t next_aligned_sector = (sector_num + n); + next_aligned_sector -= next_aligned_sector % cluster_sectors; + if (sector_num + n > next_aligned_sector) { + n = next_aligned_sector - sector_num; + } + } + n = MIN(n, bs_sectors - (sector_num - bs_offset)); n1 = n; -- 1.8.4.2