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block: Quiesce old aio context during bdrv_set_aio_context 

The fact that the bs->aio_context is changing can confuse the dataplane
iothread, because of the now fine granularity aio context lock.
bdrv_drain should rather be a bdrv_drained_begin/end pair, but since
bs->aio_context is changing, we can just use aio_disable_external and
bdrv_parent_drained_begin.

Reported-by: Ed Swierk <eswierk@skyportsystems.com>
Signed-off-by: Fam Zheng <famz@redhat.com>
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Fam Zheng 2017-04-05 14:44:24 +08:00
parent 14e9559f46
commit aabf591007
1 changed files with 5 additions and 2 deletions
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7
block.c
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@ -4396,11 +4396,12 @@ void bdrv_attach_aio_context(BlockDriverState *bs,
void bdrv_set_aio_context(BlockDriverState *bs, AioContext *new_context)
{
AioContext *ctx;
AioContext *ctx = bdrv_get_aio_context(bs);
aio_disable_external(ctx);
bdrv_parent_drained_begin(bs);
bdrv_drain(bs); /* ensure there are no in-flight requests */
ctx = bdrv_get_aio_context(bs);
while (aio_poll(ctx, false)) {
/* wait for all bottom halves to execute */
}
@ -4412,6 +4413,8 @@ void bdrv_set_aio_context(BlockDriverState *bs, AioContext *new_context)
*/
aio_context_acquire(new_context);
bdrv_attach_aio_context(bs, new_context);
bdrv_parent_drained_end(bs);
aio_enable_external(ctx);
aio_context_release(new_context);
}