nbd: Create struct for tracking export info

The NBD Protocol is introducing some additional information
about exports, such as minimum request size and alignment, as
well as an advertised maximum request size.  It will be easier
to feed this information back to the block layer if we gather
all the information into a struct, rather than adding yet more
pointer parameters during negotiation.

Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20170707203049.534-2-eblake@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

3 files changed, 10 insertions, 13 deletions

diff --git a/block/nbd-client.c b/block/nbd-client.c
index 208f907095..aab1e320b2 100644
--- a/block/nbd-client.c
+++ b/block/nbd-client.c
@@ -242,7 +242,7 @@ int nbd_client_co_pwritev(BlockDriverState *bs, uint64_t offset,
     ssize_t ret;
 
     if (flags & BDRV_REQ_FUA) {
-        assert(client->nbdflags & NBD_FLAG_SEND_FUA);
+        assert(client->info.flags & NBD_FLAG_SEND_FUA);
         request.flags |= NBD_CMD_FLAG_FUA;
     }
 
@@ -270,12 +270,12 @@ int nbd_client_co_pwrite_zeroes(BlockDriverState *bs, int64_t offset,
     };
     NBDReply reply;
 
-    if (!(client->nbdflags & NBD_FLAG_SEND_WRITE_ZEROES)) {
+    if (!(client->info.flags & NBD_FLAG_SEND_WRITE_ZEROES)) {
         return -ENOTSUP;
     }
 
     if (flags & BDRV_REQ_FUA) {
-        assert(client->nbdflags & NBD_FLAG_SEND_FUA);
+        assert(client->info.flags & NBD_FLAG_SEND_FUA);
         request.flags |= NBD_CMD_FLAG_FUA;
     }
     if (!(flags & BDRV_REQ_MAY_UNMAP)) {
@@ -299,7 +299,7 @@ int nbd_client_co_flush(BlockDriverState *bs)
     NBDReply reply;
     ssize_t ret;
 
-    if (!(client->nbdflags & NBD_FLAG_SEND_FLUSH)) {
+    if (!(client->info.flags & NBD_FLAG_SEND_FLUSH)) {
         return 0;
     }
 
@@ -327,7 +327,7 @@ int nbd_client_co_pdiscard(BlockDriverState *bs, int64_t offset, int bytes)
     NBDReply reply;
     ssize_t ret;
 
-    if (!(client->nbdflags & NBD_FLAG_SEND_TRIM)) {
+    if (!(client->info.flags & NBD_FLAG_SEND_TRIM)) {
         return 0;
     }
 
@@ -385,19 +385,17 @@ int nbd_client_init(BlockDriverState *bs,
     qio_channel_set_blocking(QIO_CHANNEL(sioc), true, NULL);
 
     ret = nbd_receive_negotiate(QIO_CHANNEL(sioc), export,
-                                &client->nbdflags,
                                 tlscreds, hostname,
-                                &client->ioc,
-                                &client->size, errp);
+                                &client->ioc, &client->info, errp);
     if (ret < 0) {
         logout("Failed to negotiate with the NBD server\n");
         return ret;
     }
-    if (client->nbdflags & NBD_FLAG_SEND_FUA) {
+    if (client->info.flags & NBD_FLAG_SEND_FUA) {
         bs->supported_write_flags = BDRV_REQ_FUA;
         bs->supported_zero_flags |= BDRV_REQ_FUA;
     }
-    if (client->nbdflags & NBD_FLAG_SEND_WRITE_ZEROES) {
+    if (client->info.flags & NBD_FLAG_SEND_WRITE_ZEROES) {
         bs->supported_zero_flags |= BDRV_REQ_MAY_UNMAP;
     }
 
diff --git a/block/nbd-client.h b/block/nbd-client.h
index 49636bc621..df80771357 100644
--- a/block/nbd-client.h
+++ b/block/nbd-client.h
@@ -20,8 +20,7 @@
 typedef struct NBDClientSession {
     QIOChannelSocket *sioc; /* The master data channel */
     QIOChannel *ioc; /* The current I/O channel which may differ (eg TLS) */
-    uint16_t nbdflags;
-    off_t size;
+    NBDExportInfo info;
 
     CoMutex send_mutex;
     CoQueue free_sema;
diff --git a/block/nbd.c b/block/nbd.c
index d529305330..4a9048c280 100644
--- a/block/nbd.c
+++ b/block/nbd.c
@@ -492,7 +492,7 @@ static int64_t nbd_getlength(BlockDriverState *bs)
 {
     BDRVNBDState *s = bs->opaque;
 
-    return s->client.size;
+    return s->client.info.size;
 }
 
 static void nbd_detach_aio_context(BlockDriverState *bs)