From 49b4262336e2875280d7d539851b5b318a86bc39 Mon Sep 17 00:00:00 2001

From: Asias He <asias@redhat.com>

Date: Thu, 12 Sep 2013 07:39:33 +0200

Subject: [PATCH 13/29] block: Introduce bs->zero_beyond_eof

RH-Author: Asias He <asias@redhat.com>

Message-id: <1378971575-22416-3-git-send-email-asias@redhat.com>

Patchwork-id: 54326

O-Subject: [RHEL7.0 qemu-kvm PATCH 2/4] block: Introduce bs->zero_beyond_eof

Bugzilla: 1007226

RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>

RH-Acked-by: Paolo Bonzini <pbonzini@redhat.com>

RH-Acked-by: Fam Zheng <famz@redhat.com>

BZ: https://bugzilla.redhat.com/show_bug.cgi?id=1007226

Brew: https://brewweb.devel.redhat.com/taskinfo?taskID=6275752

In 4146b46c42e0989cb5842e04d88ab6ccb1713a48 (block: Produce zeros when

protocols reading beyond end of file), we break qemu-iotests ./check

-qcow2 022. This happens because qcow2 temporarily sets ->growable = 1

for vmstate accesses (which are stored beyond the end of regular image

data).

We introduce the bs->zero_beyond_eof to allow qcow2_load_vmstate() to

disable ->zero_beyond_eof temporarily in addition to enable ->growable.

[Since the broken patch "block: Produce zeros when protocols reading

beyond end of file" has not been merged yet, I have applied this fix

*first* and will then apply the next patch to keep the tree bisectable.

-- Stefan]

Suggested-by: Stefan Hajnoczi <stefanha@redhat.com>

Signed-off-by: Asias He <asias@redhat.com>

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

(cherry picked from commit 0d51b4debee6fb322751a57097a1d675c7a7c38d)

---

 block.c                   | 2 ++

 block/qcow2.c             | 3 +++

 include/block/block_int.h | 3 +++

 3 files changed, 8 insertions(+)

Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>

---

 block.c                   |    2 ++

 block/qcow2.c             |    3 +++

 include/block/block_int.h |    3 +++

 3 files changed, 8 insertions(+), 0 deletions(-)

diff --git a/block.c b/block.c

index f4a89b9..dbcad0e 100644

--- a/block.c

+++ b/block.c

@@ -708,6 +708,7 @@ static int bdrv_open_common(BlockDriverState *bs, BlockDriverState *file,

     bs->open_flags = flags;

     bs->buffer_alignment = 512;

+    bs->zero_beyond_eof = true;

     open_flags = bdrv_open_flags(bs, flags);

     bs->read_only = !(open_flags & BDRV_O_RDWR);

@@ -1407,6 +1408,7 @@ void bdrv_close(BlockDriverState *bs)

         bs->valid_key = 0;

         bs->sg = 0;

         bs->growable = 0;

+        bs->zero_beyond_eof = false;

         QDECREF(bs->options);

         bs->options = NULL;

diff --git a/block/qcow2.c b/block/qcow2.c

index abdc202..70da5bd 100644

--- a/block/qcow2.c

+++ b/block/qcow2.c

@@ -1722,12 +1722,15 @@ static int qcow2_load_vmstate(BlockDriverState *bs, uint8_t *buf,

 {

     BDRVQcowState *s = bs->opaque;

     int growable = bs->growable;

+    bool zero_beyond_eof = bs->zero_beyond_eof;

     int ret;

     BLKDBG_EVENT(bs->file, BLKDBG_VMSTATE_LOAD);

     bs->growable = 1;

+    bs->zero_beyond_eof = false;

     ret = bdrv_pread(bs, qcow2_vm_state_offset(s) + pos, buf, size);

     bs->growable = growable;

+    bs->zero_beyond_eof = zero_beyond_eof;

     return ret;

 }

diff --git a/include/block/block_int.h b/include/block/block_int.h

index 6078dd3..267be48 100644

--- a/include/block/block_int.h

+++ b/include/block/block_int.h

@@ -268,6 +268,9 @@ struct BlockDriverState {

     /* Whether the disk can expand beyond total_sectors */

     int growable;

+    /* Whether produces zeros when read beyond eof */

+    bool zero_beyond_eof;

+

     /* the memory alignment required for the buffers handled by this driver */

     int buffer_alignment;

-- 

1.7.1