mm: make read_cache_page synchronous

Ensure pages are uptodate after returning from read_cache_page, which allows
us to cut out most of the filesystem-internal PageUptodate calls.

I didn't have a great look down the call chains, but this appears to fixes 7
possible use-before uptodate in hfs, 2 in hfsplus, 1 in jfs, a few in
ecryptfs, 1 in jffs2, and a possible cleared data overwritten with readpage in
block2mtd.  All depending on whether the filler is async and/or can return
with a !uptodate page.

Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 11 insertions, 0 deletions

diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index 7a8dcb82a699..b4def5e083ed 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -95,12 +95,23 @@ static inline struct page *grab_cache_page(struct address_space *mapping, unsign
 
 extern struct page * grab_cache_page_nowait(struct address_space *mapping,
                                 unsigned long index);
+extern struct page * read_cache_page_async(struct address_space *mapping,
+                                unsigned long index, filler_t *filler,
+                                void *data);
 extern struct page * read_cache_page(struct address_space *mapping,
                                 unsigned long index, filler_t *filler,
                                 void *data);
 extern int read_cache_pages(struct address_space *mapping,
                 struct list_head *pages, filler_t *filler, void *data);
 
+static inline struct page *read_mapping_page_async(
+                                                struct address_space *mapping,
+                                             unsigned long index, void *data)
+{
+        filler_t *filler = (filler_t *)mapping->a_ops->readpage;
+        return read_cache_page_async(mapping, index, filler, data);
+}
+
 static inline struct page *read_mapping_page(struct address_space *mapping,
                                              unsigned long index, void *data)
 {