Commit dcfb3beb authored by Fam Zheng's avatar Fam Zheng Committed by Stefan Hajnoczi
Browse files

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: default avatarFam Zheng <famz@redhat.com>
Signed-off-by: default avatarStefan Hajnoczi <stefanha@redhat.com>
parent 0fc9f8ea

block/mirror.c

+18 −2
Original line number Diff line number Diff line
@@ -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);



    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;

}