Commit d1263f8f authored by Peter Maydell's avatar Peter Maydell
Browse files

Merge remote-tracking branch 'remotes/famz/tags/block-pull-request' into staging 



# gpg: Signature made Tue 18 Apr 2017 15:58:32 BST
# gpg:                using RSA key 0xCA35624C6A9171C6
# gpg: Good signature from "Fam Zheng <famz@redhat.com>"
# gpg: WARNING: This key is not certified with sufficiently trusted signatures!
# gpg:          It is not certain that the signature belongs to the owner.
# Primary key fingerprint: 5003 7CB7 9706 0F76 F021  AD56 CA35 624C 6A91 71C6

* remotes/famz/tags/block-pull-request:
  block: Drain BH in bdrv_drained_begin
  block: Walk bs->children carefully in bdrv_drain_recurse

Signed-off-by: default avatarPeter Maydell <peter.maydell@linaro.org>
parents 9c6b899f 91af091f

block/io.c

+20 −3
Original line number Diff line number Diff line
@@ -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;

include/block/block.h

+14 −8
Original line number Diff line number Diff line
@@ -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)) {                                   \

        while (busy_) {                                    \

            if ((cond)) {                                  \

                waited_ = busy_ = true;                    \

                aio_context_release(ctx_);                 \

                aio_poll(qemu_get_aio_context(), true);    \

                aio_context_acquire(ctx_);                 \

            waited_ = true;                                \

            } else {                                       \

                busy_ = aio_poll(ctx_, false);             \

                waited_ |= busy_;                          \

            }                                              \

        }                                                  \

        bs_->wakeup = false;                               \

    }                                                      \