[PATCH 6/7] block/rbd: add write zeroes support

[Peter Lieven]

Signed-off-by: Peter Lieven <pl@kamp.de>
---
 block/rbd.c | 31 ++++++++++++++++++++++++++++++-
 1 file changed, 30 insertions(+), 1 deletion(-)

diff --git a/block/rbd.c b/block/rbd.c
index 2d77d0007f..27b4404adf 100644
--- a/block/rbd.c
+++ b/block/rbd.c
@@ -63,7 +63,8 @@ typedef enum {
     RBD_AIO_READ,
     RBD_AIO_WRITE,
     RBD_AIO_DISCARD,
-    RBD_AIO_FLUSH
+    RBD_AIO_FLUSH,
+    RBD_AIO_WRITE_ZEROES
 } RBDAIOCmd;
 
 typedef struct BDRVRBDState {
@@ -221,8 +222,12 @@ done:
 
 static void qemu_rbd_refresh_limits(BlockDriverState *bs, Error **errp)
 {
+    BDRVRBDState *s = bs->opaque;
     /* XXX Does RBD support AIO on less than 512-byte alignment? */
     bs->bl.request_alignment = 512;
+#ifdef LIBRBD_SUPPORTS_WRITE_ZEROES
+    bs->bl.pwrite_zeroes_alignment = s->object_size;
+#endif
 }
 
 
@@ -695,6 +700,9 @@ static int qemu_rbd_open(BlockDriverState *bs, QDict 
*options, int flags,
     }
 
     s->aio_context = bdrv_get_aio_context(bs);
+#ifdef LIBRBD_SUPPORTS_WRITE_ZEROES
+    bs->supported_zero_flags = BDRV_REQ_MAY_UNMAP;
+#endif
 
     /* When extending regular files, we get zeros from the OS */
     bs->supported_truncate_flags = BDRV_REQ_ZERO_WRITE;
@@ -808,6 +816,11 @@ static int coroutine_fn qemu_rbd_start_co(BlockDriverState 
*bs,
     case RBD_AIO_FLUSH:
         r = rbd_aio_flush(s->image, c);
         break;
+#ifdef LIBRBD_SUPPORTS_WRITE_ZEROES
+    case RBD_AIO_WRITE_ZEROES:
+        r = rbd_aio_write_zeroes(s->image, offset, bytes, c, 0, 0);
+        break;
+#endif
     default:
         r = -EINVAL;
     }
@@ -880,6 +893,19 @@ static int coroutine_fn 
qemu_rbd_co_pdiscard(BlockDriverState *bs,
     return qemu_rbd_start_co(bs, offset, count, NULL, 0, RBD_AIO_DISCARD);
 }
 
+#ifdef LIBRBD_SUPPORTS_WRITE_ZEROES
+static int
+coroutine_fn qemu_rbd_co_pwrite_zeroes(BlockDriverState *bs, int64_t offset,
+                                      int count, BdrvRequestFlags flags)
+{
+    if (!(flags & BDRV_REQ_MAY_UNMAP)) {
+        return -ENOTSUP;
+    }
+    return qemu_rbd_start_co(bs, offset, count, NULL, flags,
+                             RBD_AIO_WRITE_ZEROES);
+}
+#endif
+
 static int qemu_rbd_getinfo(BlockDriverState *bs, BlockDriverInfo *bdi)
 {
     BDRVRBDState *s = bs->opaque;
@@ -1108,6 +1134,9 @@ static BlockDriver bdrv_rbd = {
     .bdrv_co_pwritev        = qemu_rbd_co_pwritev,
     .bdrv_co_flush_to_disk  = qemu_rbd_co_flush,
     .bdrv_co_pdiscard       = qemu_rbd_co_pdiscard,
+#ifdef LIBRBD_SUPPORTS_WRITE_ZEROES
+    .bdrv_co_pwrite_zeroes  = qemu_rbd_co_pwrite_zeroes,
+#endif
 
     .bdrv_snapshot_create   = qemu_rbd_snap_create,
     .bdrv_snapshot_delete   = qemu_rbd_snap_remove,
-- 
2.17.1