xref: /linux/fs/bcachefs/thread_with_file.h (revision a1ff5a7d78a036d6c2178ee5acd6ba4946243800)
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 
39 struct task_struct;
40 
41 struct thread_with_file {
42 	struct task_struct	*task;
43 	int			ret;
44 	bool			done;
45 };
46 
47 void bch2_thread_with_file_exit(struct thread_with_file *);
48 int bch2_run_thread_with_file(struct thread_with_file *,
49 			      const struct file_operations *,
50 			      int (*fn)(void *));
51 
52 struct thread_with_stdio;
53 
54 struct 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 
60 struct thread_with_stdio {
61 	struct thread_with_file	thr;
62 	struct stdio_redirect	stdio;
63 	const struct thread_with_stdio_ops	*ops;
64 };
65 
66 void bch2_thread_with_stdio_init(struct thread_with_stdio *,
67 				 const struct thread_with_stdio_ops *);
68 int __bch2_run_thread_with_stdio(struct thread_with_stdio *);
69 int bch2_run_thread_with_stdio(struct thread_with_stdio *,
70 			       const struct thread_with_stdio_ops *);
71 int bch2_run_thread_with_stdout(struct thread_with_stdio *,
72 				const struct thread_with_stdio_ops *);
73 int bch2_stdio_redirect_read(struct stdio_redirect *, char *, size_t);
74 
75 int bch2_stdio_redirect_readline_timeout(struct stdio_redirect *, darray_char *, unsigned long);
76 int bch2_stdio_redirect_readline(struct stdio_redirect *, darray_char *);
77 
78 __printf(3, 0) ssize_t bch2_stdio_redirect_vprintf(struct stdio_redirect *, bool, const char *, va_list);
79 __printf(3, 4) ssize_t bch2_stdio_redirect_printf(struct stdio_redirect *, bool, const char *, ...);
80 
81 #endif /* _BCACHEFS_THREAD_WITH_FILE_H */
82