This source file includes following definitions.
- kernfs_sop_show_options
- kernfs_sop_show_path
- kernfs_get_node_by_id
- kernfs_fh_get_inode
- kernfs_fh_to_dentry
- kernfs_fh_to_parent
- kernfs_get_parent_dentry
- kernfs_root_from_sb
- find_next_ancestor
- kernfs_node_dentry
- kernfs_fill_super
- kernfs_test_super
- kernfs_set_super
- kernfs_super_ns
- kernfs_get_tree
- kernfs_free_fs_context
- kernfs_kill_sb
- kernfs_init
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10 #include <linux/fs.h>
11 #include <linux/mount.h>
12 #include <linux/init.h>
13 #include <linux/magic.h>
14 #include <linux/slab.h>
15 #include <linux/pagemap.h>
16 #include <linux/namei.h>
17 #include <linux/seq_file.h>
18 #include <linux/exportfs.h>
19
20 #include "kernfs-internal.h"
21
22 struct kmem_cache *kernfs_node_cache, *kernfs_iattrs_cache;
23
24 static int kernfs_sop_show_options(struct seq_file *sf, struct dentry *dentry)
25 {
26 struct kernfs_root *root = kernfs_root(kernfs_dentry_node(dentry));
27 struct kernfs_syscall_ops *scops = root->syscall_ops;
28
29 if (scops && scops->show_options)
30 return scops->show_options(sf, root);
31 return 0;
32 }
33
34 static int kernfs_sop_show_path(struct seq_file *sf, struct dentry *dentry)
35 {
36 struct kernfs_node *node = kernfs_dentry_node(dentry);
37 struct kernfs_root *root = kernfs_root(node);
38 struct kernfs_syscall_ops *scops = root->syscall_ops;
39
40 if (scops && scops->show_path)
41 return scops->show_path(sf, node, root);
42
43 seq_dentry(sf, dentry, " \t\n\\");
44 return 0;
45 }
46
47 const struct super_operations kernfs_sops = {
48 .statfs = simple_statfs,
49 .drop_inode = generic_delete_inode,
50 .evict_inode = kernfs_evict_inode,
51
52 .show_options = kernfs_sop_show_options,
53 .show_path = kernfs_sop_show_path,
54 };
55
56
57
58
59
60 struct kernfs_node *kernfs_get_node_by_id(struct kernfs_root *root,
61 const union kernfs_node_id *id)
62 {
63 struct kernfs_node *kn;
64
65 kn = kernfs_find_and_get_node_by_ino(root, id->ino);
66 if (!kn)
67 return NULL;
68 if (kn->id.generation != id->generation) {
69 kernfs_put(kn);
70 return NULL;
71 }
72 return kn;
73 }
74
75 static struct inode *kernfs_fh_get_inode(struct super_block *sb,
76 u64 ino, u32 generation)
77 {
78 struct kernfs_super_info *info = kernfs_info(sb);
79 struct inode *inode;
80 struct kernfs_node *kn;
81
82 if (ino == 0)
83 return ERR_PTR(-ESTALE);
84
85 kn = kernfs_find_and_get_node_by_ino(info->root, ino);
86 if (!kn)
87 return ERR_PTR(-ESTALE);
88 inode = kernfs_get_inode(sb, kn);
89 kernfs_put(kn);
90 if (!inode)
91 return ERR_PTR(-ESTALE);
92
93 if (generation && inode->i_generation != generation) {
94
95 iput(inode);
96 return ERR_PTR(-ESTALE);
97 }
98 return inode;
99 }
100
101 static struct dentry *kernfs_fh_to_dentry(struct super_block *sb, struct fid *fid,
102 int fh_len, int fh_type)
103 {
104 return generic_fh_to_dentry(sb, fid, fh_len, fh_type,
105 kernfs_fh_get_inode);
106 }
107
108 static struct dentry *kernfs_fh_to_parent(struct super_block *sb, struct fid *fid,
109 int fh_len, int fh_type)
110 {
111 return generic_fh_to_parent(sb, fid, fh_len, fh_type,
112 kernfs_fh_get_inode);
113 }
114
115 static struct dentry *kernfs_get_parent_dentry(struct dentry *child)
116 {
117 struct kernfs_node *kn = kernfs_dentry_node(child);
118
119 return d_obtain_alias(kernfs_get_inode(child->d_sb, kn->parent));
120 }
121
122 static const struct export_operations kernfs_export_ops = {
123 .fh_to_dentry = kernfs_fh_to_dentry,
124 .fh_to_parent = kernfs_fh_to_parent,
125 .get_parent = kernfs_get_parent_dentry,
126 };
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134
135 struct kernfs_root *kernfs_root_from_sb(struct super_block *sb)
136 {
137 if (sb->s_op == &kernfs_sops)
138 return kernfs_info(sb)->root;
139 return NULL;
140 }
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149
150 static struct kernfs_node *find_next_ancestor(struct kernfs_node *child,
151 struct kernfs_node *parent)
152 {
153 if (child == parent) {
154 pr_crit_once("BUG in find_next_ancestor: called with parent == child");
155 return NULL;
156 }
157
158 while (child->parent != parent) {
159 if (!child->parent)
160 return NULL;
161 child = child->parent;
162 }
163
164 return child;
165 }
166
167
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170
171
172 struct dentry *kernfs_node_dentry(struct kernfs_node *kn,
173 struct super_block *sb)
174 {
175 struct dentry *dentry;
176 struct kernfs_node *knparent = NULL;
177
178 BUG_ON(sb->s_op != &kernfs_sops);
179
180 dentry = dget(sb->s_root);
181
182
183 if (!kn->parent)
184 return dentry;
185
186 knparent = find_next_ancestor(kn, NULL);
187 if (WARN_ON(!knparent)) {
188 dput(dentry);
189 return ERR_PTR(-EINVAL);
190 }
191
192 do {
193 struct dentry *dtmp;
194 struct kernfs_node *kntmp;
195
196 if (kn == knparent)
197 return dentry;
198 kntmp = find_next_ancestor(kn, knparent);
199 if (WARN_ON(!kntmp)) {
200 dput(dentry);
201 return ERR_PTR(-EINVAL);
202 }
203 dtmp = lookup_one_len_unlocked(kntmp->name, dentry,
204 strlen(kntmp->name));
205 dput(dentry);
206 if (IS_ERR(dtmp))
207 return dtmp;
208 knparent = kntmp;
209 dentry = dtmp;
210 } while (true);
211 }
212
213 static int kernfs_fill_super(struct super_block *sb, struct kernfs_fs_context *kfc)
214 {
215 struct kernfs_super_info *info = kernfs_info(sb);
216 struct inode *inode;
217 struct dentry *root;
218
219 info->sb = sb;
220
221 sb->s_iflags |= SB_I_NOEXEC | SB_I_NODEV;
222 sb->s_blocksize = PAGE_SIZE;
223 sb->s_blocksize_bits = PAGE_SHIFT;
224 sb->s_magic = kfc->magic;
225 sb->s_op = &kernfs_sops;
226 sb->s_xattr = kernfs_xattr_handlers;
227 if (info->root->flags & KERNFS_ROOT_SUPPORT_EXPORTOP)
228 sb->s_export_op = &kernfs_export_ops;
229 sb->s_time_gran = 1;
230
231
232 sb->s_shrink.seeks = 0;
233
234
235 mutex_lock(&kernfs_mutex);
236 inode = kernfs_get_inode(sb, info->root->kn);
237 mutex_unlock(&kernfs_mutex);
238 if (!inode) {
239 pr_debug("kernfs: could not get root inode\n");
240 return -ENOMEM;
241 }
242
243
244 root = d_make_root(inode);
245 if (!root) {
246 pr_debug("%s: could not get root dentry!\n", __func__);
247 return -ENOMEM;
248 }
249 sb->s_root = root;
250 sb->s_d_op = &kernfs_dops;
251 return 0;
252 }
253
254 static int kernfs_test_super(struct super_block *sb, struct fs_context *fc)
255 {
256 struct kernfs_super_info *sb_info = kernfs_info(sb);
257 struct kernfs_super_info *info = fc->s_fs_info;
258
259 return sb_info->root == info->root && sb_info->ns == info->ns;
260 }
261
262 static int kernfs_set_super(struct super_block *sb, struct fs_context *fc)
263 {
264 struct kernfs_fs_context *kfc = fc->fs_private;
265
266 kfc->ns_tag = NULL;
267 return set_anon_super_fc(sb, fc);
268 }
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275
276 const void *kernfs_super_ns(struct super_block *sb)
277 {
278 struct kernfs_super_info *info = kernfs_info(sb);
279
280 return info->ns;
281 }
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292 int kernfs_get_tree(struct fs_context *fc)
293 {
294 struct kernfs_fs_context *kfc = fc->fs_private;
295 struct super_block *sb;
296 struct kernfs_super_info *info;
297 int error;
298
299 info = kzalloc(sizeof(*info), GFP_KERNEL);
300 if (!info)
301 return -ENOMEM;
302
303 info->root = kfc->root;
304 info->ns = kfc->ns_tag;
305 INIT_LIST_HEAD(&info->node);
306
307 fc->s_fs_info = info;
308 sb = sget_fc(fc, kernfs_test_super, kernfs_set_super);
309 if (IS_ERR(sb))
310 return PTR_ERR(sb);
311
312 if (!sb->s_root) {
313 struct kernfs_super_info *info = kernfs_info(sb);
314
315 kfc->new_sb_created = true;
316
317 error = kernfs_fill_super(sb, kfc);
318 if (error) {
319 deactivate_locked_super(sb);
320 return error;
321 }
322 sb->s_flags |= SB_ACTIVE;
323
324 mutex_lock(&kernfs_mutex);
325 list_add(&info->node, &info->root->supers);
326 mutex_unlock(&kernfs_mutex);
327 }
328
329 fc->root = dget(sb->s_root);
330 return 0;
331 }
332
333 void kernfs_free_fs_context(struct fs_context *fc)
334 {
335
336 kfree(fc->s_fs_info);
337 fc->s_fs_info = NULL;
338 }
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348 void kernfs_kill_sb(struct super_block *sb)
349 {
350 struct kernfs_super_info *info = kernfs_info(sb);
351
352 mutex_lock(&kernfs_mutex);
353 list_del(&info->node);
354 mutex_unlock(&kernfs_mutex);
355
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360 kill_anon_super(sb);
361 kfree(info);
362 }
363
364 void __init kernfs_init(void)
365 {
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373 kernfs_node_cache = kmem_cache_create("kernfs_node_cache",
374 sizeof(struct kernfs_node),
375 0,
376 SLAB_PANIC | SLAB_TYPESAFE_BY_RCU,
377 NULL);
378
379
380 kernfs_iattrs_cache = kmem_cache_create("kernfs_iattrs_cache",
381 sizeof(struct kernfs_iattrs),
382 0, SLAB_PANIC, NULL);
383 }