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From 455a0cc4e93815b2cd2741554076029f2c365e25 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 08:14:36 +0200
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Subject: [PATCH 11/81] block: make bdrv_has_zero_init return false for copy-on-write-images
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RH-Author: Paolo Bonzini <pbonzini@redhat.com>
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Message-id: <1382084091-16636-12-git-send-email-pbonzini@redhat.com>
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Patchwork-id: 54994
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O-Subject: [RHEL 7.0 qemu-kvm PATCH 11/26] block: make bdrv_has_zero_init return false for copy-on-write-images
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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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This helps implementing is_allocated on top of get_block_status.
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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 11212d8fa08a4e5bd56bb4f6877f9a4c0439a02b)
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---
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block.c | 5 +++++
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qemu-img.c | 9 +--------
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2 files changed, 6 insertions(+), 8 deletions(-)
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Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
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---
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block.c | 5 +++++
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qemu-img.c | 9 +--------
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2 files changed, 6 insertions(+), 8 deletions(-)
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diff --git a/block.c b/block.c
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index d838a3c..f5d6658 100644
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--- a/block.c
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+++ b/block.c
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@@ -2998,6 +2998,11 @@ int bdrv_has_zero_init(BlockDriverState *bs)
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{
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assert(bs->drv);
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+ /* If BS is a copy on write image, it is initialized to
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+ the contents of the base image, which may not be zeroes. */
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+ if (bs->backing_hd) {
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+ return 0;
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+ }
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if (bs->drv->bdrv_has_zero_init) {
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return bs->drv->bdrv_has_zero_init(bs);
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}
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diff --git a/qemu-img.c b/qemu-img.c
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index 71cbc59..a9aabd5 100644
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--- a/qemu-img.c
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+++ b/qemu-img.c
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@@ -1511,14 +1511,7 @@ static int img_convert(int argc, char **argv)
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should add a specific call to have the info to go faster */
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buf1 = buf;
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while (n > 0) {
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- /* If the output image is being created as a copy on write image,
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- copy all sectors even the ones containing only NUL bytes,
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- because they may differ from the sectors in the base image.
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-
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- If the output is to a host device, we also write out
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- sectors that are entirely 0, since whatever data was
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- already there is garbage, not 0s. */
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- if (!has_zero_init || out_baseimg ||
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+ if (!has_zero_init ||
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is_allocated_sectors_min(buf1, n, &n1, min_sparse)) {
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ret = bdrv_write(out_bs, sector_num, buf1, n1);
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if (ret < 0) {
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--
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1.7.1
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