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, 9 deletions

diff --git a/fs/sysv/dir.c b/fs/sysv/dir.c
index ebf7007fa161..e566b387fcf9 100644
--- a/fs/sysv/dir.c
+++ b/fs/sysv/dir.c
@@ -54,17 +54,9 @@ static struct page * dir_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);
+        if (!IS_ERR(page))
                 kmap(page);
-                if (!PageUptodate(page))
-                        goto fail;
-        }
         return page;
-
-fail:
-        dir_put_page(page);
-        return ERR_PTR(-EIO);
 }
 
 static int sysv_readdir(struct file * filp, void * dirent, filldir_t filldir)