From ea7c8b7754c520534feb01f1ae6f54b37a6e7c85 Mon Sep 17 00:00:00 2001 From: Fam Zheng Date: Mon, 13 Jul 2015 03:27:21 +0200 Subject: [PATCH 03/58] mirror: Do zero write on target if sectors not allocated Message-id: <1436758047-4639-4-git-send-email-famz@redhat.com> Patchwork-id: 66961 O-Subject: [RHEL-7.2 qemu-kvm-rhev PATCH 3/9] mirror: Do zero write on target if sectors not allocated Bugzilla: 1242316 RH-Acked-by: Jeffrey Cody RH-Acked-by: Stefan Hajnoczi RH-Acked-by: Paolo Bonzini 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 Signed-off-by: Stefan Hajnoczi (cherry picked from commit dcfb3beb5130694b76b57de109619fcbf9c7e5b5) Signed-off-by: Fam Zheng Signed-off-by: Miroslav Rezanina --- block/mirror.c | 20 ++++++++++++++++++-- 1 file changed, 18 insertions(+), 2 deletions(-) diff --git a/block/mirror.c b/block/mirror.c index 1814523..bd079a4 100644 --- a/block/mirror.c +++ b/block/mirror.c @@ -168,6 +168,8 @@ 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) { @@ -296,8 +298,22 @@ 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; } -- 1.8.3.1