From: Zhu Yangyang <zhuyangyan...@huawei.com>
The bdrv_drained_begin() function is a blocking function. In scenarios where
network storage
is used and network links fail, it may block for a long time.
Therefore, we add a timeout parameter to control the duration of the block.
Since bdrv_drained_begin() has been widely adopted, both bdrv_drained_begin()
and bdrv_drained_begin_timeout() will be retained.
Signed-off-by: Zhu Yangyang <zhuyangyan...@huawei.com>
---
block/io.c | 58 +++++++++++++++++++++++++++++++++-------
include/block/aio-wait.h | 47 +++++++++++++++++++++++---------
include/block/block-io.h | 22 ++++++++++++++-
util/aio-wait.c | 5 ++++
4 files changed, 108 insertions(+), 24 deletions(-)
diff --git a/block/io.c b/block/io.c
index 1ba8d1aeea..912b76c4a4 100644
--- a/block/io.c
+++ b/block/io.c
@@ -255,6 +255,8 @@ typedef struct {
bool begin;
bool poll;
BdrvChild *parent;
+ uint64_t timeout_ns;
+ int ret;
} BdrvCoDrainData;
/* Returns true if BDRV_POLL_WHILE() should go into a blocking aio_poll() */
@@ -283,6 +285,10 @@ static bool bdrv_drain_poll_top_level(BlockDriverState *bs,
return bdrv_drain_poll(bs, ignore_parent, false);
}
+static int bdrv_do_drained_begin_timeout(BlockDriverState *bs,
+ BdrvChild *parent,
+ bool poll,
+ uint64_t timeout_ns);
static void bdrv_do_drained_begin(BlockDriverState *bs, BdrvChild *parent,
bool poll);
static void bdrv_do_drained_end(BlockDriverState *bs, BdrvChild *parent);
@@ -296,7 +302,9 @@ static void bdrv_co_drain_bh_cb(void *opaque)
if (bs) {
bdrv_dec_in_flight(bs);
if (data->begin) {
- bdrv_do_drained_begin(bs, data->parent, data->poll);
+ data->ret = bdrv_do_drained_begin_timeout(bs, data->parent,
+ data->poll,
+ data->timeout_ns);
} else {
assert(!data->poll);
bdrv_do_drained_end(bs, data->parent);
@@ -310,10 +318,11 @@ static void bdrv_co_drain_bh_cb(void *opaque)
aio_co_wake(co);
}
-static void coroutine_fn bdrv_co_yield_to_drain(BlockDriverState *bs,
- bool begin,
- BdrvChild *parent,
- bool poll)
+static int coroutine_fn bdrv_co_yield_to_drain_timeout(BlockDriverState *bs,
+ bool begin,
+ BdrvChild *parent,
+ bool poll,
+ uint64_t timeout_ns)
{
BdrvCoDrainData data;
Coroutine *self = qemu_coroutine_self();
@@ -329,6 +338,8 @@ static void coroutine_fn
bdrv_co_yield_to_drain(BlockDriverState *bs,
.begin = begin,
.parent = parent,
.poll = poll,
+ .timeout_ns = timeout_ns,
+ .ret = 0
};
if (bs) {
@@ -342,16 +353,27 @@ static void coroutine_fn
bdrv_co_yield_to_drain(BlockDriverState *bs,
/* If we are resumed from some other event (such as an aio completion or a
* timer callback), it is a bug in the caller that should be fixed. */
assert(data.done);
+ return data.ret;
}
-static void bdrv_do_drained_begin(BlockDriverState *bs, BdrvChild *parent,
- bool poll)
+static void coroutine_fn bdrv_co_yield_to_drain(BlockDriverState *bs,
+ bool begin,
+ BdrvChild *parent,
+ bool poll)
+{
+ bdrv_co_yield_to_drain_timeout(bs, begin, parent, poll, 0);
+}
+
+static int bdrv_do_drained_begin_timeout(BlockDriverState *bs,
+ BdrvChild *parent,
+ bool poll,
+ uint64_t timeout_ns)
{
IO_OR_GS_CODE();
if (qemu_in_coroutine()) {
- bdrv_co_yield_to_drain(bs, true, parent, poll);
- return;
+ return bdrv_co_yield_to_drain_timeout(bs, true, parent, poll,
+ timeout_ns);
}
GLOBAL_STATE_CODE();
@@ -375,8 +397,17 @@ static void bdrv_do_drained_begin(BlockDriverState *bs,
BdrvChild *parent,
* nodes.
*/
if (poll) {
- BDRV_POLL_WHILE(bs, bdrv_drain_poll_top_level(bs, parent));
+ return BDRV_POLL_WHILE_TIMEOUT(bs,
+ bdrv_drain_poll_top_level(bs, parent),
+ timeout_ns);
}
+ return 0;
+}
+
+static void bdrv_do_drained_begin(BlockDriverState *bs, BdrvChild *parent,
+ bool poll)
+{
+ bdrv_do_drained_begin_timeout(bs, parent, poll, 0);
}
void bdrv_do_drained_begin_quiesce(BlockDriverState *bs, BdrvChild *parent)
@@ -391,6 +422,13 @@ bdrv_drained_begin(BlockDriverState *bs)
bdrv_do_drained_begin(bs, NULL, true);
}
+int coroutine_mixed_fn
+bdrv_drained_begin_timeout(BlockDriverState *bs, uint64_t timeout_ns)
+{
+ IO_OR_GS_CODE();
+ return bdrv_do_drained_begin_timeout(bs, NULL, true, timeout_ns);
+}
+
/**
* This function does not poll, nor must any of its recursively called
* functions.
diff --git a/include/block/aio-wait.h b/include/block/aio-wait.h
index cf5e8bde1c..7610880b61 100644
--- a/include/block/aio-wait.h
+++ b/include/block/aio-wait.h
@@ -59,10 +59,12 @@ typedef struct {
extern AioWait global_aio_wait;
/**
- * AIO_WAIT_WHILE_INTERNAL:
+ * AIO_WAIT_WHILE_TIMEOUT:
* @ctx: the aio context, or NULL if multiple aio contexts (for which the
* caller does not hold a lock) are involved in the polling condition.
* @cond: wait while this conditional expression is true
+ * @timeout_ns: maximum duration to wait, in nanoseconds, except the value
+ * is unsigned, 0 means infinite.
*
* Wait while a condition is true. Use this to implement synchronous
* operations that require event loop activity.
@@ -74,37 +76,54 @@ extern AioWait global_aio_wait;
* thread (with @ctx acquired exactly once). This function cannot be used to
* wait on conditions between two IOThreads since that could lead to deadlock,
* go via the main loop instead.
+ *
+ * Returns: 0 if succeeded; -ETIMEDOUT when a timeout occurs.
*/
-#define AIO_WAIT_WHILE_INTERNAL(ctx, cond) ({ \
- bool waited_ = false; \
+#define AIO_WAIT_WHILE_TIMEOUT(ctx, cond, timeout_ns) ({ \
+ int ret_ = 0; \
+ uint64_t timeout_ = (timeout_ns); \
AioWait *wait_ = &global_aio_wait; \
AioContext *ctx_ = (ctx); \
+ AioContext *current_ctx_ = NULL; \
+ QEMUTimer timer_; \
/* Increment wait_->num_waiters before evaluating cond. */ \
qatomic_inc(&wait_->num_waiters); \
/* Paired with smp_mb in aio_wait_kick(). */ \
smp_mb__after_rmw(); \
if (ctx_ && in_aio_context_home_thread(ctx_)) { \
- while ((cond)) { \
- aio_poll(ctx_, true); \
- waited_ = true; \
- } \
+ current_ctx_ = ctx_; \
} else { \
assert(qemu_get_current_aio_context() == \
qemu_get_aio_context()); \
- while ((cond)) { \
- aio_poll(qemu_get_aio_context(), true); \
- waited_ = true; \
+ current_ctx_ = qemu_get_aio_context(); \
+ } \
+ if (timeout_ > 0) { \
+ timer_init_full(&timer_, ¤t_ctx_->tlg, \
+ QEMU_CLOCK_REALTIME, \
+ SCALE_NS, 0, aio_wait_timer_cb, NULL); \
+ timer_mod_ns(&timer_, \
+ qemu_clock_get_ns(QEMU_CLOCK_REALTIME) + \
+ timeout_); \
+ } \
+ while ((cond)) { \
+ aio_poll(current_ctx_, true); \
+ if (timeout_ > 0 && !timer_pending(&timer_)) { \
+ ret_ = -ETIMEDOUT; \
+ break; \
} \
} \
+ if (timeout_ > 0) { \
+ timer_del(&timer_); \
+ } \
qatomic_dec(&wait_->num_waiters); \
- waited_; })
+ ret_; })
#define AIO_WAIT_WHILE(ctx, cond) \
- AIO_WAIT_WHILE_INTERNAL(ctx, cond)
+ AIO_WAIT_WHILE_TIMEOUT(ctx, cond, 0)
/* TODO replace this with AIO_WAIT_WHILE() in a future patch */
#define AIO_WAIT_WHILE_UNLOCKED(ctx, cond) \
- AIO_WAIT_WHILE_INTERNAL(ctx, cond)
+ AIO_WAIT_WHILE_TIMEOUT(ctx, cond, 0)
/**
* aio_wait_kick:
@@ -149,4 +168,6 @@ static inline bool in_aio_context_home_thread(AioContext
*ctx)
}
}
+void aio_wait_timer_cb(void *opaque);
+
#endif /* QEMU_AIO_WAIT_H */
diff --git a/include/block/block-io.h b/include/block/block-io.h
index b49e0537dd..844e9cf350 100644
--- a/include/block/block-io.h
+++ b/include/block/block-io.h
@@ -354,6 +354,11 @@ bdrv_co_copy_range(BdrvChild *src, int64_t src_offset,
AIO_WAIT_WHILE(bdrv_get_aio_context(bs_), \
cond); })
+#define BDRV_POLL_WHILE_TIMEOUT(bs, cond, timeout_ns) ({ \
+ BlockDriverState *bs_ = (bs); \
+ AIO_WAIT_WHILE_TIMEOUT(bdrv_get_aio_context(bs_), \
+ cond, timeout_ns); })
+
void bdrv_drain(BlockDriverState *bs);
int co_wrapper_mixed_bdrv_rdlock
@@ -432,7 +437,22 @@ bdrv_drain_poll(BlockDriverState *bs, BdrvChild
*ignore_parent,
void bdrv_drained_begin(BlockDriverState *bs);
/**
- * bdrv_do_drained_begin_quiesce:
+ * bdrv_drained_begin_timeout:
+ *
+ * Added timeout parameter for bdrv_drained_begin() to make a time limited.
+ *
+ * @timeout_ns: maximum duration to wait; 0 means infinite, equal to call
+ * bdrv_drained_begin().
+ *
+ * Returns: 0 if succeeded; -ETIMEDOUT when a timeout occurs.
+ *
+ * Note: when the timeout fails, we've already begin aquiesced section, so we
+ * still need to call bdrv_drained_end() to end the quiescent section.
+ */
+int bdrv_drained_begin_timeout(BlockDriverState *bs, uint64_t timeout_ns);
+
+/**
+ * bdrv_do_drained_badegin_quiesce:
*
* Quiesces a BDS like bdrv_drained_begin(), but does not wait for already
* running requests to complete.
diff --git a/util/aio-wait.c b/util/aio-wait.c
index b5336cf5fd..64c3714fb8 100644
--- a/util/aio-wait.c
+++ b/util/aio-wait.c
@@ -84,3 +84,8 @@ void aio_wait_bh_oneshot(AioContext *ctx, QEMUBHFunc *cb,
void *opaque)
aio_bh_schedule_oneshot(ctx, aio_wait_bh, &data);
AIO_WAIT_WHILE_UNLOCKED(NULL, !data.done);
}
+
+void aio_wait_timer_cb(void *opaque)
+{
+ /* The point is to make AIO_WAIT_WHILE_TIMEOUT()'s aio_poll() return */
+}
--
2.33.0
