readahead: sanify file_ra_state names

Rename some file_ra_state variables and remove some accessors.

It results in much simpler code.
Kudos to Rusty!

Signed-off-by: Fengguang Wu <wfg@mail.ustc.edu.cn>
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>

1 files changed, 6 insertions, 55 deletions

diff --git a/include/linux/fs.h b/include/linux/fs.h
index 29cb32d3a849..d33beadd9a43 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -695,16 +695,12 @@ struct fown_struct {
 
 /*
  * Track a single file's readahead state
- *
- *  ================#============|==================#==================|
- *                  ^            ^                  ^                  ^
- *  file_ra_state.la_index    .ra_index   .lookahead_index   .readahead_index
  */
 struct file_ra_state {
-        pgoff_t la_index;               /* enqueue time */
-        pgoff_t ra_index;               /* begin offset */
-        pgoff_t lookahead_index;        /* time to do next readahead */
-        pgoff_t readahead_index;        /* end offset */
+        pgoff_t start;                  /* where readahead started */
+        unsigned long size;             /* # of readahead pages */
+        unsigned long async_size;       /* do asynchronous readahead when
+                                           there are only # of pages ahead */
 
         unsigned long ra_pages;         /* Maximum readahead window */
         unsigned long mmap_hit;         /* Cache hit stat for mmap accesses */
@@ -714,59 +710,14 @@ struct file_ra_state {
 };
 
 /*
- * Measuring read-ahead sizes.
- *
- *                  |----------- readahead size ------------>|
- *  ===#============|==================#=====================|
- *     |------- invoke interval ------>|-- lookahead size -->|
- */
-static inline unsigned long ra_readahead_size(struct file_ra_state *ra)
-{
-        return ra->readahead_index - ra->ra_index;
-}
-
-static inline unsigned long ra_lookahead_size(struct file_ra_state *ra)
-{
-        return ra->readahead_index - ra->lookahead_index;
-}
-
-static inline unsigned long ra_invoke_interval(struct file_ra_state *ra)
-{
-        return ra->lookahead_index - ra->la_index;
-}
-
-/*
  * Check if @index falls in the readahead windows.
  */
 static inline int ra_has_index(struct file_ra_state *ra, pgoff_t index)
 {
-        return (index >= ra->la_index &&
-                index <  ra->readahead_index);
-}
-
-/*
- * Where is the old read-ahead and look-ahead?
- */
-static inline void ra_set_index(struct file_ra_state *ra,
-                                pgoff_t la_index, pgoff_t ra_index)
-{
-        ra->la_index = la_index;
-        ra->ra_index = ra_index;
+        return (index >= ra->start &&
+                index <  ra->start + ra->size);
 }
 
-/*
- * Where is the new read-ahead and look-ahead?
- */
-static inline void ra_set_size(struct file_ra_state *ra,
-                                unsigned long ra_size, unsigned long la_size)
-{
-        ra->readahead_index = ra->ra_index + ra_size;
-        ra->lookahead_index = ra->ra_index + ra_size - la_size;
-}
-
-unsigned long ra_submit(struct file_ra_state *ra,
-                       struct address_space *mapping, struct file *filp);
-
 struct file {
         /*
          * fu_list becomes invalid after file_free is called and queued via