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io_uring: process requests completed with -EAGAIN on poll list

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A request that completes with an -EAGAIN result after it has been added
to the poll list, will not be removed from that list in io_do_iopoll()
because the f_op->iopoll() will not succeed for that request.

Maintain a retryable local list similar to the done list, and explicity
reissue requests with an -EAGAIN result.

Signed-off-by: Bijan Mottahedeh <bijan.mottahedeh@oracle.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Bijan Mottahedeh 2020-04-03 13:51:33 -07:00 committed by Jens Axboe
parent c336e992cb
commit 581f981034
1 changed files with 26 additions and 3 deletions
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29
fs/io_uring.c
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@ -1744,11 +1744,24 @@ static void io_iopoll_complete(struct io_ring_ctx *ctx, unsigned int *nr_events,
io_free_req_many(ctx, &rb);
}
static void io_iopoll_queue(struct list_head *again)
{
struct io_kiocb *req;
do {
req = list_first_entry(again, struct io_kiocb, list);
list_del(&req->list);
refcount_inc(&req->refs);
io_queue_async_work(req);
} while (!list_empty(again));
}
static int io_do_iopoll(struct io_ring_ctx *ctx, unsigned int *nr_events,
long min)
{
struct io_kiocb *req, *tmp;
LIST_HEAD(done);
LIST_HEAD(again);
bool spin;
int ret;
@ -1763,9 +1776,9 @@ static int io_do_iopoll(struct io_ring_ctx *ctx, unsigned int *nr_events,
struct kiocb *kiocb = &req->rw.kiocb;
/*
* Move completed entries to our local list. If we find a
* request that requires polling, break out and complete
* the done list first, if we have entries there.
* Move completed and retryable entries to our local lists.
* If we find a request that requires polling, break out
* and complete those lists first, if we have entries there.
*/
if (req->flags & REQ_F_IOPOLL_COMPLETED) {
list_move_tail(&req->list, &done);
@ -1774,6 +1787,13 @@ static int io_do_iopoll(struct io_ring_ctx *ctx, unsigned int *nr_events,
if (!list_empty(&done))
break;
if (req->result == -EAGAIN) {
list_move_tail(&req->list, &again);
continue;
}
if (!list_empty(&again))
break;
ret = kiocb->ki_filp->f_op->iopoll(kiocb, spin);
if (ret < 0)
break;
@ -1786,6 +1806,9 @@ static int io_do_iopoll(struct io_ring_ctx *ctx, unsigned int *nr_events,
if (!list_empty(&done))
io_iopoll_complete(ctx, nr_events, &done);
if (!list_empty(&again))
io_iopoll_queue(&again);
return ret;
}