The server side is fairly straightforward: we can always advertise
support for detection of fast zero, and implement it by mapping the
request to the block layer BDRV_REQ_NO_FALLBACK.
Signed-off-by: Eric Blake <ebl...@redhat.com>
---
Again, this may be worth merging with the previous patch.
---
nbd/server.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/nbd/server.c b/nbd/server.c
index 981bc3cb1151..3c0799eda87f 100644
--- a/nbd/server.c
+++ b/nbd/server.c
@@ -1514,7 +1514,8 @@ NBDExport *nbd_export_new(BlockDriverState *bs, uint64_t
dev_offset,
exp->nbdflags |= NBD_FLAG_CAN_MULTI_CONN;
}
} else {
- exp->nbdflags |= NBD_FLAG_SEND_TRIM | NBD_FLAG_SEND_WRITE_ZEROES;
+ exp->nbdflags |= (NBD_FLAG_SEND_TRIM | NBD_FLAG_SEND_WRITE_ZEROES |
+ NBD_FLAG_SEND_FAST_ZERO);
}
assert(size <= INT64_MAX - dev_offset);
exp->size = QEMU_ALIGN_DOWN(size, BDRV_SECTOR_SIZE);
@@ -2167,7 +2168,7 @@ static int nbd_co_receive_request(NBDRequestData *req,
NBDRequest *request,
if (request->type == NBD_CMD_READ && client->structured_reply) {
valid_flags |= NBD_CMD_FLAG_DF;
} else if (request->type == NBD_CMD_WRITE_ZEROES) {
- valid_flags |= NBD_CMD_FLAG_NO_HOLE;
+ valid_flags |= NBD_CMD_FLAG_NO_HOLE | NBD_CMD_FLAG_FAST_ZERO;
} else if (request->type == NBD_CMD_BLOCK_STATUS) {
valid_flags |= NBD_CMD_FLAG_REQ_ONE;
}
@@ -2306,6 +2307,9 @@ static coroutine_fn int nbd_handle_request(NBDClient
*client,
if (!(request->flags & NBD_CMD_FLAG_NO_HOLE)) {
flags |= BDRV_REQ_MAY_UNMAP;
}
+ if (request->flags & NBD_CMD_FLAG_FAST_ZERO) {
+ flags |= BDRV_REQ_NO_FALLBACK;
+ }
ret = blk_pwrite_zeroes(exp->blk, request->from + exp->dev_offset,
request->len, flags);
return nbd_send_generic_reply(client, request->handle, ret,
--
2.21.0
