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1// SPDX-License-Identifier: GPL-2.0-or-later
2/* AFS dynamic root handling
3 *
4 * Copyright (C) 2018 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.com)
6 */
7
8#include <linux/fs.h>
9#include <linux/namei.h>
10#include <linux/dns_resolver.h>
11#include "internal.h"
12
13static atomic_t afs_autocell_ino;
14
15/*
16 * iget5() comparator for inode created by autocell operations
17 *
18 * These pseudo inodes don't match anything.
19 */
20static int afs_iget5_pseudo_test(struct inode *inode, void *opaque)
21{
22 return 0;
23}
24
25/*
26 * iget5() inode initialiser
27 */
28static int afs_iget5_pseudo_set(struct inode *inode, void *opaque)
29{
30 struct afs_super_info *as = AFS_FS_S(inode->i_sb);
31 struct afs_vnode *vnode = AFS_FS_I(inode);
32 struct afs_fid *fid = opaque;
33
34 vnode->volume = as->volume;
35 vnode->fid = *fid;
36 inode->i_ino = fid->vnode;
37 inode->i_generation = fid->unique;
38 return 0;
39}
40
41/*
42 * Create an inode for a dynamic root directory or an autocell dynamic
43 * automount dir.
44 */
45struct inode *afs_iget_pseudo_dir(struct super_block *sb, bool root)
46{
47 struct afs_super_info *as = AFS_FS_S(sb);
48 struct afs_vnode *vnode;
49 struct inode *inode;
50 struct afs_fid fid = {};
51
52 _enter("");
53
54 if (as->volume)
55 fid.vid = as->volume->vid;
56 if (root) {
57 fid.vnode = 1;
58 fid.unique = 1;
59 } else {
60 fid.vnode = atomic_inc_return(&afs_autocell_ino);
61 fid.unique = 0;
62 }
63
64 inode = iget5_locked(sb, fid.vnode,
65 afs_iget5_pseudo_test, afs_iget5_pseudo_set, &fid);
66 if (!inode) {
67 _leave(" = -ENOMEM");
68 return ERR_PTR(-ENOMEM);
69 }
70
71 _debug("GOT INODE %p { ino=%lu, vl=%llx, vn=%llx, u=%x }",
72 inode, inode->i_ino, fid.vid, fid.vnode, fid.unique);
73
74 vnode = AFS_FS_I(inode);
75
76 /* there shouldn't be an existing inode */
77 BUG_ON(!(inode->i_state & I_NEW));
78
79 netfs_inode_init(&vnode->netfs, NULL, false);
80 inode->i_size = 0;
81 inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO;
82 if (root) {
83 inode->i_op = &afs_dynroot_inode_operations;
84 inode->i_fop = &simple_dir_operations;
85 } else {
86 inode->i_op = &afs_autocell_inode_operations;
87 }
88 set_nlink(inode, 2);
89 inode->i_uid = GLOBAL_ROOT_UID;
90 inode->i_gid = GLOBAL_ROOT_GID;
91 simple_inode_init_ts(inode);
92 inode->i_blocks = 0;
93 inode->i_generation = 0;
94
95 set_bit(AFS_VNODE_PSEUDODIR, &vnode->flags);
96 if (!root) {
97 set_bit(AFS_VNODE_MOUNTPOINT, &vnode->flags);
98 inode->i_flags |= S_AUTOMOUNT;
99 }
100
101 inode->i_flags |= S_NOATIME;
102 unlock_new_inode(inode);
103 _leave(" = %p", inode);
104 return inode;
105}
106
107/*
108 * Probe to see if a cell may exist. This prevents positive dentries from
109 * being created unnecessarily.
110 */
111static int afs_probe_cell_name(struct dentry *dentry)
112{
113 struct afs_cell *cell;
114 struct afs_net *net = afs_d2net(dentry);
115 const char *name = dentry->d_name.name;
116 size_t len = dentry->d_name.len;
117 char *result = NULL;
118 int ret;
119
120 /* Names prefixed with a dot are R/W mounts. */
121 if (name[0] == '.') {
122 if (len == 1)
123 return -EINVAL;
124 name++;
125 len--;
126 }
127
128 cell = afs_find_cell(net, name, len, afs_cell_trace_use_probe);
129 if (!IS_ERR(cell)) {
130 afs_unuse_cell(net, cell, afs_cell_trace_unuse_probe);
131 return 0;
132 }
133
134 ret = dns_query(net->net, "afsdb", name, len, "srv=1",
135 &result, NULL, false);
136 if (ret == -ENODATA || ret == -ENOKEY || ret == 0)
137 ret = -ENOENT;
138 if (ret > 0 && ret >= sizeof(struct dns_server_list_v1_header)) {
139 struct dns_server_list_v1_header *v1 = (void *)result;
140
141 if (v1->hdr.zero == 0 &&
142 v1->hdr.content == DNS_PAYLOAD_IS_SERVER_LIST &&
143 v1->hdr.version == 1 &&
144 (v1->status != DNS_LOOKUP_GOOD &&
145 v1->status != DNS_LOOKUP_GOOD_WITH_BAD))
146 return -ENOENT;
147
148 }
149
150 kfree(result);
151 return ret;
152}
153
154/*
155 * Try to auto mount the mountpoint with pseudo directory, if the autocell
156 * operation is setted.
157 */
158struct inode *afs_try_auto_mntpt(struct dentry *dentry, struct inode *dir)
159{
160 struct afs_vnode *vnode = AFS_FS_I(dir);
161 struct inode *inode;
162 int ret = -ENOENT;
163
164 _enter("%p{%pd}, {%llx:%llu}",
165 dentry, dentry, vnode->fid.vid, vnode->fid.vnode);
166
167 if (!test_bit(AFS_VNODE_AUTOCELL, &vnode->flags))
168 goto out;
169
170 ret = afs_probe_cell_name(dentry);
171 if (ret < 0)
172 goto out;
173
174 inode = afs_iget_pseudo_dir(dir->i_sb, false);
175 if (IS_ERR(inode)) {
176 ret = PTR_ERR(inode);
177 goto out;
178 }
179
180 _leave("= %p", inode);
181 return inode;
182
183out:
184 _leave("= %d", ret);
185 return ret == -ENOENT ? NULL : ERR_PTR(ret);
186}
187
188/*
189 * Look up @cell in a dynroot directory. This is a substitution for the
190 * local cell name for the net namespace.
191 */
192static struct dentry *afs_lookup_atcell(struct dentry *dentry)
193{
194 struct afs_cell *cell;
195 struct afs_net *net = afs_d2net(dentry);
196 struct dentry *ret;
197 char *name;
198 int len;
199
200 if (!net->ws_cell)
201 return ERR_PTR(-ENOENT);
202
203 ret = ERR_PTR(-ENOMEM);
204 name = kmalloc(AFS_MAXCELLNAME + 1, GFP_KERNEL);
205 if (!name)
206 goto out_p;
207
208 down_read(&net->cells_lock);
209 cell = net->ws_cell;
210 if (cell) {
211 len = cell->name_len;
212 memcpy(name, cell->name, len + 1);
213 }
214 up_read(&net->cells_lock);
215
216 ret = ERR_PTR(-ENOENT);
217 if (!cell)
218 goto out_n;
219
220 ret = lookup_one_len(name, dentry->d_parent, len);
221
222 /* We don't want to d_add() the @cell dentry here as we don't want to
223 * the cached dentry to hide changes to the local cell name.
224 */
225
226out_n:
227 kfree(name);
228out_p:
229 return ret;
230}
231
232/*
233 * Look up an entry in a dynroot directory.
234 */
235static struct dentry *afs_dynroot_lookup(struct inode *dir, struct dentry *dentry,
236 unsigned int flags)
237{
238 _enter("%pd", dentry);
239
240 ASSERTCMP(d_inode(dentry), ==, NULL);
241
242 if (flags & LOOKUP_CREATE)
243 return ERR_PTR(-EOPNOTSUPP);
244
245 if (dentry->d_name.len >= AFSNAMEMAX) {
246 _leave(" = -ENAMETOOLONG");
247 return ERR_PTR(-ENAMETOOLONG);
248 }
249
250 if (dentry->d_name.len == 5 &&
251 memcmp(dentry->d_name.name, "@cell", 5) == 0)
252 return afs_lookup_atcell(dentry);
253
254 return d_splice_alias(afs_try_auto_mntpt(dentry, dir), dentry);
255}
256
257const struct inode_operations afs_dynroot_inode_operations = {
258 .lookup = afs_dynroot_lookup,
259};
260
261const struct dentry_operations afs_dynroot_dentry_operations = {
262 .d_delete = always_delete_dentry,
263 .d_release = afs_d_release,
264 .d_automount = afs_d_automount,
265};
266
267/*
268 * Create a manually added cell mount directory.
269 * - The caller must hold net->proc_cells_lock
270 */
271int afs_dynroot_mkdir(struct afs_net *net, struct afs_cell *cell)
272{
273 struct super_block *sb = net->dynroot_sb;
274 struct dentry *root, *subdir;
275 int ret;
276
277 if (!sb || atomic_read(&sb->s_active) == 0)
278 return 0;
279
280 /* Let the ->lookup op do the creation */
281 root = sb->s_root;
282 inode_lock(root->d_inode);
283 subdir = lookup_one_len(cell->name, root, cell->name_len);
284 if (IS_ERR(subdir)) {
285 ret = PTR_ERR(subdir);
286 goto unlock;
287 }
288
289 /* Note that we're retaining an extra ref on the dentry */
290 subdir->d_fsdata = (void *)1UL;
291 ret = 0;
292unlock:
293 inode_unlock(root->d_inode);
294 return ret;
295}
296
297/*
298 * Remove a manually added cell mount directory.
299 * - The caller must hold net->proc_cells_lock
300 */
301void afs_dynroot_rmdir(struct afs_net *net, struct afs_cell *cell)
302{
303 struct super_block *sb = net->dynroot_sb;
304 struct dentry *root, *subdir;
305
306 if (!sb || atomic_read(&sb->s_active) == 0)
307 return;
308
309 root = sb->s_root;
310 inode_lock(root->d_inode);
311
312 /* Don't want to trigger a lookup call, which will re-add the cell */
313 subdir = try_lookup_one_len(cell->name, root, cell->name_len);
314 if (IS_ERR_OR_NULL(subdir)) {
315 _debug("lookup %ld", PTR_ERR(subdir));
316 goto no_dentry;
317 }
318
319 _debug("rmdir %pd %u", subdir, d_count(subdir));
320
321 if (subdir->d_fsdata) {
322 _debug("unpin %u", d_count(subdir));
323 subdir->d_fsdata = NULL;
324 dput(subdir);
325 }
326 dput(subdir);
327no_dentry:
328 inode_unlock(root->d_inode);
329 _leave("");
330}
331
332/*
333 * Populate a newly created dynamic root with cell names.
334 */
335int afs_dynroot_populate(struct super_block *sb)
336{
337 struct afs_cell *cell;
338 struct afs_net *net = afs_sb2net(sb);
339 int ret;
340
341 mutex_lock(&net->proc_cells_lock);
342
343 net->dynroot_sb = sb;
344 hlist_for_each_entry(cell, &net->proc_cells, proc_link) {
345 ret = afs_dynroot_mkdir(net, cell);
346 if (ret < 0)
347 goto error;
348 }
349
350 ret = 0;
351out:
352 mutex_unlock(&net->proc_cells_lock);
353 return ret;
354
355error:
356 net->dynroot_sb = NULL;
357 goto out;
358}
359
360/*
361 * When a dynamic root that's in the process of being destroyed, depopulate it
362 * of pinned directories.
363 */
364void afs_dynroot_depopulate(struct super_block *sb)
365{
366 struct afs_net *net = afs_sb2net(sb);
367 struct dentry *root = sb->s_root, *subdir;
368
369 /* Prevent more subdirs from being created */
370 mutex_lock(&net->proc_cells_lock);
371 if (net->dynroot_sb == sb)
372 net->dynroot_sb = NULL;
373 mutex_unlock(&net->proc_cells_lock);
374
375 if (root) {
376 struct hlist_node *n;
377 inode_lock(root->d_inode);
378
379 /* Remove all the pins for dirs created for manually added cells */
380 hlist_for_each_entry_safe(subdir, n, &root->d_children, d_sib) {
381 if (subdir->d_fsdata) {
382 subdir->d_fsdata = NULL;
383 dput(subdir);
384 }
385 }
386
387 inode_unlock(root->d_inode);
388 }
389}
1// SPDX-License-Identifier: GPL-2.0-or-later
2/* AFS dynamic root handling
3 *
4 * Copyright (C) 2018 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.com)
6 */
7
8#include <linux/fs.h>
9#include <linux/namei.h>
10#include <linux/dns_resolver.h>
11#include "internal.h"
12
13static atomic_t afs_autocell_ino;
14
15/*
16 * iget5() comparator for inode created by autocell operations
17 *
18 * These pseudo inodes don't match anything.
19 */
20static int afs_iget5_pseudo_test(struct inode *inode, void *opaque)
21{
22 return 0;
23}
24
25/*
26 * iget5() inode initialiser
27 */
28static int afs_iget5_pseudo_set(struct inode *inode, void *opaque)
29{
30 struct afs_super_info *as = AFS_FS_S(inode->i_sb);
31 struct afs_vnode *vnode = AFS_FS_I(inode);
32 struct afs_fid *fid = opaque;
33
34 vnode->volume = as->volume;
35 vnode->fid = *fid;
36 inode->i_ino = fid->vnode;
37 inode->i_generation = fid->unique;
38 return 0;
39}
40
41/*
42 * Create an inode for a dynamic root directory or an autocell dynamic
43 * automount dir.
44 */
45struct inode *afs_iget_pseudo_dir(struct super_block *sb, bool root)
46{
47 struct afs_super_info *as = AFS_FS_S(sb);
48 struct afs_vnode *vnode;
49 struct inode *inode;
50 struct afs_fid fid = {};
51
52 _enter("");
53
54 if (as->volume)
55 fid.vid = as->volume->vid;
56 if (root) {
57 fid.vnode = 1;
58 fid.unique = 1;
59 } else {
60 fid.vnode = atomic_inc_return(&afs_autocell_ino);
61 fid.unique = 0;
62 }
63
64 inode = iget5_locked(sb, fid.vnode,
65 afs_iget5_pseudo_test, afs_iget5_pseudo_set, &fid);
66 if (!inode) {
67 _leave(" = -ENOMEM");
68 return ERR_PTR(-ENOMEM);
69 }
70
71 _debug("GOT INODE %p { ino=%lu, vl=%llx, vn=%llx, u=%x }",
72 inode, inode->i_ino, fid.vid, fid.vnode, fid.unique);
73
74 vnode = AFS_FS_I(inode);
75
76 /* there shouldn't be an existing inode */
77 BUG_ON(!(inode->i_state & I_NEW));
78
79 inode->i_size = 0;
80 inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO;
81 if (root) {
82 inode->i_op = &afs_dynroot_inode_operations;
83 inode->i_fop = &simple_dir_operations;
84 } else {
85 inode->i_op = &afs_autocell_inode_operations;
86 }
87 set_nlink(inode, 2);
88 inode->i_uid = GLOBAL_ROOT_UID;
89 inode->i_gid = GLOBAL_ROOT_GID;
90 inode->i_ctime = inode->i_atime = inode->i_mtime = current_time(inode);
91 inode->i_blocks = 0;
92 inode->i_generation = 0;
93
94 set_bit(AFS_VNODE_PSEUDODIR, &vnode->flags);
95 if (!root) {
96 set_bit(AFS_VNODE_MOUNTPOINT, &vnode->flags);
97 inode->i_flags |= S_AUTOMOUNT;
98 }
99
100 inode->i_flags |= S_NOATIME;
101 unlock_new_inode(inode);
102 _leave(" = %p", inode);
103 return inode;
104}
105
106/*
107 * Probe to see if a cell may exist. This prevents positive dentries from
108 * being created unnecessarily.
109 */
110static int afs_probe_cell_name(struct dentry *dentry)
111{
112 struct afs_cell *cell;
113 struct afs_net *net = afs_d2net(dentry);
114 const char *name = dentry->d_name.name;
115 size_t len = dentry->d_name.len;
116 int ret;
117
118 /* Names prefixed with a dot are R/W mounts. */
119 if (name[0] == '.') {
120 if (len == 1)
121 return -EINVAL;
122 name++;
123 len--;
124 }
125
126 cell = afs_lookup_cell_rcu(net, name, len);
127 if (!IS_ERR(cell)) {
128 afs_put_cell(net, cell);
129 return 0;
130 }
131
132 ret = dns_query(net->net, "afsdb", name, len, "srv=1",
133 NULL, NULL, false);
134 if (ret == -ENODATA)
135 ret = -EDESTADDRREQ;
136 return ret;
137}
138
139/*
140 * Try to auto mount the mountpoint with pseudo directory, if the autocell
141 * operation is setted.
142 */
143struct inode *afs_try_auto_mntpt(struct dentry *dentry, struct inode *dir)
144{
145 struct afs_vnode *vnode = AFS_FS_I(dir);
146 struct inode *inode;
147 int ret = -ENOENT;
148
149 _enter("%p{%pd}, {%llx:%llu}",
150 dentry, dentry, vnode->fid.vid, vnode->fid.vnode);
151
152 if (!test_bit(AFS_VNODE_AUTOCELL, &vnode->flags))
153 goto out;
154
155 ret = afs_probe_cell_name(dentry);
156 if (ret < 0)
157 goto out;
158
159 inode = afs_iget_pseudo_dir(dir->i_sb, false);
160 if (IS_ERR(inode)) {
161 ret = PTR_ERR(inode);
162 goto out;
163 }
164
165 _leave("= %p", inode);
166 return inode;
167
168out:
169 _leave("= %d", ret);
170 return ret == -ENOENT ? NULL : ERR_PTR(ret);
171}
172
173/*
174 * Look up @cell in a dynroot directory. This is a substitution for the
175 * local cell name for the net namespace.
176 */
177static struct dentry *afs_lookup_atcell(struct dentry *dentry)
178{
179 struct afs_cell *cell;
180 struct afs_net *net = afs_d2net(dentry);
181 struct dentry *ret;
182 unsigned int seq = 0;
183 char *name;
184 int len;
185
186 if (!net->ws_cell)
187 return ERR_PTR(-ENOENT);
188
189 ret = ERR_PTR(-ENOMEM);
190 name = kmalloc(AFS_MAXCELLNAME + 1, GFP_KERNEL);
191 if (!name)
192 goto out_p;
193
194 rcu_read_lock();
195 do {
196 read_seqbegin_or_lock(&net->cells_lock, &seq);
197 cell = rcu_dereference_raw(net->ws_cell);
198 if (cell) {
199 len = cell->name_len;
200 memcpy(name, cell->name, len + 1);
201 }
202 } while (need_seqretry(&net->cells_lock, seq));
203 done_seqretry(&net->cells_lock, seq);
204 rcu_read_unlock();
205
206 ret = ERR_PTR(-ENOENT);
207 if (!cell)
208 goto out_n;
209
210 ret = lookup_one_len(name, dentry->d_parent, len);
211
212 /* We don't want to d_add() the @cell dentry here as we don't want to
213 * the cached dentry to hide changes to the local cell name.
214 */
215
216out_n:
217 kfree(name);
218out_p:
219 return ret;
220}
221
222/*
223 * Look up an entry in a dynroot directory.
224 */
225static struct dentry *afs_dynroot_lookup(struct inode *dir, struct dentry *dentry,
226 unsigned int flags)
227{
228 _enter("%pd", dentry);
229
230 ASSERTCMP(d_inode(dentry), ==, NULL);
231
232 if (flags & LOOKUP_CREATE)
233 return ERR_PTR(-EOPNOTSUPP);
234
235 if (dentry->d_name.len >= AFSNAMEMAX) {
236 _leave(" = -ENAMETOOLONG");
237 return ERR_PTR(-ENAMETOOLONG);
238 }
239
240 if (dentry->d_name.len == 5 &&
241 memcmp(dentry->d_name.name, "@cell", 5) == 0)
242 return afs_lookup_atcell(dentry);
243
244 return d_splice_alias(afs_try_auto_mntpt(dentry, dir), dentry);
245}
246
247const struct inode_operations afs_dynroot_inode_operations = {
248 .lookup = afs_dynroot_lookup,
249};
250
251/*
252 * Dirs in the dynamic root don't need revalidation.
253 */
254static int afs_dynroot_d_revalidate(struct dentry *dentry, unsigned int flags)
255{
256 return 1;
257}
258
259/*
260 * Allow the VFS to enquire as to whether a dentry should be unhashed (mustn't
261 * sleep)
262 * - called from dput() when d_count is going to 0.
263 * - return 1 to request dentry be unhashed, 0 otherwise
264 */
265static int afs_dynroot_d_delete(const struct dentry *dentry)
266{
267 return d_really_is_positive(dentry);
268}
269
270const struct dentry_operations afs_dynroot_dentry_operations = {
271 .d_revalidate = afs_dynroot_d_revalidate,
272 .d_delete = afs_dynroot_d_delete,
273 .d_release = afs_d_release,
274 .d_automount = afs_d_automount,
275};
276
277/*
278 * Create a manually added cell mount directory.
279 * - The caller must hold net->proc_cells_lock
280 */
281int afs_dynroot_mkdir(struct afs_net *net, struct afs_cell *cell)
282{
283 struct super_block *sb = net->dynroot_sb;
284 struct dentry *root, *subdir;
285 int ret;
286
287 if (!sb || atomic_read(&sb->s_active) == 0)
288 return 0;
289
290 /* Let the ->lookup op do the creation */
291 root = sb->s_root;
292 inode_lock(root->d_inode);
293 subdir = lookup_one_len(cell->name, root, cell->name_len);
294 if (IS_ERR(subdir)) {
295 ret = PTR_ERR(subdir);
296 goto unlock;
297 }
298
299 /* Note that we're retaining an extra ref on the dentry */
300 subdir->d_fsdata = (void *)1UL;
301 ret = 0;
302unlock:
303 inode_unlock(root->d_inode);
304 return ret;
305}
306
307/*
308 * Remove a manually added cell mount directory.
309 * - The caller must hold net->proc_cells_lock
310 */
311void afs_dynroot_rmdir(struct afs_net *net, struct afs_cell *cell)
312{
313 struct super_block *sb = net->dynroot_sb;
314 struct dentry *root, *subdir;
315
316 if (!sb || atomic_read(&sb->s_active) == 0)
317 return;
318
319 root = sb->s_root;
320 inode_lock(root->d_inode);
321
322 /* Don't want to trigger a lookup call, which will re-add the cell */
323 subdir = try_lookup_one_len(cell->name, root, cell->name_len);
324 if (IS_ERR_OR_NULL(subdir)) {
325 _debug("lookup %ld", PTR_ERR(subdir));
326 goto no_dentry;
327 }
328
329 _debug("rmdir %pd %u", subdir, d_count(subdir));
330
331 if (subdir->d_fsdata) {
332 _debug("unpin %u", d_count(subdir));
333 subdir->d_fsdata = NULL;
334 dput(subdir);
335 }
336 dput(subdir);
337no_dentry:
338 inode_unlock(root->d_inode);
339 _leave("");
340}
341
342/*
343 * Populate a newly created dynamic root with cell names.
344 */
345int afs_dynroot_populate(struct super_block *sb)
346{
347 struct afs_cell *cell;
348 struct afs_net *net = afs_sb2net(sb);
349 int ret;
350
351 mutex_lock(&net->proc_cells_lock);
352
353 net->dynroot_sb = sb;
354 hlist_for_each_entry(cell, &net->proc_cells, proc_link) {
355 ret = afs_dynroot_mkdir(net, cell);
356 if (ret < 0)
357 goto error;
358 }
359
360 ret = 0;
361out:
362 mutex_unlock(&net->proc_cells_lock);
363 return ret;
364
365error:
366 net->dynroot_sb = NULL;
367 goto out;
368}
369
370/*
371 * When a dynamic root that's in the process of being destroyed, depopulate it
372 * of pinned directories.
373 */
374void afs_dynroot_depopulate(struct super_block *sb)
375{
376 struct afs_net *net = afs_sb2net(sb);
377 struct dentry *root = sb->s_root, *subdir, *tmp;
378
379 /* Prevent more subdirs from being created */
380 mutex_lock(&net->proc_cells_lock);
381 if (net->dynroot_sb == sb)
382 net->dynroot_sb = NULL;
383 mutex_unlock(&net->proc_cells_lock);
384
385 if (root) {
386 inode_lock(root->d_inode);
387
388 /* Remove all the pins for dirs created for manually added cells */
389 list_for_each_entry_safe(subdir, tmp, &root->d_subdirs, d_child) {
390 if (subdir->d_fsdata) {
391 subdir->d_fsdata = NULL;
392 dput(subdir);
393 }
394 }
395
396 inode_unlock(root->d_inode);
397 }
398}