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block/mirror: Use CoQueue to wait on in-flight ops

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Attach a CoQueue to each in-flight operation so if we need to wait for
any we can use it to wait instead of just blindly yielding and hoping
for some operation to wake us.

A later patch will use this infrastructure to allow requests accessing
the same area of the virtual disk to specifically wait for each other.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Message-id: 20180613181823.13618-4-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
This commit is contained in:
Max Reitz 2018-06-13 20:18:12 +02:00
parent 2e1990b26e
commit 12aa40822d
1 changed files with 23 additions and 11 deletions
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34
block/mirror.c
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@ -13,6 +13,7 @@
#include "qemu/osdep.h"
#include "qemu/cutils.h"
#include "qemu/coroutine.h"
#include "trace.h"
#include "block/blockjob_int.h"
#include "block/block_int.h"
@ -33,6 +34,8 @@ typedef struct MirrorBuffer {
QSIMPLEQ_ENTRY(MirrorBuffer) next;
} MirrorBuffer;
typedef struct MirrorOp MirrorOp;
typedef struct MirrorBlockJob {
BlockJob common;
BlockBackend *target;
@ -65,15 +68,15 @@ typedef struct MirrorBlockJob {
unsigned long *in_flight_bitmap;
int in_flight;
int64_t bytes_in_flight;
QTAILQ_HEAD(MirrorOpList, MirrorOp) ops_in_flight;
int ret;
bool unmap;
bool waiting_for_io;
int target_cluster_size;
int max_iov;
bool initial_zeroing_ongoing;
} MirrorBlockJob;
typedef struct MirrorOp {
struct MirrorOp {
MirrorBlockJob *s;
QEMUIOVector qiov;
int64_t offset;
@ -82,7 +85,11 @@ typedef struct MirrorOp {
/* The pointee is set by mirror_co_read(), mirror_co_zero(), and
* mirror_co_discard() before yielding for the first time */
int64_t *bytes_handled;
} MirrorOp;
CoQueue waiting_requests;
QTAILQ_ENTRY(MirrorOp) next;
};
typedef enum MirrorMethod {
MIRROR_METHOD_COPY,
@ -123,7 +130,9 @@ static void coroutine_fn mirror_iteration_done(MirrorOp *op, int ret)
chunk_num = op->offset / s->granularity;
nb_chunks = DIV_ROUND_UP(op->bytes, s->granularity);
bitmap_clear(s->in_flight_bitmap, chunk_num, nb_chunks);
QTAILQ_REMOVE(&s->ops_in_flight, op, next);
if (ret >= 0) {
if (s->cow_bitmap) {
bitmap_set(s->cow_bitmap, chunk_num, nb_chunks);
@ -133,11 +142,9 @@ static void coroutine_fn mirror_iteration_done(MirrorOp *op, int ret)
}
}
qemu_iovec_destroy(&op->qiov);
g_free(op);
if (s->waiting_for_io) {
qemu_coroutine_enter(s->common.job.co);
}
qemu_co_queue_restart_all(&op->waiting_requests);
g_free(op);
}
static void coroutine_fn mirror_write_complete(MirrorOp *op, int ret)
@ -227,10 +234,11 @@ static int mirror_cow_align(MirrorBlockJob *s, int64_t *offset,
static inline void mirror_wait_for_io(MirrorBlockJob *s)
{
assert(!s->waiting_for_io);
s->waiting_for_io = true;
qemu_coroutine_yield();
s->waiting_for_io = false;
MirrorOp *op;
op = QTAILQ_FIRST(&s->ops_in_flight);
assert(op);
qemu_co_queue_wait(&op->waiting_requests, NULL);
}
/* Perform a mirror copy operation.
@ -340,6 +348,7 @@ static unsigned mirror_perform(MirrorBlockJob *s, int64_t offset,
.bytes = bytes,
.bytes_handled = &bytes_handled,
};
qemu_co_queue_init(&op->waiting_requests);
switch (mirror_method) {
case MIRROR_METHOD_COPY:
@ -355,6 +364,7 @@ static unsigned mirror_perform(MirrorBlockJob *s, int64_t offset,
abort();
}
QTAILQ_INSERT_TAIL(&s->ops_in_flight, op, next);
qemu_coroutine_enter(co);
/* At this point, ownership of op has been moved to the coroutine
* and the object may already be freed */
@ -1290,6 +1300,8 @@ static void mirror_start_job(const char *job_id, BlockDriverState *bs,
}
}
QTAILQ_INIT(&s->ops_in_flight);
trace_mirror_start(bs, s, opaque);
job_start(&s->common.job);
return;