vfs: move ACL cache lookup into generic code

This moves logic for checking the cached ACL values from low-level
filesystems into generic code.  The end result is a streamlined ACL
check that doesn't need to load the inode->i_op->check_acl pointer at
all for the common cached case.

The filesystems also don't need to check for a non-blocking RCU walk
case in their acl_check() functions, because that is all handled at a
VFS layer.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/generic_acl.c b/fs/generic_acl.c
index 70e90b4..4949473 100644
--- a/fs/generic_acl.c
+++ b/fs/generic_acl.c
@@ -192,18 +192,13 @@
 int
 generic_check_acl(struct inode *inode, int mask)
 {
-	if (mask & MAY_NOT_BLOCK) {
-		if (!negative_cached_acl(inode, ACL_TYPE_ACCESS))
-			return -ECHILD;
-	} else {
-		struct posix_acl *acl;
+	struct posix_acl *acl;
 
-		acl = get_cached_acl(inode, ACL_TYPE_ACCESS);
-		if (acl) {
-			int error = posix_acl_permission(inode, acl, mask);
-			posix_acl_release(acl);
-			return error;
-		}
+	acl = get_cached_acl(inode, ACL_TYPE_ACCESS);
+	if (acl) {
+		int error = posix_acl_permission(inode, acl, mask);
+		posix_acl_release(acl);
+		return error;
 	}
 	return -EAGAIN;
 }