block: add bdrv_set_aio_context()

Up until now all BlockDriverState instances have used the QEMU main loop
for fd handlers, timers, and BHs.  This is not scalable on SMP guests
and hosts so we need to move to a model with multiple event loops on
different host CPUs.

bdrv_set_aio_context() assigns the AioContext event loop to use for a
particular BlockDriverState.  It first detaches the entire
BlockDriverState graph from the current AioContext and then attaches to
the new AioContext.

This function will be used by virtio-blk data-plane to assign a
BlockDriverState to its IOThread AioContext.  Make
bdrv_aio_set_context() public since data-plane should not include
block_int.h.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
blkdebug: use BlockDriverState's AioContext

Drop the assumption that we're using the main AioContext.  Convert
qemu_bh_new() to aio_bh_new() so we use the BlockDriverState's
AioContext.

The .bdrv_detach_aio_context() and .bdrv_attach_aio_context() interfaces
are not needed since no fd handlers, timers, or BHs stay registered when
requests have been drained.

Cc: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
blkverify: use BlockDriverState's AioContext

Drop the assumption that we're using the main AioContext.  Convert
qemu_bh_new() to aio_bh_new() and qemu_aio_wait() to aio_poll() so we
use the BlockDriverState's AioContext.

The .bdrv_detach_aio_context() and .bdrv_attach_aio_context() interfaces
are not needed since no fd handlers, timers, or BHs stay registered when
requests have been drained.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
curl: implement .bdrv_detach/attach_aio_context()

The curl block driver uses fd handlers, timers, and BHs.  The fd
handlers and timers are managed on behalf of libcurl, which controls
them using callback functions that the block driver implements.

The simplest way to implement .bdrv_detach/attach_aio_context() is to
clean up libcurl in the old event loop and initialize it again in the
new event loop.  We do not need to keep track of anything since there
are no pending requests when the AioContext is changed.

Also make sure to use aio_set_fd_handler() instead of
qemu_aio_set_fd_handler() and aio_bh_new() instead of qemu_bh_new() so
the current AioContext is passed in.

Cc: Alexander Graf <agraf@suse.de>
Cc: Fam Zheng <famz@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
gluster: use BlockDriverState's AioContext

Drop the assumption that we're using the main AioContext.  Use
aio_bh_new() instead of qemu_bh_new().

The .bdrv_detach_aio_context() and .bdrv_attach_aio_context() interfaces
are not needed since no fd handlers, timers, or BHs stay registered when
requests have been drained.

Cc: Bharata B Rao <bharata@linux.vnet.ibm.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
iscsi: implement .bdrv_detach/attach_aio_context()

Drop the assumption that we're using the main AioContext for Linux
AIO.  Convert qemu_aio_set_fd_handler() to aio_set_fd_handler() and
timer_new_ms() to aio_timer_new().

The .bdrv_detach/attach_aio_context() interfaces also need to be
implemented to move the fd and timer from the old to the new AioContext.

Cc: Peter Lieven <pl@kamp.de>
Cc: Ronnie Sahlberg <ronniesahlberg@gmail.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
nbd: implement .bdrv_detach/attach_aio_context()

Drop the assumption that we're using the main AioContext.  Convert
qemu_aio_set_fd_handler() calls to aio_set_fd_handler().

The .bdrv_detach/attach_aio_context() interfaces also need to be
implemented to move the socket fd handler from the old to the new
AioContext.

Cc: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
nfs: implement .bdrv_detach/attach_aio_context()

Drop the assumption that we're using the main AioContext.  The following
functions need to be converted:
 * qemu_bh_new() -> aio_bh_new()
 * qemu_aio_set_fd_handler() -> aio_set_fd_handler()
 * qemu_aio_wait() -> aio_poll()

The .bdrv_detach/attach_aio_context() interfaces also need to be
implemented to move the fd handler from the old to the new AioContext.

Cc: Richard W.M. Jones <rjones@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
qed: use BlockDriverState's AioContext

Drop the assumption that we're using the main AioContext.  Convert
qemu_bh_new() to aio_bh_new() and qemu_aio_wait() to aio_poll() so we're
using the BlockDriverState's AioContext.

Implement .bdrv_detach/attach_aio_context() interfaces to move the
QED_F_NEED_CHECK timer from the old AioContext to the new one.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
block/raw-posix: implement .bdrv_detach/attach_aio_context()

Drop the assumption that we're using the main AioContext for Linux AIO.
Convert the Linux AIO event notifier to use aio_set_event_notifier().

The .bdrv_detach/attach_aio_context() interfaces also need to be
implemented to move the event notifier handler from the old to the new
AioContext.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
block/linux-aio: fix memory and fd leak

Hot unplugging -drive aio=native,file=test.img,format=raw images leaves
the Linux AIO event notifier and struct qemu_laio_state allocated.
Luckily nothing will use the event notifier after the BlockDriverState
has been closed so the handler function is never called.

It's still worth fixing this resource leak.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
rbd: use BlockDriverState's AioContext

Drop the assumption that we're using the main AioContext.  Convert
qemu_bh_new() to aio_bh_new() and qemu_aio_wait() to aio_poll().

The .bdrv_detach_aio_context() and .bdrv_attach_aio_context() interfaces
are not needed since no fd handlers, timers, or BHs stay registered when
requests have been drained.

Cc: Josh Durgin <josh.durgin@inktank.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
sheepdog: implement .bdrv_detach/attach_aio_context()

Drop the assumption that we're using the main AioContext.  Convert
qemu_aio_set_fd_handler() to aio_set_fd_handler() and qemu_aio_wait() to
aio_poll().

The .bdrv_detach/attach_aio_context() interfaces also need to be
implemented to move the socket fd handler from the old to the new
AioContext.

Cc: MORITA Kazutaka <morita.kazutaka@lab.ntt.co.jp>
Cc: Liu Yuan <namei.unix@gmail.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
ssh: use BlockDriverState's AioContext

Drop the assumption that we're using the main AioContext.  Use
bdrv_get_aio_context() to register fd handlers in the right AioContext
for this BlockDriverState.

The .bdrv_detach_aio_context() and .bdrv_attach_aio_context() interfaces
are not needed since no fd handlers, timers, or BHs stay registered when
requests have been drained.

For now this doesn't make much difference but will allow ssh to work in
IOThread instances in the future.

Cc: Richard W.M. Jones <rjones@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
dataplane: use the QEMU block layer for I/O

Stop using a custom Linux AIO request queue from ioq.h and instead use
the QEMU block layer for I/O.

This patch adjusts the VirtIOBlockRequest struct with fields needed for
bdrv_aio_readv()/bdrv_aio_writev().  ioq.h used struct iovec and struct
iocb, which we don't need directly anymore.

Modify dataplane start/stop to set the AioContext on the
BlockDriverState.  We also no longer need to get the raw-posix file
descriptor.  This means image formats are now supported with dataplane!

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
dataplane: delete IOQueue since it is no longer used

This custom Linux AIO request queue is no longer used by virtio-blk
data-plane.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
dataplane: implement async flush

Stop using the raw-posix file descriptor for synchronous
qemu_fdatasync().  Use bdrv_aio_flush() instead and drop the
VirtIOBlockDataPlane->fd field.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
raw-posix: drop raw_get_aio_fd() since it is no longer used

virtio-blk data-plane now uses the QEMU block layer for I/O.  We do not
need raw_get_aio_fd() anymore.  It was a layering violation anyway, so
let's get rid of it.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>