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 int fd_start_outgoing_migration(MigrationState *s, const char *fdname)
  77 {
  78     s->fd = monitor_get_fd(cur_mon, fdname, NULL);
  79     if (s->fd == -1) {
  80         DPRINTF("fd_migration: invalid file descriptor identifier\n");
  81         goto err_after_get_fd;
  82     }
  83
  84     if (fcntl(s->fd, F_SETFL, O_NONBLOCK) == -1) {
  85         DPRINTF("Unable to set nonblocking mode on file descriptor\n");
  86         goto err_after_open;
  87     }
  88
  89     s->get_error = fd_errno;
  90     s->write = fd_write;
  91     s->close = fd_close;
  92
  93     migrate_fd_connect(s);
  94     return 0;
  95
  96 err_after_open:
  97     close(s->fd);
  98 err_after_get_fd:
  99     return -1;
 100 }
 101
 102 static void fd_accept_incoming_migration(void *opaque)
 103 {
 104     QEMUFile *f = opaque;
 105
 106     process_incoming_migration(f);
 107     qemu_set_fd_handler2(qemu_stdio_fd(f), NULL, NULL, NULL, NULL);
 108     qemu_fclose(f);
 109 }
 110
 111 int fd_start_incoming_migration(const char *infd)
 112 {
 113     int fd;
 114     QEMUFile *f;
 115
 116     DPRINTF("Attempting to start an incoming migration via fd\n");
 117
 118     fd = strtol(infd, NULL, 0);
 119     f = qemu_fdopen(fd, "rb");
 120     if(f == NULL) {
 121         DPRINTF("Unable to apply qemu wrapper to file descriptor\n");
 122         return -errno;
 123     }
 124
 125     qemu_set_fd_handler2(fd, NULL, fd_accept_incoming_migration, NULL, f);
 126
 127     return 0;
 128 }