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Blame SOURCES/kvm-block-honour-BlockLimits-in-bdrv_co_discard.patch.patch.patch

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From f3ba81ab59dcb21f79cf2f2053206d6b03431658 Mon Sep 17 00:00:00 2001
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Message-Id: <f3ba81ab59dcb21f79cf2f2053206d6b03431658.1389014116.git.minovotn@redhat.com>
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In-Reply-To: <c8cc35838d42aa286242772d97e3a9be7bb786ba.1389014116.git.minovotn@redhat.com>
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References: <c8cc35838d42aa286242772d97e3a9be7bb786ba.1389014116.git.minovotn@redhat.com>
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From: Paolo Bonzini <pbonzini@redhat.com>
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Date: Mon, 9 Dec 2013 14:09:03 +0100
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Subject: [PATCH 15/50] block: honour BlockLimits in bdrv_co_discard
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RH-Author: Paolo Bonzini <pbonzini@redhat.com>
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Message-id: <1386598178-11845-18-git-send-email-pbonzini@redhat.com>
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Patchwork-id: 56053
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O-Subject: [RHEL 7.0 qemu-kvm PATCH 17/52] block: honour BlockLimits in bdrv_co_discard
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Bugzilla: 1007815
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RH-Acked-by: Jeffrey Cody <jcody@redhat.com>
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RH-Acked-by: Fam Zheng <famz@redhat.com>
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RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
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From: Peter Lieven <pl@kamp.de>
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Reviewed-by: Eric Blake <eblake@redhat.com>
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Signed-off-by: Peter Lieven <pl@kamp.de>
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Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
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(cherry picked from commit 6f14da5247076bde1e00444f6d5b2b7ca8075a09)
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---
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 block.c | 37 ++++++++++++++++++++++++++++++++++++-
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 1 file changed, 36 insertions(+), 1 deletion(-)
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Signed-off-by: Michal Novotny <minovotn@redhat.com>
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---
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 block.c | 37 ++++++++++++++++++++++++++++++++++++-
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 1 file changed, 36 insertions(+), 1 deletion(-)
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diff --git a/block.c b/block.c
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index 2ed9aa9..23dbafd 100644
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--- a/block.c
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+++ b/block.c
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@@ -4424,6 +4424,11 @@ static void coroutine_fn bdrv_discard_co_entry(void *opaque)
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     rwco->ret = bdrv_co_discard(rwco->bs, rwco->sector_num, rwco->nb_sectors);
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 }
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+/* if no limit is specified in the BlockLimits use a default
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+ * of 32768 512-byte sectors (16 MiB) per request.
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+ */
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+#define MAX_DISCARD_DEFAULT 32768
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+
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 int coroutine_fn bdrv_co_discard(BlockDriverState *bs, int64_t sector_num,
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                                  int nb_sectors)
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 {
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@@ -4445,7 +4450,37 @@ int coroutine_fn bdrv_co_discard(BlockDriverState *bs, int64_t sector_num,
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     }
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     if (bs->drv->bdrv_co_discard) {
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-        return bs->drv->bdrv_co_discard(bs, sector_num, nb_sectors);
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+        int max_discard = bs->bl.max_discard ?
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+                          bs->bl.max_discard : MAX_DISCARD_DEFAULT;
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+
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+        while (nb_sectors > 0) {
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+            int ret;
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+            int num = nb_sectors;
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+
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+            /* align request */
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+            if (bs->bl.discard_alignment &&
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+                num >= bs->bl.discard_alignment &&
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+                sector_num % bs->bl.discard_alignment) {
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+                if (num > bs->bl.discard_alignment) {
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+                    num = bs->bl.discard_alignment;
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+                }
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+                num -= sector_num % bs->bl.discard_alignment;
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+            }
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+
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+            /* limit request size */
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+            if (num > max_discard) {
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+                num = max_discard;
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+            }
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+
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+            ret = bs->drv->bdrv_co_discard(bs, sector_num, num);
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+            if (ret) {
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+                return ret;
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+            }
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+
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+            sector_num += num;
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+            nb_sectors -= num;
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+        }
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+        return 0;
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     } else if (bs->drv->bdrv_aio_discard) {
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         BlockDriverAIOCB *acb;
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         CoroutineIOCompletion co = {
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-- 
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1.7.11.7
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