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qemu-img: round down request length to an aligned sector

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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>
This commit is contained in:
Peter Lieven 2013-11-27 11:07:07 +01:00 committed by Stefan Hajnoczi
parent f2521c9023
commit 24f833cd43
1 changed files with 24 additions and 8 deletions
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28
qemu-img.c
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@ -1129,8 +1129,7 @@ out3:
static int img_convert(int argc, char **argv) static int img_convert(int argc, char **argv)
{ {
int c, n, n1, bs_n, bs_i, compress, cluster_size, int c, n, n1, bs_n, bs_i, compress, cluster_sectors, skip_create;
cluster_sectors, skip_create;
int64_t ret = 0; int64_t ret = 0;
int progress = 0, flags; int progress = 0, flags;
const char *fmt, *out_fmt, *cache, *out_baseimg, *out_filename; const char *fmt, *out_fmt, *cache, *out_baseimg, *out_filename;
@ -1424,19 +1423,23 @@ static int img_convert(int argc, char **argv)
} }
} }
if (compress) { cluster_sectors = 0;
ret = bdrv_get_info(out_bs, &bdi); ret = bdrv_get_info(out_bs, &bdi);
if (ret < 0) { if (ret < 0) {
if (compress) {
error_report("could not get block driver info"); error_report("could not get block driver info");
goto out; goto out;
} }
cluster_size = bdi.cluster_size; } else {
if (cluster_size <= 0 || cluster_size > bufsectors * BDRV_SECTOR_SIZE) { cluster_sectors = bdi.cluster_size / BDRV_SECTOR_SIZE;
}
if (compress) {
if (cluster_sectors <= 0 || cluster_sectors > bufsectors) {
error_report("invalid cluster size"); error_report("invalid cluster size");
ret = -1; ret = -1;
goto out; goto out;
} }
cluster_sectors = cluster_size >> 9;
sector_num = 0; sector_num = 0;
nb_sectors = total_sectors; nb_sectors = total_sectors;
@ -1569,6 +1572,19 @@ static int img_convert(int argc, char **argv)
} }
n = MIN(nb_sectors, bufsectors); 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)); n = MIN(n, bs_sectors - (sector_num - bs_offset));
n1 = n; n1 = n;