+ struct inode *inode;
+ struct pipe_buffer bufs[PIPE_BUFFERS];
+};
+
+/*
+ * 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 *);