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, 7 deletions

diff --git a/fs/ocfs2/symlink.c b/fs/ocfs2/symlink.c
index 40dc1a5..7134007 100644
--- a/fs/ocfs2/symlink.c
+++ b/fs/ocfs2/symlink.c
@@ -67,16 +67,9 @@ static char *ocfs2_page_getlink(struct dentry * dentry,
 	page = read_mapping_page(mapping, 0, NULL);
 	if (IS_ERR(page))
 		goto sync_fail;
-	wait_on_page_locked(page);
-	if (!PageUptodate(page))
-		goto async_fail;
 	*ppage = page;
 	return kmap(page);
 
-async_fail:
-	page_cache_release(page);
-	return ERR_PTR(-EIO);
-
 sync_fail:
 	return (char*)page;
 }