bdrv_is_allocated_above() returns true in the case if qcow2 even for
completely zeroed areas as BDRV_BLOCK_ALLOCATED flag is set in both
cases. Though we have completely zeroed out the image just above or it was
already zeroed.
The patch stops using bdrv_is_allocated_above() wrapper and switches to
bdrv_get_block_status_above() to distinguish zeroed areas and areas with
data to avoid extra IO operations, which could be VERY slow.
Signed-off-by: Denis V. Lunev <d...@openvz.org>
CC: Jeff Cody <jc...@redhat.com>
CC: Kevin Wolf <kw...@redhat.com>
CC: Max Reitz <mre...@redhat.com>
---
block/mirror.c | 13 ++++++++-----
1 file changed, 8 insertions(+), 5 deletions(-)
diff --git a/block/mirror.c b/block/mirror.c
index e0b3f41..87edbd8 100644
--- a/block/mirror.c
+++ b/block/mirror.c
@@ -552,7 +552,7 @@ static int coroutine_fn mirror_dirty_init(MirrorBlockJob *s)
BlockDriverState *base = s->base;
BlockDriverState *bs = blk_bs(s->common.blk);
BlockDriverState *target_bs = blk_bs(s->target);
- int ret, n;
+ int n;
end = s->bdev_length / BDRV_SECTOR_SIZE;
@@ -590,6 +590,8 @@ static int coroutine_fn mirror_dirty_init(MirrorBlockJob *s)
/* Just to make sure we are not exceeding int limit. */
int nb_sectors = MIN(INT_MAX >> BDRV_SECTOR_BITS,
end - sector_num);
+ int64_t status;
+ BlockDriverState *file;
mirror_throttle(s);
@@ -597,13 +599,14 @@ static int coroutine_fn mirror_dirty_init(MirrorBlockJob
*s)
return 0;
}
- ret = bdrv_is_allocated_above(bs, base, sector_num, nb_sectors, &n);
- if (ret < 0) {
- return ret;
+ status = bdrv_get_block_status_above(bs, base, sector_num,
+ nb_sectors, &n, &file);
+ if (status < 0) {
+ return status;
}
assert(n > 0);
- if (ret == 1) {
+ if (status & BDRV_BLOCK_DATA) {
bdrv_set_dirty_bitmap(s->dirty_bitmap, sector_num, n);
}
sector_num += n;
--
2.7.4
