qed: add .bdrv_co_write_zeroes() support
Zero writes are a dedicated interface for writing regions of zeroes into
the image file. If clusters are not yet allocated it is possible to use
an efficient metadata representation which keeps the image file compact
and does not store individual zero bytes.
Implementing this for the QED image format is fairly straightforward.
The only issue is that when a zero write touches an existing cluster we
have to allocate a bounce buffer and perform a regular write.
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
diff --git a/block/qed.h b/block/qed.h
index abed147..62624a1 100644
--- a/block/qed.h
+++ b/block/qed.h
@@ -125,6 +125,7 @@
enum {
QED_AIOCB_WRITE = 0x0001, /* read or write? */
+ QED_AIOCB_ZERO = 0x0002, /* zero write, used with QED_AIOCB_WRITE */
};
typedef struct QEDAIOCB {
