readahead: remove the old algorithm

Remove the old readahead algorithm.
Signed-off-by: Fengguang Wu <wfg@mail.ustc.edu.cn>
Cc: Steven Pratt <slpratt@austin.ibm.com>
Cc: Ram Pai <linuxram@us.ibm.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/fs.h

@@ -701,14 +701,6 @@ struct fown_struct {
  *  file_ra_state.la_index    .ra_index   .lookahead_index   .readahead_index
  */
 struct file_ra_state {
-	unsigned long start;		/* Current window */
-	unsigned long size;
-	unsigned long flags;		/* ra flags RA_FLAG_xxx*/
-	unsigned long cache_hit;	/* cache hit count*/
-	unsigned long prev_index;	/* Cache last read() position */
-	unsigned long ahead_start;	/* Ahead window */
-	unsigned long ahead_size;
-
 	pgoff_t la_index;               /* enqueue time */
 	pgoff_t ra_index;               /* begin offset */
 	pgoff_t lookahead_index;        /* time to do next readahead */
@@ -717,10 +709,9 @@ struct file_ra_state {
 	unsigned long ra_pages;		/* Maximum readahead window */
 	unsigned long mmap_hit;		/* Cache hit stat for mmap accesses */
 	unsigned long mmap_miss;	/* Cache miss stat for mmap accesses */
+	unsigned long prev_index;	/* Cache last read() position */
 	unsigned int prev_offset;	/* Offset where last read() ended in a page */
 };
-#define RA_FLAG_MISS 0x01	/* a cache miss occured against this file */
-#define RA_FLAG_INCACHE 0x02	/* file is already in cache */
 
 /*
  * Measuring read-ahead sizes.

include/linux/mm.h

@@ -1144,13 +1144,6 @@ unsigned long page_cache_readahead_ondemand(struct address_space *mapping,
 			  struct page *page,
 			  pgoff_t offset,
 			  unsigned long size);
-unsigned long page_cache_readahead(struct address_space *mapping,
-			  struct file_ra_state *ra,
-			  struct file *filp,
-			  pgoff_t offset,
-			  unsigned long size);
-void handle_ra_miss(struct address_space *mapping, 
-		    struct file_ra_state *ra, pgoff_t offset);
 unsigned long max_sane_readahead(unsigned long nr);
 
 /* Do stack extension */