@@ -48,6 +48,8 @@ int nbd_client_co_pdiscard(BlockDriverState *bs, int64_t offset, int count);
int nbd_client_co_flush(BlockDriverState *bs);
int nbd_client_co_pwritev(BlockDriverState *bs, uint64_t offset,
uint64_t bytes, QEMUIOVector *qiov, int flags);
+int nbd_client_co_pwrite_zeroes(BlockDriverState *bs, int64_t offset,
+ int count, BdrvRequestFlags flags);
int nbd_client_co_preadv(BlockDriverState *bs, uint64_t offset,
uint64_t bytes, QEMUIOVector *qiov, int flags);
@@ -275,6 +275,41 @@ int nbd_client_co_pwritev(BlockDriverState *bs, uint64_t offset,
return -reply.error;
}
+int nbd_client_co_pwrite_zeroes(BlockDriverState *bs, int64_t offset,
+ int count, BdrvRequestFlags flags)
+{
+ ssize_t ret;
+ NbdClientSession *client = nbd_get_client_session(bs);
+ struct nbd_request request = {
+ .type = NBD_CMD_WRITE_ZEROES,
+ .from = offset,
+ .len = count,
+ };
+ struct nbd_reply reply;
+
+ if (!(client->nbdflags & NBD_FLAG_SEND_WRITE_ZEROES)) {
+ return -ENOTSUP;
+ }
+
+ if (flags & BDRV_REQ_FUA) {
+ assert(client->nbdflags & NBD_FLAG_SEND_FUA);
+ request.flags |= NBD_CMD_FLAG_FUA;
+ }
+ if (!(flags & BDRV_REQ_MAY_UNMAP)) {
+ request.flags |= NBD_CMD_FLAG_NO_HOLE;
+ }
+
+ nbd_coroutine_start(client, &request);
+ ret = nbd_co_send_request(bs, &request, NULL);
+ if (ret < 0) {
+ reply.error = -ret;
+ } else {
+ nbd_co_receive_reply(client, &request, &reply, NULL);
+ }
+ nbd_coroutine_end(client, &request);
+ return -reply.error;
+}
+
int nbd_client_co_flush(BlockDriverState *bs)
{
NbdClientSession *client = nbd_get_client_session(bs);
@@ -357,6 +357,7 @@ static int nbd_co_flush(BlockDriverState *bs)
static void nbd_refresh_limits(BlockDriverState *bs, Error **errp)
{
bs->bl.max_pdiscard = NBD_MAX_BUFFER_SIZE;
+ bs->bl.max_pwrite_zeroes = NBD_MAX_BUFFER_SIZE;
bs->bl.max_transfer = NBD_MAX_BUFFER_SIZE;
}
@@ -440,6 +441,7 @@ static BlockDriver bdrv_nbd = {
.bdrv_file_open = nbd_open,
.bdrv_co_preadv = nbd_client_co_preadv,
.bdrv_co_pwritev = nbd_client_co_pwritev,
+ .bdrv_co_pwrite_zeroes = nbd_client_co_pwrite_zeroes,
.bdrv_close = nbd_close,
.bdrv_co_flush_to_os = nbd_co_flush,
.bdrv_co_pdiscard = nbd_client_co_pdiscard,
@@ -458,6 +460,7 @@ static BlockDriver bdrv_nbd_tcp = {
.bdrv_file_open = nbd_open,
.bdrv_co_preadv = nbd_client_co_preadv,
.bdrv_co_pwritev = nbd_client_co_pwritev,
+ .bdrv_co_pwrite_zeroes = nbd_client_co_pwrite_zeroes,
.bdrv_close = nbd_close,
.bdrv_co_flush_to_os = nbd_co_flush,
.bdrv_co_pdiscard = nbd_client_co_pdiscard,
@@ -476,6 +479,7 @@ static BlockDriver bdrv_nbd_unix = {
.bdrv_file_open = nbd_open,
.bdrv_co_preadv = nbd_client_co_preadv,
.bdrv_co_pwritev = nbd_client_co_pwritev,
+ .bdrv_co_pwrite_zeroes = nbd_client_co_pwrite_zeroes,
.bdrv_close = nbd_close,
.bdrv_co_flush_to_os = nbd_co_flush,
.bdrv_co_pdiscard = nbd_client_co_pdiscard,
Upstream NBD protocol recently added the ability to efficiently write zeroes without having to send the zeroes over the wire, along with a flag to control whether the client wants a hole. The generic block code takes care of falling back to the obvious write of lots of zeroes if we return -ENOTSUP because the server does not have WRITE_ZEROES. Signed-off-by: Eric Blake <eblake@redhat.com> --- v4: rebase to byte-based limits v3: rebase, tell block layer about our support --- block/nbd-client.h | 2 ++ block/nbd-client.c | 35 +++++++++++++++++++++++++++++++++++ block/nbd.c | 4 ++++ 3 files changed, 41 insertions(+)