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[PATCH 1/2] io/block: Refactoring the bdrv_drained_begin() function and
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From: |
zoudongjie |
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Subject: |
[PATCH 1/2] io/block: Refactoring the bdrv_drained_begin() function and implement a timeout mechanism. |
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Date: |
Sat, 8 Mar 2025 18:16:17 +0800 |
From: Zhu Yangyang <zhuyangyang14@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 <zhuyangyang14@huawei.com>
---
block/io.c | 55 ++++++++++++++++++++++++++++++-------
include/block/aio-wait.h | 58 ++++++++++++++++++++++++++++++++++++++++
include/block/block-io.h | 7 +++++
util/aio-wait.c | 7 +++++
4 files changed, 117 insertions(+), 10 deletions(-)
diff --git a/block/io.c b/block/io.c
index d369b994df..03b8b2dca7 100644
--- a/block/io.c
+++ b/block/io.c
@@ -255,6 +255,8 @@ typedef struct {
bool begin;
bool poll;
BdrvChild *parent;
+ int ret;
+ int64_t timeout;
} BdrvCoDrainData;
/* Returns true if BDRV_POLL_WHILE() should go into a blocking aio_poll() */
@@ -283,6 +285,8 @@ 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, int64_t timeout);
static void bdrv_do_drained_begin(BlockDriverState *bs, BdrvChild *parent,
bool poll);
static void bdrv_do_drained_end(BlockDriverState *bs, BdrvChild *parent);
@@ -296,7 +300,8 @@ 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);
} else {
assert(!data->poll);
bdrv_do_drained_end(bs, data->parent);
@@ -310,10 +315,11 @@ 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,
+ int64_t timeout)
{
BdrvCoDrainData data;
Coroutine *self = qemu_coroutine_self();
@@ -329,6 +335,8 @@ static void coroutine_fn
bdrv_co_yield_to_drain(BlockDriverState *bs,
.begin = begin,
.parent = parent,
.poll = poll,
+ .timeout = timeout,
+ .ret = 0
};
if (bs) {
@@ -342,16 +350,25 @@ 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, -1);
+}
+
+static int bdrv_do_drained_begin_timeout(BlockDriverState *bs,
+ BdrvChild *parent, bool poll, int64_t timeout_ms)
{
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_ms);
}
GLOBAL_STATE_CODE();
@@ -375,8 +392,20 @@ static void bdrv_do_drained_begin(BlockDriverState *bs,
BdrvChild *parent,
* nodes.
*/
if (poll) {
- BDRV_POLL_WHILE(bs, bdrv_drain_poll_top_level(bs, parent));
+ if (timeout_ms < 0) {
+ BDRV_POLL_WHILE(bs, bdrv_drain_poll_top_level(bs, parent));
+ } else {
+ return BDRV_POLL_WHILE_TIMEOUT(
+ bs, bdrv_drain_poll_top_level(bs, parent), timeout_ms);
+ }
}
+ return 0;
+}
+
+static void bdrv_do_drained_begin(BlockDriverState *bs, BdrvChild *parent,
+ bool poll)
+{
+ bdrv_do_drained_begin_timeout(bs, parent, poll, -1);
}
void bdrv_do_drained_begin_quiesce(BlockDriverState *bs, BdrvChild *parent)
@@ -390,6 +419,12 @@ bdrv_drained_begin(BlockDriverState *bs)
IO_OR_GS_CODE();
bdrv_do_drained_begin(bs, NULL, true);
}
+int coroutine_mixed_fn
+bdrv_drained_begin_timeout(BlockDriverState *bs, int64_t timeout_ms)
+{
+ IO_OR_GS_CODE();
+ return bdrv_do_drained_begin_timeout(bs, NULL, true, timeout_ms);
+}
/**
* This function does not poll, nor must any of its recursively called
diff --git a/include/block/aio-wait.h b/include/block/aio-wait.h
index cf5e8bde1c..efbcb9777a 100644
--- a/include/block/aio-wait.h
+++ b/include/block/aio-wait.h
@@ -28,6 +28,8 @@
#include "block/aio.h"
#include "qemu/main-loop.h"
+#define AIO_WAIT_INTERVAL 10 /* ms */
+
/**
* AioWait:
*
@@ -56,6 +58,11 @@ typedef struct {
unsigned num_waiters;
} AioWait;
+typedef struct {
+ struct QEMUTimer *timer;
+ int64_t interval;
+} AioWaitTimer;
+
extern AioWait global_aio_wait;
/**
@@ -99,6 +106,55 @@ extern AioWait global_aio_wait;
qatomic_dec(&wait_->num_waiters); \
waited_; })
+/**
+ * AIO_WAIT_WHILE_TIMEOUT:
+ *
+ * Refer to the implementation of AIO_WAIT_WHILE_INTERNAL,
+ * the timeout parameter is added.
+ */
+#define AIO_WAIT_WHILE_TIMEOUT(ctx, cond, timeout) ({ \
+ int ret_ = 0; \
+ AioWait *wait_ = &global_aio_wait; \
+ AioContext *ctx_ = (ctx); \
+ int64_t start_ = qemu_clock_get_ms(QEMU_CLOCK_REALTIME); \
+ int64_t deadline_ = start_ + (timeout); \
+ /* Ensure that the aio_poll exits periodically to check timeout. */ \
+ AioWaitTimer *s_ = g_malloc0(sizeof(AioWaitTimer)); \
+ s_->interval = AIO_WAIT_INTERVAL; \
+ /* 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_)) { \
+ s_->timer = aio_timer_new(ctx_, QEMU_CLOCK_REALTIME, \
+ SCALE_MS, aio_wait_timer_retry, s_); \
+ aio_wait_timer_retry(s_); \
+ while ((cond)) { \
+ aio_poll(ctx_, true); \
+ if (qemu_clock_get_ms(QEMU_CLOCK_REALTIME) > deadline_) { \
+ ret_ = -ETIMEDOUT; \
+ break; \
+ } \
+ } \
+ } else { \
+ s_->timer = aio_timer_new(qemu_get_aio_context(), \
+ QEMU_CLOCK_REALTIME, SCALE_MS, aio_wait_timer_retry, s_); \
+ aio_wait_timer_retry(s_); \
+ while ((cond)) { \
+ assert(qemu_get_current_aio_context() == \
+ qemu_get_aio_context()); \
+ aio_poll(qemu_get_aio_context(), true); \
+ if (qemu_clock_get_ms(QEMU_CLOCK_REALTIME) > deadline_) { \
+ ret_ = -ETIMEDOUT; \
+ break; \
+ } \
+ } \
+ } \
+ qatomic_dec(&wait_->num_waiters); \
+ timer_free(s_->timer); \
+ g_free(s_); \
+ ret_; })
+
#define AIO_WAIT_WHILE(ctx, cond) \
AIO_WAIT_WHILE_INTERNAL(ctx, cond)
@@ -149,4 +205,6 @@ static inline bool in_aio_context_home_thread(AioContext
*ctx)
}
}
+void aio_wait_timer_retry(void *opaque);
+
#endif /* QEMU_AIO_WAIT_H */
diff --git a/include/block/block-io.h b/include/block/block-io.h
index b49e0537dd..84f92d2b09 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) ({ \
+ BlockDriverState *bs_ = (bs); \
+ AIO_WAIT_WHILE_TIMEOUT(bdrv_get_aio_context(bs_), \
+ cond, timeout); })
+
void bdrv_drain(BlockDriverState *bs);
int co_wrapper_mixed_bdrv_rdlock
@@ -431,6 +436,8 @@ bdrv_drain_poll(BlockDriverState *bs, BdrvChild
*ignore_parent,
*/
void bdrv_drained_begin(BlockDriverState *bs);
+int bdrv_drained_begin_timeout(BlockDriverState *bs, int64_t timeout_ms);
+
/**
* bdrv_do_drained_begin_quiesce:
*
diff --git a/util/aio-wait.c b/util/aio-wait.c
index b5336cf5fd..9aed165529 100644
--- a/util/aio-wait.c
+++ b/util/aio-wait.c
@@ -84,3 +84,10 @@ 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_retry(void *opaque)
+{
+ AioWaitTimer *s = opaque;
+
+ timer_mod(s->timer, qemu_clock_get_ms(QEMU_CLOCK_REALTIME) + s->interval);
+}
--
2.33.0