Cachefiles: Fix up scripted S_ISDIR/S_ISREG/S_ISLNK conversions

Fix up the following scripted S_ISDIR/S_ISREG/S_ISLNK conversions (or lack
thereof) in cachefiles:

 (1) Cachefiles mostly wants to use d_can_lookup() rather than d_is_dir() as
     it doesn't want to deal with automounts in its cache.

 (2) Coccinelle didn't find S_IS* expressions in ASSERT() statements in
     cachefiles.

Signed-off-by: David Howells <[email protected]>
Signed-off-by: Al Viro <[email protected]>
diff --git a/fs/cachefiles/rdwr.c b/fs/cachefiles/rdwr.c
index 616db0e7..c6cd8d7 100644
--- a/fs/cachefiles/rdwr.c
+++ b/fs/cachefiles/rdwr.c
@@ -900,7 +900,7 @@
 		return -ENOBUFS;
 	}
 
-	ASSERT(S_ISREG(object->backer->d_inode->i_mode));
+	ASSERT(d_is_reg(object->backer));
 
 	cache = container_of(object->fscache.cache,
 			     struct cachefiles_cache, cache);