readahead: code cleanup

Rename file_ra_state.prev_page to prev_index and file_ra_state.offset to
prev_offset.  Also update of prev_index in do_generic_mapping_read() is now
moved close to the update of prev_offset.

[wfg@mail.ustc.edu.cn: fix it]
Signed-off-by: Jan Kara <jack@suse.cz>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: WU Fengguang <wfg@mail.ustc.edu.cn>
Signed-off-by: Fengguang Wu <wfg@mail.ustc.edu.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 4 insertions, 3 deletions

diff --git a/mm/filemap.c b/mm/filemap.c
index 07f5b77114a3..5631d6b2a62d 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -877,8 +877,8 @@ void do_generic_mapping_read(struct address_space *mapping,
         cached_page = NULL;
         index = *ppos >> PAGE_CACHE_SHIFT;
         next_index = index;
-        prev_index = ra.prev_page;
-        prev_offset = ra.offset;
+        prev_index = ra.prev_index;
+        prev_offset = ra.prev_offset;
         last_index = (*ppos + desc->count + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT;
         offset = *ppos & ~PAGE_CACHE_MASK;
 
@@ -947,7 +947,8 @@ page_ok:
                 offset += ret;
                 index += offset >> PAGE_CACHE_SHIFT;
                 offset &= ~PAGE_CACHE_MASK;
-                prev_offset = ra.offset = offset;
+                prev_offset = offset;
+                ra.prev_offset = offset;
 
                 page_cache_release(page);
                 if (ret == nr && desc->count)