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