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