fs: dcache reduce branches in lookup path

Reduce some branches and memory accesses in dcache lookup by adding dentry
flags to indicate common d_ops are set, rather than having to check them.
This saves a pointer memory access (dentry->d_op) in common path lookup
situations, and saves another pointer load and branch in cases where we
have d_op but not the particular operation.

Patched with:

git grep -E '[.>]([[:space:]])*d_op([[:space:]])*=' | xargs sed -e 's/\([^\t ]*\)->d_op = \(.*\);/d_set_d_op(\1, \2);/' -e 's/\([^\t ]*\)\.d_op = \(.*\);/d_set_d_op(\&\1, \2);/' -i

Signed-off-by: Nick Piggin <npiggin@kernel.dk>
diff --git a/fs/cifs/link.c b/fs/cifs/link.c
index 85cdbf8..fe2f6a9 100644
--- a/fs/cifs/link.c
+++ b/fs/cifs/link.c
@@ -525,9 +525,9 @@
 			      rc);
 		} else {
 			if (pTcon->nocase)
-				direntry->d_op = &cifs_ci_dentry_ops;
+				d_set_d_op(direntry, &cifs_ci_dentry_ops);
 			else
-				direntry->d_op = &cifs_dentry_ops;
+				d_set_d_op(direntry, &cifs_dentry_ops);
 			d_instantiate(direntry, newinode);
 		}
 	}