36  * Before encoding a non-upper directory file handle from real layer N, we need
39  * "layer N connected" ancestor and verifying that all parents along the way are
40  * "layer N connectable". If an ancestor that is NOT "layer N connectable" is
41  * found, we need to copy up an ancestor, which is "layer N connectable", thus
42  * making that ancestor "layer N connected". For example:
44  * layer 1: /a
45  * layer 2: /a/b/c
47  * The overlay dentry /a is NOT "layer 2 connectable", because if dir /a is
49  * layer 1. The dir /a from layer 2 will never be indexed, so the algorithm (*)
54  * /a/b/c, which is "layer 2 connectable", on encode time. That ancestor is
55  * /a/b. After copy up (and index) of /a/b, it will become "layer 2 connected"
61  * entry /a in the lower layers above layer N and find the indexed dir /a from
62  * layer 1. If that improvement is made, then the check for "layer N connected"
64  * example above, /a will be "layer 2 connectable". However, if layer 2 dir /a
65  * is a target of a layer 1 redirect, then /a will NOT be "layer 2 connectable":
67  * layer 1: /A (redirect = /a)
68  * layer 2: /a/b/c
71 /* Return the lowest layer for encoding a connectable file handle */
76 	/* We can get overlay root from root of any layer */  in ovl_connectable_layer()
82 	 * lower layer  in ovl_connectable_layer()
89 	return ovl_lowerstack(oe)->layer->idx;  in ovl_connectable_layer()
94  * have the same uppermost lower layer as the origin's layer. We may need to
98  * Return the connected origin layer or < 0 on error.
111 	origin_layer = ovl_lowerstack(oe)->layer->idx;  in ovl_connect_layer()
115 	/* Find the topmost origin layer connectable ancestor of @dentry */  in ovl_connect_layer()
125 		 * If @parent is not origin layer connectable, then copy up  in ovl_connect_layer()
126 		 * @next which is origin layer connectable and we are done.  in ovl_connect_layer()
184 	/* No upper layer? */  in ovl_check_encode_origin()
197 	 * Root is never indexed, so if there's an upper layer, encode upper for  in ovl_check_encode_origin()
213 	 * ovl_connect_layer() will try to make origin's layer "connected" by  in ovl_check_encode_origin()
313 		ovl_lowerstack(oe)->layer = lowerpath->layer;  in ovl_obtain_alias()
329 /* Get the upper or lower dentry in stack whose on layer @idx */
340 		if (lowerstack[i].layer->idx == idx)  in ovl_dentry_real_at()
349  * dentry is @real. If @real is on upper layer, we lookup a child overlay
355 					  const struct ovl_layer *layer)  in ovl_lookup_real_one()  argument
372 	if (ovl_dentry_real_at(connected, layer->idx) != parent)  in ovl_lookup_real_one()
377 	 * from racing with underlying layer rename. In this case, we don't  in ovl_lookup_real_one()
396 	} else if (ovl_dentry_real_at(this, layer->idx) != real) {  in ovl_lookup_real_one()
408 	pr_warn_ratelimited("failed to lookup one by real (%pd2, layer=%d, connected=%pd2, err=%i)\n",  in ovl_lookup_real_one()
409 			    real, layer->idx, connected, err);  in ovl_lookup_real_one()
416 				      const struct ovl_layer *layer);
423 					    const struct ovl_layer *layer)  in ovl_lookup_real_inode()  argument
434 	inode = ovl_lookup_inode(sb, real, !layer->idx);  in ovl_lookup_real_inode()
446 	if (!this && layer->idx && ovl_indexdir(sb) && !WARN_ON(!d_is_dir(real))) {  in ovl_lookup_real_inode()
461 		 * ovl_lookup_real() in lower layer may call recursively once to  in ovl_lookup_real_inode()
462 		 * ovl_lookup_real() in upper layer. The first level call walks  in ovl_lookup_real_inode()
474 	if (ovl_dentry_real_at(this, layer->idx) != real) {  in ovl_lookup_real_inode()
488 					       const struct ovl_layer *layer)  in ovl_lookup_real_ancestor()  argument
493 	if (real == layer->mnt->mnt_root)  in ovl_lookup_real_ancestor()
505 		ancestor = ovl_lookup_real_inode(sb, next, layer);  in ovl_lookup_real_ancestor()
509 		if (parent == layer->mnt->mnt_root) {  in ovl_lookup_real_ancestor()
515 		 * If @real has been moved out of the layer root directory,  in ovl_lookup_real_ancestor()
536  * If @real is on upper layer, we lookup a child overlay dentry with the same
541 				      const struct ovl_layer *layer)  in ovl_lookup_real()  argument
546 	connected = ovl_lookup_real_ancestor(sb, real, layer);  in ovl_lookup_real()
554 								   layer->idx);  in ovl_lookup_real()
569 			 * we will not find 'real_connected' and hit the layer  in ovl_lookup_real()
575 			if (parent == layer->mnt->mnt_root) {  in ovl_lookup_real()
582 			 * If real file has been moved out of the layer root  in ovl_lookup_real()
597 			this = ovl_lookup_real_one(connected, next, layer);  in ovl_lookup_real()
613 								layer);  in ovl_lookup_real()
632 	pr_warn_ratelimited("failed to lookup by real (%pd2, layer=%d, connected=%pd2, err=%i)\n",  in ovl_lookup_real()
633 			    real, layer->idx, connected, err);  in ovl_lookup_real()
647 	const struct ovl_layer *layer = upper ? &ofs->layers[0] : lowerpath->layer;  in ovl_get_dentry()  local
665 	return ovl_lookup_real(sb, real, layer);  in ovl_get_dentry()
741 	/* Find origin.dentry again with ovl_acceptable() layer check */  in ovl_lower_fh_to_d()