Blame SOURCES/kvm-block-use-bdrv_has_zero_init-to-return-BDRV_BLOCK_ZE.patch

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From 95dd0c697b1b924c282cad302fc7f5af3330993d Mon Sep 17 00:00:00 2001
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From: Paolo Bonzini <pbonzini@redhat.com>
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Date: Fri, 18 Oct 2013 08:14:40 +0200
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Subject: [PATCH 15/81] block: use bdrv_has_zero_init to return BDRV_BLOCK_ZERO
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RH-Author: Paolo Bonzini <pbonzini@redhat.com>
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Message-id: <1382084091-16636-16-git-send-email-pbonzini@redhat.com>
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Patchwork-id: 54998
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O-Subject: [RHEL 7.0 qemu-kvm PATCH 15/26] block: use bdrv_has_zero_init to return BDRV_BLOCK_ZERO
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Bugzilla: 989646
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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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RH-Acked-by: Kevin Wolf <kwolf@redhat.com>
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Alternatively, this could use a "discard zeroes data" flag returned
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by bdrv_get_info.
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Reviewed-by: Eric Blake <eblake@redhat.com>
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Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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(cherry picked from commit 415b5b013ce74126e71459b922a92377918ae2ef)
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---
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 block.c | 11 ++++++++++-
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 1 file changed, 10 insertions(+), 1 deletion(-)
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Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
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---
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 block.c |   11 ++++++++++-
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 1 files changed, 10 insertions(+), 1 deletions(-)
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diff --git a/block.c b/block.c
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index 8c583bf..00bc3b2 100644
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--- a/block.c
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+++ b/block.c
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@@ -3041,6 +3041,7 @@ static int64_t coroutine_fn bdrv_co_get_block_status(BlockDriverState *bs,
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 {
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     int64_t length;
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     int64_t n;
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+    int64_t ret;
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     length = bdrv_getlength(bs);
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     if (length < 0) {
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@@ -3062,7 +3063,15 @@ static int64_t coroutine_fn bdrv_co_get_block_status(BlockDriverState *bs,
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         return BDRV_BLOCK_DATA;
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     }
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-    return bs->drv->bdrv_co_get_block_status(bs, sector_num, nb_sectors, pnum);
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+    ret = bs->drv->bdrv_co_get_block_status(bs, sector_num, nb_sectors, pnum);
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+    if (ret < 0) {
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+        return ret;
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+    }
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+
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+    if (!(ret & BDRV_BLOCK_DATA) && bdrv_has_zero_init(bs)) {
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+        ret |= BDRV_BLOCK_ZERO;
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+    }
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+    return ret;
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 }
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 /* Coroutine wrapper for bdrv_get_block_status() */
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-- 
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1.7.1
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