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From 49b4262336e2875280d7d539851b5b318a86bc39 Mon Sep 17 00:00:00 2001
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From: Asias He <asias@redhat.com>
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Date: Thu, 12 Sep 2013 07:39:33 +0200
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Subject: [PATCH 13/29] block: Introduce bs->zero_beyond_eof
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RH-Author: Asias He <asias@redhat.com>
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Message-id: <1378971575-22416-3-git-send-email-asias@redhat.com>
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Patchwork-id: 54326
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O-Subject: [RHEL7.0 qemu-kvm PATCH 2/4] block: Introduce bs->zero_beyond_eof
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Bugzilla: 1007226
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RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
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RH-Acked-by: Paolo Bonzini <pbonzini@redhat.com>
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RH-Acked-by: Fam Zheng <famz@redhat.com>
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BZ: https://bugzilla.redhat.com/show_bug.cgi?id=1007226
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Brew: https://brewweb.devel.redhat.com/taskinfo?taskID=6275752
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In 4146b46c42e0989cb5842e04d88ab6ccb1713a48 (block: Produce zeros when
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protocols reading beyond end of file), we break qemu-iotests ./check
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-qcow2 022. This happens because qcow2 temporarily sets ->growable = 1
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for vmstate accesses (which are stored beyond the end of regular image
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data).
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We introduce the bs->zero_beyond_eof to allow qcow2_load_vmstate() to
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disable ->zero_beyond_eof temporarily in addition to enable ->growable.
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[Since the broken patch "block: Produce zeros when protocols reading
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beyond end of file" has not been merged yet, I have applied this fix
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*first* and will then apply the next patch to keep the tree bisectable.
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-- Stefan]
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Suggested-by: Stefan Hajnoczi <stefanha@redhat.com>
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Signed-off-by: Asias He <asias@redhat.com>
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Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
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(cherry picked from commit 0d51b4debee6fb322751a57097a1d675c7a7c38d)
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---
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 block.c                   | 2 ++
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 block/qcow2.c             | 3 +++
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 include/block/block_int.h | 3 +++
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 3 files changed, 8 insertions(+)
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Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
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---
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 block.c                   |    2 ++
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 block/qcow2.c             |    3 +++
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 include/block/block_int.h |    3 +++
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 3 files changed, 8 insertions(+), 0 deletions(-)
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diff --git a/block.c b/block.c
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index f4a89b9..dbcad0e 100644
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--- a/block.c
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+++ b/block.c
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@@ -708,6 +708,7 @@ static int bdrv_open_common(BlockDriverState *bs, BlockDriverState *file,
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     bs->open_flags = flags;
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     bs->buffer_alignment = 512;
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+    bs->zero_beyond_eof = true;
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     open_flags = bdrv_open_flags(bs, flags);
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     bs->read_only = !(open_flags & BDRV_O_RDWR);
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@@ -1407,6 +1408,7 @@ void bdrv_close(BlockDriverState *bs)
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         bs->valid_key = 0;
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         bs->sg = 0;
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         bs->growable = 0;
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+        bs->zero_beyond_eof = false;
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         QDECREF(bs->options);
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         bs->options = NULL;
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diff --git a/block/qcow2.c b/block/qcow2.c
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index abdc202..70da5bd 100644
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--- a/block/qcow2.c
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+++ b/block/qcow2.c
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@@ -1722,12 +1722,15 @@ static int qcow2_load_vmstate(BlockDriverState *bs, uint8_t *buf,
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 {
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     BDRVQcowState *s = bs->opaque;
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     int growable = bs->growable;
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+    bool zero_beyond_eof = bs->zero_beyond_eof;
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     int ret;
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     BLKDBG_EVENT(bs->file, BLKDBG_VMSTATE_LOAD);
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     bs->growable = 1;
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+    bs->zero_beyond_eof = false;
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     ret = bdrv_pread(bs, qcow2_vm_state_offset(s) + pos, buf, size);
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     bs->growable = growable;
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+    bs->zero_beyond_eof = zero_beyond_eof;
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     return ret;
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 }
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diff --git a/include/block/block_int.h b/include/block/block_int.h
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index 6078dd3..267be48 100644
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--- a/include/block/block_int.h
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+++ b/include/block/block_int.h
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@@ -268,6 +268,9 @@ struct BlockDriverState {
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     /* Whether the disk can expand beyond total_sectors */
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     int growable;
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+    /* Whether produces zeros when read beyond eof */
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+    bool zero_beyond_eof;
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+
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     /* the memory alignment required for the buffers handled by this driver */
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     int buffer_alignment;
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-- 
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1.7.1
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