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[Qemu-devel] [PATCH] qcow2: Unset zero_beyond_eof in save_vmstate
From: |
Max Reitz |
Subject: |
[Qemu-devel] [PATCH] qcow2: Unset zero_beyond_eof in save_vmstate |
Date: |
Sun, 20 Oct 2013 21:52:35 +0200 |
Saving the VM state is done using bdrv_pwrite. This function may perform
a read-modify-write, which in this case results in data being read from
beyond the end of the virtual disk. Since we are actually trying to
access an area which is not a part of the virtual disk, zero_beyond_eof
has to be set to false before performing the partial write, otherwise
the VM state may become corrupted.
Signed-off-by: Max Reitz <address@hidden>
---
Follow-up to (depends on):
- qcow2: Restore total_sectors value in save_vmstate
---
block/qcow2.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/block/qcow2.c b/block/qcow2.c
index 5c05bb5..3e11f25 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -1941,12 +1941,15 @@ static int qcow2_save_vmstate(BlockDriverState *bs,
QEMUIOVector *qiov,
BDRVQcowState *s = bs->opaque;
int64_t total_sectors = bs->total_sectors;
int growable = bs->growable;
+ bool zero_beyond_eof = bs->zero_beyond_eof;
int ret;
BLKDBG_EVENT(bs->file, BLKDBG_VMSTATE_SAVE);
bs->growable = 1;
+ bs->zero_beyond_eof = false;
ret = bdrv_pwritev(bs, qcow2_vm_state_offset(s) + pos, qiov);
bs->growable = growable;
+ bs->zero_beyond_eof = zero_beyond_eof;
// bdrv_co_do_writev will have increased the total_sectors value to include
// the VM state - the VM state is however not an actual part of the block
// device, therefore, we need to restore the old value.
--
1.8.3.1
- [Qemu-devel] [PATCH] qcow2: Unset zero_beyond_eof in save_vmstate,
Max Reitz <=