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                                               int blk,
  82                                               int inc)
  83 {
  84     FdMigrationState *s;
  85     struct sockaddr_un addr;
  86     int ret;
  87
  88     addr.sun_family = AF_UNIX;
  89     snprintf(addr.sun_path, sizeof(addr.sun_path), "%s", path);
  90
  91     s = qemu_mallocz(sizeof(*s));
  92
  93     s->get_error = unix_errno;
  94     s->write = unix_write;
  95     s->close = unix_close;
  96     s->mig_state.cancel = migrate_fd_cancel;
  97     s->mig_state.get_status = migrate_fd_get_status;
  98     s->mig_state.release = migrate_fd_release;
  99
 100     s->mig_state.blk = blk;
 101     s->mig_state.shared = inc;
 102
 103     s->state = MIG_STATE_ACTIVE;
 104     s->mon_resume = NULL;
 105     s->bandwidth_limit = bandwidth_limit;
 106     s->fd = socket(PF_UNIX, SOCK_STREAM, 0);
 107     if (s->fd < 0) {
 108         dprintf("Unable to open socket");
 109         goto err_after_alloc;
 110     }
 111
 112     socket_set_nonblock(s->fd);
 113
 114     if (!detach)
 115         migrate_fd_monitor_suspend(s);
 116
 117     do {
 118         ret = connect(s->fd, (struct sockaddr *)&addr, sizeof(addr));
 119         if (ret == -1)
 120             ret = -(s->get_error(s));
 121
 122         if (ret == -EINPROGRESS || ret == -EWOULDBLOCK)
 123             qemu_set_fd_handler2(s->fd, NULL, NULL, unix_wait_for_connect, s);
 124     } while (ret == -EINTR);
 125
 126     if (ret < 0 && ret != -EINPROGRESS && ret != -EWOULDBLOCK) {
 127         dprintf("connect failed\n");
 128         goto err_after_open;
 129     } else if (ret >= 0)
 130         migrate_fd_connect(s);
 131
 132     return &s->mig_state;
 133
 134 err_after_open:
 135     close(s->fd);
 136
 137 err_after_alloc:
 138     qemu_free(s);
 139     return NULL;
 140 }
 141
 142 static void unix_accept_incoming_migration(void *opaque)
 143 {
 144     struct sockaddr_un addr;
 145     socklen_t addrlen = sizeof(addr);
 146     int s = (unsigned long)opaque;
 147     QEMUFile *f;
 148     int c, ret;
 149
 150     do {
 151         c = accept(s, (struct sockaddr *)&addr, &addrlen);
 152     } while (c == -1 && socket_error() == EINTR);
 153
 154     dprintf("accepted migration\n");
 155
 156     if (c == -1) {
 157         fprintf(stderr, "could not accept migration connection\n");
 158         return;
 159     }
 160
 161     f = qemu_fopen_socket(c);
 162     if (f == NULL) {
 163         fprintf(stderr, "could not qemu_fopen socket\n");
 164         goto out;
 165     }
 166
 167     ret = qemu_loadvm_state(f);
 168     if (ret < 0) {
 169         fprintf(stderr, "load of migration failed\n");
 170         goto out_fopen;
 171     }
 172     qemu_announce_self();
 173     dprintf("successfully loaded vm state\n");
 174
 175     /* we've successfully migrated, close the server socket */
 176     qemu_set_fd_handler2(s, NULL, NULL, NULL, NULL);
 177     close(s);
 178
 179 out_fopen:
 180     qemu_fclose(f);
 181 out:
 182     close(c);
 183 }
 184
 185 int unix_start_incoming_migration(const char *path)
 186 {
 187     struct sockaddr_un un;
 188     int sock;
 189
 190     dprintf("Attempting to start an incoming migration\n");
 191
 192     sock = socket(PF_UNIX, SOCK_STREAM, 0);
 193     if (sock < 0) {
 194         fprintf(stderr, "Could not open unix socket: %s\n", strerror(errno));
 195         return -EINVAL;
 196     }
 197
 198     memset(&un, 0, sizeof(un));
 199     un.sun_family = AF_UNIX;
 200     snprintf(un.sun_path, sizeof(un.sun_path), "%s", path);
 201
 202     unlink(un.sun_path);
 203     if (bind(sock, (struct sockaddr*) &un, sizeof(un)) < 0) {
 204         fprintf(stderr, "bind(unix:%s): %s\n", un.sun_path, strerror(errno));
 205         goto err;
 206     }
 207     if (listen(sock, 1) < 0) {
 208         fprintf(stderr, "listen(unix:%s): %s\n", un.sun_path, strerror(errno));
 209         goto err;
 210     }
 211
 212     qemu_set_fd_handler2(sock, NULL, unix_accept_incoming_migration, NULL,
 213                          (void *)(unsigned long)sock);
 214
 215     return 0;
 216
 217 err:
 218     close(sock);
 219
 220     return -EINVAL;
 221 }