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1 | #ifndef _LINUX_PIPE_FS_I_H |
2 | #define _LINUX_PIPE_FS_I_H |
3 | |
4 | #define PIPE_DEF_BUFFERS 16 |
5 | |
6 | #define PIPE_BUF_FLAG_LRU 0x01 /* page is on the LRU */ |
7 | #define PIPE_BUF_FLAG_ATOMIC 0x02 /* was atomically mapped */ |
8 | #define PIPE_BUF_FLAG_GIFT 0x04 /* page is a gift */ |
9 | #define PIPE_BUF_FLAG_PACKET 0x08 /* read() as a packet */ |
10 | |
11 | /** |
12 | * struct pipe_buffer - a linux kernel pipe buffer |
13 | * @page: the page containing the data for the pipe buffer |
14 | * @offset: offset of data inside the @page |
15 | * @len: length of data inside the @page |
16 | * @ops: operations associated with this buffer. See @pipe_buf_operations. |
17 | * @flags: pipe buffer flags. See above. |
18 | * @private: private data owned by the ops. |
19 | **/ |
20 | struct pipe_buffer { |
21 | struct page *page; |
22 | unsigned int offset, len; |
23 | const struct pipe_buf_operations *ops; |
24 | unsigned int flags; |
25 | unsigned long private; |
26 | }; |
27 | |
28 | /** |
29 | * struct pipe_inode_info - a linux kernel pipe |
30 | * @mutex: mutex protecting the whole thing |
31 | * @wait: reader/writer wait point in case of empty/full pipe |
32 | * @nrbufs: the number of non-empty pipe buffers in this pipe |
33 | * @buffers: total number of buffers (should be a power of 2) |
34 | * @curbuf: the current pipe buffer entry |
35 | * @tmp_page: cached released page |
36 | * @readers: number of current readers of this pipe |
37 | * @writers: number of current writers of this pipe |
38 | * @files: number of struct file refering this pipe (protected by ->i_lock) |
39 | * @waiting_writers: number of writers blocked waiting for room |
40 | * @r_counter: reader counter |
41 | * @w_counter: writer counter |
42 | * @fasync_readers: reader side fasync |
43 | * @fasync_writers: writer side fasync |
44 | * @bufs: the circular array of pipe buffers |
45 | **/ |
46 | struct pipe_inode_info { |
47 | struct mutex mutex; |
48 | wait_queue_head_t wait; |
49 | unsigned int nrbufs, curbuf, buffers; |
50 | unsigned int readers; |
51 | unsigned int writers; |
52 | unsigned int files; |
53 | unsigned int waiting_writers; |
54 | unsigned int r_counter; |
55 | unsigned int w_counter; |
56 | struct page *tmp_page; |
57 | struct fasync_struct *fasync_readers; |
58 | struct fasync_struct *fasync_writers; |
59 | struct pipe_buffer *bufs; |
60 | }; |
61 | |
62 | /* |
63 | * Note on the nesting of these functions: |
64 | * |
65 | * ->confirm() |
66 | * ->steal() |
67 | * ... |
68 | * ->map() |
69 | * ... |
70 | * ->unmap() |
71 | * |
72 | * That is, ->map() must be called on a confirmed buffer, |
73 | * same goes for ->steal(). See below for the meaning of each |
74 | * operation. Also see kerneldoc in fs/pipe.c for the pipe |
75 | * and generic variants of these hooks. |
76 | */ |
77 | struct pipe_buf_operations { |
78 | /* |
79 | * This is set to 1, if the generic pipe read/write may coalesce |
80 | * data into an existing buffer. If this is set to 0, a new pipe |
81 | * page segment is always used for new data. |
82 | */ |
83 | int can_merge; |
84 | |
85 | /* |
86 | * ->map() returns a virtual address mapping of the pipe buffer. |
87 | * The last integer flag reflects whether this should be an atomic |
88 | * mapping or not. The atomic map is faster, however you can't take |
89 | * page faults before calling ->unmap() again. So if you need to eg |
90 | * access user data through copy_to/from_user(), then you must get |
91 | * a non-atomic map. ->map() uses the kmap_atomic slot for |
92 | * atomic maps, you have to be careful if mapping another page as |
93 | * source or destination for a copy. |
94 | */ |
95 | void * (*map)(struct pipe_inode_info *, struct pipe_buffer *, int); |
96 | |
97 | /* |
98 | * Undoes ->map(), finishes the virtual mapping of the pipe buffer. |
99 | */ |
100 | void (*unmap)(struct pipe_inode_info *, struct pipe_buffer *, void *); |
101 | |
102 | /* |
103 | * ->confirm() verifies that the data in the pipe buffer is there |
104 | * and that the contents are good. If the pages in the pipe belong |
105 | * to a file system, we may need to wait for IO completion in this |
106 | * hook. Returns 0 for good, or a negative error value in case of |
107 | * error. |
108 | */ |
109 | int (*confirm)(struct pipe_inode_info *, struct pipe_buffer *); |
110 | |
111 | /* |
112 | * When the contents of this pipe buffer has been completely |
113 | * consumed by a reader, ->release() is called. |
114 | */ |
115 | void (*release)(struct pipe_inode_info *, struct pipe_buffer *); |
116 | |
117 | /* |
118 | * Attempt to take ownership of the pipe buffer and its contents. |
119 | * ->steal() returns 0 for success, in which case the contents |
120 | * of the pipe (the buf->page) is locked and now completely owned |
121 | * by the caller. The page may then be transferred to a different |
122 | * mapping, the most often used case is insertion into different |
123 | * file address space cache. |
124 | */ |
125 | int (*steal)(struct pipe_inode_info *, struct pipe_buffer *); |
126 | |
127 | /* |
128 | * Get a reference to the pipe buffer. |
129 | */ |
130 | void (*get)(struct pipe_inode_info *, struct pipe_buffer *); |
131 | }; |
132 | |
133 | /* Differs from PIPE_BUF in that PIPE_SIZE is the length of the actual |
134 | memory allocation, whereas PIPE_BUF makes atomicity guarantees. */ |
135 | #define PIPE_SIZE PAGE_SIZE |
136 | |
137 | /* Pipe lock and unlock operations */ |
138 | void pipe_lock(struct pipe_inode_info *); |
139 | void pipe_unlock(struct pipe_inode_info *); |
140 | void pipe_double_lock(struct pipe_inode_info *, struct pipe_inode_info *); |
141 | |
142 | extern unsigned int pipe_max_size, pipe_min_size; |
143 | int pipe_proc_fn(struct ctl_table *, int, void __user *, size_t *, loff_t *); |
144 | |
145 | |
146 | /* Drop the inode semaphore and wait for a pipe event, atomically */ |
147 | void pipe_wait(struct pipe_inode_info *pipe); |
148 | |
149 | struct pipe_inode_info *alloc_pipe_info(void); |
150 | void free_pipe_info(struct pipe_inode_info *); |
151 | |
152 | /* Generic pipe buffer ops functions */ |
153 | void *generic_pipe_buf_map(struct pipe_inode_info *, struct pipe_buffer *, int); |
154 | void generic_pipe_buf_unmap(struct pipe_inode_info *, struct pipe_buffer *, void *); |
155 | void generic_pipe_buf_get(struct pipe_inode_info *, struct pipe_buffer *); |
156 | int generic_pipe_buf_confirm(struct pipe_inode_info *, struct pipe_buffer *); |
157 | int generic_pipe_buf_steal(struct pipe_inode_info *, struct pipe_buffer *); |
158 | void generic_pipe_buf_release(struct pipe_inode_info *, struct pipe_buffer *); |
159 | |
160 | /* for F_SETPIPE_SZ and F_GETPIPE_SZ */ |
161 | long pipe_fcntl(struct file *, unsigned int, unsigned long arg); |
162 | struct pipe_inode_info *get_pipe_info(struct file *file); |
163 | |
164 | int create_pipe_files(struct file **, int); |
165 | |
166 | #endif |
167 |
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