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authorPeter Lieven <pl@kamp.de>2013-11-27 11:07:07 +0100
committerStefan Hajnoczi <stefanha@redhat.com>2013-12-06 16:53:03 +0100
commit24f833cd43dbfb5f8ae99e8a6d3691671622d3ea (patch)
tree1f8487a0afb9293471fbde2e095a0bdb28f6ddb1 /qemu-img.c
parentf2521c9023067a007d18b844fe7639c1c5b6f2ac (diff)
qemu-img: round down request length to an aligned sector
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 <pbonzini@redhat.com> Signed-off-by: Peter Lieven <pl@kamp.de> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Diffstat (limited to 'qemu-img.c')
-rw-r--r--qemu-img.c32
1 files changed, 24 insertions, 8 deletions
diff --git a/qemu-img.c b/qemu-img.c
index 0725f22cc2..76f05f2e94 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;