[PATCH] relayfs: add relayfs_remove_file()
[linux-2.6/kmemtrace.git] / include / linux / relayfs_fs.h
blob921540b1cdf8f323ef808395993c200dfeafe1f1
1 /*
2 * linux/include/linux/relayfs_fs.h
4 * Copyright (C) 2002, 2003 - Tom Zanussi (zanussi@us.ibm.com), IBM Corp
5 * Copyright (C) 1999, 2000, 2001, 2002 - Karim Yaghmour (karim@opersys.com)
7 * RelayFS definitions and declarations
8 */
10 #ifndef _LINUX_RELAYFS_FS_H
11 #define _LINUX_RELAYFS_FS_H
13 #include <linux/config.h>
14 #include <linux/types.h>
15 #include <linux/sched.h>
16 #include <linux/wait.h>
17 #include <linux/list.h>
18 #include <linux/fs.h>
19 #include <linux/poll.h>
20 #include <linux/kref.h>
23 * Tracks changes to rchan/rchan_buf structs
25 #define RELAYFS_CHANNEL_VERSION 6
28 * Per-cpu relay channel buffer
30 struct rchan_buf
32 void *start; /* start of channel buffer */
33 void *data; /* start of current sub-buffer */
34 size_t offset; /* current offset into sub-buffer */
35 size_t subbufs_produced; /* count of sub-buffers produced */
36 size_t subbufs_consumed; /* count of sub-buffers consumed */
37 struct rchan *chan; /* associated channel */
38 wait_queue_head_t read_wait; /* reader wait queue */
39 struct work_struct wake_readers; /* reader wake-up work struct */
40 struct dentry *dentry; /* channel file dentry */
41 struct kref kref; /* channel buffer refcount */
42 struct page **page_array; /* array of current buffer pages */
43 unsigned int page_count; /* number of current buffer pages */
44 unsigned int finalized; /* buffer has been finalized */
45 size_t *padding; /* padding counts per sub-buffer */
46 size_t prev_padding; /* temporary variable */
47 size_t bytes_consumed; /* bytes consumed in cur read subbuf */
48 unsigned int cpu; /* this buf's cpu */
49 } ____cacheline_aligned;
52 * Relay channel data structure
54 struct rchan
56 u32 version; /* the version of this struct */
57 size_t subbuf_size; /* sub-buffer size */
58 size_t n_subbufs; /* number of sub-buffers per buffer */
59 size_t alloc_size; /* total buffer size allocated */
60 struct rchan_callbacks *cb; /* client callbacks */
61 struct kref kref; /* channel refcount */
62 void *private_data; /* for user-defined data */
63 size_t last_toobig; /* tried to log event > subbuf size */
64 struct rchan_buf *buf[NR_CPUS]; /* per-cpu channel buffers */
68 * Relayfs inode
70 struct relayfs_inode_info
72 struct inode vfs_inode;
73 void *data;
76 static inline struct relayfs_inode_info *RELAYFS_I(struct inode *inode)
78 return container_of(inode, struct relayfs_inode_info, vfs_inode);
82 * Relay channel client callbacks
84 struct rchan_callbacks
87 * subbuf_start - called on buffer-switch to a new sub-buffer
88 * @buf: the channel buffer containing the new sub-buffer
89 * @subbuf: the start of the new sub-buffer
90 * @prev_subbuf: the start of the previous sub-buffer
91 * @prev_padding: unused space at the end of previous sub-buffer
93 * The client should return 1 to continue logging, 0 to stop
94 * logging.
96 * NOTE: subbuf_start will also be invoked when the buffer is
97 * created, so that the first sub-buffer can be initialized
98 * if necessary. In this case, prev_subbuf will be NULL.
100 * NOTE: the client can reserve bytes at the beginning of the new
101 * sub-buffer by calling subbuf_start_reserve() in this callback.
103 int (*subbuf_start) (struct rchan_buf *buf,
104 void *subbuf,
105 void *prev_subbuf,
106 size_t prev_padding);
109 * buf_mapped - relayfs buffer mmap notification
110 * @buf: the channel buffer
111 * @filp: relayfs file pointer
113 * Called when a relayfs file is successfully mmapped
115 void (*buf_mapped)(struct rchan_buf *buf,
116 struct file *filp);
119 * buf_unmapped - relayfs buffer unmap notification
120 * @buf: the channel buffer
121 * @filp: relayfs file pointer
123 * Called when a relayfs file is successfully unmapped
125 void (*buf_unmapped)(struct rchan_buf *buf,
126 struct file *filp);
130 * relayfs kernel API, fs/relayfs/relay.c
133 struct rchan *relay_open(const char *base_filename,
134 struct dentry *parent,
135 size_t subbuf_size,
136 size_t n_subbufs,
137 struct rchan_callbacks *cb);
138 extern void relay_close(struct rchan *chan);
139 extern void relay_flush(struct rchan *chan);
140 extern void relay_subbufs_consumed(struct rchan *chan,
141 unsigned int cpu,
142 size_t consumed);
143 extern void relay_reset(struct rchan *chan);
144 extern int relay_buf_full(struct rchan_buf *buf);
146 extern size_t relay_switch_subbuf(struct rchan_buf *buf,
147 size_t length);
148 extern struct dentry *relayfs_create_dir(const char *name,
149 struct dentry *parent);
150 extern int relayfs_remove_dir(struct dentry *dentry);
151 extern struct dentry *relayfs_create_file(const char *name,
152 struct dentry *parent,
153 int mode,
154 struct file_operations *fops,
155 void *data);
156 extern int relayfs_remove_file(struct dentry *dentry);
159 * relay_write - write data into the channel
160 * @chan: relay channel
161 * @data: data to be written
162 * @length: number of bytes to write
164 * Writes data into the current cpu's channel buffer.
166 * Protects the buffer by disabling interrupts. Use this
167 * if you might be logging from interrupt context. Try
168 * __relay_write() if you know you won't be logging from
169 * interrupt context.
171 static inline void relay_write(struct rchan *chan,
172 const void *data,
173 size_t length)
175 unsigned long flags;
176 struct rchan_buf *buf;
178 local_irq_save(flags);
179 buf = chan->buf[smp_processor_id()];
180 if (unlikely(buf->offset + length > chan->subbuf_size))
181 length = relay_switch_subbuf(buf, length);
182 memcpy(buf->data + buf->offset, data, length);
183 buf->offset += length;
184 local_irq_restore(flags);
188 * __relay_write - write data into the channel
189 * @chan: relay channel
190 * @data: data to be written
191 * @length: number of bytes to write
193 * Writes data into the current cpu's channel buffer.
195 * Protects the buffer by disabling preemption. Use
196 * relay_write() if you might be logging from interrupt
197 * context.
199 static inline void __relay_write(struct rchan *chan,
200 const void *data,
201 size_t length)
203 struct rchan_buf *buf;
205 buf = chan->buf[get_cpu()];
206 if (unlikely(buf->offset + length > buf->chan->subbuf_size))
207 length = relay_switch_subbuf(buf, length);
208 memcpy(buf->data + buf->offset, data, length);
209 buf->offset += length;
210 put_cpu();
214 * relay_reserve - reserve slot in channel buffer
215 * @chan: relay channel
216 * @length: number of bytes to reserve
218 * Returns pointer to reserved slot, NULL if full.
220 * Reserves a slot in the current cpu's channel buffer.
221 * Does not protect the buffer at all - caller must provide
222 * appropriate synchronization.
224 static inline void *relay_reserve(struct rchan *chan, size_t length)
226 void *reserved;
227 struct rchan_buf *buf = chan->buf[smp_processor_id()];
229 if (unlikely(buf->offset + length > buf->chan->subbuf_size)) {
230 length = relay_switch_subbuf(buf, length);
231 if (!length)
232 return NULL;
234 reserved = buf->data + buf->offset;
235 buf->offset += length;
237 return reserved;
241 * subbuf_start_reserve - reserve bytes at the start of a sub-buffer
242 * @buf: relay channel buffer
243 * @length: number of bytes to reserve
245 * Helper function used to reserve bytes at the beginning of
246 * a sub-buffer in the subbuf_start() callback.
248 static inline void subbuf_start_reserve(struct rchan_buf *buf,
249 size_t length)
251 BUG_ON(length >= buf->chan->subbuf_size - 1);
252 buf->offset = length;
256 * exported relayfs file operations, fs/relayfs/inode.c
259 extern struct file_operations relayfs_file_operations;
261 #endif /* _LINUX_RELAYFS_FS_H */