pipe: change the ->pin() operation to ->confirm()

The name 'pin' was badly chosen, it doesn't pin a pipe buffer
in the most commonly used sense in the kernel. So change the
name to 'confirm', after debating this issue with Hugh
Dickins a bit.

A good return from ->confirm() means that the buffer is really
there, and that the contents are good.

Signed-off-by: Jens Axboe <[email protected]>
diff --git a/include/linux/pipe_fs_i.h b/include/linux/pipe_fs_i.h
index 4409167..cc09fe8 100644
--- a/include/linux/pipe_fs_i.h
+++ b/include/linux/pipe_fs_i.h
@@ -35,20 +35,21 @@
 /*
  * 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().
  */
 struct pipe_buf_operations {
 	int can_merge;
 	void * (*map)(struct pipe_inode_info *, struct pipe_buffer *, int);
 	void (*unmap)(struct pipe_inode_info *, struct pipe_buffer *, void *);
-	int (*pin)(struct pipe_inode_info *, struct pipe_buffer *);
+	int (*confirm)(struct pipe_inode_info *, struct pipe_buffer *);
 	void (*release)(struct pipe_inode_info *, struct pipe_buffer *);
 	int (*steal)(struct pipe_inode_info *, struct pipe_buffer *);
 	void (*get)(struct pipe_inode_info *, struct pipe_buffer *);
@@ -69,7 +70,7 @@
 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 *);
 
 #endif