Commit 36f72fe2 authored by Pavel Begunkov's avatar Pavel Begunkov Committed by Jens Axboe
Browse files

io_uring: share fixed_file_refs b/w multiple rsrcs 



Double fixed files for splice/tee are done in a nasty way, it takes 2
ref_node refs, and during the second time it blindly overrides
req->fixed_file_refs hoping that it haven't changed. That works because
all that is done under iouring_lock in a single go but is error-prone.

Bind everything explicitly to a single ref_node and take only one ref,
with current ref_node ordering it's guaranteed to keep all files valid
awhile the request is inflight.

That's mainly a cleanup + preparation for generic resource handling,
but also saves pcpu_ref get/put for splice/tee with 2 fixed files.

Signed-off-by: default avatarPavel Begunkov <asml.silence@gmail.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent c98de08c

fs/io_uring.c

+15 −8
Original line number Diff line number Diff line
@@ -1037,6 +1037,16 @@ static inline void io_clean_op(struct io_kiocb *req) 
		__io_clean_op(req);

}



static inline void io_set_resource_node(struct io_kiocb *req)

{

	struct io_ring_ctx *ctx = req->ctx;



	if (!req->fixed_file_refs) {

		req->fixed_file_refs = &ctx->file_data->node->refs;

		percpu_ref_get(req->fixed_file_refs);

	}

}



static bool io_match_task(struct io_kiocb *head,

			  struct task_struct *task,

			  struct files_struct *files)
@@ -1919,9 +1929,7 @@ fallback: 
static inline void io_put_file(struct io_kiocb *req, struct file *file,

			  bool fixed)

{

	if (fixed)

		percpu_ref_put(req->fixed_file_refs);

	else

	if (!fixed)

		fput(file);

}
@@ -1933,7 +1941,8 @@ static void io_dismantle_req(struct io_kiocb *req) 
		kfree(req->async_data);

	if (req->file)

		io_put_file(req, req->file, (req->flags & REQ_F_FIXED_FILE));



	if (req->fixed_file_refs)

		percpu_ref_put(req->fixed_file_refs);

	io_req_clean_work(req);

}
@@ -6310,10 +6319,7 @@ static struct file *io_file_get(struct io_submit_state *state, 
			return NULL;

		fd = array_index_nospec(fd, ctx->nr_user_files);

		file = io_file_from_index(ctx, fd);

		if (file) {

			req->fixed_file_refs = &ctx->file_data->node->refs;

			percpu_ref_get(req->fixed_file_refs);

		}

		io_set_resource_node(req);

	} else {

		trace_io_uring_file_get(ctx, fd);

		file = __io_file_get(state, fd);
@@ -6691,6 +6697,7 @@ static int io_init_req(struct io_ring_ctx *ctx, struct io_kiocb *req, 
	req->ctx = ctx;

	req->flags = 0;

	req->link = NULL;

	req->fixed_file_refs = NULL;

	/* one is dropped after submission, the other at completion */

	refcount_set(&req->refs, 2);

	req->task = current;

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