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io_uring: fix sporadic double CQE entry for close

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We punt close to async for the final fput(), but we log the completion
even before that even in that case. We rely on the request not having
a files table assigned to detect what the final async close should do.
However, if we punt the async queue to __io_queue_sqe(), we'll get
->files assigned and this makes io_close_finish() think it should both
close the filp again (which does no harm) AND log a new CQE event for
this request. This causes duplicate CQEs.

Queue the request up for async manually so we don't grab files
needlessly and trigger this condition.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Jens Axboe 2020-01-31 17:16:48 -07:00
parent 9250f9ee19
commit 1a417f4e61
1 changed files with 8 additions and 5 deletions
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13
fs/io_uring.c
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@ -2843,16 +2843,13 @@ static void io_close_finish(struct io_wq_work **workptr)
int ret;
ret = filp_close(req->close.put_file, req->work.files);
if (ret < 0) {
if (ret < 0)
req_set_fail_links(req);
}
io_cqring_add_event(req, ret);
}
fput(req->close.put_file);
/* we bypassed the re-issue, drop the submission reference */
io_put_req(req);
io_put_req_find_next(req, &nxt);
if (nxt)
io_wq_assign_next(workptr, nxt);
@ -2894,7 +2891,13 @@ static int io_close(struct io_kiocb *req, struct io_kiocb **nxt,
eagain:
req->work.func = io_close_finish;
return -EAGAIN;
/*
* Do manual async queue here to avoid grabbing files - we don't
* need the files, and it'll cause io_close_finish() to close
* the file again and cause a double CQE entry for this request
*/
io_queue_async_work(req);
return 0;
}
static int io_prep_sfr(struct io_kiocb *req, const struct io_uring_sqe *sqe)