Signed-off-by: Peter Lieven <p...@kamp.de>
---
block.c | 29 +++++++++++++++++++++++++++++
include/block/block.h | 2 ++
include/block/block_int.h | 13 +++++++++++++
3 files changed, 44 insertions(+)
diff --git a/block.c b/block.c
index e7bf6af..ac35cb5 100644
--- a/block.c
+++ b/block.c
@@ -3101,6 +3101,35 @@ int bdrv_has_zero_init(BlockDriverState *bs)
return 0;
}
+bool bdrv_has_discard_zeroes(BlockDriverState *bs)
+{
+ assert(bs->drv);
+
+ if (bs->backing_hd) {
+ return false;
+ }
+ if (bs->drv->bdrv_has_discard_zeroes) {
+ return bs->drv->bdrv_has_discard_zeroes(bs);
+ }
+
+ return false;
+}
+
+bool bdrv_has_discard_write_zeroes(BlockDriverState *bs)
+{
+ assert(bs->drv);
+
+ if (bs->backing_hd || !(bs->open_flags & BDRV_O_UNMAP)) {
+ return false;
+ }
+
+ if (bs->drv->bdrv_has_discard_write_zeroes) {
+ return bs->drv->bdrv_has_discard_write_zeroes(bs);
+ }
+
+ return false;
+}
+
typedef struct BdrvCoGetBlockStatusData {
BlockDriverState *bs;
BlockDriverState *base;
diff --git a/include/block/block.h b/include/block/block.h
index b72c81a..2de226f 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -310,6 +310,8 @@ int bdrv_discard(BlockDriverState *bs, int64_t sector_num,
int nb_sectors);
int bdrv_co_discard(BlockDriverState *bs, int64_t sector_num, int nb_sectors);
int bdrv_has_zero_init_1(BlockDriverState *bs);
int bdrv_has_zero_init(BlockDriverState *bs);
+bool bdrv_has_discard_zeroes(BlockDriverState *bs);
+bool bdrv_has_discard_write_zeroes(BlockDriverState *bs);
int64_t bdrv_get_block_status(BlockDriverState *bs, int64_t sector_num,
int nb_sectors, int *pnum);
int bdrv_is_allocated(BlockDriverState *bs, int64_t sector_num, int nb_sectors,
diff --git a/include/block/block_int.h b/include/block/block_int.h
index 56e1994..cf78c3f 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -211,6 +211,19 @@ struct BlockDriver {
*/
int (*bdrv_has_zero_init)(BlockDriverState *bs);
+ /*
+ * Returns true if discarded blocks read back as zeroes.
+ */
+ bool (*bdrv_has_discard_zeroes)(BlockDriverState *bs);
+
+ /*
+ * Returns true if the driver can optimize writing zeroes by discarding
+ * sectors. It is additionally required that the block device is
+ * opened with BDRV_O_UNMAP and the that write zeroes request carries
+ * the BDRV_REQ_MAY_UNMAP flag for this to work.
+ */
+ bool (*bdrv_has_discard_write_zeroes)(BlockDriverState *bs);
+
QLIST_ENTRY(BlockDriver) list;
};
--
1.7.9.5
