Make relay buffers variable-length.

index 35912d6..91e253f 100644
@@ -27,8 +27,7 @@
 /*
  * relay channel flags
  */
-#define RCHAN_MODE_OVERWRITE		0x00000001	/* 'flight' mode */
-#define RCHAN_GLOBAL_BUFFER		0x00000002	/* not using per-cpu */
+#define RCHAN_GLOBAL_BUFFER		0x00000001	/* not using per-cpu */
 
 struct relay_page
 {

@@ -44,16 +43,15 @@ struct rchan_buf
 	void *data;			/* address of current page */
 	struct relay_page *page;	/* current write page */
 	size_t offset;			/* current offset into page */
-	size_t consumed_offset;		/* bytes consumed in cur page */
-	size_t produced;		/* count of pages produced */
-	size_t consumed;		/* count of pages consumed */
 	struct rchan *chan;		/* associated channel */
 	wait_queue_head_t read_wait;	/* reader wait queue */
 	struct timer_list timer; 	/* reader wake-up timer */
 	struct dentry *dentry;		/* channel file dentry */
 	struct kref kref;		/* channel buffer refcount */
 	struct list_head pages;		/* current set of unconsumed pages */
-	unsigned int page_count;	/* number of current buffer pages */
+	size_t consumed_offset;		/* bytes consumed in cur page */
+	size_t nr_pages;		/* number of unconsumed pages */
+	struct list_head pool;		/* current set of unused pages */
 	unsigned int finalized;		/* buffer has been finalized */
 	size_t early_bytes;		/* bytes consumed before VFS inited */
 	unsigned int cpu;		/* this buf's cpu */

@@ -67,7 +65,6 @@ struct rchan
 	u32 version;			/* the version of this struct */
 	size_t n_pages;			/* number of pages per buffer */
 	size_t n_pages_wakeup;		/* wake up readers after filling n */
-	size_t alloc_size;		/* total buffer size allocated */
 	struct rchan_callbacks *cb;	/* client callbacks */
 	struct kref kref;		/* channel refcount */
 	void *private_data;		/* for user-defined data */

@@ -107,25 +104,6 @@ struct rchan_callbacks
 			  void *page_data);
 
 	/*
-	 * buf_mapped - relay buffer mmap notification
-	 * @buf: the channel buffer
-	 * @filp: relay file pointer
-	 *
-	 * Called when a relay file is successfully mmapped
-	 */
-        void (*buf_mapped)(struct rchan_buf *buf,
-			   struct file *filp);
-
-	/*
-	 * buf_unmapped - relay buffer unmap notification
-	 * @buf: the channel buffer
-	 * @filp: relay file pointer
-	 *
-	 * Called when a relay file is successfully unmapped
-	 */
-        void (*buf_unmapped)(struct rchan_buf *buf,
-			     struct file *filp);
-	/*
 	 * create_buf_file - create file to represent a relay channel buffer
 	 * @filename: the name of the file to create
 	 * @parent: the parent of the file to create

@@ -184,23 +162,21 @@ struct rchan_callbacks
  * CONFIG_RELAY kernel API, kernel/relay.c
  */
 
-struct rchan *relay_open(const char *base_filename,
-			 struct dentry *parent,
-			 size_t n_pages,
-			 size_t n_pages_wakeup,
-			 struct rchan_callbacks *cb,
-			 void *private_data,
-			 unsigned long rchan_flags);
-extern int relay_late_setup_files(struct rchan *chan,
-				  const char *base_filename,
-				  struct dentry *parent);
+extern struct rchan *relay_open(const char *base_filename,
+				struct dentry *parent,
+				size_t n_pages,
+				size_t n_pages_wakeup,
+				struct rchan_callbacks *cb,
+				void *private_data,
+				unsigned long rchan_flags);
 extern void relay_close(struct rchan *chan);
 extern void relay_flush(struct rchan *chan);
-extern void relay_pages_consumed(struct rchan *chan,
-				 unsigned int cpu,
-				 size_t consumed);
 extern void relay_reset(struct rchan *chan);
-extern int relay_buf_full(struct rchan_buf *buf);
+extern void relay_add_page(struct rchan_buf *buf, struct page *page);
+
+extern int relay_late_setup_files(struct rchan *chan,
+				  const char *base_filename,
+				  struct dentry *parent);
 
 extern size_t relay_switch_page_default_callback(struct rchan_buf *buf,
 						 size_t length,

@@ -221,7 +197,7 @@ static inline void relay_wakeup_readers(struct rchan_buf *buf)
 {
 	size_t wakeup = buf->chan->n_pages_wakeup;
 
-	if (wakeup && (buf->produced % wakeup == 0) &&
+	if (wakeup && (buf->nr_pages % wakeup == 0) &&
 	    (waitqueue_active(&buf->read_wait)))
 		/*
 		 * Calling wake_up_interruptible() from here

@@ -264,17 +240,6 @@ static inline void relay_update_filesize(struct rchan_buf *buf, size_t length)
 }
 
 /**
- *	relay_inc_produced - increase number of pages produced by 1
- *	@buf: relay channel buffer
- *
- *	switch_page() helper function.
- */
-static inline void relay_inc_produced(struct rchan_buf *buf)
-{
-	buf->produced++;
-}
-
-/**
  *	relay_write - write data into the channel
  *	@chan: relay channel
  *	@data: data to be written

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