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io_uring: don't do opcode prep twice

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Calling into opcode prep handlers may be dangerous, as they re-read
SQE but might not re-initialise requests completely. If io_req_defer()
passed fast checks and is done with preparations, punt it async.

As all other cases are covered with nulling @sqe, this guarantees that
io_[opcode]_prep() are visited only once per request.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Pavel Begunkov 2020-07-23 20:25:20 +03:00 committed by Jens Axboe
parent 23b3628e45
commit ae34817bd9
1 changed files with 2 additions and 1 deletions
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3
fs/io_uring.c
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@ -5447,7 +5447,8 @@ static int io_req_defer(struct io_kiocb *req, const struct io_uring_sqe *sqe)
if (!req_need_defer(req, seq) && list_empty(&ctx->defer_list)) {
spin_unlock_irq(&ctx->completion_lock);
kfree(de);
return 0;
io_queue_async_work(req);
return -EIOCBQUEUED;
}
trace_io_uring_defer(ctx, req, req->user_data);