qemu/scsi
Leonardo Bras b88651cb4d QIOChannel: Add flags on io_writev and introduce io_flush callback
Add flags to io_writev and introduce io_flush as optional callback to
QIOChannelClass, allowing the implementation of zero copy writes by
subclasses.

How to use them:
- Write data using qio_channel_writev*(...,QIO_CHANNEL_WRITE_FLAG_ZERO_COPY),
- Wait write completion with qio_channel_flush().

Notes:
As some zero copy write implementations work asynchronously, it's
recommended to keep the write buffer untouched until the return of
qio_channel_flush(), to avoid the risk of sending an updated buffer
instead of the buffer state during write.

As io_flush callback is optional, if a subclass does not implement it, then:
- io_flush will return 0 without changing anything.

Also, some functions like qio_channel_writev_full_all() were adapted to
receive a flag parameter. That allows shared code between zero copy and
non-zero copy writev, and also an easier implementation on new flags.

Signed-off-by: Leonardo Bras <leobras@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Message-Id: <20220513062836.965425-3-leobras@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
2022-05-16 13:56:24 +01:00
..
meson.build meson: convert block 2020-08-21 06:30:18 -04:00
pr-helper.h Normalize header guard symbol definition. 2019-05-13 08:58:55 +02:00
pr-manager-helper.c QIOChannel: Add flags on io_writev and introduce io_flush callback 2022-05-16 13:56:24 +01:00
pr-manager-stub.c pr-manager: add query-pr-managers QMP command 2018-06-28 19:05:35 +02:00
pr-manager.c qapi: Use QAPI_LIST_APPEND in trivial cases 2021-01-28 08:08:45 +01:00
qemu-pr-helper.c util: replace qemu_get_local_state_pathname() 2022-04-21 17:09:09 +04:00
trace-events docs: fix references to docs/devel/tracing.rst 2021-06-02 06:51:09 +02:00
trace.h trace: switch position of headers to what Meson requires 2020-08-21 06:18:24 -04:00
utils.c scsi: fix sense code for EREMOTEIO 2021-03-16 14:30:30 -04:00