From 070f95bad47e0d0f1884b93184369b3c9322cd4c Mon Sep 17 00:00:00 2001 Message-Id: <070f95bad47e0d0f1884b93184369b3c9322cd4c.1389014116.git.minovotn@redhat.com> In-Reply-To: References: From: Paolo Bonzini Date: Mon, 9 Dec 2013 14:09:37 +0100 Subject: [PATCH 49/50] qemu-img: round down request length to an aligned sector RH-Author: Paolo Bonzini Message-id: <1386598178-11845-52-git-send-email-pbonzini@redhat.com> Patchwork-id: 56088 O-Subject: [RHEL 7.0 qemu-kvm PATCH 51/52] qemu-img: round down request length to an aligned sector Bugzilla: 1039557 RH-Acked-by: Jeffrey Cody RH-Acked-by: Fam Zheng RH-Acked-by: Stefan Hajnoczi 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 (cherry picked from commit 24f833cd43dbfb5f8ae99e8a6d3691671622d3ea) --- qemu-img.c | 32 ++++++++++++++++++++++++-------- 1 file changed, 24 insertions(+), 8 deletions(-) Signed-off-by: Michal Novotny --- qemu-img.c | 32 ++++++++++++++++++++++++-------- 1 file changed, 24 insertions(+), 8 deletions(-) diff --git a/qemu-img.c b/qemu-img.c index 6890bb1..55bb82c 100644 --- a/qemu-img.c +++ b/qemu-img.c @@ -1122,8 +1122,7 @@ 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; @@ -1395,19 +1394,23 @@ 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; @@ -1540,6 +1543,19 @@ 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; -- 1.7.11.7