274 строки
8.6 KiB
C
274 строки
8.6 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
|
|
#ifndef _LINUX_PIPE_FS_I_H
|
|
#define _LINUX_PIPE_FS_I_H
|
|
|
|
#define PIPE_DEF_BUFFERS 16
|
|
|
|
#define PIPE_BUF_FLAG_LRU 0x01 /* page is on the LRU */
|
|
#define PIPE_BUF_FLAG_ATOMIC 0x02 /* was atomically mapped */
|
|
#define PIPE_BUF_FLAG_GIFT 0x04 /* page is a gift */
|
|
#define PIPE_BUF_FLAG_PACKET 0x08 /* read() as a packet */
|
|
#define PIPE_BUF_FLAG_CAN_MERGE 0x10 /* can merge buffers */
|
|
#define PIPE_BUF_FLAG_WHOLE 0x20 /* read() must return entire buffer or error */
|
|
#ifdef CONFIG_WATCH_QUEUE
|
|
#define PIPE_BUF_FLAG_LOSS 0x40 /* Message loss happened after this buffer */
|
|
#endif
|
|
|
|
/**
|
|
* struct pipe_buffer - a linux kernel pipe buffer
|
|
* @page: the page containing the data for the pipe buffer
|
|
* @offset: offset of data inside the @page
|
|
* @len: length of data inside the @page
|
|
* @ops: operations associated with this buffer. See @pipe_buf_operations.
|
|
* @flags: pipe buffer flags. See above.
|
|
* @private: private data owned by the ops.
|
|
**/
|
|
struct pipe_buffer {
|
|
struct page *page;
|
|
unsigned int offset, len;
|
|
const struct pipe_buf_operations *ops;
|
|
unsigned int flags;
|
|
unsigned long private;
|
|
};
|
|
|
|
/**
|
|
* struct pipe_inode_info - a linux kernel pipe
|
|
* @mutex: mutex protecting the whole thing
|
|
* @rd_wait: reader wait point in case of empty pipe
|
|
* @wr_wait: writer wait point in case of full pipe
|
|
* @head: The point of buffer production
|
|
* @tail: The point of buffer consumption
|
|
* @note_loss: The next read() should insert a data-lost message
|
|
* @max_usage: The maximum number of slots that may be used in the ring
|
|
* @ring_size: total number of buffers (should be a power of 2)
|
|
* @nr_accounted: The amount this pipe accounts for in user->pipe_bufs
|
|
* @tmp_page: cached released page
|
|
* @readers: number of current readers of this pipe
|
|
* @writers: number of current writers of this pipe
|
|
* @files: number of struct file referring this pipe (protected by ->i_lock)
|
|
* @r_counter: reader counter
|
|
* @w_counter: writer counter
|
|
* @poll_usage: is this pipe used for epoll, which has crazy wakeups?
|
|
* @fasync_readers: reader side fasync
|
|
* @fasync_writers: writer side fasync
|
|
* @bufs: the circular array of pipe buffers
|
|
* @user: the user who created this pipe
|
|
* @watch_queue: If this pipe is a watch_queue, this is the stuff for that
|
|
**/
|
|
struct pipe_inode_info {
|
|
struct mutex mutex;
|
|
wait_queue_head_t rd_wait, wr_wait;
|
|
unsigned int head;
|
|
unsigned int tail;
|
|
unsigned int max_usage;
|
|
unsigned int ring_size;
|
|
#ifdef CONFIG_WATCH_QUEUE
|
|
bool note_loss;
|
|
#endif
|
|
unsigned int nr_accounted;
|
|
unsigned int readers;
|
|
unsigned int writers;
|
|
unsigned int files;
|
|
unsigned int r_counter;
|
|
unsigned int w_counter;
|
|
unsigned int poll_usage;
|
|
struct page *tmp_page;
|
|
struct fasync_struct *fasync_readers;
|
|
struct fasync_struct *fasync_writers;
|
|
struct pipe_buffer *bufs;
|
|
struct user_struct *user;
|
|
#ifdef CONFIG_WATCH_QUEUE
|
|
struct watch_queue *watch_queue;
|
|
#endif
|
|
};
|
|
|
|
/*
|
|
* Note on the nesting of these functions:
|
|
*
|
|
* ->confirm()
|
|
* ->try_steal()
|
|
*
|
|
* That is, ->try_steal() must be called on a confirmed buffer. See below for
|
|
* the meaning of each operation. Also see the kerneldoc in fs/pipe.c for the
|
|
* pipe and generic variants of these hooks.
|
|
*/
|
|
struct pipe_buf_operations {
|
|
/*
|
|
* ->confirm() verifies that the data in the pipe buffer is there
|
|
* and that the contents are good. If the pages in the pipe belong
|
|
* to a file system, we may need to wait for IO completion in this
|
|
* hook. Returns 0 for good, or a negative error value in case of
|
|
* error. If not present all pages are considered good.
|
|
*/
|
|
int (*confirm)(struct pipe_inode_info *, struct pipe_buffer *);
|
|
|
|
/*
|
|
* When the contents of this pipe buffer has been completely
|
|
* consumed by a reader, ->release() is called.
|
|
*/
|
|
void (*release)(struct pipe_inode_info *, struct pipe_buffer *);
|
|
|
|
/*
|
|
* Attempt to take ownership of the pipe buffer and its contents.
|
|
* ->try_steal() returns %true for success, in which case the contents
|
|
* of the pipe (the buf->page) is locked and now completely owned by the
|
|
* caller. The page may then be transferred to a different mapping, the
|
|
* most often used case is insertion into different file address space
|
|
* cache.
|
|
*/
|
|
bool (*try_steal)(struct pipe_inode_info *, struct pipe_buffer *);
|
|
|
|
/*
|
|
* Get a reference to the pipe buffer.
|
|
*/
|
|
bool (*get)(struct pipe_inode_info *, struct pipe_buffer *);
|
|
};
|
|
|
|
/**
|
|
* pipe_empty - Return true if the pipe is empty
|
|
* @head: The pipe ring head pointer
|
|
* @tail: The pipe ring tail pointer
|
|
*/
|
|
static inline bool pipe_empty(unsigned int head, unsigned int tail)
|
|
{
|
|
return head == tail;
|
|
}
|
|
|
|
/**
|
|
* pipe_occupancy - Return number of slots used in the pipe
|
|
* @head: The pipe ring head pointer
|
|
* @tail: The pipe ring tail pointer
|
|
*/
|
|
static inline unsigned int pipe_occupancy(unsigned int head, unsigned int tail)
|
|
{
|
|
return head - tail;
|
|
}
|
|
|
|
/**
|
|
* pipe_full - Return true if the pipe is full
|
|
* @head: The pipe ring head pointer
|
|
* @tail: The pipe ring tail pointer
|
|
* @limit: The maximum amount of slots available.
|
|
*/
|
|
static inline bool pipe_full(unsigned int head, unsigned int tail,
|
|
unsigned int limit)
|
|
{
|
|
return pipe_occupancy(head, tail) >= limit;
|
|
}
|
|
|
|
/**
|
|
* pipe_space_for_user - Return number of slots available to userspace
|
|
* @head: The pipe ring head pointer
|
|
* @tail: The pipe ring tail pointer
|
|
* @pipe: The pipe info structure
|
|
*/
|
|
static inline unsigned int pipe_space_for_user(unsigned int head, unsigned int tail,
|
|
struct pipe_inode_info *pipe)
|
|
{
|
|
unsigned int p_occupancy, p_space;
|
|
|
|
p_occupancy = pipe_occupancy(head, tail);
|
|
if (p_occupancy >= pipe->max_usage)
|
|
return 0;
|
|
p_space = pipe->ring_size - p_occupancy;
|
|
if (p_space > pipe->max_usage)
|
|
p_space = pipe->max_usage;
|
|
return p_space;
|
|
}
|
|
|
|
/**
|
|
* pipe_buf_get - get a reference to a pipe_buffer
|
|
* @pipe: the pipe that the buffer belongs to
|
|
* @buf: the buffer to get a reference to
|
|
*
|
|
* Return: %true if the reference was successfully obtained.
|
|
*/
|
|
static inline __must_check bool pipe_buf_get(struct pipe_inode_info *pipe,
|
|
struct pipe_buffer *buf)
|
|
{
|
|
return buf->ops->get(pipe, buf);
|
|
}
|
|
|
|
/**
|
|
* pipe_buf_release - put a reference to a pipe_buffer
|
|
* @pipe: the pipe that the buffer belongs to
|
|
* @buf: the buffer to put a reference to
|
|
*/
|
|
static inline void pipe_buf_release(struct pipe_inode_info *pipe,
|
|
struct pipe_buffer *buf)
|
|
{
|
|
const struct pipe_buf_operations *ops = buf->ops;
|
|
|
|
buf->ops = NULL;
|
|
ops->release(pipe, buf);
|
|
}
|
|
|
|
/**
|
|
* pipe_buf_confirm - verify contents of the pipe buffer
|
|
* @pipe: the pipe that the buffer belongs to
|
|
* @buf: the buffer to confirm
|
|
*/
|
|
static inline int pipe_buf_confirm(struct pipe_inode_info *pipe,
|
|
struct pipe_buffer *buf)
|
|
{
|
|
if (!buf->ops->confirm)
|
|
return 0;
|
|
return buf->ops->confirm(pipe, buf);
|
|
}
|
|
|
|
/**
|
|
* pipe_buf_try_steal - attempt to take ownership of a pipe_buffer
|
|
* @pipe: the pipe that the buffer belongs to
|
|
* @buf: the buffer to attempt to steal
|
|
*/
|
|
static inline bool pipe_buf_try_steal(struct pipe_inode_info *pipe,
|
|
struct pipe_buffer *buf)
|
|
{
|
|
if (!buf->ops->try_steal)
|
|
return false;
|
|
return buf->ops->try_steal(pipe, buf);
|
|
}
|
|
|
|
/* Differs from PIPE_BUF in that PIPE_SIZE is the length of the actual
|
|
memory allocation, whereas PIPE_BUF makes atomicity guarantees. */
|
|
#define PIPE_SIZE PAGE_SIZE
|
|
|
|
/* Pipe lock and unlock operations */
|
|
void pipe_lock(struct pipe_inode_info *);
|
|
void pipe_unlock(struct pipe_inode_info *);
|
|
void pipe_double_lock(struct pipe_inode_info *, struct pipe_inode_info *);
|
|
|
|
/* Wait for a pipe to be readable/writable while dropping the pipe lock */
|
|
void pipe_wait_readable(struct pipe_inode_info *);
|
|
void pipe_wait_writable(struct pipe_inode_info *);
|
|
|
|
struct pipe_inode_info *alloc_pipe_info(void);
|
|
void free_pipe_info(struct pipe_inode_info *);
|
|
|
|
/* Generic pipe buffer ops functions */
|
|
bool generic_pipe_buf_get(struct pipe_inode_info *, struct pipe_buffer *);
|
|
bool generic_pipe_buf_try_steal(struct pipe_inode_info *, struct pipe_buffer *);
|
|
void generic_pipe_buf_release(struct pipe_inode_info *, struct pipe_buffer *);
|
|
|
|
extern const struct pipe_buf_operations nosteal_pipe_buf_ops;
|
|
|
|
#ifdef CONFIG_WATCH_QUEUE
|
|
unsigned long account_pipe_buffers(struct user_struct *user,
|
|
unsigned long old, unsigned long new);
|
|
bool too_many_pipe_buffers_soft(unsigned long user_bufs);
|
|
bool too_many_pipe_buffers_hard(unsigned long user_bufs);
|
|
bool pipe_is_unprivileged_user(void);
|
|
#endif
|
|
|
|
/* for F_SETPIPE_SZ and F_GETPIPE_SZ */
|
|
#ifdef CONFIG_WATCH_QUEUE
|
|
int pipe_resize_ring(struct pipe_inode_info *pipe, unsigned int nr_slots);
|
|
#endif
|
|
long pipe_fcntl(struct file *, unsigned int, unsigned long arg);
|
|
struct pipe_inode_info *get_pipe_info(struct file *file, bool for_splice);
|
|
|
|
int create_pipe_files(struct file **, int);
|
|
unsigned int round_pipe_size(unsigned long size);
|
|
|
|
#endif
|