From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:50361) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YsqQE-00005y-JI for qemu-devel@nongnu.org; Thu, 14 May 2015 06:31:23 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1YsqQD-0005jQ-La for qemu-devel@nongnu.org; Thu, 14 May 2015 06:31:22 -0400 Sender: Paolo Bonzini Message-ID: <5554796E.6020509@redhat.com> Date: Thu, 14 May 2015 12:31:10 +0200 From: Paolo Bonzini MIME-Version: 1.0 References: <1431431315-32079-1-git-send-email-famz@redhat.com> <1431431315-32079-3-git-send-email-famz@redhat.com> In-Reply-To: <1431431315-32079-3-git-send-email-famz@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v3 2/6] block: Fix dirty bitmap in bdrv_co_discard List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Fam Zheng , qemu-devel@nongnu.org Cc: Kevin Wolf , qemu-block@nongnu.org, Jeff Cody , Stefan Hajnoczi , jsnow@redhat.com, wangxiaolong@ucloud.cn On 12/05/2015 13:48, Fam Zheng wrote: > Unsetting dirty globally with discard is not very correct. The discard may zero > out sectors (depending on can_write_zeroes_with_unmap), we should replicate > this change to destinition side to make sure that the guest sees the same data. > > Calling bdrv_reset_dirty also troubles mirror job because the hbitmap iterator > doesn't expect unsetting of bits after current position. > > So let's do it the opposite way which fixes both problems: set the dirty bits > if we are to discard it. > > Reported-by: wangxiaolong@ucloud.cn > Signed-off-by: Fam Zheng Reviewed-by: Paolo Bonzini > --- > block/io.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/block/io.c b/block/io.c > index 1ce62c4..809688b 100644 > --- a/block/io.c > +++ b/block/io.c > @@ -2343,8 +2343,6 @@ int coroutine_fn bdrv_co_discard(BlockDriverState *bs, int64_t sector_num, > return -EROFS; > } > > - bdrv_reset_dirty(bs, sector_num, nb_sectors); > - > /* Do nothing if disabled. */ > if (!(bs->open_flags & BDRV_O_UNMAP)) { > return 0; > @@ -2354,6 +2352,8 @@ int coroutine_fn bdrv_co_discard(BlockDriverState *bs, int64_t sector_num, > return 0; > } > > + bdrv_set_dirty(bs, sector_num, nb_sectors); > + > max_discard = MIN_NON_ZERO(bs->bl.max_discard, BDRV_REQUEST_MAX_SECTORS); > while (nb_sectors > 0) { > int ret; >