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, 0 insertions, 3 deletions

diff --git a/fs/ext2/dir.c b/fs/ext2/dir.c
index e89bfc8cf957..1d1e7e30d70e 100644
--- a/fs/ext2/dir.c
+++ b/fs/ext2/dir.c
@@ -161,10 +161,7 @@ static struct page * ext2_get_page(struct inode *dir, unsigned long n)
         struct address_space *mapping = dir->i_mapping;
         struct page *page = read_mapping_page(mapping, n, NULL);
         if (!IS_ERR(page)) {
-                wait_on_page_locked(page);
                 kmap(page);
-                if (!PageUptodate(page))
-                        goto fail;
                 if (!PageChecked(page))
                         ext2_check_page(page);
                 if (PageError(page))