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_socket.h"
  18 #include "migration.h"
  19 #include "monitor.h"
  20 #include "qemu-char.h"
  21 #include "buffered_file.h"
  22 #include "block.h"
  23 #include "qemu_socket.h"
  24
  25 //#define DEBUG_MIGRATION_FD
  26
  27 #ifdef DEBUG_MIGRATION_FD
  28 #define DPRINTF(fmt, ...) \
  29     do { printf("migration-fd: " fmt, ## __VA_ARGS__); } while (0)
  30 #else
  31 #define DPRINTF(fmt, ...) \
  32     do { } while (0)
  33 #endif
  34
  35 static int fd_errno(MigrationState *s)
  36 {
  37     return errno;
  38 }
  39
  40 static int fd_write(MigrationState *s, const void * buf, size_t size)
  41 {
  42     return write(s->fd, buf, size);
  43 }
  44
  45 static int fd_close(MigrationState *s)
  46 {
  47     struct stat st;
  48     int ret;
  49
  50     DPRINTF("fd_close\n");
  51     if (s->fd != -1) {
  52         ret = fstat(s->fd, &st);
  53         if (ret == 0 && S_ISREG(st.st_mode)) {
  54             /*
  55              * If the file handle is a regular file make sure the
  56              * data is flushed to disk before signaling success.
  57              */
  58             ret = fsync(s->fd);
  59             if (ret != 0) {
  60                 ret = -errno;
  61                 perror("migration-fd: fsync");
  62                 return ret;
  63             }
  64         }
  65         ret = close(s->fd);
  66         s->fd = -1;
  67         if (ret != 0) {
  68             ret = -errno;
  69             perror("migration-fd: close");
  70             return ret;
  71         }
  72     }
  73     return 0;
  74 }
  75
  76 void fd_start_outgoing_migration(MigrationState *s, const char *fdname, Error **errp)
  77 {
  78     s->fd = monitor_get_fd(cur_mon, fdname, errp);
  79     if (s->fd == -1) {
  80         return;
  81     }
  82
  83     fcntl(s->fd, F_SETFL, O_NONBLOCK);
  84     s->get_error = fd_errno;
  85     s->write = fd_write;
  86     s->close = fd_close;
  87
  88     migrate_fd_connect(s);
  89 }
  90
  91 static void fd_accept_incoming_migration(void *opaque)
  92 {
  93     QEMUFile *f = opaque;
  94
  95     process_incoming_migration(f);
  96     qemu_set_fd_handler2(qemu_stdio_fd(f), NULL, NULL, NULL, NULL);
  97     qemu_fclose(f);
  98 }
  99
 100 void fd_start_incoming_migration(const char *infd, Error **errp)
 101 {
 102     int fd;
 103     QEMUFile *f;
 104
 105     DPRINTF("Attempting to start an incoming migration via fd\n");
 106
 107     fd = strtol(infd, NULL, 0);
 108     f = qemu_fdopen(fd, "rb");
 109     if(f == NULL) {
 110         error_setg_errno(errp, errno, "failed to open the source descriptor");
 111         return;
 112     }
 113
 114     qemu_set_fd_handler2(fd, NULL, fd_accept_incoming_migration, NULL, f);
 115 }