[PATCH V3 5/6] block/rbd: add write zeroes support

[Peter Lieven]

Signed-off-by: Peter Lieven <pl@kamp.de>
---
 block/rbd.c | 37 ++++++++++++++++++++++++++++++++++++-
 1 file changed, 36 insertions(+), 1 deletion(-)

diff --git a/block/rbd.c b/block/rbd.c
index 0d8612a988..ee13f08a74 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 {
@@ -705,6 +706,10 @@ static int qemu_rbd_open(BlockDriverState *bs, QDict 
*options, int flags,
         }
     }
 
+#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;
 
@@ -818,6 +823,18 @@ 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: {
+        int zero_flags = 0;
+#ifdef RBD_WRITE_ZEROES_FLAG_THICK_PROVISION
+        if (!(flags & BDRV_REQ_MAY_UNMAP)) {
+            zero_flags = RBD_WRITE_ZEROES_FLAG_THICK_PROVISION;
+        }
+#endif
+        r = rbd_aio_write_zeroes(s->image, offset, bytes, c, zero_flags, 0);
+        break;
+    }
+#endif
     default:
         r = -EINVAL;
     }
@@ -888,6 +905,21 @@ 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)
+{
+#ifndef RBD_WRITE_ZEROES_FLAG_THICK_PROVISION
+    if (!(flags & BDRV_REQ_MAY_UNMAP)) {
+        return -ENOTSUP;
+    }
+#endif
+    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;
@@ -1113,6 +1145,9 @@ 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