From: Fam Zheng <f...@redhat.com>
If guest discards a source cluster, mirroring with bdrv_aio_readv is overkill.
Some protocols do zero upon discard, where it's best to use
bdrv_aio_write_zeroes, otherwise, bdrv_aio_discard will be enough.
Signed-off-by: Fam Zheng <f...@redhat.com>
Message-id: 1433742974-20128-4-git-send-email-f...@redhat.com
Signed-off-by: Stefan Hajnoczi <stefa...@redhat.com>
---
block/mirror.c | 20 ++++++++++++++++++--
1 file changed, 18 insertions(+), 2 deletions(-)
diff --git a/block/mirror.c b/block/mirror.c
index d2515c7..3c38695 100644
--- a/block/mirror.c
+++ b/block/mirror.c
@@ -164,6 +164,8 @@ static uint64_t coroutine_fn
mirror_iteration(MirrorBlockJob *s)
int64_t end, sector_num, next_chunk, next_sector, hbitmap_next_sector;
uint64_t delay_ns = 0;
MirrorOp *op;
+ int pnum;
+ int64_t ret;
s->sector_num = hbitmap_iter_next(&s->hbi);
if (s->sector_num < 0) {
@@ -290,8 +292,22 @@ static uint64_t coroutine_fn
mirror_iteration(MirrorBlockJob *s)
s->in_flight++;
s->sectors_in_flight += nb_sectors;
trace_mirror_one_iteration(s, sector_num, nb_sectors);
- bdrv_aio_readv(source, sector_num, &op->qiov, nb_sectors,
- mirror_read_complete, op);
+
+ ret = bdrv_get_block_status_above(source, NULL, sector_num,
+ nb_sectors, &pnum);
+ if (ret < 0 || pnum < nb_sectors ||
+ (ret & BDRV_BLOCK_DATA && !(ret & BDRV_BLOCK_ZERO))) {
+ bdrv_aio_readv(source, sector_num, &op->qiov, nb_sectors,
+ mirror_read_complete, op);
+ } else if (ret & BDRV_BLOCK_ZERO) {
+ bdrv_aio_write_zeroes(s->target, sector_num, op->nb_sectors,
+ s->unmap ? BDRV_REQ_MAY_UNMAP : 0,
+ mirror_write_complete, op);
+ } else {
+ assert(!(ret & BDRV_BLOCK_DATA));
+ bdrv_aio_discard(s->target, sector_num, op->nb_sectors,
+ mirror_write_complete, op);
+ }
return delay_ns;
}
--
2.4.2
