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, 1 insertions, 2 deletions

diff --git a/fs/ntfs/aops.h b/fs/ntfs/aops.h
index 9393f4b1e298..caecc58f529c 100644
--- a/fs/ntfs/aops.h
+++ b/fs/ntfs/aops.h
@@ -89,9 +89,8 @@ static inline struct page *ntfs_map_page(struct address_space *mapping,
         struct page *page = read_mapping_page(mapping, index, NULL);
 
         if (!IS_ERR(page)) {
-                wait_on_page_locked(page);
                 kmap(page);
-                if (PageUptodate(page) && !PageError(page))
+                if (!PageError(page))
                         return page;
                 ntfs_unmap_page(page);
                 return ERR_PTR(-EIO);