The Thursday 14 Aug 2014 à 17:41:41 (+0800), Ming Lei wrote :
> 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:
s/with below ideas/with the following ideas/g
>
> - for -EAGAIN or partial completion, retry the submision by
s/submision/submission/
> schedule an BH in following completion cb
s/schedule an/sheduling a/
> - 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 | 99
> +++++++++++++++++++++++++++++++++++++++++------------
> 1 file changed, 77 insertions(+), 22 deletions(-)
>
> diff --git a/block/linux-aio.c b/block/linux-aio.c
> index 7ac7e8c..4cdf507 100644
> --- a/block/linux-aio.c
> +++ b/block/linux-aio.c
> @@ -38,11 +38,19 @@ struct qemu_laiocb {
> QLIST_ENTRY(qemu_laiocb) node;
> };
>
> +/*
> + * TODO: support to batch I/O from multiple bs in one same
> + * AIO context, one important use case is multi-lun scsi,
> + * so in future the IO queue should be per AIO context.
> + */
> typedef struct {
In QEMU we typically write the name twice in these kind of declarations:
typedef struct LaioQueue {
... stuff ...
} LaioQueue;
> struct iocb *iocbs[MAX_QUEUED_IO];
> int plugged;
Are plugged values either 0 and 1 ?
If so it should be "bool plugged;"
> unsigned int size;
> unsigned int idx;
See:
benoit@Laure:~/code/qemu$ git grep "unsigned int"|wc
2283 14038 154201
benoit@Laure:~/code/qemu$ git grep "uint32"|wc
12535 63129 810822
Maybe you could use the most popular type.
> +
> + /* handle -EAGAIN and partial completion */
> + QEMUBH *retry;
> } LaioQueue;
>
> struct qemu_laio_state {
> @@ -86,6 +94,12 @@ static void qemu_laio_process_completion(struct
> qemu_laio_state *s,
> qemu_aio_release(laiocb);
> }
>
> +static void qemu_laio_start_retry(struct qemu_laio_state *s)
> +{
> + if (s->io_q.idx)
> + qemu_bh_schedule(s->io_q.retry);
In QEMU this test is writen like this:
if (s->io_q.idx) {
qemu_bh_schedule(s->io_q.retry);
}
I suggest you ran ./scripts/checkpatch.pl on your series before submitting it.
> +}
> +
> static void qemu_laio_completion_cb(EventNotifier *e)
> {
> struct qemu_laio_state *s = container_of(e, struct qemu_laio_state, e);
> @@ -108,6 +122,7 @@ static void qemu_laio_completion_cb(EventNotifier *e)
> qemu_laio_process_completion(s, laiocb);
> }
> }
> + qemu_laio_start_retry(s);
> }
>
> static void laio_cancel(BlockDriverAIOCB *blockacb)
> @@ -127,6 +142,7 @@ static void laio_cancel(BlockDriverAIOCB *blockacb)
> ret = io_cancel(laiocb->ctx->ctx, &laiocb->iocb, &event);
> if (ret == 0) {
> laiocb->ret = -ECANCELED;
> + qemu_laio_start_retry(laiocb->ctx);
> return;
> }
>
> @@ -154,45 +170,80 @@ 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;
> + }
> +
> + ret = io_submit(s->ctx, len, s->io_q.iocbs);
> + if (ret == -EAGAIN) { /* retry in following completion cb */
> + return 0;
> + } else if (ret < 0) {
> + if (enqueue) {
> + return ret;
> + }
>
> - /* empty io queue */
> - s->io_q.idx = 0;
> + /* in non-queue path, all IOs have to be completed */
> + abort_queue(s);
> + ret = len;
> + } else if (ret == 0) {
> + goto out;
> + }
>
> - if (ret < 0) {
> - i = 0;
> - } else {
> - i = ret;
> + for (i = ret; i < len; i++) {
> + s->io_q.iocbs[j++] = s->io_q.iocbs[i];
> }
>
> - for (; i < len; i++) {
> - struct qemu_laiocb *laiocb =
> - container_of(s->io_q.iocbs[i], struct qemu_laiocb, iocb);
> + out:
> + /*
> + * update io queue, for partial completion, retry will be
> + * started automatically in following completion cb.
> + */
> + s->io_q.idx -= ret;
>
> - 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)
> +static void ioq_submit_retry(void *opaque)
> +{
> + struct qemu_laio_state *s = opaque;
> + 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 +265,7 @@ 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 +309,9 @@ 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 +325,7 @@ 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);
> + qemu_bh_delete(s->io_q.retry);
> }
>
> void laio_attach_aio_context(void *s_, AioContext *new_context)
> @@ -279,6 +333,7 @@ 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);
> + s->io_q.retry = aio_bh_new(new_context, ioq_submit_retry, s);
> }
>
> void *laio_init(void)
> --
> 1.7.9.5
>
>
