migration-fd.c

   1 /*
   2  * QEMU live migration via generic fd
   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  * Contributions after 2012-01-13 are licensed under the terms of the
  13  * GNU GPL, version 2 or (at your option) any later version.
  14  */
  15
  16 #include "qemu-common.h"
  17 #include "qemu/sockets.h"
  18 #include "migration/migration.h"
  19 #include "monitor/monitor.h"
  20 #include "migration/qemu-file.h"
  21 #include "block/block.h"
  22
  23 //#define DEBUG_MIGRATION_FD
  24
  25 #ifdef DEBUG_MIGRATION_FD
  26 #define DPRINTF(fmt, ...) \
  27     do { printf("migration-fd: " fmt, ## __VA_ARGS__); } while (0)
  28 #else
  29 #define DPRINTF(fmt, ...) \
  30     do { } while (0)
  31 #endif
  32
  33 static int fd_errno(MigrationState *s)
  34 {
  35     return errno;
  36 }
  37
  38 static int fd_write(MigrationState *s, const void * buf, size_t size)
  39 {
  40     return write(s->fd, buf, size);
  41 }
  42
  43 static int fd_close(MigrationState *s)
  44 {
  45     struct stat st;
  46     int ret;
  47
  48     DPRINTF("fd_close\n");
  49     ret = fstat(s->fd, &st);
  50     if (ret == 0 && S_ISREG(st.st_mode)) {
  51         /*
  52          * If the file handle is a regular file make sure the
  53          * data is flushed to disk before signaling success.
  54          */
  55         ret = fsync(s->fd);
  56         if (ret != 0) {
  57             ret = -errno;
  58             perror("migration-fd: fsync");
  59             return ret;
  60         }
  61     }
  62     ret = close(s->fd);
  63     s->fd = -1;
  64     if (ret != 0) {
  65         ret = -errno;
  66         perror("migration-fd: close");
  67     }
  68     return ret;
  69 }
  70
  71 void fd_start_outgoing_migration(MigrationState *s, const char *fdname, Error **errp)
  72 {
  73     s->fd = monitor_get_fd(cur_mon, fdname, errp);
  74     if (s->fd == -1) {
  75         return;
  76     }
  77
  78     fcntl(s->fd, F_SETFL, O_NONBLOCK);
  79     s->get_error = fd_errno;
  80     s->write = fd_write;
  81     s->close = fd_close;
  82
  83     migrate_fd_connect(s);
  84 }
  85
  86 static void fd_accept_incoming_migration(void *opaque)
  87 {
  88     QEMUFile *f = opaque;
  89
  90     qemu_set_fd_handler2(qemu_get_fd(f), NULL, NULL, NULL, NULL);
  91     process_incoming_migration(f);
  92 }
  93
  94 void fd_start_incoming_migration(const char *infd, Error **errp)
  95 {
  96     int fd;
  97     QEMUFile *f;
  98
  99     DPRINTF("Attempting to start an incoming migration via fd\n");
 100
 101     fd = strtol(infd, NULL, 0);
 102     f = qemu_fdopen(fd, "rb");
 103     if(f == NULL) {
 104         error_setg_errno(errp, errno, "failed to open the source descriptor");
 105         return;
 106     }
 107
 108     qemu_set_fd_handler2(fd, NULL, fd_accept_incoming_migration, NULL, f);
 109 }