1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef _BCACHEFS_THREAD_WITH_FILE_H
3#define _BCACHEFS_THREAD_WITH_FILE_H
4
5#include "thread_with_file_types.h"
6
7/*
8 * Thread with file: Run a kthread and connect it to a file descriptor, so that
9 * it can be interacted with via fd read/write methods and closing the file
10 * descriptor stops the kthread.
11 *
12 * We have two different APIs:
13 *
14 * thread_with_file, the low level version.
15 * You get to define the full file_operations, including your release function,
16 * which means that you must call bch2_thread_with_file_exit() from your
17 * .release method
18 *
19 * thread_with_stdio, the higher level version
20 * This implements full piping of input and output, including .poll.
21 *
22 * Notes on behaviour:
23 *  - kthread shutdown behaves like writing or reading from a pipe that has been
24 *    closed
25 *  - Input and output buffers are 4096 bytes, although buffers may in some
26 *    situations slightly exceed that limit so as to avoid chopping off a
27 *    message in the middle in nonblocking mode.
28 *  - Input/output buffers are lazily allocated, with GFP_NOWAIT allocations -
29 *    should be fine but might change in future revisions.
30 *  - Output buffer may grow past 4096 bytes to deal with messages that are
31 *    bigger than 4096 bytes
32 *  - Writing may be done blocking or nonblocking; in nonblocking mode, we only
33 *    drop entire messages.
34 *
35 * To write, use stdio_redirect_printf()
36 * To read, use stdio_redirect_read() or stdio_redirect_readline()
37 */
38
39struct task_struct;
40
41struct thread_with_file {
42	struct task_struct	*task;
43	int			ret;
44	bool			done;
45};
46
47void bch2_thread_with_file_exit(struct thread_with_file *);
48int bch2_run_thread_with_file(struct thread_with_file *,
49			      const struct file_operations *,
50			      int (*fn)(void *));
51
52struct thread_with_stdio;
53
54struct thread_with_stdio_ops {
55	void (*exit)(struct thread_with_stdio *);
56	int (*fn)(struct thread_with_stdio *);
57	long (*unlocked_ioctl)(struct thread_with_stdio *, unsigned int, unsigned long);
58};
59
60struct thread_with_stdio {
61	struct thread_with_file	thr;
62	struct stdio_redirect	stdio;
63	const struct thread_with_stdio_ops	*ops;
64};
65
66void bch2_thread_with_stdio_init(struct thread_with_stdio *,
67				 const struct thread_with_stdio_ops *);
68int __bch2_run_thread_with_stdio(struct thread_with_stdio *);
69int bch2_run_thread_with_stdio(struct thread_with_stdio *,
70			       const struct thread_with_stdio_ops *);
71int bch2_run_thread_with_stdout(struct thread_with_stdio *,
72				const struct thread_with_stdio_ops *);
73int bch2_stdio_redirect_read(struct stdio_redirect *, char *, size_t);
74int bch2_stdio_redirect_readline(struct stdio_redirect *, char *, size_t);
75
76__printf(3, 0) ssize_t bch2_stdio_redirect_vprintf(struct stdio_redirect *, bool, const char *, va_list);
77__printf(3, 4) ssize_t bch2_stdio_redirect_printf(struct stdio_redirect *, bool, const char *, ...);
78
79#endif /* _BCACHEFS_THREAD_WITH_FILE_H */
80