In the enqueue path, we can't complete request, otherwise
"Co-routine re-entered recursively" may be caused, so this
patch fixes the issue with below ideas:
- for -EAGAIN or partial completion, retry the submission by
an introduced event handler
- for part of completion, also update the io queue
- for other failure, return the failure if in enqueue path,
otherwise, abort all queued I/O
Signed-off-by: Ming Lei <ming....@canonical.com>
---
block/linux-aio.c | 90 ++++++++++++++++++++++++++++++++++++++++-------------
1 file changed, 68 insertions(+), 22 deletions(-)
diff --git a/block/linux-aio.c b/block/linux-aio.c
index 7ac7e8c..5eb9c92 100644
--- a/block/linux-aio.c
+++ b/block/linux-aio.c
@@ -51,6 +51,7 @@ struct qemu_laio_state {
/* io queue for submit at batch */
LaioQueue io_q;
+ EventNotifier retry; /* handle -EAGAIN and partial completion */
};
static inline ssize_t io_event_ret(struct io_event *ev)
@@ -154,45 +155,80 @@ static void ioq_init(LaioQueue *io_q)
io_q->plugged = 0;
}
-static int ioq_submit(struct qemu_laio_state *s)
+static void abort_queue(struct qemu_laio_state *s)
+{
+ int i;
+ for (i = 0; i < s->io_q.idx; i++) {
+ struct qemu_laiocb *laiocb = container_of(s->io_q.iocbs[i],
+ struct qemu_laiocb,
+ iocb);
+ laiocb->ret = -EIO;
+ qemu_laio_process_completion(s, laiocb);
+ }
+}
+
+static int ioq_submit(struct qemu_laio_state *s, bool enqueue)
{
int ret, i = 0;
int len = s->io_q.idx;
+ int j = 0;
- do {
- ret = io_submit(s->ctx, len, s->io_q.iocbs);
- } while (i++ < 3 && ret == -EAGAIN);
+ if (!len) {
+ return 0;
+ }
- /* empty io queue */
- s->io_q.idx = 0;
+ ret = io_submit(s->ctx, len, s->io_q.iocbs);
+ if (ret == -EAGAIN) {
+ event_notifier_set(&s->retry);
+ return 0;
+ } else if (ret < 0) {
+ if (enqueue) {
+ return ret;
+ }
- if (ret < 0) {
- i = 0;
- } else {
- i = ret;
+ /* in non-queue path, all IOs have to be completed */
+ abort_queue(s);
+ ret = len;
+ } else if (ret == 0) {
+ goto out;
}
- 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);
+ for (i = ret; i < len; i++) {
+ s->io_q.iocbs[j++] = s->io_q.iocbs[i];
}
+
+ out:
+ /* update io queue */
+ s->io_q.idx -= ret;
+
return ret;
}
-static void ioq_enqueue(struct qemu_laio_state *s, struct iocb *iocb)
+static void ioq_submit_retry(EventNotifier *e)
+{
+ struct qemu_laio_state *s = container_of(e, struct qemu_laio_state, retry);
+
+ event_notifier_test_and_clear(e);
+ ioq_submit(s, false);
+}
+
+static int ioq_enqueue(struct qemu_laio_state *s, struct iocb *iocb)
{
unsigned int idx = s->io_q.idx;
+ if (unlikely(idx == s->io_q.size)) {
+ return -1;
+ }
+
s->io_q.iocbs[idx++] = iocb;
s->io_q.idx = idx;
- /* submit immediately if queue is full */
- if (idx == s->io_q.size) {
- ioq_submit(s);
+ /* submit immediately if queue depth is above 2/3 */
+ if (idx > s->io_q.size * 2 / 3) {
+ return ioq_submit(s, true);
}
+
+ return 0;
}
void laio_io_plug(BlockDriverState *bs, void *aio_ctx)
@@ -214,7 +250,7 @@ int laio_io_unplug(BlockDriverState *bs, void *aio_ctx,
bool unplug)
}
if (s->io_q.idx > 0) {
- ret = ioq_submit(s);
+ ret = ioq_submit(s, false);
}
return ret;
@@ -258,7 +294,9 @@ BlockDriverAIOCB *laio_submit(BlockDriverState *bs, void
*aio_ctx, int fd,
goto out_free_aiocb;
}
} else {
- ioq_enqueue(s, iocbs);
+ if (ioq_enqueue(s, iocbs) < 0) {
+ goto out_free_aiocb;
+ }
}
return &laiocb->common;
@@ -272,6 +310,7 @@ void laio_detach_aio_context(void *s_, AioContext
*old_context)
struct qemu_laio_state *s = s_;
aio_set_event_notifier(old_context, &s->e, NULL);
+ aio_set_event_notifier(old_context, &s->retry, NULL);
}
void laio_attach_aio_context(void *s_, AioContext *new_context)
@@ -279,6 +318,7 @@ 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);
+ aio_set_event_notifier(new_context, &s->retry, ioq_submit_retry);
}
void *laio_init(void)
@@ -295,9 +335,14 @@ void *laio_init(void)
}
ioq_init(&s->io_q);
+ if (event_notifier_init(&s->retry, false) < 0) {
+ goto out_notifer_init;
+ }
return s;
+out_notifer_init:
+ io_destroy(s->ctx);
out_close_efd:
event_notifier_cleanup(&s->e);
out_free_state:
@@ -310,6 +355,7 @@ void laio_cleanup(void *s_)
struct qemu_laio_state *s = s_;
event_notifier_cleanup(&s->e);
+ event_notifier_cleanup(&s->retry);
if (io_destroy(s->ctx) != 0) {
fprintf(stderr, "%s: destroy AIO context %p failed\n",
--
1.7.9.5
