1// SPDX-License-Identifier: GPL-2.0
  2
  3#include <linux/fs.h>
  4#include <linux/types.h>
  5#include "ctree.h"
  6#include "disk-io.h"
  7#include "btrfs_inode.h"
  8#include "export.h"
  9#include "accessors.h"
 10#include "super.h"
 11
 12#define BTRFS_FID_SIZE_NON_CONNECTABLE (offsetof(struct btrfs_fid, \
 13						 parent_objectid) / 4)
 14#define BTRFS_FID_SIZE_CONNECTABLE (offsetof(struct btrfs_fid, \
 15					     parent_root_objectid) / 4)
 16#define BTRFS_FID_SIZE_CONNECTABLE_ROOT (sizeof(struct btrfs_fid) / 4)
 17
 18static int btrfs_encode_fh(struct inode *inode, u32 *fh, int *max_len,
 19			   struct inode *parent)
 20{
 21	struct btrfs_fid *fid = (struct btrfs_fid *)fh;
 22	int len = *max_len;
 23	int type;
 24
 25	if (parent && (len < BTRFS_FID_SIZE_CONNECTABLE)) {
 26		*max_len = BTRFS_FID_SIZE_CONNECTABLE;
 27		return FILEID_INVALID;
 28	} else if (len < BTRFS_FID_SIZE_NON_CONNECTABLE) {
 29		*max_len = BTRFS_FID_SIZE_NON_CONNECTABLE;
 30		return FILEID_INVALID;
 31	}
 32
 33	len  = BTRFS_FID_SIZE_NON_CONNECTABLE;
 34	type = FILEID_BTRFS_WITHOUT_PARENT;
 35
 36	fid->objectid = btrfs_ino(BTRFS_I(inode));
 37	fid->root_objectid = btrfs_root_id(BTRFS_I(inode)->root);
 38	fid->gen = inode->i_generation;
 39
 40	if (parent) {
 41		u64 parent_root_id;
 42
 43		fid->parent_objectid = btrfs_ino(BTRFS_I(parent));
 44		fid->parent_gen = parent->i_generation;
 45		parent_root_id = btrfs_root_id(BTRFS_I(parent)->root);
 46
 47		if (parent_root_id != fid->root_objectid) {
 48			fid->parent_root_objectid = parent_root_id;
 49			len = BTRFS_FID_SIZE_CONNECTABLE_ROOT;
 50			type = FILEID_BTRFS_WITH_PARENT_ROOT;
 51		} else {
 52			len = BTRFS_FID_SIZE_CONNECTABLE;
 53			type = FILEID_BTRFS_WITH_PARENT;
 54		}
 55	}
 56
 57	*max_len = len;
 58	return type;
 59}
 60
 61/*
 62 * Read dentry of inode with @objectid from filesystem root @root_objectid.
 63 *
 64 * @sb:             the filesystem super block
 65 * @objectid:       inode objectid
 66 * @root_objectid:  object id of the subvolume root where to look up the inode
 67 * @generation:     optional, if not zero, verify that the found inode
 68 *                  generation matches
 69 *
 70 * Return dentry alias for the inode, otherwise an error. In case the
 71 * generation does not match return ESTALE.
 72 */
 73struct dentry *btrfs_get_dentry(struct super_block *sb, u64 objectid,
 74				u64 root_objectid, u64 generation)
 75{
 76	struct btrfs_fs_info *fs_info = btrfs_sb(sb);
 77	struct btrfs_root *root;
 78	struct inode *inode;
 79
 80	if (objectid < BTRFS_FIRST_FREE_OBJECTID)
 81		return ERR_PTR(-ESTALE);
 82
 83	root = btrfs_get_fs_root(fs_info, root_objectid, true);
 84	if (IS_ERR(root))
 85		return ERR_CAST(root);
 86
 87	inode = btrfs_iget(objectid, root);
 88	btrfs_put_root(root);
 89	if (IS_ERR(inode))
 90		return ERR_CAST(inode);
 91
 92	if (generation != 0 && generation != inode->i_generation) {
 93		iput(inode);
 94		return ERR_PTR(-ESTALE);
 95	}
 96
 97	return d_obtain_alias(inode);
 98}
 99
100static struct dentry *btrfs_fh_to_parent(struct super_block *sb, struct fid *fh,
101					 int fh_len, int fh_type)
102{
103	struct btrfs_fid *fid = (struct btrfs_fid *) fh;
104	u64 objectid, root_objectid;
105	u32 generation;
106
107	if (fh_type == FILEID_BTRFS_WITH_PARENT) {
108		if (fh_len <  BTRFS_FID_SIZE_CONNECTABLE)
109			return NULL;
110		root_objectid = fid->root_objectid;
111	} else if (fh_type == FILEID_BTRFS_WITH_PARENT_ROOT) {
112		if (fh_len < BTRFS_FID_SIZE_CONNECTABLE_ROOT)
113			return NULL;
114		root_objectid = fid->parent_root_objectid;
115	} else
116		return NULL;
117
118	objectid = fid->parent_objectid;
119	generation = fid->parent_gen;
120
121	return btrfs_get_dentry(sb, objectid, root_objectid, generation);
122}
123
124static struct dentry *btrfs_fh_to_dentry(struct super_block *sb, struct fid *fh,
125					 int fh_len, int fh_type)
126{
127	struct btrfs_fid *fid = (struct btrfs_fid *) fh;
128	u64 objectid, root_objectid;
129	u32 generation;
130
131	if ((fh_type != FILEID_BTRFS_WITH_PARENT ||
132	     fh_len < BTRFS_FID_SIZE_CONNECTABLE) &&
133	    (fh_type != FILEID_BTRFS_WITH_PARENT_ROOT ||
134	     fh_len < BTRFS_FID_SIZE_CONNECTABLE_ROOT) &&
135	    (fh_type != FILEID_BTRFS_WITHOUT_PARENT ||
136	     fh_len < BTRFS_FID_SIZE_NON_CONNECTABLE))
137		return NULL;
138
139	objectid = fid->objectid;
140	root_objectid = fid->root_objectid;
141	generation = fid->gen;
142
143	return btrfs_get_dentry(sb, objectid, root_objectid, generation);
144}
145
146struct dentry *btrfs_get_parent(struct dentry *child)
147{
148	struct inode *dir = d_inode(child);
149	struct btrfs_fs_info *fs_info = btrfs_sb(dir->i_sb);
150	struct btrfs_root *root = BTRFS_I(dir)->root;
151	struct btrfs_path *path;
152	struct extent_buffer *leaf;
153	struct btrfs_root_ref *ref;
154	struct btrfs_key key;
155	struct btrfs_key found_key;
156	int ret;
157
158	path = btrfs_alloc_path();
159	if (!path)
160		return ERR_PTR(-ENOMEM);
161
162	if (btrfs_ino(BTRFS_I(dir)) == BTRFS_FIRST_FREE_OBJECTID) {
163		key.objectid = btrfs_root_id(root);
164		key.type = BTRFS_ROOT_BACKREF_KEY;
165		key.offset = (u64)-1;
166		root = fs_info->tree_root;
167	} else {
168		key.objectid = btrfs_ino(BTRFS_I(dir));
169		key.type = BTRFS_INODE_REF_KEY;
170		key.offset = (u64)-1;
171	}
172
173	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
174	if (ret < 0)
175		goto fail;
176	if (ret == 0) {
177		/*
178		 * Key with offset of -1 found, there would have to exist an
179		 * inode with such number or a root with such id.
180		 */
181		ret = -EUCLEAN;
182		goto fail;
183	}
184
185	if (path->slots[0] == 0) {
186		ret = -ENOENT;
187		goto fail;
188	}
189
190	path->slots[0]--;
191	leaf = path->nodes[0];
192
193	btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
194	if (found_key.objectid != key.objectid || found_key.type != key.type) {
195		ret = -ENOENT;
196		goto fail;
197	}
198
199	if (found_key.type == BTRFS_ROOT_BACKREF_KEY) {
200		ref = btrfs_item_ptr(leaf, path->slots[0],
201				     struct btrfs_root_ref);
202		key.objectid = btrfs_root_ref_dirid(leaf, ref);
203	} else {
204		key.objectid = found_key.offset;
205	}
206	btrfs_free_path(path);
207
208	if (found_key.type == BTRFS_ROOT_BACKREF_KEY) {
209		return btrfs_get_dentry(fs_info->sb, key.objectid,
210					found_key.offset, 0);
211	}
212
213	return d_obtain_alias(btrfs_iget(key.objectid, root));
214fail:
215	btrfs_free_path(path);
216	return ERR_PTR(ret);
217}
218
219static int btrfs_get_name(struct dentry *parent, char *name,
220			  struct dentry *child)
221{
222	struct inode *inode = d_inode(child);
223	struct inode *dir = d_inode(parent);
224	struct btrfs_fs_info *fs_info = inode_to_fs_info(inode);
225	struct btrfs_path *path;
226	struct btrfs_root *root = BTRFS_I(dir)->root;
227	struct btrfs_inode_ref *iref;
228	struct btrfs_root_ref *rref;
229	struct extent_buffer *leaf;
230	unsigned long name_ptr;
231	struct btrfs_key key;
232	int name_len;
233	int ret;
234	u64 ino;
235
236	if (!S_ISDIR(dir->i_mode))
237		return -EINVAL;
238
239	ino = btrfs_ino(BTRFS_I(inode));
240
241	path = btrfs_alloc_path();
242	if (!path)
243		return -ENOMEM;
244
245	if (ino == BTRFS_FIRST_FREE_OBJECTID) {
246		key.objectid = btrfs_root_id(BTRFS_I(inode)->root);
247		key.type = BTRFS_ROOT_BACKREF_KEY;
248		key.offset = (u64)-1;
249		root = fs_info->tree_root;
250	} else {
251		key.objectid = ino;
252		key.offset = btrfs_ino(BTRFS_I(dir));
253		key.type = BTRFS_INODE_REF_KEY;
254	}
255
256	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
257	if (ret < 0) {
258		btrfs_free_path(path);
259		return ret;
260	} else if (ret > 0) {
261		if (ino == BTRFS_FIRST_FREE_OBJECTID) {
262			path->slots[0]--;
263		} else {
264			btrfs_free_path(path);
265			return -ENOENT;
266		}
267	}
268	leaf = path->nodes[0];
269
270	if (ino == BTRFS_FIRST_FREE_OBJECTID) {
271		rref = btrfs_item_ptr(leaf, path->slots[0],
272				     struct btrfs_root_ref);
273		name_ptr = (unsigned long)(rref + 1);
274		name_len = btrfs_root_ref_name_len(leaf, rref);
275	} else {
276		iref = btrfs_item_ptr(leaf, path->slots[0],
277				      struct btrfs_inode_ref);
278		name_ptr = (unsigned long)(iref + 1);
279		name_len = btrfs_inode_ref_name_len(leaf, iref);
280	}
281
282	read_extent_buffer(leaf, name, name_ptr, name_len);
283	btrfs_free_path(path);
284
285	/*
286	 * have to add the null termination to make sure that reconnect_path
287	 * gets the right len for strlen
288	 */
289	name[name_len] = '\0';
290
291	return 0;
292}
293
294const struct export_operations btrfs_export_ops = {
295	.encode_fh	= btrfs_encode_fh,
296	.fh_to_dentry	= btrfs_fh_to_dentry,
297	.fh_to_parent	= btrfs_fh_to_parent,
298	.get_parent	= btrfs_get_parent,
299	.get_name	= btrfs_get_name,
300};

  1// SPDX-License-Identifier: GPL-2.0
  2
  3#include <linux/fs.h>
  4#include <linux/types.h>
  5#include "ctree.h"
  6#include "disk-io.h"
  7#include "btrfs_inode.h"
  8#include "export.h"
  9#include "accessors.h"
 10#include "super.h"
 11
 12#define BTRFS_FID_SIZE_NON_CONNECTABLE (offsetof(struct btrfs_fid, \
 13						 parent_objectid) / 4)
 14#define BTRFS_FID_SIZE_CONNECTABLE (offsetof(struct btrfs_fid, \
 15					     parent_root_objectid) / 4)
 16#define BTRFS_FID_SIZE_CONNECTABLE_ROOT (sizeof(struct btrfs_fid) / 4)
 17
 18static int btrfs_encode_fh(struct inode *inode, u32 *fh, int *max_len,
 19			   struct inode *parent)
 20{
 21	struct btrfs_fid *fid = (struct btrfs_fid *)fh;
 22	int len = *max_len;
 23	int type;
 24
 25	if (parent && (len < BTRFS_FID_SIZE_CONNECTABLE)) {
 26		*max_len = BTRFS_FID_SIZE_CONNECTABLE;
 27		return FILEID_INVALID;
 28	} else if (len < BTRFS_FID_SIZE_NON_CONNECTABLE) {
 29		*max_len = BTRFS_FID_SIZE_NON_CONNECTABLE;
 30		return FILEID_INVALID;
 31	}
 32
 33	len  = BTRFS_FID_SIZE_NON_CONNECTABLE;
 34	type = FILEID_BTRFS_WITHOUT_PARENT;
 35
 36	fid->objectid = btrfs_ino(BTRFS_I(inode));
 37	fid->root_objectid = BTRFS_I(inode)->root->root_key.objectid;
 38	fid->gen = inode->i_generation;
 39
 40	if (parent) {
 41		u64 parent_root_id;
 42
 43		fid->parent_objectid = BTRFS_I(parent)->location.objectid;
 44		fid->parent_gen = parent->i_generation;
 45		parent_root_id = BTRFS_I(parent)->root->root_key.objectid;
 46
 47		if (parent_root_id != fid->root_objectid) {
 48			fid->parent_root_objectid = parent_root_id;
 49			len = BTRFS_FID_SIZE_CONNECTABLE_ROOT;
 50			type = FILEID_BTRFS_WITH_PARENT_ROOT;
 51		} else {
 52			len = BTRFS_FID_SIZE_CONNECTABLE;
 53			type = FILEID_BTRFS_WITH_PARENT;
 54		}
 55	}
 56
 57	*max_len = len;
 58	return type;
 59}
 60
 61/*
 62 * Read dentry of inode with @objectid from filesystem root @root_objectid.
 63 *
 64 * @sb:             the filesystem super block
 65 * @objectid:       inode objectid
 66 * @root_objectid:  object id of the subvolume root where to look up the inode
 67 * @generation:     optional, if not zero, verify that the found inode
 68 *                  generation matches
 69 *
 70 * Return dentry alias for the inode, otherwise an error. In case the
 71 * generation does not match return ESTALE.
 72 */
 73struct dentry *btrfs_get_dentry(struct super_block *sb, u64 objectid,
 74				u64 root_objectid, u64 generation)
 75{
 76	struct btrfs_fs_info *fs_info = btrfs_sb(sb);
 77	struct btrfs_root *root;
 78	struct inode *inode;
 79
 80	if (objectid < BTRFS_FIRST_FREE_OBJECTID)
 81		return ERR_PTR(-ESTALE);
 82
 83	root = btrfs_get_fs_root(fs_info, root_objectid, true);
 84	if (IS_ERR(root))
 85		return ERR_CAST(root);
 86
 87	inode = btrfs_iget(sb, objectid, root);
 88	btrfs_put_root(root);
 89	if (IS_ERR(inode))
 90		return ERR_CAST(inode);
 91
 92	if (generation != 0 && generation != inode->i_generation) {
 93		iput(inode);
 94		return ERR_PTR(-ESTALE);
 95	}
 96
 97	return d_obtain_alias(inode);
 98}
 99
100static struct dentry *btrfs_fh_to_parent(struct super_block *sb, struct fid *fh,
101					 int fh_len, int fh_type)
102{
103	struct btrfs_fid *fid = (struct btrfs_fid *) fh;
104	u64 objectid, root_objectid;
105	u32 generation;
106
107	if (fh_type == FILEID_BTRFS_WITH_PARENT) {
108		if (fh_len <  BTRFS_FID_SIZE_CONNECTABLE)
109			return NULL;
110		root_objectid = fid->root_objectid;
111	} else if (fh_type == FILEID_BTRFS_WITH_PARENT_ROOT) {
112		if (fh_len < BTRFS_FID_SIZE_CONNECTABLE_ROOT)
113			return NULL;
114		root_objectid = fid->parent_root_objectid;
115	} else
116		return NULL;
117
118	objectid = fid->parent_objectid;
119	generation = fid->parent_gen;
120
121	return btrfs_get_dentry(sb, objectid, root_objectid, generation);
122}
123
124static struct dentry *btrfs_fh_to_dentry(struct super_block *sb, struct fid *fh,
125					 int fh_len, int fh_type)
126{
127	struct btrfs_fid *fid = (struct btrfs_fid *) fh;
128	u64 objectid, root_objectid;
129	u32 generation;
130
131	if ((fh_type != FILEID_BTRFS_WITH_PARENT ||
132	     fh_len < BTRFS_FID_SIZE_CONNECTABLE) &&
133	    (fh_type != FILEID_BTRFS_WITH_PARENT_ROOT ||
134	     fh_len < BTRFS_FID_SIZE_CONNECTABLE_ROOT) &&
135	    (fh_type != FILEID_BTRFS_WITHOUT_PARENT ||
136	     fh_len < BTRFS_FID_SIZE_NON_CONNECTABLE))
137		return NULL;
138
139	objectid = fid->objectid;
140	root_objectid = fid->root_objectid;
141	generation = fid->gen;
142
143	return btrfs_get_dentry(sb, objectid, root_objectid, generation);
144}
145
146struct dentry *btrfs_get_parent(struct dentry *child)
147{
148	struct inode *dir = d_inode(child);
149	struct btrfs_fs_info *fs_info = btrfs_sb(dir->i_sb);
150	struct btrfs_root *root = BTRFS_I(dir)->root;
151	struct btrfs_path *path;
152	struct extent_buffer *leaf;
153	struct btrfs_root_ref *ref;
154	struct btrfs_key key;
155	struct btrfs_key found_key;
156	int ret;
157
158	path = btrfs_alloc_path();
159	if (!path)
160		return ERR_PTR(-ENOMEM);
161
162	if (btrfs_ino(BTRFS_I(dir)) == BTRFS_FIRST_FREE_OBJECTID) {
163		key.objectid = root->root_key.objectid;
164		key.type = BTRFS_ROOT_BACKREF_KEY;
165		key.offset = (u64)-1;
166		root = fs_info->tree_root;
167	} else {
168		key.objectid = btrfs_ino(BTRFS_I(dir));
169		key.type = BTRFS_INODE_REF_KEY;
170		key.offset = (u64)-1;
171	}
172
173	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
174	if (ret < 0)
175		goto fail;
176	if (ret == 0) {
177		/*
178		 * Key with offset of -1 found, there would have to exist an
179		 * inode with such number or a root with such id.
180		 */
181		ret = -EUCLEAN;
182		goto fail;
183	}
184
185	if (path->slots[0] == 0) {
186		ret = -ENOENT;
187		goto fail;
188	}
189
190	path->slots[0]--;
191	leaf = path->nodes[0];
192
193	btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
194	if (found_key.objectid != key.objectid || found_key.type != key.type) {
195		ret = -ENOENT;
196		goto fail;
197	}
198
199	if (found_key.type == BTRFS_ROOT_BACKREF_KEY) {
200		ref = btrfs_item_ptr(leaf, path->slots[0],
201				     struct btrfs_root_ref);
202		key.objectid = btrfs_root_ref_dirid(leaf, ref);
203	} else {
204		key.objectid = found_key.offset;
205	}
206	btrfs_free_path(path);
207
208	if (found_key.type == BTRFS_ROOT_BACKREF_KEY) {
209		return btrfs_get_dentry(fs_info->sb, key.objectid,
210					found_key.offset, 0);
211	}
212
213	return d_obtain_alias(btrfs_iget(fs_info->sb, key.objectid, root));
214fail:
215	btrfs_free_path(path);
216	return ERR_PTR(ret);
217}
218
219static int btrfs_get_name(struct dentry *parent, char *name,
220			  struct dentry *child)
221{
222	struct inode *inode = d_inode(child);
223	struct inode *dir = d_inode(parent);
224	struct btrfs_fs_info *fs_info = inode_to_fs_info(inode);
225	struct btrfs_path *path;
226	struct btrfs_root *root = BTRFS_I(dir)->root;
227	struct btrfs_inode_ref *iref;
228	struct btrfs_root_ref *rref;
229	struct extent_buffer *leaf;
230	unsigned long name_ptr;
231	struct btrfs_key key;
232	int name_len;
233	int ret;
234	u64 ino;
235
236	if (!S_ISDIR(dir->i_mode))
237		return -EINVAL;
238
239	ino = btrfs_ino(BTRFS_I(inode));
240
241	path = btrfs_alloc_path();
242	if (!path)
243		return -ENOMEM;
244
245	if (ino == BTRFS_FIRST_FREE_OBJECTID) {
246		key.objectid = BTRFS_I(inode)->root->root_key.objectid;
247		key.type = BTRFS_ROOT_BACKREF_KEY;
248		key.offset = (u64)-1;
249		root = fs_info->tree_root;
250	} else {
251		key.objectid = ino;
252		key.offset = btrfs_ino(BTRFS_I(dir));
253		key.type = BTRFS_INODE_REF_KEY;
254	}
255
256	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
257	if (ret < 0) {
258		btrfs_free_path(path);
259		return ret;
260	} else if (ret > 0) {
261		if (ino == BTRFS_FIRST_FREE_OBJECTID) {
262			path->slots[0]--;
263		} else {
264			btrfs_free_path(path);
265			return -ENOENT;
266		}
267	}
268	leaf = path->nodes[0];
269
270	if (ino == BTRFS_FIRST_FREE_OBJECTID) {
271		rref = btrfs_item_ptr(leaf, path->slots[0],
272				     struct btrfs_root_ref);
273		name_ptr = (unsigned long)(rref + 1);
274		name_len = btrfs_root_ref_name_len(leaf, rref);
275	} else {
276		iref = btrfs_item_ptr(leaf, path->slots[0],
277				      struct btrfs_inode_ref);
278		name_ptr = (unsigned long)(iref + 1);
279		name_len = btrfs_inode_ref_name_len(leaf, iref);
280	}
281
282	read_extent_buffer(leaf, name, name_ptr, name_len);
283	btrfs_free_path(path);
284
285	/*
286	 * have to add the null termination to make sure that reconnect_path
287	 * gets the right len for strlen
288	 */
289	name[name_len] = '\0';
290
291	return 0;
292}
293
294const struct export_operations btrfs_export_ops = {
295	.encode_fh	= btrfs_encode_fh,
296	.fh_to_dentry	= btrfs_fh_to_dentry,
297	.fh_to_parent	= btrfs_fh_to_parent,
298	.get_parent	= btrfs_get_parent,
299	.get_name	= btrfs_get_name,
300};