From c7c2769c0e5769eaad9d968fe2161505b657e02a Mon Sep 17 00:00:00 2001 From: "Denis V. Lunev" Date: Thu, 14 Jul 2016 16:33:28 +0300 Subject: [PATCH] mirror: efficiently zero out target With a bdrv_co_write_zeroes method on a target BDS and when this method is working as indicated by the bdrv_can_write_zeroes_with_unmap(), zeroes will not be placed into the wire. Thus the target could be very efficiently zeroed out. This should be done with the largest chunk possible. Signed-off-by: Denis V. Lunev Reviewed-by: Vladimir Sementsov-Ogievskiy Reviewed-by: Fam Zheng Message-id: 1468503209-19498-8-git-send-email-den@openvz.org CC: Stefan Hajnoczi CC: Kevin Wolf CC: Max Reitz CC: Jeff Cody CC: Eric Blake Signed-off-by: Jeff Cody --- block/mirror.c | 28 ++++++++++++++++++++++++++-- 1 file changed, 26 insertions(+), 2 deletions(-) diff --git a/block/mirror.c b/block/mirror.c index b7b1ded30f..0262b03989 100644 --- a/block/mirror.c +++ b/block/mirror.c @@ -538,8 +538,32 @@ static int coroutine_fn mirror_dirty_init(MirrorBlockJob *s) end = s->bdev_length / BDRV_SECTOR_SIZE; if (base == NULL && !bdrv_has_zero_init(target_bs)) { - bdrv_set_dirty_bitmap(s->dirty_bitmap, 0, end); - return 0; + if (!bdrv_can_write_zeroes_with_unmap(target_bs)) { + bdrv_set_dirty_bitmap(s->dirty_bitmap, 0, end); + return 0; + } + + for (sector_num = 0; sector_num < end; ) { + int nb_sectors = MIN(end - sector_num, + QEMU_ALIGN_DOWN(INT_MAX, s->granularity) >> BDRV_SECTOR_BITS); + + mirror_throttle(s); + + if (block_job_is_cancelled(&s->common)) { + return 0; + } + + if (s->in_flight >= MAX_IN_FLIGHT) { + trace_mirror_yield(s, s->in_flight, s->buf_free_count, -1); + mirror_wait_for_io(s); + continue; + } + + mirror_do_zero_or_discard(s, sector_num, nb_sectors, false); + sector_num += nb_sectors; + } + + mirror_drain(s); } /* First part, loop on the sectors and initialize the dirty bitmap. */