44  * Before encoding a non-upper directory file handle from real layer N, we need
47  * "layer N connected" ancestor and verifying that all parents along the way are
48  * "layer N connectable". If an ancestor that is NOT "layer N connectable" is
49  * found, we need to copy up an ancestor, which is "layer N connectable", thus
50  * making that ancestor "layer N connected". For example:
52  * layer 1: /a
53  * layer 2: /a/b/c
55  * The overlay dentry /a is NOT "layer 2 connectable", because if dir /a is
57  * layer 1. The dir /a from layer 2 will never be indexed, so the algorithm (*)
62  * /a/b/c, which is "layer 2 connectable", on encode time. That ancestor is
63  * /a/b. After copy up (and index) of /a/b, it will become "layer 2 connected"
69  * entry /a in the lower layers above layer N and find the indexed dir /a from
70  * layer 1. If that improvement is made, then the check for "layer N connected"
72  * example above, /a will be "layer 2 connectable". However, if layer 2 dir /a
73  * is a target of a layer 1 redirect, then /a will NOT be "layer 2 connectable":
75  * layer 1: /A (redirect = /a)
76  * layer 2: /a/b/c
79 /* Return the lowest layer for encoding a connectable file handle */
84 	/* We can get overlay root from root of any layer */  in ovl_connectable_layer()
90 	 * lower layer  in ovl_connectable_layer()
97 	return oe->lowerstack[0].layer->idx;  in ovl_connectable_layer()
102  * have the same uppermost lower layer as the origin's layer. We may need to
106  * Return the connected origin layer or < 0 on error.
118 	origin_layer = OVL_E(dentry)->lowerstack[0].layer->idx;  in ovl_connect_layer()
122 	/* Find the topmost origin layer connectable ancestor of @dentry */  in ovl_connect_layer()
132 		 * If @parent is not origin layer connectable, then copy up  in ovl_connect_layer()
133 		 * @next which is origin layer connectable and we are done.  in ovl_connect_layer()
197 	 * Root is never indexed, so if there's an upper layer, encode upper for  in ovl_check_encode_origin()
207 	 * ovl_connect_layer() will try to make origin's layer "connected" by  in ovl_check_encode_origin()
333 			oe->lowerstack->layer = lowerpath->layer;  in ovl_obtain_alias()
348 /* Get the upper or lower dentry in stach whose on layer @idx */
358 		if (oe->lowerstack[i].layer->idx == idx)  in ovl_dentry_real_at()
367  * dentry is @real. If @real is on upper layer, we lookup a child overlay
373 					  struct ovl_layer *layer)  in ovl_lookup_real_one()  argument
390 	if (ovl_dentry_real_at(connected, layer->idx) != parent)  in ovl_lookup_real_one()
395 	 * from racing with underlying layer rename. In this case, we don't  in ovl_lookup_real_one()
408 	} else if (ovl_dentry_real_at(this, layer->idx) != real) {  in ovl_lookup_real_one()
421 …pr_warn_ratelimited("overlayfs: failed to lookup one by real (%pd2, layer=%d, connected=%pd2, err=…  in ovl_lookup_real_one()
422 			    real, layer->idx, connected, err);  in ovl_lookup_real_one()
429 				      struct ovl_layer *layer);
436 					    struct ovl_layer *layer)  in ovl_lookup_real_inode()  argument
448 	inode = ovl_lookup_inode(sb, real, !layer->idx);  in ovl_lookup_real_inode()
460 	if (!this && layer->idx && ofs->indexdir && !WARN_ON(!d_is_dir(real))) {  in ovl_lookup_real_inode()
475 		 * ovl_lookup_real() in lower layer may call recursively once to  in ovl_lookup_real_inode()
476 		 * ovl_lookup_real() in upper layer. The first level call walks  in ovl_lookup_real_inode()
488 	if (ovl_dentry_real_at(this, layer->idx) != real) {  in ovl_lookup_real_inode()
502 					       struct ovl_layer *layer)  in ovl_lookup_real_ancestor()  argument
507 	if (real == layer->mnt->mnt_root)  in ovl_lookup_real_ancestor()
519 		ancestor = ovl_lookup_real_inode(sb, next, layer);  in ovl_lookup_real_ancestor()
523 		if (parent == layer->mnt->mnt_root) {  in ovl_lookup_real_ancestor()
529 		 * If @real has been moved out of the layer root directory,  in ovl_lookup_real_ancestor()
550  * If @real is on upper layer, we lookup a child overlay dentry with the same
555 				      struct ovl_layer *layer)  in ovl_lookup_real()  argument
560 	connected = ovl_lookup_real_ancestor(sb, real, layer);  in ovl_lookup_real()
568 								   layer->idx);  in ovl_lookup_real()
583 			 * we will not find 'real_connected' and hit the layer  in ovl_lookup_real()
589 			if (parent == layer->mnt->mnt_root) {  in ovl_lookup_real()
596 			 * If real file has been moved out of the layer root  in ovl_lookup_real()
611 			this = ovl_lookup_real_one(connected, next, layer);  in ovl_lookup_real()
627 								layer);  in ovl_lookup_real()
646 …pr_warn_ratelimited("overlayfs: failed to lookup by real (%pd2, layer=%d, connected=%pd2, err=%i)\…  in ovl_lookup_real()
647 			    real, layer->idx, connected, err);  in ovl_lookup_real()
662 	struct ovl_layer *layer = upper ? &upper_layer : lowerpath->layer;  in ovl_get_dentry()  local
680 	return ovl_lookup_real(sb, real, layer);  in ovl_get_dentry()
756 	/* Find origin.dentry again with ovl_acceptable() layer check */  in ovl_lower_fh_to_d()