From 56adc601b22b81ae4c681af6b13f38e560f16867 Mon Sep 17 00:00:00 2001 From: Kevin Wolf Date: Wed, 11 Dec 2013 19:50:32 +0100 Subject: [PATCH 04/37] block: Inherit opt_transfer_length MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Message-id: <1392117622-28812-5-git-send-email-kwolf@redhat.com> Patchwork-id: 57169 O-Subject: [RHEL-7.0 qemu-kvm PATCH v2 04/37] block: Inherit opt_transfer_length Bugzilla: 748906 RH-Acked-by: Laszlo Ersek RH-Acked-by: Stefan Hajnoczi RH-Acked-by: Max Reitz When there is a format driver between the backend, it's not guaranteed that exposing the opt_transfer_length for the format driver results in the optimal requests (because of fragmentation etc.), but it can't make things worse, so let's just do it. Signed-off-by: Kevin Wolf Reviewed-by: Wenchao Xia Reviewed-by: Max Reitz Reviewed-by: Benoît Canet (cherry picked from commit 466ad822deef3a03757d505218a52993c5d56b5d) Signed-off-by: Kevin Wolf --- block.c | 20 +++++++++++++++++++- 1 file changed, 19 insertions(+), 1 deletion(-) --- block.c | 20 +++++++++++++++++++- 1 files changed, 19 insertions(+), 1 deletions(-) diff --git a/block.c b/block.c index 26eebcc..8b36d05 100644 --- a/block.c +++ b/block.c @@ -452,7 +452,25 @@ static int bdrv_refresh_limits(BlockDriverState *bs) memset(&bs->bl, 0, sizeof(bs->bl)); - if (drv && drv->bdrv_refresh_limits) { + if (!drv) { + return 0; + } + + /* Take some limits from the children as a default */ + if (bs->file) { + bdrv_refresh_limits(bs->file); + bs->bl.opt_transfer_length = bs->file->bl.opt_transfer_length; + } + + if (bs->backing_hd) { + bdrv_refresh_limits(bs->backing_hd); + bs->bl.opt_transfer_length = + MAX(bs->bl.opt_transfer_length, + bs->backing_hd->bl.opt_transfer_length); + } + + /* Then let the driver override it */ + if (drv->bdrv_refresh_limits) { return drv->bdrv_refresh_limits(bs); } -- 1.7.1