1 files changed, 19 insertions, 6 deletions

diff --git a/block/nbd.c b/block/nbd.c
index 9e99a4ddb5..4a7f37da1c 100644
--- a/block/nbd.c
+++ b/block/nbd.c
@@ -1305,10 +1305,11 @@ nbd_client_co_pwrite_zeroes(BlockDriverState *bs, int64_t offset, int64_t bytes,
     NBDRequest request = {
         .type = NBD_CMD_WRITE_ZEROES,
         .from = offset,
-        .len = bytes,  /* .len is uint32_t actually */
+        .len = bytes,
     };
 
-    assert(bytes <= UINT32_MAX); /* rely on max_pwrite_zeroes */
+    /* rely on max_pwrite_zeroes */
+    assert(bytes <= UINT32_MAX || s->info.mode >= NBD_MODE_EXTENDED);
 
     assert(!(s->info.flags & NBD_FLAG_READ_ONLY));
     if (!(s->info.flags & NBD_FLAG_SEND_WRITE_ZEROES)) {
@@ -1355,10 +1356,11 @@ nbd_client_co_pdiscard(BlockDriverState *bs, int64_t offset, int64_t bytes)
     NBDRequest request = {
         .type = NBD_CMD_TRIM,
         .from = offset,
-        .len = bytes, /* len is uint32_t */
+        .len = bytes,
     };
 
-    assert(bytes <= UINT32_MAX); /* rely on max_pdiscard */
+    /* rely on max_pdiscard */
+    assert(bytes <= UINT32_MAX || s->info.mode >= NBD_MODE_EXTENDED);
 
     assert(!(s->info.flags & NBD_FLAG_READ_ONLY));
     if (!(s->info.flags & NBD_FLAG_SEND_TRIM) || !bytes) {
@@ -1380,8 +1382,7 @@ static int coroutine_fn GRAPH_RDLOCK nbd_client_co_block_status(
     NBDRequest request = {
         .type = NBD_CMD_BLOCK_STATUS,
         .from = offset,
-        .len = MIN(QEMU_ALIGN_DOWN(INT_MAX, bs->bl.request_alignment),
-                   MIN(bytes, s->info.size - offset)),
+        .len = MIN(bytes, s->info.size - offset),
         .flags = NBD_CMD_FLAG_REQ_ONE,
     };
 
@@ -1391,6 +1392,10 @@ static int coroutine_fn GRAPH_RDLOCK nbd_client_co_block_status(
         *file = bs;
         return BDRV_BLOCK_DATA | BDRV_BLOCK_OFFSET_VALID;
     }
+    if (s->info.mode < NBD_MODE_EXTENDED) {
+        request.len = MIN(QEMU_ALIGN_DOWN(INT_MAX, bs->bl.request_alignment),
+                          request.len);
+    }
 
     /*
      * Work around the fact that the block layer doesn't do
@@ -1955,6 +1960,14 @@ static void nbd_refresh_limits(BlockDriverState *bs, Error **errp)
     bs->bl.max_pwrite_zeroes = max;
     bs->bl.max_transfer = max;
 
+    /*
+     * Assume that if the server supports extended headers, it also
+     * supports unlimited size zero and trim commands.
+     */
+    if (s->info.mode >= NBD_MODE_EXTENDED) {
+        bs->bl.max_pdiscard = bs->bl.max_pwrite_zeroes = 0;
+    }
+
     if (s->info.opt_block &&
         s->info.opt_block > bs->bl.opt_transfer) {
         bs->bl.opt_transfer = s->info.opt_block;