#define MAX_QUEUED_IO 128
struct qemu_laiocb {
- BlockDriverAIOCB common;
+ BlockAIOCB common;
struct qemu_laio_state *ctx;
struct iocb iocb;
ssize_t ret;
size_t nbytes;
QEMUIOVector *qiov;
bool is_read;
- QLIST_ENTRY(qemu_laiocb) node;
+ QSIMPLEQ_ENTRY(qemu_laiocb) next;
};
typedef struct {
- struct iocb *iocbs[MAX_QUEUED_IO];
int plugged;
- unsigned int size;
- unsigned int idx;
+ unsigned int n;
+ bool blocked;
+ QSIMPLEQ_HEAD(, qemu_laiocb) pending;
} LaioQueue;
struct qemu_laio_state {
/* io queue for submit at batch */
LaioQueue io_q;
+
+ /* I/O completion processing */
+ QEMUBH *completion_bh;
+ struct io_event events[MAX_EVENTS];
+ int event_idx;
+ int event_max;
};
+static void ioq_submit(struct qemu_laio_state *s);
+
static inline ssize_t io_event_ret(struct io_event *ev)
{
return (ssize_t)(((uint64_t)ev->res2 << 32) | ev->res);
ret = -EINVAL;
}
}
-
- laiocb->common.cb(laiocb->common.opaque, ret);
}
+ laiocb->common.cb(laiocb->common.opaque, ret);
- qemu_aio_release(laiocb);
+ qemu_aio_unref(laiocb);
}
-static void qemu_laio_completion_cb(EventNotifier *e)
+/* The completion BH fetches completed I/O requests and invokes their
+ * callbacks.
+ *
+ * The function is somewhat tricky because it supports nested event loops, for
+ * example when a request callback invokes aio_poll(). In order to do this,
+ * the completion events array and index are kept in qemu_laio_state. The BH
+ * reschedules itself as long as there are completions pending so it will
+ * either be called again in a nested event loop or will be called after all
+ * events have been completed. When there are no events left to complete, the
+ * BH returns without rescheduling.
+ */
+static void qemu_laio_completion_bh(void *opaque)
{
- struct qemu_laio_state *s = container_of(e, struct qemu_laio_state, e);
-
- while (event_notifier_test_and_clear(&s->e)) {
- struct io_event events[MAX_EVENTS];
- struct timespec ts = { 0 };
- int nevents, i;
+ struct qemu_laio_state *s = opaque;
+ /* Fetch more completion events when empty */
+ if (s->event_idx == s->event_max) {
do {
- nevents = io_getevents(s->ctx, MAX_EVENTS, MAX_EVENTS, events, &ts);
- } while (nevents == -EINTR);
+ struct timespec ts = { 0 };
+ s->event_max = io_getevents(s->ctx, MAX_EVENTS, MAX_EVENTS,
+ s->events, &ts);
+ } while (s->event_max == -EINTR);
+
+ s->event_idx = 0;
+ if (s->event_max <= 0) {
+ s->event_max = 0;
+ return; /* no more events */
+ }
+ }
- for (i = 0; i < nevents; i++) {
- struct iocb *iocb = events[i].obj;
- struct qemu_laiocb *laiocb =
- container_of(iocb, struct qemu_laiocb, iocb);
+ /* Reschedule so nested event loops see currently pending completions */
+ qemu_bh_schedule(s->completion_bh);
- laiocb->ret = io_event_ret(&events[i]);
- qemu_laio_process_completion(s, laiocb);
- }
+ /* Process completion events */
+ while (s->event_idx < s->event_max) {
+ struct iocb *iocb = s->events[s->event_idx].obj;
+ struct qemu_laiocb *laiocb =
+ container_of(iocb, struct qemu_laiocb, iocb);
+
+ laiocb->ret = io_event_ret(&s->events[s->event_idx]);
+ s->event_idx++;
+
+ qemu_laio_process_completion(s, laiocb);
+ }
+
+ if (!s->io_q.plugged && !QSIMPLEQ_EMPTY(&s->io_q.pending)) {
+ ioq_submit(s);
+ }
+}
+
+static void qemu_laio_completion_cb(EventNotifier *e)
+{
+ struct qemu_laio_state *s = container_of(e, struct qemu_laio_state, e);
+
+ if (event_notifier_test_and_clear(&s->e)) {
+ qemu_bh_schedule(s->completion_bh);
}
}
-static void laio_cancel(BlockDriverAIOCB *blockacb)
+static void laio_cancel(BlockAIOCB *blockacb)
{
struct qemu_laiocb *laiocb = (struct qemu_laiocb *)blockacb;
struct io_event event;
int ret;
- if (laiocb->ret != -EINPROGRESS)
+ if (laiocb->ret != -EINPROGRESS) {
return;
-
- /*
- * Note that as of Linux 2.6.31 neither the block device code nor any
- * filesystem implements cancellation of AIO request.
- * Thus the polling loop below is the normal code path.
- */
+ }
ret = io_cancel(laiocb->ctx->ctx, &laiocb->iocb, &event);
- if (ret == 0) {
- laiocb->ret = -ECANCELED;
+ laiocb->ret = -ECANCELED;
+ if (ret != 0) {
+ /* iocb is not cancelled, cb will be called by the event loop later */
return;
}
- /*
- * We have to wait for the iocb to finish.
- *
- * The only way to get the iocb status update is by polling the io context.
- * We might be able to do this slightly more optimal by removing the
- * O_NONBLOCK flag.
- */
- while (laiocb->ret == -EINPROGRESS) {
- qemu_laio_completion_cb(&laiocb->ctx->e);
- }
+ laiocb->common.cb(laiocb->common.opaque, laiocb->ret);
}
static const AIOCBInfo laio_aiocb_info = {
.aiocb_size = sizeof(struct qemu_laiocb),
- .cancel = laio_cancel,
+ .cancel_async = laio_cancel,
};
static void ioq_init(LaioQueue *io_q)
{
- io_q->size = MAX_QUEUED_IO;
- io_q->idx = 0;
+ QSIMPLEQ_INIT(&io_q->pending);
io_q->plugged = 0;
+ io_q->n = 0;
+ io_q->blocked = false;
}
-static int ioq_submit(struct qemu_laio_state *s)
+static void ioq_submit(struct qemu_laio_state *s)
{
- int ret, i = 0;
- int len = s->io_q.idx;
+ int ret, len;
+ struct qemu_laiocb *aiocb;
+ struct iocb *iocbs[MAX_QUEUED_IO];
+ QSIMPLEQ_HEAD(, qemu_laiocb) completed;
do {
- ret = io_submit(s->ctx, len, s->io_q.iocbs);
- } while (i++ < 3 && ret == -EAGAIN);
-
- /* empty io queue */
- s->io_q.idx = 0;
-
- if (ret < 0) {
- i = 0;
- } else {
- i = ret;
- }
-
- for (; i < len; i++) {
- struct qemu_laiocb *laiocb =
- container_of(s->io_q.iocbs[i], struct qemu_laiocb, iocb);
-
- laiocb->ret = (ret < 0) ? ret : -EIO;
- qemu_laio_process_completion(s, laiocb);
- }
- return ret;
-}
-
-static void ioq_enqueue(struct qemu_laio_state *s, struct iocb *iocb)
-{
- unsigned int idx = s->io_q.idx;
+ len = 0;
+ QSIMPLEQ_FOREACH(aiocb, &s->io_q.pending, next) {
+ iocbs[len++] = &aiocb->iocb;
+ if (len == MAX_QUEUED_IO) {
+ break;
+ }
+ }
- s->io_q.iocbs[idx++] = iocb;
- s->io_q.idx = idx;
+ ret = io_submit(s->ctx, len, iocbs);
+ if (ret == -EAGAIN) {
+ break;
+ }
+ if (ret < 0) {
+ abort();
+ }
- /* submit immediately if queue is full */
- if (idx == s->io_q.size) {
- ioq_submit(s);
- }
+ s->io_q.n -= ret;
+ aiocb = container_of(iocbs[ret - 1], struct qemu_laiocb, iocb);
+ QSIMPLEQ_SPLIT_AFTER(&s->io_q.pending, aiocb, next, &completed);
+ } while (ret == len && !QSIMPLEQ_EMPTY(&s->io_q.pending));
+ s->io_q.blocked = (s->io_q.n > 0);
}
void laio_io_plug(BlockDriverState *bs, void *aio_ctx)
s->io_q.plugged++;
}
-int laio_io_unplug(BlockDriverState *bs, void *aio_ctx, bool unplug)
+void laio_io_unplug(BlockDriverState *bs, void *aio_ctx, bool unplug)
{
struct qemu_laio_state *s = aio_ctx;
- int ret = 0;
assert(s->io_q.plugged > 0 || !unplug);
if (unplug && --s->io_q.plugged > 0) {
- return 0;
+ return;
}
- if (s->io_q.idx > 0) {
- ret = ioq_submit(s);
+ if (!s->io_q.blocked && !QSIMPLEQ_EMPTY(&s->io_q.pending)) {
+ ioq_submit(s);
}
-
- return ret;
}
-BlockDriverAIOCB *laio_submit(BlockDriverState *bs, void *aio_ctx, int fd,
+BlockAIOCB *laio_submit(BlockDriverState *bs, void *aio_ctx, int fd,
int64_t sector_num, QEMUIOVector *qiov, int nb_sectors,
- BlockDriverCompletionFunc *cb, void *opaque, int type)
+ BlockCompletionFunc *cb, void *opaque, int type)
{
struct qemu_laio_state *s = aio_ctx;
struct qemu_laiocb *laiocb;
}
io_set_eventfd(&laiocb->iocb, event_notifier_get_fd(&s->e));
- if (!s->io_q.plugged) {
- if (io_submit(s->ctx, 1, &iocbs) < 0) {
- goto out_free_aiocb;
- }
- } else {
- ioq_enqueue(s, iocbs);
+ QSIMPLEQ_INSERT_TAIL(&s->io_q.pending, laiocb, next);
+ s->io_q.n++;
+ if (!s->io_q.blocked &&
+ (!s->io_q.plugged || s->io_q.n >= MAX_QUEUED_IO)) {
+ ioq_submit(s);
}
return &laiocb->common;
out_free_aiocb:
- qemu_aio_release(laiocb);
+ qemu_aio_unref(laiocb);
return NULL;
}
{
struct qemu_laio_state *s = s_;
- aio_set_event_notifier(old_context, &s->e, NULL);
+ aio_set_event_notifier(old_context, &s->e, false, NULL);
+ qemu_bh_delete(s->completion_bh);
}
void laio_attach_aio_context(void *s_, AioContext *new_context)
{
struct qemu_laio_state *s = s_;
- aio_set_event_notifier(new_context, &s->e, qemu_laio_completion_cb);
+ s->completion_bh = aio_bh_new(new_context, qemu_laio_completion_bh, s);
+ aio_set_event_notifier(new_context, &s->e, false,
+ qemu_laio_completion_cb);
}
void *laio_init(void)
projects / qemu.git / blobdiff