#define PIPEFS_MAGIC 0x50495045
-#define PIPE_BUFFERS (16)
+#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 */
+
+/**
+ * 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;
- struct pipe_buf_operations *ops;
-};
-
-struct pipe_buf_operations {
- int can_merge;
- void * (*map)(struct file *, struct pipe_inode_info *, struct pipe_buffer *);
- void (*unmap)(struct pipe_inode_info *, struct pipe_buffer *);
- void (*release)(struct pipe_inode_info *, struct pipe_buffer *);
+ const struct pipe_buf_operations *ops;
+ unsigned int flags;
+ unsigned long private;
};
+/**
+ * struct pipe_inode_info - a linux kernel pipe
+ * @wait: reader/writer wait point in case of empty/full pipe
+ * @nrbufs: the number of non-empty pipe buffers in this pipe
+ * @curbuf: the current pipe buffer entry
+ * @tmp_page: cached released page
+ * @readers: number of current readers of this pipe
+ * @writers: number of current writers of this pipe
+ * @waiting_writers: number of writers blocked waiting for room
+ * @r_counter: reader counter
+ * @w_counter: writer counter
+ * @fasync_readers: reader side fasync
+ * @fasync_writers: writer side fasync
+ * @inode: inode this pipe is attached to
+ * @bufs: the circular array of pipe buffers
+ **/
struct pipe_inode_info {
wait_queue_head_t wait;
- unsigned int nrbufs, curbuf;
- struct pipe_buffer bufs[PIPE_BUFFERS];
- struct page *tmp_page;
- unsigned int start;
+ unsigned int nrbufs, curbuf, buffers;
unsigned int readers;
unsigned int writers;
unsigned int waiting_writers;
unsigned int r_counter;
unsigned int w_counter;
+ struct page *tmp_page;
struct fasync_struct *fasync_readers;
struct fasync_struct *fasync_writers;
+ struct inode *inode;
+ struct pipe_buffer *bufs;
+};
+
+/*
+ * Note on the nesting of these functions:
+ *
+ * ->confirm()
+ * ->steal()
+ * ...
+ * ->map()
+ * ...
+ * ->unmap()
+ *
+ * That is, ->map() must be called on a confirmed buffer,
+ * same goes for ->steal(). See below for the meaning of each
+ * operation. Also see kerneldoc in fs/pipe.c for the pipe
+ * and generic variants of these hooks.
+ */
+struct pipe_buf_operations {
+ /*
+ * This is set to 1, if the generic pipe read/write may coalesce
+ * data into an existing buffer. If this is set to 0, a new pipe
+ * page segment is always used for new data.
+ */
+ int can_merge;
+
+ /*
+ * ->map() returns a virtual address mapping of the pipe buffer.
+ * The last integer flag reflects whether this should be an atomic
+ * mapping or not. The atomic map is faster, however you can't take
+ * page faults before calling ->unmap() again. So if you need to eg
+ * access user data through copy_to/from_user(), then you must get
+ * a non-atomic map. ->map() uses the KM_USER0 atomic slot for
+ * atomic maps, so you can't map more than one pipe_buffer at once
+ * and you have to be careful if mapping another page as source
+ * or destination for a copy (IOW, it has to use something else
+ * than KM_USER0).
+ */
+ void * (*map)(struct pipe_inode_info *, struct pipe_buffer *, int);
+
+ /*
+ * Undoes ->map(), finishes the virtual mapping of the pipe buffer.
+ */
+ void (*unmap)(struct pipe_inode_info *, struct pipe_buffer *, void *);
+
+ /*
+ * ->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.
+ */
+ 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.
+ * ->steal() returns 0 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.
+ */
+ int (*steal)(struct pipe_inode_info *, struct pipe_buffer *);
+
+ /*
+ * Get a reference to the pipe buffer.
+ */
+ void (*get)(struct pipe_inode_info *, struct pipe_buffer *);
};
/* 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
-#define PIPE_MUTEX(inode) (&(inode).i_mutex)
-#define PIPE_WAIT(inode) (&(inode).i_pipe->wait)
-#define PIPE_READERS(inode) ((inode).i_pipe->readers)
-#define PIPE_WRITERS(inode) ((inode).i_pipe->writers)
-#define PIPE_WAITING_WRITERS(inode) ((inode).i_pipe->waiting_writers)
-#define PIPE_RCOUNTER(inode) ((inode).i_pipe->r_counter)
-#define PIPE_WCOUNTER(inode) ((inode).i_pipe->w_counter)
-#define PIPE_FASYNC_READERS(inode) (&((inode).i_pipe->fasync_readers))
-#define PIPE_FASYNC_WRITERS(inode) (&((inode).i_pipe->fasync_writers))
+/* 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 *);
+
+extern unsigned int pipe_max_pages;
/* Drop the inode semaphore and wait for a pipe event, atomically */
-void pipe_wait(struct inode * inode);
+void pipe_wait(struct pipe_inode_info *pipe);
+
+struct pipe_inode_info * alloc_pipe_info(struct inode * inode);
+void free_pipe_info(struct inode * inode);
+void __free_pipe_info(struct pipe_inode_info *);
+
+/* Generic pipe buffer ops functions */
+void *generic_pipe_buf_map(struct pipe_inode_info *, struct pipe_buffer *, int);
+void generic_pipe_buf_unmap(struct pipe_inode_info *, struct pipe_buffer *, void *);
+void generic_pipe_buf_get(struct pipe_inode_info *, struct pipe_buffer *);
+int generic_pipe_buf_confirm(struct pipe_inode_info *, struct pipe_buffer *);
+int generic_pipe_buf_steal(struct pipe_inode_info *, struct pipe_buffer *);
+void generic_pipe_buf_release(struct pipe_inode_info *, struct pipe_buffer *);
-struct inode* pipe_new(struct inode* inode);
-void free_pipe_info(struct inode* inode);
+/* for F_SETPIPE_SZ and F_GETPIPE_SZ */
+long pipe_fcntl(struct file *, unsigned int, unsigned long arg);
#endif
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