[PATCH 00/20] migration: remove QEMUFileOps concept and assume use of QIOChannel

["Daniel P. Berrangé" <berrange@redhat.com>]

Quite a while ago now, the majority of QEMUFile implementations were
switched over to use QIOChannel APIs, but a couple remained.

The newish multifd code is directly using QIOChannel, only calling
in to QEMUFile for the VMState transfer and for rate limiting
purposes.

This series finishes the job of converting QEMUFile to always have
a QIOChannel as its backend, enabling a removal of QEMUFileOps.

Most callers still need to use the QEMUFile APIs though, as that
performs buffering of reads/writes.

As a followup to this series, however, it would be practical to
introduce a QIOChannelCache that layers on top of another QIOChannel
to add buffering equivalent to what QEMUFile does, possibly with
the rate limiting too.

At that point QEMUFile would not really be doing much at all and
could possibly go away entirely, leaving just the MigrationState
object for global state tracking, managing one or more QIOChannel
objects for the data transfer. I think this could simplify future
evolution of migration code.

I'm not likely to have time in the immediate future to work on
such a followup though.

Daniel P. Berrangé (20):
  io: add a QIOChannelNull equivalent to /dev/null
  migration: switch to use QIOChannelNull for dummy channel
  migration: remove unreachble RDMA code in save_hook impl
  migration: rename rate limiting fields in QEMUFile
  migration: rename 'pos' field in QEMUFile to 'bytes_processed'
  migration: rename qemu_ftell to qemu_file_total_transferred
  migration: rename qemu_update_position to qemu_file_credit_transfer
  migration: introduce a QIOChannel impl for BlockDriverState VMState
  migration: convert savevm to use QIOChannelBlock for VMState
  migration: stop passing 'opaque' parameter to QEMUFile hooks
  migration: hardcode assumption that QEMUFile is backed with QIOChannel
  migration: introduce new constructors for QEMUFile
  migration: remove unused QEMUFileGetFD typedef
  migration: remove the QEMUFileOps 'shut_down' callback
  migration: remove the QEMUFileOps 'set_blocking' callback
  migration: remove the QEMUFileOps 'close' callback
  migration: remove the QEMUFileOps 'get_buffer' callback
  migration: remove the QEMUFileOps 'writev_buffer' callback
  migration: remove the QEMUFileOps 'get_return_path' callback
  migration: remove the QEMUFileOps abstraction

 include/io/channel-null.h         |  55 +++++++
 io/channel-null.c                 | 237 ++++++++++++++++++++++++++++++
 io/meson.build                    |   1 +
 io/trace-events                   |   3 +
 migration/block.c                 |  10 +-
 migration/channel-block.c         | 195 ++++++++++++++++++++++++
 migration/channel-block.h         |  59 ++++++++
 migration/channel.c               |   4 +-
 migration/colo.c                  |   5 +-
 migration/meson.build             |   2 +-
 migration/migration.c             |   9 +-
 migration/qemu-file-channel.c     | 194 ------------------------
 migration/qemu-file-channel.h     |  32 ----
 migration/qemu-file.c             | 188 +++++++++++++-----------
 migration/qemu-file.h             | 122 +++++++--------
 migration/ram.c                   |   8 +-
 migration/rdma.c                  | 144 +++++-------------
 migration/savevm.c                |  55 ++-----
 migration/vmstate.c               |   4 +-
 tests/unit/meson.build            |   1 +
 tests/unit/test-io-channel-null.c |  95 ++++++++++++
 tests/unit/test-vmstate.c         |   5 +-
 22 files changed, 870 insertions(+), 558 deletions(-)
 create mode 100644 include/io/channel-null.h
 create mode 100644 io/channel-null.c
 create mode 100644 migration/channel-block.c
 create mode 100644 migration/channel-block.h
 delete mode 100644 migration/qemu-file-channel.c
 delete mode 100644 migration/qemu-file-channel.h
 create mode 100644 tests/unit/test-io-channel-null.c

-- 
2.36.1