diff options
Diffstat (limited to 'nbd/server.c')
| -rw-r--r-- | nbd/server.c | 48 |
1 files changed, 44 insertions, 4 deletions
diff --git a/nbd/server.c b/nbd/server.c index e84d012..49ed574 100644 --- a/nbd/server.c +++ b/nbd/server.c @@ -365,6 +365,8 @@ static int nbd_negotiate_handle_info(NBDClient *client, uint32_t length, uint16_t request; uint32_t namelen; bool sendname = false; + bool blocksize = false; + uint32_t sizes[3]; char buf[sizeof(uint64_t) + sizeof(uint16_t)]; const char *msg; @@ -412,11 +414,16 @@ static int nbd_negotiate_handle_info(NBDClient *client, uint32_t length, length -= sizeof(request); trace_nbd_negotiate_handle_info_request(request, nbd_info_lookup(request)); - /* For now, we only care about NBD_INFO_NAME; everything else - * is either a request we don't know or something we send - * regardless of request. */ - if (request == NBD_INFO_NAME) { + /* We care about NBD_INFO_NAME and NBD_INFO_BLOCK_SIZE; + * everything else is either a request we don't know or + * something we send regardless of request */ + switch (request) { + case NBD_INFO_NAME: sendname = true; + break; + case NBD_INFO_BLOCK_SIZE: + blocksize = true; + break; } } @@ -448,6 +455,27 @@ static int nbd_negotiate_handle_info(NBDClient *client, uint32_t length, } } + /* Send NBD_INFO_BLOCK_SIZE always, but tweak the minimum size + * according to whether the client requested it, and according to + * whether this is OPT_INFO or OPT_GO. */ + /* minimum - 1 for back-compat, or 512 if client is new enough. + * TODO: consult blk_bs(blk)->bl.request_alignment? */ + sizes[0] = (opt == NBD_OPT_INFO || blocksize) ? BDRV_SECTOR_SIZE : 1; + /* preferred - Hard-code to 4096 for now. + * TODO: is blk_bs(blk)->bl.opt_transfer appropriate? */ + sizes[1] = 4096; + /* maximum - At most 32M, but smaller as appropriate. */ + sizes[2] = MIN(blk_get_max_transfer(exp->blk), NBD_MAX_BUFFER_SIZE); + trace_nbd_negotiate_handle_info_block_size(sizes[0], sizes[1], sizes[2]); + cpu_to_be32s(&sizes[0]); + cpu_to_be32s(&sizes[1]); + cpu_to_be32s(&sizes[2]); + rc = nbd_negotiate_send_info(client, opt, NBD_INFO_BLOCK_SIZE, + sizeof(sizes), sizes, errp); + if (rc < 0) { + return rc; + } + /* Send NBD_INFO_EXPORT always */ trace_nbd_negotiate_new_style_size_flags(exp->size, exp->nbdflags | myflags); @@ -459,6 +487,18 @@ static int nbd_negotiate_handle_info(NBDClient *client, uint32_t length, return rc; } + /* If the client is just asking for NBD_OPT_INFO, but forgot to + * request block sizes, return an error. + * TODO: consult blk_bs(blk)->request_align, and only error if it + * is not 1? */ + if (opt == NBD_OPT_INFO && !blocksize) { + return nbd_negotiate_send_rep_err(client->ioc, + NBD_REP_ERR_BLOCK_SIZE_REQD, opt, + errp, + "request NBD_INFO_BLOCK_SIZE to " + "use this export"); + } + /* Final reply */ rc = nbd_negotiate_send_rep(client->ioc, NBD_REP_ACK, opt, errp); if (rc < 0) { |