1 // SPDX-License-Identifier: GPL-2.0-only
7  * Copyright (C) 2017-2018 CTERA Networks. All Rights Reserved.
41  * Before encoding a non-upper directory file handle from real layer N, we need
43  * lower decoded dentry. This is done by following the overlay ancestry up to a
53  * copied up and renamed, upper dir /a will be indexed by lower dir /a from
56  * dentry from the connected lower dentry /a/b/c.
61  * and when the time comes to decode the file handle from lower dentry /a/b/c,
66  * entry /a in the lower layers above layer N and find the indexed dir /a from
68  * will need to verify there are no redirects in lower layers above N. In the
82 	if (dentry == dentry->d_sb->s_root)  in ovl_connectable_layer()
87 	 * lower layer  in ovl_connectable_layer()
93 	/* We can get upper/overlay path from indexed/lower dentry */  in ovl_connectable_layer()
94 	return ovl_lowerstack(oe)->layer->idx;  in ovl_connectable_layer()
99  * have the same uppermost lower layer as the origin's layer. We may need to
112 	if (WARN_ON(dentry == dentry->d_sb->s_root) ||  in ovl_connect_layer()
114 		return -EIO;  in ovl_connect_layer()
116 	origin_layer = ovl_lowerstack(oe)->layer->idx;  in ovl_connect_layer()
125 			err = -EIO;  in ovl_connect_layer()
159  * encoding also after copy up. If non-pure upper is not indexed, then it was
160  * copied up before NFS export was enabled. In that case we don't need to worry
162  * file handle. Overlay root dentry is a private case of non-indexed upper.
168  * --------------------------------
170  *  Non-indexed upper	| U
172  *  Non-upper		| L (*)
175  * L = lower file handle
177  * (*) Decoding a connected overlay dir from real lower dentry is not always
178  * possible when there are redirects in lower layers and non-indexed merge dirs.
179  * To mitigate those case, we may copy up the lower dir ancestor before encode
180  * of a decodable file handle for non-upper dir.
182  * Return 0 for upper file handle, > 0 for lower file handle or < 0 on error.
186 	struct ovl_fs *ofs = OVL_FS(dentry->d_sb);  in ovl_check_encode_origin()
187 	bool decodable = ofs->config.nfs_export;  in ovl_check_encode_origin()
189 	/* Lower file handle for non-upper non-decodable */  in ovl_check_encode_origin()
201 	if (dentry == dentry->d_sb->s_root)  in ovl_check_encode_origin()
205 	 * Upper decodable file handle for non-indexed upper.  in ovl_check_encode_origin()
213 	 * lower dir or under a non-indexed upper is not always possible.  in ovl_check_encode_origin()
220 	/* Lower file handle for indexed and non-upper dir/non-dir */  in ovl_check_encode_origin()
232 	 * Check if we should encode a lower or upper file handle and maybe  in ovl_dentry_to_fid()
233 	 * copy up an ancestor to make lower file handle connectable.  in ovl_dentry_to_fid()
239 	/* Encode an upper or lower file handle */  in ovl_dentry_to_fid()
263 	struct ovl_fs *ofs = OVL_FS(inode->i_sb);  in ovl_encode_fh()
295 	struct dentry *lower = lowerpath ? lowerpath->dentry : NULL;  in ovl_obtain_alias()  local
305 	if (d_is_dir(upper ?: lower))  in ovl_obtain_alias()
306 		return ERR_PTR(-EIO);  in ovl_obtain_alias()
308 	oe = ovl_alloc_entry(!!lower);  in ovl_obtain_alias()
310 		return ERR_PTR(-ENOMEM);  in ovl_obtain_alias()
313 	if (lower) {  in ovl_obtain_alias()
314 		ovl_lowerstack(oe)->dentry = dget(lower);  in ovl_obtain_alias()
315 		ovl_lowerstack(oe)->layer = lowerpath->layer;  in ovl_obtain_alias()
332 	dentry = d_alloc_anon(inode->i_sb);  in ovl_obtain_alias()
345 	dentry = ERR_PTR(-ENOMEM);  in ovl_obtain_alias()
351 /* Get the upper or lower dentry in stack whose on layer @idx */
362 		if (lowerstack[i].layer->idx == idx)  in ovl_dentry_real_at()
388 	 * connected overlay dir, we return -ECHILD and restart the lookup of  in ovl_lookup_real_one()
392 	err = -ECHILD;  in ovl_lookup_real_one()
394 	if (ovl_dentry_real_at(connected, layer->idx) != parent)  in ovl_lookup_real_one()
399 	 * from racing with underlying layer rename. In this case, we don't  in ovl_lookup_real_one()
406 	 * permission checking altogether, but for now just use non-idmap  in ovl_lookup_real_one()
414 	} else if (!this || !this->d_inode) {  in ovl_lookup_real_one()
416 		err = -ENOENT;  in ovl_lookup_real_one()
418 	} else if (ovl_dentry_real_at(this, layer->idx) != real) {  in ovl_lookup_real_one()
420 		err = -ESTALE;  in ovl_lookup_real_one()
431 			    real, layer->idx, connected, err);  in ovl_lookup_real_one()
456 	inode = ovl_lookup_inode(sb, real, !layer->idx);  in ovl_lookup_real_inode()
465 	 * For decoded lower dir file handle, lookup index by origin to check  in ovl_lookup_real_inode()
466 	 * if lower dir was copied up and and/or removed.  in ovl_lookup_real_inode()
468 	if (!this && layer->idx && ofs->indexdir && !WARN_ON(!d_is_dir(real))) {  in ovl_lookup_real_inode()
483 		 * ovl_lookup_real() in lower layer may call recursively once to  in ovl_lookup_real_inode()
485 		 * back lower parents to the topmost indexed parent. The second  in ovl_lookup_real_inode()
489 		this = ovl_lookup_real(sb, upper, &ofs->layers[0]);  in ovl_lookup_real_inode()
496 	if (ovl_dentry_real_at(this, layer->idx) != real) {  in ovl_lookup_real_inode()
498 		this = ERR_PTR(-EIO);  in ovl_lookup_real_inode()
513 	struct dentry *ancestor = ERR_PTR(-EIO);  in ovl_lookup_real_ancestor()
515 	if (real == layer->mnt->mnt_root)  in ovl_lookup_real_ancestor()
516 		return dget(sb->s_root);  in ovl_lookup_real_ancestor()
531 		if (parent == layer->mnt->mnt_root) {  in ovl_lookup_real_ancestor()
532 			ancestor = dget(sb->s_root);  in ovl_lookup_real_ancestor()
539 		 * by legit overlay rename, so we return error in that case.  in ovl_lookup_real_ancestor()
542 			ancestor = ERR_PTR(-EXDEV);  in ovl_lookup_real_ancestor()
576 								   layer->idx);  in ovl_lookup_real()
592 			 * root. In that case, we need to restart connecting.  in ovl_lookup_real()
593 			 * This game can go on forever in the worst case. We  in ovl_lookup_real()
597 			if (parent == layer->mnt->mnt_root) {  in ovl_lookup_real()
599 				connected = dget(sb->s_root);  in ovl_lookup_real()
607 			 * return error in that case.  in ovl_lookup_real()
610 				err = -EXDEV;  in ovl_lookup_real()
626 			 * In this case, we need to restart the lookup from the  in ovl_lookup_real()
633 			if (err == -ECHILD) {  in ovl_lookup_real()
655 			    real, layer->idx, connected, err);  in ovl_lookup_real()
661  * Get an overlay dentry from upper/lower real dentries and index.
669 	const struct ovl_layer *layer = upper ? &ofs->layers[0] : lowerpath->layer;  in ovl_get_dentry()
670 	struct dentry *real = upper ?: (index ?: lowerpath->dentry);  in ovl_get_dentry()
673 	 * Obtain a disconnected overlay dentry from a non-dir real dentry  in ovl_get_dentry()
680 	if ((real->d_flags & DCACHE_DISCONNECTED) || d_unhashed(real))  in ovl_get_dentry()
681 		return ERR_PTR(-ENOENT);  in ovl_get_dentry()
698 		return ERR_PTR(-EACCES);  in ovl_upper_fh_to_d()
727 	    !(origin.dentry->d_flags & DCACHE_DISCONNECTED)) {  in ovl_lower_fh_to_d()
741 	if (ofs->indexdir) {  in ovl_lower_fh_to_d()
777 	/* Get a connected non-upper dir or disconnected non-dir */  in ovl_lower_fh_to_d()
794 	/* If on-wire inner fid is aligned - nothing to do */  in ovl_fid_to_fh()
799 		return ERR_PTR(-EINVAL);  in ovl_fid_to_fh()
802 		return ERR_PTR(-EINVAL);  in ovl_fid_to_fh()
806 		return ERR_PTR(-ENOMEM);  in ovl_fid_to_fh()
809 	memcpy(fh->buf, fid, buflen - OVL_FH_WIRE_OFFSET);  in ovl_fid_to_fh()
831 	flags = fh->fb.flags;  in ovl_fh_to_dentry()
836 	if (IS_ERR(dentry) && err != -ESTALE)  in ovl_fh_to_dentry()
840 	/* We may have needed to re-align OVL_FILEID_V0 */  in ovl_fh_to_dentry()
857 	return ERR_PTR(-EACCES);  in ovl_fh_to_parent()
868 	return -EIO;  in ovl_get_name()
878 	return ERR_PTR(-EIO);  in ovl_get_parent()
889 /* encode_fh() encodes non-decodable file handles with nfs_export=off */