#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;
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 page *tmp_page;
+ unsigned int readers;
+ unsigned int writers;
+ unsigned int waiting_writers;
+ unsigned int r_counter;
+ unsigned int w_counter;
+ struct fasync_struct *fasync_readers;
+ struct fasync_struct *fasync_writers;
+ struct inode *inode;
+ struct pipe_buffer bufs[PIPE_BUFFERS];
};
/*
* Note on the nesting of these functions:
*
- * ->pin()
+ * ->confirm()
* ->steal()
* ...
* ->map()
* ...
* ->unmap()
*
- * That is, ->map() must be called on a pinned buffer, same goes for ->steal().
+ * 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 *);
- int (*pin)(struct pipe_inode_info *, struct pipe_buffer *);
+
+ /*
+ * ->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 *);
- void (*get)(struct pipe_inode_info *, struct pipe_buffer *);
-};
-struct pipe_inode_info {
- wait_queue_head_t wait;
- unsigned int nrbufs, curbuf;
- struct page *tmp_page;
- unsigned int readers;
- unsigned int writers;
- unsigned int waiting_writers;
- unsigned int r_counter;
- unsigned int w_counter;
- struct fasync_struct *fasync_readers;
- struct fasync_struct *fasync_writers;
- struct inode *inode;
- struct pipe_buffer bufs[PIPE_BUFFERS];
+ /*
+ * 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
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_pin(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 *);
-/*
- * splice is tied to pipes as a transport (at least for now), so we'll just
- * add the splice flags here.
- */
-#define SPLICE_F_MOVE (0x01) /* move pages instead of copying */
-#define SPLICE_F_NONBLOCK (0x02) /* don't block on the pipe splicing (but */
- /* we may still block on the fd we splice */
- /* from/to, of course */
-#define SPLICE_F_MORE (0x04) /* expect more data */
-#define SPLICE_F_GIFT (0x08) /* pages passed in are a gift */
-
-/*
- * Passed to the actors
- */
-struct splice_desc {
- unsigned int len, total_len; /* current and remaining length */
- unsigned int flags; /* splice flags */
- struct file *file; /* file to read/write */
- loff_t pos; /* file position */
-};
-
-typedef int (splice_actor)(struct pipe_inode_info *, struct pipe_buffer *,
- struct splice_desc *);
-
-extern ssize_t splice_from_pipe(struct pipe_inode_info *, struct file *,
- loff_t *, size_t, unsigned int,
- splice_actor *);
-
-extern ssize_t __splice_from_pipe(struct pipe_inode_info *, struct file *,
- loff_t *, size_t, unsigned int,
- splice_actor *);
-
#endif
projects / karo-tx-linux.git / blobdiff