fbdev: mm: Deferred IO support

This implements deferred IO support in fbdev.  Deferred IO is a way to delay
and repurpose IO.  This implementation is done using mm's page_mkwrite and
page_mkclean hooks in order to detect, delay and then rewrite IO.  This
functionality is used by hecubafb.

[adaplas]
This is useful for graphics hardware with no directly addressable/mappable
framebuffer. Implementing this will allow the "framebuffer" to be accesible
from user space via mmap().

Signed-off-by: Jaya Kumar <jayakumar.lkml@gmail.com>
Signed-off-by: Antonino Daplas <adaplas@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 1 insertions, 0 deletions

diff --git a/mm/rmap.c b/mm/rmap.c
index 75a32be64a21..304f51985c78 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -505,6 +505,7 @@ int page_mkclean(struct page *page)
 
         return ret;
 }
+EXPORT_SYMBOL_GPL(page_mkclean);
 
 /**
  * page_set_anon_rmap - setup new anonymous rmap