migration-unix.c

   1 /*
   2  * QEMU live migration via Unix Domain Sockets
   3  *
   4  * Copyright Red Hat, Inc. 2009
   5  *
   6  * Authors:
   7  *  Chris Lalancette <clalance@redhat.com>
   8  *
   9  * This work is licensed under the terms of the GNU GPL, version 2.  See
  10  * the COPYING file in the top-level directory.
  11  *
  12  */
  13
  14 #include "qemu-common.h"
  15 #include "qemu_socket.h"
  16 #include "migration.h"
  17 #include "qemu-char.h"
  18 #include "sysemu.h"
  19 #include "buffered_file.h"
  20 #include "block.h"
  21
  22 //#define DEBUG_MIGRATION_UNIX
  23
  24 #ifdef DEBUG_MIGRATION_UNIX
  25 #define dprintf(fmt, ...) \
  26     do { printf("migration-unix: " fmt, ## __VA_ARGS__); } while (0)
  27 #else
  28 #define dprintf(fmt, ...) \
  29     do { } while (0)
  30 #endif
  31
  32 static int unix_errno(FdMigrationState *s)
  33 {
  34     return errno;
  35 }
  36
  37 static int unix_write(FdMigrationState *s, const void * buf, size_t size)
  38 {
  39     return write(s->fd, buf, size);
  40 }
  41
  42 static int unix_close(FdMigrationState *s)
  43 {
  44     dprintf("unix_close\n");
  45     if (s->fd != -1) {
  46         close(s->fd);
  47         s->fd = -1;
  48     }
  49     return 0;
  50 }
  51
  52 static void unix_wait_for_connect(void *opaque)
  53 {
  54     FdMigrationState *s = opaque;
  55     int val, ret;
  56     socklen_t valsize = sizeof(val);
  57
  58     dprintf("connect completed\n");
  59     do {
  60         ret = getsockopt(s->fd, SOL_SOCKET, SO_ERROR, (void *) &val, &valsize);
  61     } while (ret == -1 && (s->get_error(s)) == EINTR);
  62
  63     if (ret < 0) {
  64         migrate_fd_error(s);
  65         return;
  66     }
  67
  68     qemu_set_fd_handler2(s->fd, NULL, NULL, NULL, NULL);
  69
  70     if (val == 0)
  71         migrate_fd_connect(s);
  72     else {
  73         dprintf("error connecting %d\n", val);
  74         migrate_fd_error(s);
  75     }
  76 }
  77
  78 MigrationState *unix_start_outgoing_migration(const char *path,
  79                                               int64_t bandwidth_limit,
  80                                               int detach)
  81 {
  82     FdMigrationState *s;
  83     struct sockaddr_un addr;
  84     int ret;
  85
  86     addr.sun_family = AF_UNIX;
  87     snprintf(addr.sun_path, sizeof(addr.sun_path), "%s", path);
  88
  89     s = qemu_mallocz(sizeof(*s));
  90
  91     s->get_error = unix_errno;
  92     s->write = unix_write;
  93     s->close = unix_close;
  94     s->mig_state.cancel = migrate_fd_cancel;
  95     s->mig_state.get_status = migrate_fd_get_status;
  96     s->mig_state.release = migrate_fd_release;
  97
  98     s->state = MIG_STATE_ACTIVE;
  99     s->mon_resume = NULL;
 100     s->bandwidth_limit = bandwidth_limit;
 101     s->fd = socket(PF_UNIX, SOCK_STREAM, 0);
 102     if (s->fd < 0) {
 103         dprintf("Unable to open socket");
 104         goto err_after_alloc;
 105     }
 106
 107     socket_set_nonblock(s->fd);
 108
 109     if (!detach)
 110         migrate_fd_monitor_suspend(s);
 111
 112     do {
 113         ret = connect(s->fd, (struct sockaddr *)&addr, sizeof(addr));
 114         if (ret == -1)
 115             ret = -(s->get_error(s));
 116
 117         if (ret == -EINPROGRESS || ret == -EWOULDBLOCK)
 118             qemu_set_fd_handler2(s->fd, NULL, NULL, unix_wait_for_connect, s);
 119     } while (ret == -EINTR);
 120
 121     if (ret < 0 && ret != -EINPROGRESS && ret != -EWOULDBLOCK) {
 122         dprintf("connect failed\n");
 123         goto err_after_open;
 124     } else if (ret >= 0)
 125         migrate_fd_connect(s);
 126
 127     return &s->mig_state;
 128
 129 err_after_open:
 130     close(s->fd);
 131
 132 err_after_alloc:
 133     qemu_free(s);
 134     return NULL;
 135 }
 136
 137 static void unix_accept_incoming_migration(void *opaque)
 138 {
 139     struct sockaddr_un addr;
 140     socklen_t addrlen = sizeof(addr);
 141     int s = (unsigned long)opaque;
 142     QEMUFile *f;
 143     int c, ret;
 144
 145     do {
 146         c = accept(s, (struct sockaddr *)&addr, &addrlen);
 147     } while (c == -1 && socket_error() == EINTR);
 148
 149     dprintf("accepted migration\n");
 150
 151     if (c == -1) {
 152         fprintf(stderr, "could not accept migration connection\n");
 153         return;
 154     }
 155
 156     f = qemu_fopen_socket(c);
 157     if (f == NULL) {
 158         fprintf(stderr, "could not qemu_fopen socket\n");
 159         goto out;
 160     }
 161
 162     ret = qemu_loadvm_state(f);
 163     if (ret < 0) {
 164         fprintf(stderr, "load of migration failed\n");
 165         goto out_fopen;
 166     }
 167     qemu_announce_self();
 168     dprintf("successfully loaded vm state\n");
 169
 170     /* we've successfully migrated, close the server socket */
 171     qemu_set_fd_handler2(s, NULL, NULL, NULL, NULL);
 172     close(s);
 173
 174 out_fopen:
 175     qemu_fclose(f);
 176 out:
 177     close(c);
 178 }
 179
 180 int unix_start_incoming_migration(const char *path)
 181 {
 182     struct sockaddr_un un;
 183     int sock;
 184
 185     dprintf("Attempting to start an incoming migration\n");
 186
 187     sock = socket(PF_UNIX, SOCK_STREAM, 0);
 188     if (sock < 0) {
 189         fprintf(stderr, "Could not open unix socket: %s\n", strerror(errno));
 190         return -EINVAL;
 191     }
 192
 193     memset(&un, 0, sizeof(un));
 194     un.sun_family = AF_UNIX;
 195     snprintf(un.sun_path, sizeof(un.sun_path), "%s", path);
 196
 197     unlink(un.sun_path);
 198     if (bind(sock, (struct sockaddr*) &un, sizeof(un)) < 0) {
 199         fprintf(stderr, "bind(unix:%s): %s\n", un.sun_path, strerror(errno));
 200         goto err;
 201     }
 202     if (listen(sock, 1) < 0) {
 203         fprintf(stderr, "listen(unix:%s): %s\n", un.sun_path, strerror(errno));
 204         goto err;
 205     }
 206
 207     qemu_set_fd_handler2(sock, NULL, unix_accept_incoming_migration, NULL,
 208                          (void *)(unsigned long)sock);
 209
 210     return 0;
 211
 212 err:
 213     close(sock);
 214
 215     return -EINVAL;
 216 }