readahead: split ondemand readahead interface into two functions

Split ondemand readahead interface into two functions.  I think this makes it
a little clearer for non-readahead experts (like Rusty).

Internally they both call ondemand_readahead(), but the page argument is
changed to an obvious boolean flag.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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, 14 insertions, 6 deletions

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 3d0d7d285237..50a0ed1d1806 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1138,12 +1138,20 @@ int do_page_cache_readahead(struct address_space *mapping, struct file *filp,
                         pgoff_t offset, unsigned long nr_to_read);
 int force_page_cache_readahead(struct address_space *mapping, struct file *filp,
                         pgoff_t offset, unsigned long nr_to_read);
-unsigned long page_cache_readahead_ondemand(struct address_space *mapping,
-                          struct file_ra_state *ra,
-                          struct file *filp,
-                          struct page *page,
-                          pgoff_t offset,
-                          unsigned long size);
+
+void page_cache_sync_readahead(struct address_space *mapping,
+                               struct file_ra_state *ra,
+                               struct file *filp,
+                               pgoff_t offset,
+                               unsigned long size);
+
+void page_cache_async_readahead(struct address_space *mapping,
+                                struct file_ra_state *ra,
+                                struct file *filp,
+                                struct page *pg,
+                                pgoff_t offset,
+                                unsigned long size);
+
 unsigned long max_sane_readahead(unsigned long nr);
 
 /* Do stack extension */