We currently check REQ_F_POLLED before arming async poll for a
notification to retry. If it's set, then we don't allow poll and will
punt to io-wq instead. This is done to prevent a situation where a buggy
driver will repeatedly return that there's space/data available yet we
get -EAGAIN.
However, if we already transferred data, then it should be safe to rely
on poll again. Gate the check on whether or not REQ_F_PARTIAL_IO is
also set.
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
---
fs/io_uring.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)
diff --git a/fs/io_uring.c b/fs/io_uring.c
index f06c6fed540b..6a4460cad9c0 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -6263,7 +6263,9 @@ static int io_arm_poll_handler(struct io_kiocb *req, unsigned issue_flags)
if (!def->pollin && !def->pollout)
return IO_APOLL_ABORTED;
- if (!file_can_poll(req->file) || (req->flags & REQ_F_POLLED))
+ if (!file_can_poll(req->file))
+ return IO_APOLL_ABORTED;
+ if ((req->flags & (REQ_F_POLLED|REQ_F_PARTIAL_IO)) == REQ_F_POLLED)
return IO_APOLL_ABORTED;
if (def->pollin) {
@@ -6278,8 +6280,10 @@ static int io_arm_poll_handler(struct io_kiocb *req, unsigned issue_flags)
}
if (def->poll_exclusive)
mask |= EPOLLEXCLUSIVE;
- if (!(issue_flags & IO_URING_F_UNLOCKED) &&
- !list_empty(&ctx->apoll_cache)) {
+ if (req->flags & REQ_F_POLLED) {
+ apoll = req->apoll;
+ } else if (!(issue_flags & IO_URING_F_UNLOCKED) &&
+ !list_empty(&ctx->apoll_cache)) {
apoll = list_first_entry(&ctx->apoll_cache, struct async_poll,
poll.wait.entry);
list_del_init(&apoll->poll.wait.entry);
--
2.35.1
