io_uring: don't use retry based buffered reads for non-async bdev (f5cac8b1) · Commits · 戴 / test

Some block devices, like dm, bubble back -EAGAIN through the completion handler. We check for this in io_read(), but don't honor it for when we have copied the iov. Return -EAGAIN for this case before retrying, to force punt to io-wq. Fixes: ("io_uring: support true async buffered reads, if file provides it") Reported-by:

Zorro Lang <zlang@redhat.com> Tested-by:

Zorro Lang <zlang@redhat.com> Signed-off-by:

Jens Axboe <axboe@kernel.dk>

fs/io_uring.c

+5 −1

Original line number	Diff line number	Diff line
		@@ -3130,6 +3130,7 @@ static int io_read(struct io_kiocb *req, bool force_nonblock,
		struct iov_iter __iter, *iter = &__iter;
		ssize_t io_size, ret, ret2;
		size_t iov_count;
		bool no_async;

		if (req->io)
		iter = &req->io->rw.iter;
		@@ -3147,7 +3148,8 @@ static int io_read(struct io_kiocb *req, bool force_nonblock,
		kiocb->ki_flags &= ~IOCB_NOWAIT;

		/* If the file doesn't support async, just async punt */
		if (force_nonblock && !io_file_supports_async(req->file, READ))
		no_async = force_nonblock && !io_file_supports_async(req->file, READ);
		if (no_async)
		goto copy_iov;

		ret = rw_verify_area(READ, req->file, io_kiocb_ppos(kiocb), iov_count);
		@@ -3191,6 +3193,8 @@ copy_iov:
		ret = ret2;
		goto out_free;
		}
		if (no_async)
		return -EAGAIN;
		/* it's copied and will be cleaned with ->io */
		iovec = NULL;
		/* now use our persistent iterator, if we aren't already */

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