block: vhdx - add log write support
This adds support for writing to the VHDX log.
For spec details, see VHDX Specification Format v1.00:
https://www.microsoft.com/en-us/download/details.aspx?id=34750
There are a few limitations to this log support:
1.) There is no caching yet
2.) The log is flushed after each entry
The primary write interface, vhdx_log_write_and_flush(), performs a log
write followed by an immediate flush of the log.
As each log entry sector is a minimum of 4KB, partial sector writes are
filled in with data from the disk write destination.
If the current file log GUID is 0, a new GUID is generated and updated
in the header.
Signed-off-by: Jeff Cody <jcody@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
diff --git a/block/vhdx.h b/block/vhdx.h
index d906559..6abbf50 100644
--- a/block/vhdx.h
+++ b/block/vhdx.h
@@ -398,6 +398,9 @@
int vhdx_parse_log(BlockDriverState *bs, BDRVVHDXState *s, bool *flushed);
+int vhdx_log_write_and_flush(BlockDriverState *bs, BDRVVHDXState *s,
+ void *data, uint32_t length, uint64_t offset);
+
static inline void leguid_to_cpus(MSGUID *guid)
{
le32_to_cpus(&guid->data1);
