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authorFam Zheng <famz@redhat.com>2015-06-08 13:56:09 +0800
committerStefan Hajnoczi <stefanha@redhat.com>2015-07-02 10:06:23 +0100
commitdcfb3beb5130694b76b57de109619fcbf9c7e5b5 (patch)
treeaf8a045ab17230ead191ffba9886025c6b12a35e /block/mirror.c
parent0fc9f8ea2800b76eaea20a8a3a91fbeeb4bfa81b (diff)
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mirror: Do zero write on target if sectors not allocated
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 <famz@redhat.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Diffstat (limited to 'block/mirror.c')
-rw-r--r--block/mirror.c20
1 files changed, 18 insertions, 2 deletions
diff --git a/block/mirror.c b/block/mirror.c
index 4be06a5..8888cea 100644
--- a/block/mirror.c
+++ b/block/mirror.c
@@ -165,6 +165,8 @@ 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) {
@@ -291,8 +293,22 @@ 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;
}