004a89fce9
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>
176 lines
6.4 KiB
C
176 lines
6.4 KiB
C
/*
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* Copyright (C) 2016 Red Hat, Inc.
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* Copyright (C) 2005 Anthony Liguori <anthony@codemonkey.ws>
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*
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* Network Block Device
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; under version 2 of the License.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, see <http://www.gnu.org/licenses/>.
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*/
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#ifndef NBD_H
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#define NBD_H
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#include "qemu-common.h"
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#include "qemu/option.h"
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#include "io/channel-socket.h"
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#include "crypto/tlscreds.h"
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/* Handshake phase structs - this struct is passed on the wire */
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struct nbd_option {
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uint64_t magic; /* NBD_OPTS_MAGIC */
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uint32_t option; /* NBD_OPT_* */
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uint32_t length;
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} QEMU_PACKED;
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typedef struct nbd_option nbd_option;
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struct nbd_opt_reply {
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uint64_t magic; /* NBD_REP_MAGIC */
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uint32_t option; /* NBD_OPT_* */
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uint32_t type; /* NBD_REP_* */
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uint32_t length;
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} QEMU_PACKED;
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typedef struct nbd_opt_reply nbd_opt_reply;
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/* Transmission phase structs
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*
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* Note: these are _NOT_ the same as the network representation of an NBD
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* request and reply!
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*/
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struct NBDRequest {
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uint64_t handle;
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uint64_t from;
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uint32_t len;
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uint16_t flags; /* NBD_CMD_FLAG_* */
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uint16_t type; /* NBD_CMD_* */
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};
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typedef struct NBDRequest NBDRequest;
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struct NBDReply {
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uint64_t handle;
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uint32_t error;
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};
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typedef struct NBDReply NBDReply;
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/* Transmission (export) flags: sent from server to client during handshake,
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but describe what will happen during transmission */
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#define NBD_FLAG_HAS_FLAGS (1 << 0) /* Flags are there */
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#define NBD_FLAG_READ_ONLY (1 << 1) /* Device is read-only */
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#define NBD_FLAG_SEND_FLUSH (1 << 2) /* Send FLUSH */
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#define NBD_FLAG_SEND_FUA (1 << 3) /* Send FUA (Force Unit Access) */
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#define NBD_FLAG_ROTATIONAL (1 << 4) /* Use elevator algorithm - rotational media */
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#define NBD_FLAG_SEND_TRIM (1 << 5) /* Send TRIM (discard) */
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#define NBD_FLAG_SEND_WRITE_ZEROES (1 << 6) /* Send WRITE_ZEROES */
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/* New-style handshake (global) flags, sent from server to client, and
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control what will happen during handshake phase. */
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#define NBD_FLAG_FIXED_NEWSTYLE (1 << 0) /* Fixed newstyle protocol. */
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#define NBD_FLAG_NO_ZEROES (1 << 1) /* End handshake without zeroes. */
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/* New-style client flags, sent from client to server to control what happens
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during handshake phase. */
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#define NBD_FLAG_C_FIXED_NEWSTYLE (1 << 0) /* Fixed newstyle protocol. */
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#define NBD_FLAG_C_NO_ZEROES (1 << 1) /* End handshake without zeroes. */
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/* Reply types. */
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#define NBD_REP_ERR(value) ((UINT32_C(1) << 31) | (value))
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#define NBD_REP_ACK (1) /* Data sending finished. */
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#define NBD_REP_SERVER (2) /* Export description. */
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#define NBD_REP_ERR_UNSUP NBD_REP_ERR(1) /* Unknown option */
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#define NBD_REP_ERR_POLICY NBD_REP_ERR(2) /* Server denied */
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#define NBD_REP_ERR_INVALID NBD_REP_ERR(3) /* Invalid length */
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#define NBD_REP_ERR_PLATFORM NBD_REP_ERR(4) /* Not compiled in */
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#define NBD_REP_ERR_TLS_REQD NBD_REP_ERR(5) /* TLS required */
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#define NBD_REP_ERR_SHUTDOWN NBD_REP_ERR(7) /* Server shutting down */
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/* Request flags, sent from client to server during transmission phase */
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#define NBD_CMD_FLAG_FUA (1 << 0) /* 'force unit access' during write */
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#define NBD_CMD_FLAG_NO_HOLE (1 << 1) /* don't punch hole on zero run */
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/* Supported request types */
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enum {
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NBD_CMD_READ = 0,
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NBD_CMD_WRITE = 1,
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NBD_CMD_DISC = 2,
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NBD_CMD_FLUSH = 3,
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NBD_CMD_TRIM = 4,
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/* 5 reserved for failed experiment NBD_CMD_CACHE */
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NBD_CMD_WRITE_ZEROES = 6,
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};
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#define NBD_DEFAULT_PORT 10809
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/* Maximum size of a single READ/WRITE data buffer */
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#define NBD_MAX_BUFFER_SIZE (32 * 1024 * 1024)
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/* Maximum size of an export name. The NBD spec requires 256 and
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* suggests that servers support up to 4096, but we stick to only the
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* required size so that we can stack-allocate the names, and because
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* going larger would require an audit of more code to make sure we
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* aren't overflowing some other buffer. */
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#define NBD_MAX_NAME_SIZE 256
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/* Details collected by NBD_OPT_EXPORT_NAME and NBD_OPT_GO */
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struct NBDExportInfo {
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uint64_t size;
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uint16_t flags;
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};
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typedef struct NBDExportInfo NBDExportInfo;
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ssize_t nbd_rwv(QIOChannel *ioc, struct iovec *iov, size_t niov, size_t length,
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bool do_read, Error **errp);
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int nbd_receive_negotiate(QIOChannel *ioc, const char *name,
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QCryptoTLSCreds *tlscreds, const char *hostname,
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QIOChannel **outioc, NBDExportInfo *info,
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Error **errp);
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int nbd_init(int fd, QIOChannelSocket *sioc, NBDExportInfo *info,
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Error **errp);
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ssize_t nbd_send_request(QIOChannel *ioc, NBDRequest *request);
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ssize_t nbd_receive_reply(QIOChannel *ioc, NBDReply *reply, Error **errp);
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int nbd_client(int fd);
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int nbd_disconnect(int fd);
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typedef struct NBDExport NBDExport;
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typedef struct NBDClient NBDClient;
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NBDExport *nbd_export_new(BlockDriverState *bs, off_t dev_offset, off_t size,
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uint16_t nbdflags, void (*close)(NBDExport *),
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bool writethrough, BlockBackend *on_eject_blk,
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Error **errp);
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void nbd_export_close(NBDExport *exp);
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void nbd_export_get(NBDExport *exp);
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void nbd_export_put(NBDExport *exp);
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BlockBackend *nbd_export_get_blockdev(NBDExport *exp);
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NBDExport *nbd_export_find(const char *name);
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void nbd_export_set_name(NBDExport *exp, const char *name);
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void nbd_export_set_description(NBDExport *exp, const char *description);
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void nbd_export_close_all(void);
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void nbd_client_new(NBDExport *exp,
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QIOChannelSocket *sioc,
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QCryptoTLSCreds *tlscreds,
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const char *tlsaclname,
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void (*close_fn)(NBDClient *, bool));
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void nbd_client_get(NBDClient *client);
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void nbd_client_put(NBDClient *client);
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void nbd_server_start(SocketAddress *addr, const char *tls_creds,
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Error **errp);
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#endif
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