@@ -673,6 +673,9 @@ int nbd_client_co_preadv(BlockDriverState *bs, uint64_t offset,
assert(bytes <= NBD_MAX_BUFFER_SIZE);
assert(!flags);
+ if (!bytes) {
+ return 0;
+ }
ret = nbd_co_send_request(bs, &request, NULL);
if (ret < 0) {
@@ -705,6 +708,9 @@ int nbd_client_co_pwritev(BlockDriverState *bs, uint64_t offset,
assert(bytes <= NBD_MAX_BUFFER_SIZE);
+ if (!bytes) {
+ return 0;
+ }
return nbd_co_request(bs, &request, qiov);
}
@@ -731,6 +737,9 @@ int nbd_client_co_pwrite_zeroes(BlockDriverState *bs, int64_t offset,
request.flags |= NBD_CMD_FLAG_NO_HOLE;
}
+ if (!bytes) {
+ return 0;
+ }
return nbd_co_request(bs, &request, NULL);
}
@@ -759,7 +768,7 @@ int nbd_client_co_pdiscard(BlockDriverState *bs, int64_t offset, int bytes)
};
assert(!(client->info.flags & NBD_FLAG_READ_ONLY));
- if (!(client->info.flags & NBD_FLAG_SEND_TRIM)) {
+ if (!(client->info.flags & NBD_FLAG_SEND_TRIM) || !bytes) {
return 0;
}
The NBD spec is being clarified to state that clients should not send 0-length requests to the server, as the server behavior is undefined. While such requests are unlikely to occur from real guest behavior, qemu-io can force the driver to perform them; avoid any questionable server implementations by short-circuiting such operations as a no-op success (we are relying on the block layer for already filtering out things like invalid offset, write to a read-only volume, and so forth). Signed-off-by: Eric Blake <eblake@redhat.com> --- block/nbd-client.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-)