Even though the NBD spec has been altered to allow us to accept NBD_CMD_READ larger than the max payload size (provided our response is a hole or broken up over more than one data chunk), we are not planning to take advantage of that, and continue to cap NBD_CMD_READ to 32M regardless of header size.
For NBD_CMD_WRITE_ZEROES and NBD_CMD_TRIM, the block layer already supports 64-bit operations without any effort on our part. For NBD_CMD_BLOCK_STATUS, the client's length is a hint; the easiest approach for now is to truncate our answer back to 32 bits, which lets us delay the effort of implementing NBD_REPLY_TYPE_BLOCK_STATUS_EXT to a separate patch. Signed-off-by: Eric Blake <ebl...@redhat.com> --- nbd/nbd-internal.h | 7 ++- nbd/server.c | 132 +++++++++++++++++++++++++++++++++++---------- 2 files changed, 108 insertions(+), 31 deletions(-) diff --git a/nbd/nbd-internal.h b/nbd/nbd-internal.h index 0016793ff4..f9fe0b6ce3 100644 --- a/nbd/nbd-internal.h +++ b/nbd/nbd-internal.h @@ -1,7 +1,7 @@ /* * NBD Internal Declarations * - * Copyright (C) 2016-2021 Red Hat, Inc. + * Copyright (C) 2016-2022 Red Hat, Inc. * * This work is licensed under the terms of the GNU GPL, version 2 or later. * See the COPYING file in the top-level directory. @@ -35,8 +35,11 @@ * https://github.com/yoe/nbd/blob/master/doc/proto.md */ -/* Size of all NBD_OPT_*, without payload */ +/* Size of all compact NBD_CMD_*, without payload */ #define NBD_REQUEST_SIZE (4 + 2 + 2 + 8 + 8 + 4) +/* Size of all extended NBD_CMD_*, without payload */ +#define NBD_EXTENDED_REQUEST_SIZE (4 + 2 + 2 + 8 + 8 + 8) + /* Size of all NBD_REP_* sent in answer to most NBD_OPT_*, without payload */ #define NBD_REPLY_SIZE (4 + 4 + 8) /* Size of reply to NBD_OPT_EXPORT_NAME */ diff --git a/nbd/server.c b/nbd/server.c index 4d1400430b..b46655b4d8 100644 --- a/nbd/server.c +++ b/nbd/server.c @@ -141,7 +141,7 @@ struct NBDClient { uint32_t check_align; /* If non-zero, check for aligned client requests */ - bool structured_reply; + bool structured_reply; /* also set true if extended_headers is set */ bool extended_headers; NBDExportMetaContexts export_meta; @@ -1260,6 +1260,10 @@ static int nbd_negotiate_options(NBDClient *client, Error **errp) case NBD_OPT_STRUCTURED_REPLY: if (length) { ret = nbd_reject_length(client, false, errp); + } else if (client->extended_headers) { + ret = nbd_negotiate_send_rep_err( + client, NBD_REP_ERR_EXT_HEADER_REQD, errp, + "extended headers already negotiated"); } else if (client->structured_reply) { ret = nbd_negotiate_send_rep_err( client, NBD_REP_ERR_INVALID, errp, @@ -1276,6 +1280,19 @@ static int nbd_negotiate_options(NBDClient *client, Error **errp) errp); break; + case NBD_OPT_EXTENDED_HEADERS: + if (length) { + ret = nbd_reject_length(client, false, errp); + } else if (client->extended_headers) { + ret = nbd_negotiate_send_rep_err( + client, NBD_REP_ERR_INVALID, errp, + "extended headers already negotiated"); + } else { + ret = nbd_negotiate_send_rep(client, NBD_REP_ACK, errp); + client->structured_reply = client->extended_headers = true; + } + break; + default: ret = nbd_opt_drop(client, NBD_REP_ERR_UNSUP, errp, "Unsupported option %" PRIu32 " (%s)", @@ -1411,11 +1428,13 @@ nbd_read_eof(NBDClient *client, void *buffer, size_t size, Error **errp) static int nbd_receive_request(NBDClient *client, NBDRequest *request, Error **errp) { - uint8_t buf[NBD_REQUEST_SIZE]; - uint32_t magic; + uint8_t buf[NBD_EXTENDED_REQUEST_SIZE]; + uint32_t magic, expect; int ret; + size_t size = client->extended_headers ? NBD_EXTENDED_REQUEST_SIZE + : NBD_REQUEST_SIZE; - ret = nbd_read_eof(client, buf, sizeof(buf), errp); + ret = nbd_read_eof(client, buf, size, errp); if (ret < 0) { return ret; } @@ -1423,13 +1442,21 @@ static int nbd_receive_request(NBDClient *client, NBDRequest *request, return -EIO; } - /* Request - [ 0 .. 3] magic (NBD_REQUEST_MAGIC) - [ 4 .. 5] flags (NBD_CMD_FLAG_FUA, ...) - [ 6 .. 7] type (NBD_CMD_READ, ...) - [ 8 .. 15] handle - [16 .. 23] from - [24 .. 27] len + /* + * Compact request + * [ 0 .. 3] magic (NBD_REQUEST_MAGIC) + * [ 4 .. 5] flags (NBD_CMD_FLAG_FUA, ...) + * [ 6 .. 7] type (NBD_CMD_READ, ...) + * [ 8 .. 15] handle + * [16 .. 23] from + * [24 .. 27] len + * Extended request + * [ 0 .. 3] magic (NBD_EXTENDED_REQUEST_MAGIC) + * [ 4 .. 5] flags (NBD_CMD_FLAG_FUA, NBD_CMD_FLAG_PAYLOAD_LEN, ...) + * [ 6 .. 7] type (NBD_CMD_READ, ...) + * [ 8 .. 15] handle + * [16 .. 23] from + * [24 .. 31] len */ magic = ldl_be_p(buf); @@ -1437,12 +1464,18 @@ static int nbd_receive_request(NBDClient *client, NBDRequest *request, request->type = lduw_be_p(buf + 6); request->handle = ldq_be_p(buf + 8); request->from = ldq_be_p(buf + 16); - request->len = ldl_be_p(buf + 24); /* widen 32 to 64 bits */ + if (client->extended_headers) { + request->len = ldq_be_p(buf + 24); + expect = NBD_EXTENDED_REQUEST_MAGIC; + } else { + request->len = ldl_be_p(buf + 24); /* widen 32 to 64 bits */ + expect = NBD_REQUEST_MAGIC; + } trace_nbd_receive_request(magic, request->flags, request->type, request->from, request->len); - if (magic != NBD_REQUEST_MAGIC) { + if (magic != expect) { error_setg(errp, "invalid magic (got 0x%" PRIx32 ")", magic); return -EINVAL; } @@ -1890,14 +1923,37 @@ static int coroutine_fn nbd_co_send_iov(NBDClient *client, struct iovec *iov, } static inline void set_be_simple_reply(NBDClient *client, struct iovec *iov, - uint64_t error, NBDRequest *request) + uint32_t error, NBDStructuredError *err, + NBDRequest *request) { - NBDSimpleReply *reply = iov->iov_base; + if (client->extended_headers) { + NBDExtendedReplyChunk *chunk = iov->iov_base; - iov->iov_len = sizeof(*reply); - stl_be_p(&reply->magic, NBD_SIMPLE_REPLY_MAGIC); - stl_be_p(&reply->error, error); - stq_be_p(&reply->handle, request->handle); + iov->iov_len = sizeof(*chunk); + stl_be_p(&chunk->magic, NBD_EXTENDED_REPLY_MAGIC); + stw_be_p(&chunk->flags, NBD_REPLY_FLAG_DONE); + stq_be_p(&chunk->handle, request->handle); + stq_be_p(&chunk->offset, request->from); + if (error) { + assert(!iov[1].iov_base); + iov[1].iov_base = err; + iov[1].iov_len = sizeof(*err); + stw_be_p(&chunk->type, NBD_REPLY_TYPE_ERROR); + stq_be_p(&chunk->length, sizeof(*err)); + stl_be_p(&err->error, error); + stw_be_p(&err->message_length, 0); + } else { + stw_be_p(&chunk->type, NBD_REPLY_TYPE_NONE); + stq_be_p(&chunk->length, 0); + } + } else { + NBDSimpleReply *reply = iov->iov_base; + + iov->iov_len = sizeof(*reply); + stl_be_p(&reply->magic, NBD_SIMPLE_REPLY_MAGIC); + stl_be_p(&reply->error, error); + stq_be_p(&reply->handle, request->handle); + } } static int nbd_co_send_simple_reply(NBDClient *client, NBDRequest *request, @@ -1908,30 +1964,44 @@ static int nbd_co_send_simple_reply(NBDClient *client, NBDRequest *request, { NBDReply hdr; int nbd_err = system_errno_to_nbd_errno(error); + NBDStructuredError err; struct iovec iov[] = { {.iov_base = &hdr}, {.iov_base = data, .iov_len = len} }; + assert(!len || !nbd_err); trace_nbd_co_send_simple_reply(request->handle, nbd_err, nbd_err_lookup(nbd_err), len); - set_be_simple_reply(client, &iov[0], nbd_err, request); + set_be_simple_reply(client, &iov[0], nbd_err, &err, request); - return nbd_co_send_iov(client, iov, len ? 2 : 1, errp); + return nbd_co_send_iov(client, iov, iov[1].iov_len ? 2 : 1, errp); } static inline void set_be_chunk(NBDClient *client, struct iovec *iov, uint16_t flags, uint16_t type, NBDRequest *request, uint32_t length) { - NBDStructuredReplyChunk *chunk = iov->iov_base; + if (client->extended_headers) { + NBDExtendedReplyChunk *chunk = iov->iov_base; - iov->iov_len = sizeof(*chunk); - stl_be_p(&chunk->magic, NBD_STRUCTURED_REPLY_MAGIC); - stw_be_p(&chunk->flags, flags); - stw_be_p(&chunk->type, type); - stq_be_p(&chunk->handle, request->handle); - stl_be_p(&chunk->length, length); + iov->iov_len = sizeof(*chunk); + stl_be_p(&chunk->magic, NBD_EXTENDED_REPLY_MAGIC); + stw_be_p(&chunk->flags, flags); + stw_be_p(&chunk->type, type); + stq_be_p(&chunk->handle, request->handle); + stq_be_p(&chunk->offset, request->from); + stq_be_p(&chunk->length, length); + } else { + NBDStructuredReplyChunk *chunk = iov->iov_base; + + iov->iov_len = sizeof(*chunk); + stl_be_p(&chunk->magic, NBD_STRUCTURED_REPLY_MAGIC); + stw_be_p(&chunk->flags, flags); + stw_be_p(&chunk->type, type); + stq_be_p(&chunk->handle, request->handle); + stl_be_p(&chunk->length, length); + } } static int coroutine_fn nbd_co_send_structured_done(NBDClient *client, @@ -2595,7 +2665,11 @@ static coroutine_fn int nbd_handle_request(NBDClient *client, return nbd_send_generic_reply(client, request, -EINVAL, "need non-zero length", errp); } - assert(request->len <= UINT32_MAX); + if (request->len > UINT32_MAX) { + /* For now, truncate our response to a 32 bit window */ + request->len = QEMU_ALIGN_DOWN(BDRV_REQUEST_MAX_BYTES, + client->check_align ?: 1); + } if (client->export_meta.count) { bool dont_fragment = request->flags & NBD_CMD_FLAG_REQ_ONE; int contexts_remaining = client->export_meta.count; -- 2.38.1
