From cbb0018e9f8e4c3fdaf71410d5f91d43151936ce Mon Sep 17 00:00:00 2001
From: Anthony Liguori <aliguori@redhat.com>
Date: Mon, 8 Aug 2011 16:13:55 -0700
Subject: [RHEL6 qemu-kvm PATCH 12/19] block: add BDRV_O_INCOMING migration consistency hint
RH-Author: Anthony Liguori <aliguori@redhat.com>
Message-id: <1312820040-2612-13-git-send-email-aliguori@redhat.com>
Patchwork-id: 31110
O-Subject: [RHEL6.2 qemu PATCH 12/17] block: add BDRV_O_INCOMING migration consistency hint
Bugzilla: 633380
RH-Acked-by: Kevin Wolf <kwolf@redhat.com>
RH-Acked-by: Paolo Bonzini <pbonzini@redhat.com>
From: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Add a flag to indicate that incoming migration is pending and care needs
to be taken for data consistency. Block drivers should not modify the
image file before incoming migration is complete since the migration
source host is still using the image file.
Note that a simpler alternative would be this 1-liner:
dinfo->bdrv->read_only = incoming_expected;
Unfortunately this is not possible because too many other places in QEMU
test bdrv_is_read_only() and use it for their own evil purposes. For
example, ide_init_drive() will error out because read-only harddisks are
not supported. We're mixing guest and host side read-only concepts so
this simpler alternative does not work.
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Anthony Liguori <aliguori@redhat.com>
Bugzilla: 633380
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
---
block.h | 1 +
blockdev.c | 9 ++++++++-
2 files changed, 9 insertions(+), 1 deletions(-)
diff --git a/block.h b/block.h
index 4a87ea2..54c5527 100644
--- a/block.h
+++ b/block.h
@@ -33,6 +33,7 @@ typedef struct QEMUSnapshotInfo {
#define BDRV_O_NATIVE_AIO 0x0080 /* use native AIO instead of the thread pool */
#define BDRV_O_NO_BACKING 0x0100 /* don't open the backing file */
#define BDRV_O_NO_FLUSH 0x0200 /* disable flushing on this disk */
+#define BDRV_O_INCOMING 0x0800 /* consistency hint for incoming migration */
#define BDRV_O_CACHE_MASK (BDRV_O_NOCACHE | BDRV_O_CACHE_WB)
diff --git a/blockdev.c b/blockdev.c
index 148e99e..88a7c64 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -223,7 +223,14 @@ static int parse_block_error_action(const char *buf, int is_read)
static int drive_open(DriveInfo *dinfo)
{
- int res = bdrv_open(dinfo->bdrv, dinfo->file, dinfo->bdrv_flags, dinfo->drv);
+ int res;
+ int bdrv_flags = dinfo->bdrv_flags;
+
+ if (incoming_expected) {
+ bdrv_flags |= BDRV_O_INCOMING;
+ }
+
+ res = bdrv_open(dinfo->bdrv, dinfo->file, bdrv_flags, dinfo->drv);
if (res < 0) {
error_report("could not open disk image %s: %s",
--
1.7.3.2