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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: Peter Maydell <peter.maydell@linaro.org>
This commit is contained in:
Peter Maydell 2017-04-18 16:18:15 +01:00
commit d1263f8f18
2 changed files with 34 additions and 11 deletions
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23
block/io.c
View File

@ -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;

22
include/block/block.h
View File

@ -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; \
} \