diff options
author | Stefan Hajnoczi <stefanha@redhat.com> | 2023-05-16 15:02:29 -0400 |
---|---|---|
committer | Kevin Wolf <kwolf@redhat.com> | 2023-05-30 17:32:02 +0200 |
commit | f6eac904f6825d47adc6102c8d7b59b8ba5b778e (patch) | |
tree | 5b1faf62077883c92fd8619063bd3738680c20e0 /hw/block | |
parent | ab61335025b1274bd7042219203524045b23e0d3 (diff) | |
download | qemu-f6eac904f6825d47adc6102c8d7b59b8ba5b778e.zip qemu-f6eac904f6825d47adc6102c8d7b59b8ba5b778e.tar.gz qemu-f6eac904f6825d47adc6102c8d7b59b8ba5b778e.tar.bz2 |
xen-block: implement BlockDevOps->drained_begin()
Detach event channels during drained sections to stop I/O submission
from the ring. xen-block is no longer reliant on aio_disable_external()
after this patch. This will allow us to remove the
aio_disable_external() API once all other code that relies on it is
converted.
Extend xen_device_set_event_channel_context() to allow ctx=NULL. The
event channel still exists but the event loop does not monitor the file
descriptor. Event channel processing can resume by calling
xen_device_set_event_channel_context() with a non-NULL ctx.
Factor out xen_device_set_event_channel_context() calls in
hw/block/dataplane/xen-block.c into attach/detach helper functions.
Incidentally, these don't require the AioContext lock because
aio_set_fd_handler() is thread-safe.
It's safer to register BlockDevOps after the dataplane instance has been
created. The BlockDevOps .drained_begin/end() callbacks depend on the
dataplane instance, so move the blk_set_dev_ops() call after
xen_block_dataplane_create().
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20230516190238.8401-12-stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Diffstat (limited to 'hw/block')
-rw-r--r-- | hw/block/dataplane/xen-block.c | 42 | ||||
-rw-r--r-- | hw/block/dataplane/xen-block.h | 2 | ||||
-rw-r--r-- | hw/block/xen-block.c | 24 |
3 files changed, 54 insertions, 14 deletions
diff --git a/hw/block/dataplane/xen-block.c b/hw/block/dataplane/xen-block.c index d8bc39d..2597f38 100644 --- a/hw/block/dataplane/xen-block.c +++ b/hw/block/dataplane/xen-block.c @@ -664,6 +664,30 @@ void xen_block_dataplane_destroy(XenBlockDataPlane *dataplane) g_free(dataplane); } +void xen_block_dataplane_detach(XenBlockDataPlane *dataplane) +{ + if (!dataplane || !dataplane->event_channel) { + return; + } + + /* Only reason for failure is a NULL channel */ + xen_device_set_event_channel_context(dataplane->xendev, + dataplane->event_channel, + NULL, &error_abort); +} + +void xen_block_dataplane_attach(XenBlockDataPlane *dataplane) +{ + if (!dataplane || !dataplane->event_channel) { + return; + } + + /* Only reason for failure is a NULL channel */ + xen_device_set_event_channel_context(dataplane->xendev, + dataplane->event_channel, + dataplane->ctx, &error_abort); +} + void xen_block_dataplane_stop(XenBlockDataPlane *dataplane) { XenDevice *xendev; @@ -674,13 +698,11 @@ void xen_block_dataplane_stop(XenBlockDataPlane *dataplane) xendev = dataplane->xendev; - aio_context_acquire(dataplane->ctx); - if (dataplane->event_channel) { - /* Only reason for failure is a NULL channel */ - xen_device_set_event_channel_context(xendev, dataplane->event_channel, - qemu_get_aio_context(), - &error_abort); + if (!blk_in_drain(dataplane->blk)) { + xen_block_dataplane_detach(dataplane); } + + aio_context_acquire(dataplane->ctx); /* Xen doesn't have multiple users for nodes, so this can't fail */ blk_set_aio_context(dataplane->blk, qemu_get_aio_context(), &error_abort); aio_context_release(dataplane->ctx); @@ -819,11 +841,9 @@ void xen_block_dataplane_start(XenBlockDataPlane *dataplane, blk_set_aio_context(dataplane->blk, dataplane->ctx, NULL); aio_context_release(old_context); - /* Only reason for failure is a NULL channel */ - aio_context_acquire(dataplane->ctx); - xen_device_set_event_channel_context(xendev, dataplane->event_channel, - dataplane->ctx, &error_abort); - aio_context_release(dataplane->ctx); + if (!blk_in_drain(dataplane->blk)) { + xen_block_dataplane_attach(dataplane); + } return; diff --git a/hw/block/dataplane/xen-block.h b/hw/block/dataplane/xen-block.h index 76dcd51..7b8e9df 100644 --- a/hw/block/dataplane/xen-block.h +++ b/hw/block/dataplane/xen-block.h @@ -26,5 +26,7 @@ void xen_block_dataplane_start(XenBlockDataPlane *dataplane, unsigned int protocol, Error **errp); void xen_block_dataplane_stop(XenBlockDataPlane *dataplane); +void xen_block_dataplane_attach(XenBlockDataPlane *dataplane); +void xen_block_dataplane_detach(XenBlockDataPlane *dataplane); #endif /* HW_BLOCK_DATAPLANE_XEN_BLOCK_H */ diff --git a/hw/block/xen-block.c b/hw/block/xen-block.c index f5a7445..f099914 100644 --- a/hw/block/xen-block.c +++ b/hw/block/xen-block.c @@ -189,8 +189,26 @@ static void xen_block_resize_cb(void *opaque) xen_device_backend_printf(xendev, "state", "%u", state); } +/* Suspend request handling */ +static void xen_block_drained_begin(void *opaque) +{ + XenBlockDevice *blockdev = opaque; + + xen_block_dataplane_detach(blockdev->dataplane); +} + +/* Resume request handling */ +static void xen_block_drained_end(void *opaque) +{ + XenBlockDevice *blockdev = opaque; + + xen_block_dataplane_attach(blockdev->dataplane); +} + static const BlockDevOps xen_block_dev_ops = { - .resize_cb = xen_block_resize_cb, + .resize_cb = xen_block_resize_cb, + .drained_begin = xen_block_drained_begin, + .drained_end = xen_block_drained_end, }; static void xen_block_realize(XenDevice *xendev, Error **errp) @@ -242,8 +260,6 @@ static void xen_block_realize(XenDevice *xendev, Error **errp) return; } - blk_set_dev_ops(blk, &xen_block_dev_ops, blockdev); - if (conf->discard_granularity == -1) { conf->discard_granularity = conf->physical_block_size; } @@ -277,6 +293,8 @@ static void xen_block_realize(XenDevice *xendev, Error **errp) blockdev->dataplane = xen_block_dataplane_create(xendev, blk, conf->logical_block_size, blockdev->props.iothread); + + blk_set_dev_ops(blk, &xen_block_dev_ops, blockdev); } static void xen_block_frontend_changed(XenDevice *xendev, |