Commit 1f59bc0f authored by Pavel Begunkov's avatar Pavel Begunkov Committed by Jens Axboe
Browse files

io_uring: don't scm-account for non af_unix sockets 



io_uring deals with file reference loops by registering all fixed files
in the SCM/GC infrastrucure. However, only a small subset of all file
types can keep long-term references to other files and those that don't
are not interesting for the garbage collector as they can't be in a
reference loop. They neither can be directly recycled by GC nor affect
loop searching.

Let's skip io_uring SCM accounting for loop-less files, i.e. all but
af_unix sockets, quite imroving fixed file updates performance and
greatly helpnig with memory footprint.

Signed-off-by: default avatarPavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/9c44ecf6e89d69130a8c4360cce2183ffc5ddd6f.1649277098.git.asml.silence@gmail.com


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent b4f20bb4

fs/io_uring.c

+38 −13
Original line number Diff line number Diff line
@@ -1223,6 +1223,18 @@ struct sock *io_uring_get_socket(struct file *file) 
}

EXPORT_SYMBOL(io_uring_get_socket);



#if defined(CONFIG_UNIX)

static inline bool io_file_need_scm(struct file *filp)

{

	return !!unix_get_socket(filp);

}

#else

static inline bool io_file_need_scm(struct file *filp)

{

	return 0;

}

#endif



static void io_ring_submit_unlock(struct io_ring_ctx *ctx, unsigned issue_flags)

{

	lockdep_assert_held(&ctx->uring_lock);
@@ -8426,6 +8438,17 @@ static void io_free_file_tables(struct io_file_table *table) 


static void __io_sqe_files_unregister(struct io_ring_ctx *ctx)

{

	int i;



	for (i = 0; i < ctx->nr_user_files; i++) {

		struct file *file = io_file_from_index(ctx, i);



		if (!file || io_file_need_scm(file))

			continue;

		io_fixed_file_slot(&ctx->file_table, i)->file_ptr = 0;

		fput(file);

	}



#if defined(CONFIG_UNIX)

	if (ctx->ring_sock) {

		struct sock *sock = ctx->ring_sock->sk;
@@ -8434,16 +8457,6 @@ static void __io_sqe_files_unregister(struct io_ring_ctx *ctx) 
		while ((skb = skb_dequeue(&sock->sk_receive_queue)) != NULL)

			kfree_skb(skb);

	}

#else

	int i;



	for (i = 0; i < ctx->nr_user_files; i++) {

		struct file *file;



		file = io_file_from_index(ctx, i);

		if (file)

			fput(file);

	}

#endif

	io_free_file_tables(&ctx->file_table);

	io_rsrc_data_free(ctx->file_data);
@@ -8592,7 +8605,9 @@ static struct io_sq_data *io_get_sq_data(struct io_uring_params *p, 
/*

 * Ensure the UNIX gc is aware of our file set, so we are certain that

 * the io_uring can be safely unregistered on process exit, even if we have

 * loops in the file referencing.

 * loops in the file referencing. We account only files that can hold other

 * files because otherwise they can't form a loop and so are not interesting

 * for GC.

 */

static int __io_sqe_files_scm(struct io_ring_ctx *ctx, int nr, int offset)

{
@@ -8618,8 +8633,9 @@ static int __io_sqe_files_scm(struct io_ring_ctx *ctx, int nr, int offset) 
	for (i = 0; i < nr; i++) {

		struct file *file = io_file_from_index(ctx, i + offset);



		if (!file)

		if (!file || !io_file_need_scm(file))

			continue;



		fpl->fp[nr_files] = get_file(file);

		unix_inflight(fpl->user, fpl->fp[nr_files]);

		nr_files++;
@@ -8636,7 +8652,7 @@ static int __io_sqe_files_scm(struct io_ring_ctx *ctx, int nr, int offset) 
		for (i = 0; i < nr; i++) {

			struct file *file = io_file_from_index(ctx, i + offset);



			if (file)

			if (file && io_file_need_scm(file))

				fput(file);

		}

	} else {
@@ -8678,6 +8694,7 @@ static int io_sqe_files_scm(struct io_ring_ctx *ctx) 


		if (file)

			fput(file);

		io_fixed_file_slot(&ctx->file_table, total)->file_ptr = 0;

		total++;

	}
@@ -8699,6 +8716,11 @@ static void io_rsrc_file_put(struct io_ring_ctx *ctx, struct io_rsrc_put *prsrc) 
	struct sk_buff *skb;

	int i;



	if (!io_file_need_scm(file)) {

		fput(file);

		return;

	}



	__skb_queue_head_init(&list);



	/*
@@ -8893,6 +8915,9 @@ static int io_sqe_file_register(struct io_ring_ctx *ctx, struct file *file, 
	struct sk_buff_head *head = &sock->sk_receive_queue;

	struct sk_buff *skb;



	if (!io_file_need_scm(file))

		return 0;



	/*

	 * See if we can merge this file into an existing skb SCM_RIGHTS

	 * file set. If there's no room, fall back to allocating a new skb