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block: Remove bdrv_set_aio_context()

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All callers of bdrv_set_aio_context() are eliminated now, they have
moved to bdrv_try_set_aio_context() and related safe functions. Remove
bdrv_set_aio_context().

With this, we can now know that the .set_aio_ctx callback must be
present in bdrv_set_aio_context_ignore() because
bdrv_can_set_aio_context() would have returned false previously, so
instead of checking the condition, we can assert it.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Kevin Wolf 2019-05-07 18:31:38 +02:00
parent 26bf15e441
commit 42a65f02f9
3 changed files with 16 additions and 27 deletions
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30
block.c
View File

@ -5789,8 +5789,17 @@ static void bdrv_attach_aio_context(BlockDriverState *bs,
bs->walking_aio_notifiers = false;
}
/* @ignore will accumulate all visited BdrvChild object. The caller is
* responsible for freeing the list afterwards. */
/*
* Changes the AioContext used for fd handlers, timers, and BHs by this
* BlockDriverState and all its children and parents.
*
* The caller must own the AioContext lock for the old AioContext of bs, but it
* must not own the AioContext lock for new_context (unless new_context is the
* same as the current context of bs).
*
* @ignore will accumulate all visited BdrvChild object. The caller is
* responsible for freeing the list afterwards.
*/
void bdrv_set_aio_context_ignore(BlockDriverState *bs,
AioContext *new_context, GSList **ignore)
{
@ -5813,10 +5822,9 @@ void bdrv_set_aio_context_ignore(BlockDriverState *bs,
if (g_slist_find(*ignore, child)) {
continue;
}
if (child->role->set_aio_ctx) {
*ignore = g_slist_prepend(*ignore, child);
child->role->set_aio_ctx(child, new_context, ignore);
}
assert(child->role->set_aio_ctx);
*ignore = g_slist_prepend(*ignore, child);
child->role->set_aio_ctx(child, new_context, ignore);
}
bdrv_detach_aio_context(bs);
@ -5830,16 +5838,6 @@ void bdrv_set_aio_context_ignore(BlockDriverState *bs,
aio_context_release(new_context);
}
/* The caller must own the AioContext lock for the old AioContext of bs, but it
* must not own the AioContext lock for new_context (unless new_context is
* the same as the current context of bs). */
void bdrv_set_aio_context(BlockDriverState *bs, AioContext *new_context)
{
GSList *ignore_list = NULL;
bdrv_set_aio_context_ignore(bs, new_context, &ignore_list);
g_slist_free(ignore_list);
}
static bool bdrv_parent_can_set_aio_context(BdrvChild *c, AioContext *ctx,
GSList **ignore, Error **errp)
{

4
docs/devel/multiple-iothreads.txt
View File

@ -109,7 +109,7 @@ The AioContext originates from the QEMU block layer, even though nowadays
AioContext is a generic event loop that can be used by any QEMU subsystem.
The block layer has support for AioContext integrated. Each BlockDriverState
is associated with an AioContext using bdrv_set_aio_context() and
is associated with an AioContext using bdrv_try_set_aio_context() and
bdrv_get_aio_context(). This allows block layer code to process I/O inside the
right AioContext. Other subsystems may wish to follow a similar approach.
@ -134,5 +134,5 @@ Long-running jobs (usually in the form of coroutines) are best scheduled in
the BlockDriverState's AioContext to avoid the need to acquire/release around
each bdrv_*() call. The functions bdrv_add/remove_aio_context_notifier,
or alternatively blk_add/remove_aio_context_notifier if you use BlockBackends,
can be used to get a notification whenever bdrv_set_aio_context() moves a
can be used to get a notification whenever bdrv_try_set_aio_context() moves a
BlockDriverState to a different AioContext.

9
include/block/block.h
View File

@ -583,15 +583,6 @@ AioContext *bdrv_get_aio_context(BlockDriverState *bs);
*/
void bdrv_coroutine_enter(BlockDriverState *bs, Coroutine *co);
/**
* bdrv_set_aio_context:
*
* Changes the #AioContext used for fd handlers, timers, and BHs by this
* BlockDriverState and all its children.
*
* This function must be called with iothread lock held.
*/
void bdrv_set_aio_context(BlockDriverState *bs, AioContext *new_context);
void bdrv_set_aio_context_ignore(BlockDriverState *bs,
AioContext *new_context, GSList **ignore);
int bdrv_try_set_aio_context(BlockDriverState *bs, AioContext *ctx,