1 // SPDX-License-Identifier: GPL-2.0-only
7  * Copyright (C) 2017-2018 CTERA Networks. All Rights Reserved.
36  * Before encoding a non-upper directory file handle from real layer N, we need
37  * to check if it will be possible to reconnect an overlay dentry from the real
53  * To avoid this problem on decode time, we need to copy up an ancestor of
54  * /a/b/c, which is "layer 2 connectable", on encode time. That ancestor is
56  * and when the time comes to decode the file handle from lower dentry /a/b/c,
77 	if (dentry == dentry->d_sb->s_root)  in ovl_connectable_layer()
89 	return ovl_lowerstack(oe)->layer->idx;  in ovl_connectable_layer()
107 	if (WARN_ON(dentry == dentry->d_sb->s_root) ||  in ovl_connect_layer()
109 		return -EIO;  in ovl_connect_layer()
111 	origin_layer = ovl_lowerstack(oe)->layer->idx;  in ovl_connect_layer()
120 			err = -EIO;  in ovl_connect_layer()
154  * encoding also after copy up. If non-pure upper is not indexed, then it was
157  * file handle. Overlay root dentry is a private case of non-indexed upper.
163  * --------------------------------
165  *  Non-indexed upper	| U
167  *  Non-upper		| L (*)
172  * (*) Decoding a connected overlay dir from real lower dentry is not always
173  * possible when there are redirects in lower layers and non-indexed merge dirs.
175  * of a decodable file handle for non-upper dir.
181 	struct ovl_fs *ofs = OVL_FS(dentry->d_sb);  in ovl_check_encode_origin()
182 	bool decodable = ofs->config.nfs_export;  in ovl_check_encode_origin()
188 	/* Lower file handle for non-upper non-decodable */  in ovl_check_encode_origin()
200 	if (dentry == dentry->d_sb->s_root)  in ovl_check_encode_origin()
204 	 * Upper decodable file handle for non-indexed upper.  in ovl_check_encode_origin()
212 	 * lower dir or under a non-indexed upper is not always possible.  in ovl_check_encode_origin()
219 	/* Lower file handle for indexed and non-upper dir/non-dir */  in ovl_check_encode_origin()
262 	struct ovl_fs *ofs = OVL_FS(inode->i_sb);  in ovl_encode_fh()
287  * Find or instantiate an overlay dentry from real dentries and index.
294 	struct dentry *lower = lowerpath ? lowerpath->dentry : NULL;  in ovl_obtain_alias()
304 		return ERR_PTR(-EIO);  in ovl_obtain_alias()
308 		return ERR_PTR(-ENOMEM);  in ovl_obtain_alias()
312 		ovl_lowerstack(oe)->dentry = dget(lower);  in ovl_obtain_alias()
313 		ovl_lowerstack(oe)->layer = lowerpath->layer;  in ovl_obtain_alias()
340 		if (lowerstack[i].layer->idx == idx)  in ovl_dentry_real_at()
348  * Lookup a child overlay dentry to get a connected overlay dentry whose real
349  * dentry is @real. If @real is on upper layer, we lookup a child overlay
350  * dentry with the same name as the real dentry. Otherwise, we need to consult
354 					  struct dentry *real,  in ovl_lookup_real_one()  argument
363 	 * Lookup child overlay dentry by real name. The dir mutex protects us  in ovl_lookup_real_one()
365 	 * real has already been moved to a parent that is not under the  in ovl_lookup_real_one()
366 	 * connected overlay dir, we return -ECHILD and restart the lookup of  in ovl_lookup_real_one()
367 	 * connected real path from the top.  in ovl_lookup_real_one()
370 	err = -ECHILD;  in ovl_lookup_real_one()
371 	parent = dget_parent(real);  in ovl_lookup_real_one()
372 	if (ovl_dentry_real_at(connected, layer->idx) != parent)  in ovl_lookup_real_one()
376 	 * We also need to take a snapshot of real dentry name to protect us  in ovl_lookup_real_one()
379 	 * pointer because we hold no lock on the real dentry.  in ovl_lookup_real_one()
381 	take_dentry_name_snapshot(&name, real);  in ovl_lookup_real_one()
384 	 * permission checking altogether, but for now just use non-idmap  in ovl_lookup_real_one()
392 	} else if (!this || !this->d_inode) {  in ovl_lookup_real_one()
394 		err = -ENOENT;  in ovl_lookup_real_one()
396 	} else if (ovl_dentry_real_at(this, layer->idx) != real) {  in ovl_lookup_real_one()
398 		err = -ESTALE;  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()
415 				      struct dentry *real,
419  * Lookup an indexed or hashed overlay dentry by real inode.
422 					    struct dentry *real,  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()
447 		index = ovl_lookup_index(ofs, NULL, real, false);  in ovl_lookup_real_inode()
467 		this = ovl_lookup_real(sb, upper, &ofs->layers[0]);  in ovl_lookup_real_inode()
474 	if (ovl_dentry_real_at(this, layer->idx) != real) {  in ovl_lookup_real_inode()
476 		this = ERR_PTR(-EIO);  in ovl_lookup_real_inode()
483  * Lookup an indexed or hashed overlay dentry, whose real dentry is an
484  * ancestor of @real.
487 					       struct dentry *real,  in ovl_lookup_real_ancestor()  argument
491 	struct dentry *ancestor = ERR_PTR(-EIO);  in ovl_lookup_real_ancestor()
493 	if (real == layer->mnt->mnt_root)  in ovl_lookup_real_ancestor()
494 		return dget(sb->s_root);  in ovl_lookup_real_ancestor()
497 	next = dget(real);  in ovl_lookup_real_ancestor()
503 		 * cache or in index by real inode.  in ovl_lookup_real_ancestor()
509 		if (parent == layer->mnt->mnt_root) {  in ovl_lookup_real_ancestor()
510 			ancestor = dget(sb->s_root);  in ovl_lookup_real_ancestor()
515 		 * If @real has been moved out of the layer root directory,  in ovl_lookup_real_ancestor()
516 		 * we will eventully hit the real fs root. This cannot happen  in ovl_lookup_real_ancestor()
520 			ancestor = ERR_PTR(-EXDEV);  in ovl_lookup_real_ancestor()
535  * Lookup a connected overlay dentry whose real dentry is @real.
536  * If @real is on upper layer, we lookup a child overlay dentry with the same
537  * path the real dentry. Otherwise, we need to consult index for lookup.
540 				      struct dentry *real,  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()
556 		if (real_connected == real)  in ovl_lookup_real()
560 		next = dget(real);  in ovl_lookup_real()
568 			 * If real has been moved out of 'real_connected',  in ovl_lookup_real()
575 			if (parent == layer->mnt->mnt_root) {  in ovl_lookup_real()
577 				connected = dget(sb->s_root);  in ovl_lookup_real()
582 			 * If real file has been moved out of the layer root  in ovl_lookup_real()
583 			 * directory, we will eventully hit the real fs root.  in ovl_lookup_real()
588 				err = -EXDEV;  in ovl_lookup_real()
606 			 * still an ancestor of 'real'. There is a good chance  in ovl_lookup_real()
611 			if (err == -ECHILD) {  in ovl_lookup_real()
612 				this = ovl_lookup_real_ancestor(sb, real,  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()
639  * Get an overlay dentry from upper/lower real dentries and index.
647 	const struct ovl_layer *layer = upper ? &ofs->layers[0] : lowerpath->layer;  in ovl_get_dentry()
648 	struct dentry *real = upper ?: (index ?: lowerpath->dentry);  in ovl_get_dentry()  local
651 	 * Obtain a disconnected overlay dentry from a non-dir real dentry  in ovl_get_dentry()
654 	if (!d_is_dir(real))  in ovl_get_dentry()
658 	if ((real->d_flags & DCACHE_DISCONNECTED) || d_unhashed(real))  in ovl_get_dentry()
659 		return ERR_PTR(-ENOENT);  in ovl_get_dentry()
662 	 * If real dentry is connected and hashed, get a connected overlay  in ovl_get_dentry()
663 	 * dentry whose real dentry is @real.  in ovl_get_dentry()
665 	return ovl_lookup_real(sb, real, layer);  in ovl_get_dentry()
676 		return ERR_PTR(-EACCES);  in ovl_upper_fh_to_d()
705 	    !(origin.dentry->d_flags & DCACHE_DISCONNECTED)) {  in ovl_lower_fh_to_d()
755 	/* Get a connected non-upper dir or disconnected non-dir */  in ovl_lower_fh_to_d()
772 	/* If on-wire inner fid is aligned - nothing to do */  in ovl_fid_to_fh()
777 		return ERR_PTR(-EINVAL);  in ovl_fid_to_fh()
780 		return ERR_PTR(-EINVAL);  in ovl_fid_to_fh()
784 		return ERR_PTR(-ENOMEM);  in ovl_fid_to_fh()
787 	memcpy(fh->buf, fid, buflen - OVL_FH_WIRE_OFFSET);  in ovl_fid_to_fh()
809 	flags = fh->fb.flags;  in ovl_fh_to_dentry()
814 	if (IS_ERR(dentry) && err != -ESTALE)  in ovl_fh_to_dentry()
818 	/* We may have needed to re-align OVL_FILEID_V0 */  in ovl_fh_to_dentry()
835 	return ERR_PTR(-EACCES);  in ovl_fh_to_parent()
846 	return -EIO;  in ovl_get_name()
856 	return ERR_PTR(-EIO);  in ovl_get_parent()
867 /* encode_fh() encodes non-decodable file handles with nfs_export=off */