Blame SOURCES/kvm-block-return-BDRV_BLOCK_ZERO-past-end-of-backing-fil.patch

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From 231ea3db5b4c6b9de25fa62b2e6c39ebc4987a6f 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 08:14:41 +0200
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Subject: [PATCH 16/81] block: return BDRV_BLOCK_ZERO past end of backing file
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RH-Author: Paolo Bonzini <pbonzini@redhat.com>
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Message-id: <1382084091-16636-17-git-send-email-pbonzini@redhat.com>
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Patchwork-id: 54999
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O-Subject: [RHEL 7.0 qemu-kvm PATCH 16/26] block: return BDRV_BLOCK_ZERO past end of backing file
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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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If the sectors are unallocated and we are past the end of the
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backing file, they will read as zero.
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Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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(cherry picked from commit f0ad5712d5d15ff272b9e107910be4aae468fb3d)
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---
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 block.c | 12 ++++++++++--
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 1 file changed, 10 insertions(+), 2 deletions(-)
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Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
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---
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 block.c |   12 ++++++++++--
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 1 files changed, 10 insertions(+), 2 deletions(-)
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diff --git a/block.c b/block.c
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index 00bc3b2..36a2f24 100644
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--- a/block.c
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+++ b/block.c
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@@ -3068,8 +3068,16 @@ static int64_t coroutine_fn bdrv_co_get_block_status(BlockDriverState *bs,
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         return ret;
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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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+    if (!(ret & BDRV_BLOCK_DATA)) {
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+        if (bdrv_has_zero_init(bs)) {
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+            ret |= BDRV_BLOCK_ZERO;
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+        } else {
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+            BlockDriverState *bs2 = bs->backing_hd;
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+            int64_t length2 = bdrv_getlength(bs2);
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+            if (length2 >= 0 && sector_num >= (length2 >> BDRV_SECTOR_BITS)) {
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+                ret |= BDRV_BLOCK_ZERO;
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+            }
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+        }
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     }
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     return ret;
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 }
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-- 
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1.7.1
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