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()
83 		return oe->numlower;  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 oe->lowerstack[0].layer->idx;  in ovl_connectable_layer()
99  * have the same uppermost lower layer as the origin's layer. We may need to
111 	if (WARN_ON(dentry == dentry->d_sb->s_root) ||  in ovl_connect_layer()
113 		return -EIO;  in ovl_connect_layer()
115 	origin_layer = OVL_E(dentry)->lowerstack[0].layer->idx;  in ovl_connect_layer()
124 			err = -EIO;  in ovl_connect_layer()
158  * encoding also after copy up. If non-pure upper is not indexed, then it was
159  * copied up before NFS export was enabled. In that case we don't need to worry
161  * file handle. Overlay root dentry is a private case of non-indexed upper.
167  * --------------------------------
169  *  Non-indexed upper	| U
171  *  Non-upper		| L (*)
174  * L = lower file handle
176  * (*) Connecting an overlay dir from real lower dentry is not always
177  * possible when there are redirects in lower layers and non-indexed merge dirs.
178  * To mitigate those case, we may copy up the lower dir ancestor before encode
179  * a lower dir file handle.
181  * Return 0 for upper file handle, > 0 for lower file handle or < 0 on error.
185 	struct ovl_fs *ofs = dentry->d_sb->s_fs_info;  in ovl_check_encode_origin()
192 	 * Upper file handle for non-indexed upper.  in ovl_check_encode_origin()
203 	 * lower dir or under a non-indexed upper is not always possible.  in ovl_check_encode_origin()
210 	/* Lower file handle for indexed and non-upper dir/non-dir */  in ovl_check_encode_origin()
221 	 * Check if we should encode a lower or upper file handle and maybe  in ovl_dentry_to_fid()
222 	 * copy up an ancestor to make lower file handle connectable.  in ovl_dentry_to_fid()
228 	/* Encode an upper or lower file handle */  in ovl_dentry_to_fid()
283 	struct dentry *lower = lowerpath ? lowerpath->dentry : NULL;  in ovl_obtain_alias()  local
291 		.numlower = !!lower  in ovl_obtain_alias()
295 	if (d_is_dir(upper ?: lower))  in ovl_obtain_alias()
296 		return ERR_PTR(-EIO);  in ovl_obtain_alias()
312 	dentry = d_alloc_anon(inode->i_sb);  in ovl_obtain_alias()
315 	oe = ovl_alloc_entry(lower ? 1 : 0);  in ovl_obtain_alias()
319 	if (lower) {  in ovl_obtain_alias()
320 		oe->lowerstack->dentry = dget(lower);  in ovl_obtain_alias()
321 		oe->lowerstack->layer = lowerpath->layer;  in ovl_obtain_alias()
323 	dentry->d_fsdata = oe;  in ovl_obtain_alias()
333 	dentry = ERR_PTR(-ENOMEM);  in ovl_obtain_alias()
339 /* Get the upper or lower dentry in stach whose on layer @idx */
342 	struct ovl_entry *oe = dentry->d_fsdata;  in ovl_dentry_real_at()
348 	for (i = 0; i < oe->numlower; i++) {  in ovl_dentry_real_at()
349 		if (oe->lowerstack[i].layer->idx == idx)  in ovl_dentry_real_at()
350 			return oe->lowerstack[i].dentry;  in ovl_dentry_real_at()
375 	 * connected overlay dir, we return -ECHILD and restart the lookup of  in ovl_lookup_real_one()
379 	err = -ECHILD;  in ovl_lookup_real_one()
381 	if (ovl_dentry_real_at(connected, layer->idx) != parent)  in ovl_lookup_real_one()
386 	 * from racing with underlying layer rename. In this case, we don't  in ovl_lookup_real_one()
396 	} else if (!this || !this->d_inode) {  in ovl_lookup_real_one()
398 		err = -ENOENT;  in ovl_lookup_real_one()
400 	} else if (ovl_dentry_real_at(this, layer->idx) != real) {  in ovl_lookup_real_one()
402 		err = -ESTALE;  in ovl_lookup_real_one()
413 			    real, layer->idx, connected, err);  in ovl_lookup_real_one()
429 	struct ovl_fs *ofs = sb->s_fs_info;  in ovl_lookup_real_inode()
438 	inode = ovl_lookup_inode(sb, real, !layer->idx);  in ovl_lookup_real_inode()
447 	 * For decoded lower dir file handle, lookup index by origin to check  in ovl_lookup_real_inode()
448 	 * if lower dir was copied up and and/or removed.  in ovl_lookup_real_inode()
450 	if (!this && layer->idx && ofs->indexdir && !WARN_ON(!d_is_dir(real))) {  in ovl_lookup_real_inode()
465 		 * ovl_lookup_real() in lower layer may call recursively once to  in ovl_lookup_real_inode()
467 		 * back lower parents to the topmost indexed parent. The second  in ovl_lookup_real_inode()
471 		this = ovl_lookup_real(sb, upper, &ofs->layers[0]);  in ovl_lookup_real_inode()
478 	if (ovl_dentry_real_at(this, layer->idx) != real) {  in ovl_lookup_real_inode()
480 		this = ERR_PTR(-EIO);  in ovl_lookup_real_inode()
495 	struct dentry *ancestor = ERR_PTR(-EIO);  in ovl_lookup_real_ancestor()
497 	if (real == layer->mnt->mnt_root)  in ovl_lookup_real_ancestor()
498 		return dget(sb->s_root);  in ovl_lookup_real_ancestor()
513 		if (parent == layer->mnt->mnt_root) {  in ovl_lookup_real_ancestor()
514 			ancestor = dget(sb->s_root);  in ovl_lookup_real_ancestor()
521 		 * by legit overlay rename, so we return error in that case.  in ovl_lookup_real_ancestor()
524 			ancestor = ERR_PTR(-EXDEV);  in ovl_lookup_real_ancestor()
558 								   layer->idx);  in ovl_lookup_real()
574 			 * root. In that case, we need to restart connecting.  in ovl_lookup_real()
575 			 * This game can go on forever in the worst case. We  in ovl_lookup_real()
579 			if (parent == layer->mnt->mnt_root) {  in ovl_lookup_real()
581 				connected = dget(sb->s_root);  in ovl_lookup_real()
589 			 * return error in that case.  in ovl_lookup_real()
592 				err = -EXDEV;  in ovl_lookup_real()
608 			 * In this case, we need to restart the lookup from the  in ovl_lookup_real()
615 			if (err == -ECHILD) {  in ovl_lookup_real()
637 			    real, layer->idx, connected, err);  in ovl_lookup_real()
643  * Get an overlay dentry from upper/lower real dentries and index.
650 	struct ovl_fs *ofs = sb->s_fs_info;  in ovl_get_dentry()
651 	const struct ovl_layer *layer = upper ? &ofs->layers[0] : lowerpath->layer;  in ovl_get_dentry()
652 	struct dentry *real = upper ?: (index ?: lowerpath->dentry);  in ovl_get_dentry()
655 	 * Obtain a disconnected overlay dentry from a non-dir real dentry  in ovl_get_dentry()
662 	if ((real->d_flags & DCACHE_DISCONNECTED) || d_unhashed(real))  in ovl_get_dentry()
663 		return ERR_PTR(-ENOENT);  in ovl_get_dentry()
675 	struct ovl_fs *ofs = sb->s_fs_info;  in ovl_upper_fh_to_d()
680 		return ERR_PTR(-EACCES);  in ovl_upper_fh_to_d()
695 	struct ovl_fs *ofs = sb->s_fs_info;  in ovl_lower_fh_to_d()
709 	    !(origin.dentry->d_flags & DCACHE_DISCONNECTED)) {  in ovl_lower_fh_to_d()
723 	if (ofs->indexdir) {  in ovl_lower_fh_to_d()
759 	/* Get a connected non-upper dir or disconnected non-dir */  in ovl_lower_fh_to_d()
776 	/* If on-wire inner fid is aligned - nothing to do */  in ovl_fid_to_fh()
781 		return ERR_PTR(-EINVAL);  in ovl_fid_to_fh()
784 		return ERR_PTR(-EINVAL);  in ovl_fid_to_fh()
788 		return ERR_PTR(-ENOMEM);  in ovl_fid_to_fh()
791 	memcpy(&fh->fb, fid, buflen - OVL_FH_WIRE_OFFSET);  in ovl_fid_to_fh()
813 	flags = fh->fb.flags;  in ovl_fh_to_dentry()
818 	if (IS_ERR(dentry) && err != -ESTALE)  in ovl_fh_to_dentry()
822 	/* We may have needed to re-align OVL_FILEID_V0 */  in ovl_fh_to_dentry()
839 	return ERR_PTR(-EACCES);  in ovl_fh_to_parent()
850 	return -EIO;  in ovl_get_name()
860 	return ERR_PTR(-EIO);  in ovl_get_parent()