diff options
| -rw-r--r-- | block/io.c | 23 | ||||
| -rw-r--r-- | include/block/block.h | 22 |
2 files changed, 34 insertions, 11 deletions
diff --git a/block/io.c b/block/io.c index 8706bfa578..a7142e00e8 100644 --- a/block/io.c +++ b/block/io.c @@ -158,7 +158,7 @@ bool bdrv_requests_pending(BlockDriverState *bs) static bool bdrv_drain_recurse(BlockDriverState *bs) { - BdrvChild *child; + BdrvChild *child, *tmp; bool waited; waited = BDRV_POLL_WHILE(bs, atomic_read(&bs->in_flight) > 0); @@ -167,8 +167,25 @@ static bool bdrv_drain_recurse(BlockDriverState *bs) bs->drv->bdrv_drain(bs); } - QLIST_FOREACH(child, &bs->children, next) { - waited |= bdrv_drain_recurse(child->bs); + QLIST_FOREACH_SAFE(child, &bs->children, next, tmp) { + BlockDriverState *bs = child->bs; + bool in_main_loop = + qemu_get_current_aio_context() == qemu_get_aio_context(); + assert(bs->refcnt > 0); + if (in_main_loop) { + /* In case the recursive bdrv_drain_recurse processes a + * block_job_defer_to_main_loop BH and modifies the graph, + * let's hold a reference to bs until we are done. + * + * IOThread doesn't have such a BH, and it is not safe to call + * bdrv_unref without BQL, so skip doing it there. + */ + bdrv_ref(bs); + } + waited |= bdrv_drain_recurse(bs); + if (in_main_loop) { + bdrv_unref(bs); + } } return waited; diff --git a/include/block/block.h b/include/block/block.h index 97d4330292..5ddc0cf21b 100644 --- a/include/block/block.h +++ b/include/block/block.h @@ -381,12 +381,13 @@ void bdrv_drain_all(void); #define BDRV_POLL_WHILE(bs, cond) ({ \ bool waited_ = false; \ + bool busy_ = true; \ BlockDriverState *bs_ = (bs); \ AioContext *ctx_ = bdrv_get_aio_context(bs_); \ if (aio_context_in_iothread(ctx_)) { \ - while ((cond)) { \ - aio_poll(ctx_, true); \ - waited_ = true; \ + while ((cond) || busy_) { \ + busy_ = aio_poll(ctx_, (cond)); \ + waited_ |= !!(cond) | busy_; \ } \ } else { \ assert(qemu_get_current_aio_context() == \ @@ -398,11 +399,16 @@ void bdrv_drain_all(void); */ \ assert(!bs_->wakeup); \ bs_->wakeup = true; \ - while ((cond)) { \ - aio_context_release(ctx_); \ - aio_poll(qemu_get_aio_context(), true); \ - aio_context_acquire(ctx_); \ - waited_ = true; \ + while (busy_) { \ + if ((cond)) { \ + waited_ = busy_ = true; \ + aio_context_release(ctx_); \ + aio_poll(qemu_get_aio_context(), true); \ + aio_context_acquire(ctx_); \ + } else { \ + busy_ = aio_poll(ctx_, false); \ + waited_ |= busy_; \ + } \ } \ bs_->wakeup = false; \ } \ |