Merge remote-tracking branch 'bonzini/migr-coroutine' into staging

Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

* bonzini/migr-coroutine:
  migration: move process_incoming_migration to a coroutine
  migration: handle EAGAIN while reading QEMUFile
  migration: move qemu_fclose to process_incoming_migration
  migration: close socket QEMUFile from socket_close
  migration: xxx_close will only be called once
  migration: use closesocket, not close
  migration: use migrate_fd_close in migrate_fd_cleanup
  migration: clean up server sockets and handlers before invoking process_incoming_migration
  migration: replace qemu_stdio_fd with qemu_get_fd
  migration: add qemu_get_fd
  migration: consolidate QEMUFile methods in a single QEMUFileOps struct
  migration: unify stdio-based QEMUFile operations

8 files changed, 215 insertions, 154 deletions

diff --git a/buffered_file.c b/buffered_file.c
index ed92df1053..bd0f61d8c9 100644
--- a/buffered_file.c
+++ b/buffered_file.c
@@ -174,6 +174,13 @@ static int buffered_close(void *opaque)
  *   1: Time to stop
  *   negative: There has been an error
  */
+static int buffered_get_fd(void *opaque)
+{
+    QEMUFileBuffered *s = opaque;
+
+    return qemu_get_fd(s->file);
+}
+
 static int buffered_rate_limit(void *opaque)
 {
     QEMUFileBuffered *s = opaque;
@@ -234,6 +241,15 @@ static void buffered_rate_tick(void *opaque)
     buffered_put_buffer(s, NULL, 0, 0);
 }
 
+static const QEMUFileOps buffered_file_ops = {
+    .get_fd =         buffered_get_fd,
+    .put_buffer =     buffered_put_buffer,
+    .close =          buffered_close,
+    .rate_limit =     buffered_rate_limit,
+    .get_rate_limit = buffered_get_rate_limit,
+    .set_rate_limit = buffered_set_rate_limit,
+};
+
 QEMUFile *qemu_fopen_ops_buffered(MigrationState *migration_state)
 {
     QEMUFileBuffered *s;
@@ -243,10 +259,7 @@ QEMUFile *qemu_fopen_ops_buffered(MigrationState *migration_state)
     s->migration_state = migration_state;
     s->xfer_limit = migration_state->bandwidth_limit / 10;
 
-    s->file = qemu_fopen_ops(s, buffered_put_buffer, NULL,
-                             buffered_close, buffered_rate_limit,
-                             buffered_set_rate_limit,
-			     buffered_get_rate_limit);
+    s->file = qemu_fopen_ops(s, &buffered_file_ops);
 
     s->timer = qemu_new_timer_ms(rt_clock, buffered_rate_tick, s);
 
diff --git a/migration-exec.c b/migration-exec.c
index 519af57ac7..2b6fcb4262 100644
--- a/migration-exec.c
+++ b/migration-exec.c
@@ -48,14 +48,12 @@ static int exec_close(MigrationState *s)
 {
     int ret = 0;
     DPRINTF("exec_close\n");
-    if (s->opaque) {
-        ret = qemu_fclose(s->opaque);
-        s->opaque = NULL;
-        s->fd = -1;
-        if (ret >= 0 && !(WIFEXITED(ret) && WEXITSTATUS(ret) == 0)) {
-            /* close succeeded, but non-zero exit code: */
-            ret = -EIO; /* fake errno value */
-        }
+    ret = qemu_fclose(s->opaque);
+    s->opaque = NULL;
+    s->fd = -1;
+    if (ret >= 0 && !(WIFEXITED(ret) && WEXITSTATUS(ret) == 0)) {
+        /* close succeeded, but non-zero exit code: */
+        ret = -EIO; /* fake errno value */
     }
     return ret;
 }
@@ -87,9 +85,8 @@ static void exec_accept_incoming_migration(void *opaque)
 {
     QEMUFile *f = opaque;
 
+    qemu_set_fd_handler2(qemu_get_fd(f), NULL, NULL, NULL, NULL);
     process_incoming_migration(f);
-    qemu_set_fd_handler2(qemu_stdio_fd(f), NULL, NULL, NULL, NULL);
-    qemu_fclose(f);
 }
 
 void exec_start_incoming_migration(const char *command, Error **errp)
@@ -103,6 +100,6 @@ void exec_start_incoming_migration(const char *command, Error **errp)
         return;
     }
 
-    qemu_set_fd_handler2(qemu_stdio_fd(f), NULL,
+    qemu_set_fd_handler2(qemu_get_fd(f), NULL,
 			 exec_accept_incoming_migration, NULL, f);
 }
diff --git a/migration-fd.c b/migration-fd.c
index ce6932d7c3..5fe28e09fd 100644
--- a/migration-fd.c
+++ b/migration-fd.c
@@ -48,29 +48,26 @@ static int fd_close(MigrationState *s)
     int ret;
 
     DPRINTF("fd_close\n");
-    if (s->fd != -1) {
-        ret = fstat(s->fd, &st);
-        if (ret == 0 && S_ISREG(st.st_mode)) {
-            /*
-             * If the file handle is a regular file make sure the
-             * data is flushed to disk before signaling success.
-             */
-            ret = fsync(s->fd);
-            if (ret != 0) {
-                ret = -errno;
-                perror("migration-fd: fsync");
-                return ret;
-            }
-        }
-        ret = close(s->fd);
-        s->fd = -1;
+    ret = fstat(s->fd, &st);
+    if (ret == 0 && S_ISREG(st.st_mode)) {
+        /*
+         * If the file handle is a regular file make sure the
+         * data is flushed to disk before signaling success.
+         */
+        ret = fsync(s->fd);
         if (ret != 0) {
             ret = -errno;
-            perror("migration-fd: close");
+            perror("migration-fd: fsync");
             return ret;
         }
     }
-    return 0;
+    ret = close(s->fd);
+    s->fd = -1;
+    if (ret != 0) {
+        ret = -errno;
+        perror("migration-fd: close");
+    }
+    return ret;
 }
 
 void fd_start_outgoing_migration(MigrationState *s, const char *fdname, Error **errp)
@@ -92,9 +89,8 @@ static void fd_accept_incoming_migration(void *opaque)
 {
     QEMUFile *f = opaque;
 
+    qemu_set_fd_handler2(qemu_get_fd(f), NULL, NULL, NULL, NULL);
     process_incoming_migration(f);
-    qemu_set_fd_handler2(qemu_stdio_fd(f), NULL, NULL, NULL, NULL);
-    qemu_fclose(f);
 }
 
 void fd_start_incoming_migration(const char *infd, Error **errp)
diff --git a/migration-tcp.c b/migration-tcp.c
index 46f6ac545c..5e855fe72f 100644
--- a/migration-tcp.c
+++ b/migration-tcp.c
@@ -44,11 +44,8 @@ static int tcp_close(MigrationState *s)
 {
     int r = 0;
     DPRINTF("tcp_close\n");
-    if (s->fd != -1) {
-        if (close(s->fd) < 0) {
-            r = -errno;
-        }
-        s->fd = -1;
+    if (closesocket(s->fd) < 0) {
+        r = -socket_error();
     }
     return r;
 }
@@ -88,12 +85,14 @@ static void tcp_accept_incoming_migration(void *opaque)
     do {
         c = qemu_accept(s, (struct sockaddr *)&addr, &addrlen);
     } while (c == -1 && socket_error() == EINTR);
+    qemu_set_fd_handler2(s, NULL, NULL, NULL, NULL);
+    closesocket(s);
 
     DPRINTF("accepted migration\n");
 
     if (c == -1) {
         fprintf(stderr, "could not accept migration connection\n");
-        goto out2;
+        goto out;
     }
 
     f = qemu_fopen_socket(c);
@@ -103,12 +102,10 @@ static void tcp_accept_incoming_migration(void *opaque)
     }
 
     process_incoming_migration(f);
-    qemu_fclose(f);
+    return;
+
 out:
-    close(c);
-out2:
-    qemu_set_fd_handler2(s, NULL, NULL, NULL, NULL);
-    close(s);
+    closesocket(c);
 }
 
 void tcp_start_incoming_migration(const char *host_port, Error **errp)
diff --git a/migration-unix.c b/migration-unix.c
index ed3db3a39a..dba72b4a54 100644
--- a/migration-unix.c
+++ b/migration-unix.c
@@ -44,11 +44,8 @@ static int unix_close(MigrationState *s)
 {
     int r = 0;
     DPRINTF("unix_close\n");
-    if (s->fd != -1) {
-        if (close(s->fd) < 0) {
-            r = -errno;
-        }
-        s->fd = -1;
+    if (close(s->fd) < 0) {
+        r = -errno;
     }
     return r;
 }
@@ -88,12 +85,14 @@ static void unix_accept_incoming_migration(void *opaque)
     do {
         c = qemu_accept(s, (struct sockaddr *)&addr, &addrlen);
     } while (c == -1 && errno == EINTR);
+    qemu_set_fd_handler2(s, NULL, NULL, NULL, NULL);
+    close(s);
 
     DPRINTF("accepted migration\n");
 
     if (c == -1) {
         fprintf(stderr, "could not accept migration connection\n");
-        goto out2;
+        goto out;
     }
 
     f = qemu_fopen_socket(c);
@@ -103,12 +102,10 @@ static void unix_accept_incoming_migration(void *opaque)
     }
 
     process_incoming_migration(f);
-    qemu_fclose(f);
+    return;
+
 out:
     close(c);
-out2:
-    qemu_set_fd_handler2(s, NULL, NULL, NULL, NULL);
-    close(s);
 }
 
 void unix_start_incoming_migration(const char *path, Error **errp)
diff --git a/migration.c b/migration.c
index 300ab75aaf..73ce170ddf 100644
--- a/migration.c
+++ b/migration.c
@@ -83,9 +83,15 @@ void qemu_start_incoming_migration(const char *uri, Error **errp)
     }
 }
 
-void process_incoming_migration(QEMUFile *f)
+static void process_incoming_migration_co(void *opaque)
 {
-    if (qemu_loadvm_state(f) < 0) {
+    QEMUFile *f = opaque;
+    int ret;
+
+    ret = qemu_loadvm_state(f);
+    qemu_set_fd_handler(qemu_get_fd(f), NULL, NULL, NULL);
+    qemu_fclose(f);
+    if (ret < 0) {
         fprintf(stderr, "load of migration failed\n");
         exit(0);
     }
@@ -103,6 +109,23 @@ void process_incoming_migration(QEMUFile *f)
     }
 }
 
+static void enter_migration_coroutine(void *opaque)
+{
+    Coroutine *co = opaque;
+    qemu_coroutine_enter(co, NULL);
+}
+
+void process_incoming_migration(QEMUFile *f)
+{
+    Coroutine *co = qemu_coroutine_create(process_incoming_migration_co);
+    int fd = qemu_get_fd(f);
+
+    assert(fd != -1);
+    socket_set_nonblock(fd);
+    qemu_set_fd_handler(fd, enter_migration_coroutine, NULL, co);
+    qemu_coroutine_enter(co, f);
+}
+
 /* amount of nanoseconds we are willing to wait for migration to be down.
  * the choice of nanoseconds is because it is the maximum resolution that
  * get_clock() can achieve. It is an internal measure. All user-visible
@@ -243,21 +266,13 @@ static int migrate_fd_cleanup(MigrationState *s)
 {
     int ret = 0;
 
-    if (s->fd != -1) {
-        qemu_set_fd_handler2(s->fd, NULL, NULL, NULL, NULL);
-    }
-
     if (s->file) {
         DPRINTF("closing file\n");
         ret = qemu_fclose(s->file);
         s->file = NULL;
     }
 
-    if (s->fd != -1) {
-        close(s->fd);
-        s->fd = -1;
-    }
-
+    migrate_fd_close(s);
     return ret;
 }
 
@@ -393,8 +408,13 @@ int migrate_fd_wait_for_unfreeze(MigrationState *s)
 
 int migrate_fd_close(MigrationState *s)
 {
-    qemu_set_fd_handler2(s->fd, NULL, NULL, NULL, NULL);
-    return s->close(s);
+    int rc = 0;
+    if (s->fd != -1) {
+        qemu_set_fd_handler2(s->fd, NULL, NULL, NULL, NULL);
+        rc = s->close(s);
+        s->fd = -1;
+    }
+    return rc;
 }
 
 void add_migration_state_change_notifier(Notifier *notify)
diff --git a/qemu-file.h b/qemu-file.h
index 9c8985b610..d64bdbb19b 100644
--- a/qemu-file.h
+++ b/qemu-file.h
@@ -47,6 +47,10 @@ typedef int (QEMUFileGetBufferFunc)(void *opaque, uint8_t *buf,
  */
 typedef int (QEMUFileCloseFunc)(void *opaque);
 
+/* Called to return the OS file descriptor associated to the QEMUFile.
+ */
+typedef int (QEMUFileGetFD)(void *opaque);
+
 /* Called to determine if the file has exceeded its bandwidth allocation.  The
  * bandwidth capping is a soft limit, not a hard limit.
  */
@@ -59,18 +63,23 @@ typedef int (QEMUFileRateLimit)(void *opaque);
 typedef int64_t (QEMUFileSetRateLimit)(void *opaque, int64_t new_rate);
 typedef int64_t (QEMUFileGetRateLimit)(void *opaque);
 
-QEMUFile *qemu_fopen_ops(void *opaque, QEMUFilePutBufferFunc *put_buffer,
-                         QEMUFileGetBufferFunc *get_buffer,
-                         QEMUFileCloseFunc *close,
-                         QEMUFileRateLimit *rate_limit,
-                         QEMUFileSetRateLimit *set_rate_limit,
-                         QEMUFileGetRateLimit *get_rate_limit);
+typedef struct QEMUFileOps {
+    QEMUFilePutBufferFunc *put_buffer;
+    QEMUFileGetBufferFunc *get_buffer;
+    QEMUFileCloseFunc *close;
+    QEMUFileGetFD *get_fd;
+    QEMUFileRateLimit *rate_limit;
+    QEMUFileSetRateLimit *set_rate_limit;
+    QEMUFileGetRateLimit *get_rate_limit;
+} QEMUFileOps;
+
+QEMUFile *qemu_fopen_ops(void *opaque, const QEMUFileOps *ops);
 QEMUFile *qemu_fopen(const char *filename, const char *mode);
 QEMUFile *qemu_fdopen(int fd, const char *mode);
 QEMUFile *qemu_fopen_socket(int fd);
 QEMUFile *qemu_popen(FILE *popen_file, const char *mode);
 QEMUFile *qemu_popen_cmd(const char *command, const char *mode);
-int qemu_stdio_fd(QEMUFile *f);
+int qemu_get_fd(QEMUFile *f);
 int qemu_fclose(QEMUFile *f);
 void qemu_put_buffer(QEMUFile *f, const uint8_t *buf, int size);
 void qemu_put_byte(QEMUFile *f, int v);
diff --git a/savevm.c b/savevm.c
index 43d3d1bbeb..5d04d59688 100644
--- a/savevm.c
+++ b/savevm.c
@@ -163,12 +163,7 @@ void qemu_announce_self(void)
 #define IO_BUF_SIZE 32768
 
 struct QEMUFile {
-    QEMUFilePutBufferFunc *put_buffer;
-    QEMUFileGetBufferFunc *get_buffer;
-    QEMUFileCloseFunc *close;
-    QEMUFileRateLimit *rate_limit;
-    QEMUFileSetRateLimit *set_rate_limit;
-    QEMUFileGetRateLimit *get_rate_limit;
+    const QEMUFileOps *ops;
     void *opaque;
     int is_write;
 
@@ -193,28 +188,52 @@ typedef struct QEMUFileSocket
     QEMUFile *file;
 } QEMUFileSocket;
 
+static int socket_get_fd(void *opaque)
+{
+    QEMUFileSocket *s = opaque;
+
+    return s->fd;
+}
+
 static int socket_get_buffer(void *opaque, uint8_t *buf, int64_t pos, int size)
 {
     QEMUFileSocket *s = opaque;
     ssize_t len;
 
-    do {
+    for (;;) {
         len = qemu_recv(s->fd, buf, size, 0);
-    } while (len == -1 && socket_error() == EINTR);
+        if (len != -1) {
+            break;
+        }
+        if (socket_error() == EAGAIN) {
+            assert(qemu_in_coroutine());
+            qemu_coroutine_yield();
+        } else if (socket_error() != EINTR) {
+            break;
+        }
+    }
 
-    if (len == -1)
+    if (len == -1) {
         len = -socket_error();
-
+    }
     return len;
 }
 
 static int socket_close(void *opaque)
 {
     QEMUFileSocket *s = opaque;
+    closesocket(s->fd);
     g_free(s);
     return 0;
 }
 
+static int stdio_get_fd(void *opaque)
+{
+    QEMUFileStdio *s = opaque;
+
+    return fileno(s->stdio_file);
+}
+
 static int stdio_put_buffer(void *opaque, const uint8_t *buf, int64_t pos, int size)
 {
     QEMUFileStdio *s = opaque;
@@ -227,10 +246,19 @@ static int stdio_get_buffer(void *opaque, uint8_t *buf, int64_t pos, int size)
     FILE *fp = s->stdio_file;
     int bytes;
 
-    do {
+    for (;;) {
         clearerr(fp);
         bytes = fread(buf, 1, size, fp);
-    } while ((bytes == 0) && ferror(fp) && (errno == EINTR));
+        if (bytes != 0 || !ferror(fp)) {
+            break;
+        }
+        if (errno == EAGAIN) {
+            assert(qemu_in_coroutine());
+            qemu_coroutine_yield();
+        } else if (errno != EINTR) {
+            break;
+        }
+    }
     return bytes;
 }
 
@@ -257,6 +285,18 @@ static int stdio_fclose(void *opaque)
     return ret;
 }
 
+static const QEMUFileOps stdio_pipe_read_ops = {
+    .get_fd =     stdio_get_fd,
+    .get_buffer = stdio_get_buffer,
+    .close =      stdio_pclose
+};
+
+static const QEMUFileOps stdio_pipe_write_ops = {
+    .get_fd =     stdio_get_fd,
+    .put_buffer = stdio_put_buffer,
+    .close =      stdio_pclose
+};
+
 QEMUFile *qemu_popen(FILE *stdio_file, const char *mode)
 {
     QEMUFileStdio *s;
@@ -271,11 +311,9 @@ QEMUFile *qemu_popen(FILE *stdio_file, const char *mode)
     s->stdio_file = stdio_file;
 
     if(mode[0] == 'r') {
-        s->file = qemu_fopen_ops(s, NULL, stdio_get_buffer, stdio_pclose, 
-				 NULL, NULL, NULL);
+        s->file = qemu_fopen_ops(s, &stdio_pipe_read_ops);
     } else {
-        s->file = qemu_fopen_ops(s, stdio_put_buffer, NULL, stdio_pclose, 
-				 NULL, NULL, NULL);
+        s->file = qemu_fopen_ops(s, &stdio_pipe_write_ops);
     }
     return s->file;
 }
@@ -292,16 +330,17 @@ QEMUFile *qemu_popen_cmd(const char *command, const char *mode)
     return qemu_popen(popen_file, mode);
 }
 
-int qemu_stdio_fd(QEMUFile *f)
-{
-    QEMUFileStdio *p;
-    int fd;
-
-    p = (QEMUFileStdio *)f->opaque;
-    fd = fileno(p->stdio_file);
+static const QEMUFileOps stdio_file_read_ops = {
+    .get_fd =     stdio_get_fd,
+    .get_buffer = stdio_get_buffer,
+    .close =      stdio_fclose
+};
 
-    return fd;
-}
+static const QEMUFileOps stdio_file_write_ops = {
+    .get_fd =     stdio_get_fd,
+    .put_buffer = stdio_put_buffer,
+    .close =      stdio_fclose
+};
 
 QEMUFile *qemu_fdopen(int fd, const char *mode)
 {
@@ -320,11 +359,9 @@ QEMUFile *qemu_fdopen(int fd, const char *mode)
         goto fail;
 
     if(mode[0] == 'r') {
-        s->file = qemu_fopen_ops(s, NULL, stdio_get_buffer, stdio_fclose, 
-				 NULL, NULL, NULL);
+        s->file = qemu_fopen_ops(s, &stdio_file_read_ops);
     } else {
-        s->file = qemu_fopen_ops(s, stdio_put_buffer, NULL, stdio_fclose, 
-				 NULL, NULL, NULL);
+        s->file = qemu_fopen_ops(s, &stdio_file_write_ops);
     }
     return s->file;
 
@@ -333,31 +370,21 @@ fail:
     return NULL;
 }
 
+static const QEMUFileOps socket_read_ops = {
+    .get_fd =     socket_get_fd,
+    .get_buffer = socket_get_buffer,
+    .close =      socket_close
+};
+
 QEMUFile *qemu_fopen_socket(int fd)
 {
     QEMUFileSocket *s = g_malloc0(sizeof(QEMUFileSocket));
 
     s->fd = fd;
-    s->file = qemu_fopen_ops(s, NULL, socket_get_buffer, socket_close, 
-			     NULL, NULL, NULL);
+    s->file = qemu_fopen_ops(s, &socket_read_ops);
     return s->file;
 }
 
-static int file_put_buffer(void *opaque, const uint8_t *buf,
-                            int64_t pos, int size)
-{
-    QEMUFileStdio *s = opaque;
-    fseek(s->stdio_file, pos, SEEK_SET);
-    return fwrite(buf, 1, size, s->stdio_file);
-}
-
-static int file_get_buffer(void *opaque, uint8_t *buf, int64_t pos, int size)
-{
-    QEMUFileStdio *s = opaque;
-    fseek(s->stdio_file, pos, SEEK_SET);
-    return fread(buf, 1, size, s->stdio_file);
-}
-
 QEMUFile *qemu_fopen(const char *filename, const char *mode)
 {
     QEMUFileStdio *s;
@@ -376,11 +403,9 @@ QEMUFile *qemu_fopen(const char *filename, const char *mode)
         goto fail;
     
     if(mode[0] == 'w') {
-        s->file = qemu_fopen_ops(s, file_put_buffer, NULL, stdio_fclose, 
-				 NULL, NULL, NULL);
+        s->file = qemu_fopen_ops(s, &stdio_file_write_ops);
     } else {
-        s->file = qemu_fopen_ops(s, NULL, file_get_buffer, stdio_fclose, 
-			       NULL, NULL, NULL);
+        s->file = qemu_fopen_ops(s, &stdio_file_read_ops);
     }
     return s->file;
 fail:
@@ -405,32 +430,31 @@ static int bdrv_fclose(void *opaque)
     return bdrv_flush(opaque);
 }
 
+static const QEMUFileOps bdrv_read_ops = {
+    .get_buffer = block_get_buffer,
+    .close =      bdrv_fclose
+};
+
+static const QEMUFileOps bdrv_write_ops = {
+    .put_buffer = block_put_buffer,
+    .close =      bdrv_fclose
+};
+
 static QEMUFile *qemu_fopen_bdrv(BlockDriverState *bs, int is_writable)
 {
     if (is_writable)
-        return qemu_fopen_ops(bs, block_put_buffer, NULL, bdrv_fclose, 
-			      NULL, NULL, NULL);
-    return qemu_fopen_ops(bs, NULL, block_get_buffer, bdrv_fclose, NULL, NULL, NULL);
+        return qemu_fopen_ops(bs, &bdrv_write_ops);
+    return qemu_fopen_ops(bs, &bdrv_read_ops);
 }
 
-QEMUFile *qemu_fopen_ops(void *opaque, QEMUFilePutBufferFunc *put_buffer,
-                         QEMUFileGetBufferFunc *get_buffer,
-                         QEMUFileCloseFunc *close,
-                         QEMUFileRateLimit *rate_limit,
-                         QEMUFileSetRateLimit *set_rate_limit,
-                         QEMUFileGetRateLimit *get_rate_limit)
+QEMUFile *qemu_fopen_ops(void *opaque, const QEMUFileOps *ops)
 {
     QEMUFile *f;
 
     f = g_malloc0(sizeof(QEMUFile));
 
     f->opaque = opaque;
-    f->put_buffer = put_buffer;
-    f->get_buffer = get_buffer;
-    f->close = close;
-    f->rate_limit = rate_limit;
-    f->set_rate_limit = set_rate_limit;
-    f->get_rate_limit = get_rate_limit;
+    f->ops = ops;
     f->is_write = 0;
 
     return f;
@@ -453,11 +477,11 @@ static int qemu_fflush(QEMUFile *f)
 {
     int ret = 0;
 
-    if (!f->put_buffer)
+    if (!f->ops->put_buffer)
         return 0;
 
     if (f->is_write && f->buf_index > 0) {
-        ret = f->put_buffer(f->opaque, f->buf, f->buf_offset, f->buf_index);
+        ret = f->ops->put_buffer(f->opaque, f->buf, f->buf_offset, f->buf_index);
         if (ret >= 0) {
             f->buf_offset += f->buf_index;
         }
@@ -471,7 +495,7 @@ static void qemu_fill_buffer(QEMUFile *f)
     int len;
     int pending;
 
-    if (!f->get_buffer)
+    if (!f->ops->get_buffer)
         return;
 
     if (f->is_write)
@@ -484,7 +508,7 @@ static void qemu_fill_buffer(QEMUFile *f)
     f->buf_index = 0;
     f->buf_size = pending;
 
-    len = f->get_buffer(f->opaque, f->buf + pending, f->buf_offset,
+    len = f->ops->get_buffer(f->opaque, f->buf + pending, f->buf_offset,
                         IO_BUF_SIZE - pending);
     if (len > 0) {
         f->buf_size += len;
@@ -495,6 +519,14 @@ static void qemu_fill_buffer(QEMUFile *f)
         qemu_file_set_error(f, len);
 }
 
+int qemu_get_fd(QEMUFile *f)
+{
+    if (f->ops->get_fd) {
+        return f->ops->get_fd(f->opaque);
+    }
+    return -1;
+}
+
 /** Closes the file
  *
  * Returns negative error value if any error happened on previous operations or
@@ -508,8 +540,8 @@ int qemu_fclose(QEMUFile *f)
     int ret;
     ret = qemu_fflush(f);
 
-    if (f->close) {
-        int ret2 = f->close(f->opaque);
+    if (f->ops->close) {
+        int ret2 = f->ops->close(f->opaque);
         if (ret >= 0) {
             ret = ret2;
         }
@@ -526,7 +558,7 @@ int qemu_fclose(QEMUFile *f)
 
 int qemu_file_put_notify(QEMUFile *f)
 {
-    return f->put_buffer(f->opaque, NULL, 0, 0);
+    return f->ops->put_buffer(f->opaque, NULL, 0, 0);
 }
 
 void qemu_put_buffer(QEMUFile *f, const uint8_t *buf, int size)
@@ -673,16 +705,16 @@ static int64_t qemu_ftell(QEMUFile *f)
 
 int qemu_file_rate_limit(QEMUFile *f)
 {
-    if (f->rate_limit)
-        return f->rate_limit(f->opaque);
+    if (f->ops->rate_limit)
+        return f->ops->rate_limit(f->opaque);
 
     return 0;
 }
 
 int64_t qemu_file_get_rate_limit(QEMUFile *f)
 {
-    if (f->get_rate_limit)
-        return f->get_rate_limit(f->opaque);
+    if (f->ops->get_rate_limit)
+        return f->ops->get_rate_limit(f->opaque);
 
     return 0;
 }
@@ -691,8 +723,8 @@ int64_t qemu_file_set_rate_limit(QEMUFile *f, int64_t new_rate)
 {
     /* any failed or completed migration keeps its state to allow probing of
      * migration data, but has no associated file anymore */
-    if (f && f->set_rate_limit)
-        return f->set_rate_limit(f->opaque, new_rate);
+    if (f && f->ops->set_rate_limit)
+        return f->ops->set_rate_limit(f->opaque, new_rate);
 
     return 0;
 }