]> git.proxmox.com Git - mirror_ubuntu-bionic-kernel.git/blob - include/linux/dcache.h
cpumask: reduce stack usage in SD_x_INIT initializers
[mirror_ubuntu-bionic-kernel.git] / include / linux / dcache.h
1 #ifndef __LINUX_DCACHE_H
2 #define __LINUX_DCACHE_H
3
4 #ifdef __KERNEL__
5
6 #include <asm/atomic.h>
7 #include <linux/list.h>
8 #include <linux/spinlock.h>
9 #include <linux/cache.h>
10 #include <linux/rcupdate.h>
11
12 struct nameidata;
13 struct path;
14 struct vfsmount;
15
16 /*
17 * linux/include/linux/dcache.h
18 *
19 * Dirent cache data structures
20 *
21 * (C) Copyright 1997 Thomas Schoebel-Theuer,
22 * with heavy changes by Linus Torvalds
23 */
24
25 #define IS_ROOT(x) ((x) == (x)->d_parent)
26
27 /*
28 * "quick string" -- eases parameter passing, but more importantly
29 * saves "metadata" about the string (ie length and the hash).
30 *
31 * hash comes first so it snuggles against d_parent in the
32 * dentry.
33 */
34 struct qstr {
35 unsigned int hash;
36 unsigned int len;
37 const unsigned char *name;
38 };
39
40 struct dentry_stat_t {
41 int nr_dentry;
42 int nr_unused;
43 int age_limit; /* age in seconds */
44 int want_pages; /* pages requested by system */
45 int dummy[2];
46 };
47 extern struct dentry_stat_t dentry_stat;
48
49 /* Name hashing routines. Initial hash value */
50 /* Hash courtesy of the R5 hash in reiserfs modulo sign bits */
51 #define init_name_hash() 0
52
53 /* partial hash update function. Assume roughly 4 bits per character */
54 static inline unsigned long
55 partial_name_hash(unsigned long c, unsigned long prevhash)
56 {
57 return (prevhash + (c << 4) + (c >> 4)) * 11;
58 }
59
60 /*
61 * Finally: cut down the number of bits to a int value (and try to avoid
62 * losing bits)
63 */
64 static inline unsigned long end_name_hash(unsigned long hash)
65 {
66 return (unsigned int) hash;
67 }
68
69 /* Compute the hash for a name string. */
70 static inline unsigned int
71 full_name_hash(const unsigned char *name, unsigned int len)
72 {
73 unsigned long hash = init_name_hash();
74 while (len--)
75 hash = partial_name_hash(*name++, hash);
76 return end_name_hash(hash);
77 }
78
79 struct dcookie_struct;
80
81 #define DNAME_INLINE_LEN_MIN 36
82
83 struct dentry {
84 atomic_t d_count;
85 unsigned int d_flags; /* protected by d_lock */
86 spinlock_t d_lock; /* per dentry lock */
87 struct inode *d_inode; /* Where the name belongs to - NULL is
88 * negative */
89 /*
90 * The next three fields are touched by __d_lookup. Place them here
91 * so they all fit in a cache line.
92 */
93 struct hlist_node d_hash; /* lookup hash list */
94 struct dentry *d_parent; /* parent directory */
95 struct qstr d_name;
96
97 struct list_head d_lru; /* LRU list */
98 /*
99 * d_child and d_rcu can share memory
100 */
101 union {
102 struct list_head d_child; /* child of parent list */
103 struct rcu_head d_rcu;
104 } d_u;
105 struct list_head d_subdirs; /* our children */
106 struct list_head d_alias; /* inode alias list */
107 unsigned long d_time; /* used by d_revalidate */
108 struct dentry_operations *d_op;
109 struct super_block *d_sb; /* The root of the dentry tree */
110 void *d_fsdata; /* fs-specific data */
111 #ifdef CONFIG_PROFILING
112 struct dcookie_struct *d_cookie; /* cookie, if any */
113 #endif
114 int d_mounted;
115 unsigned char d_iname[DNAME_INLINE_LEN_MIN]; /* small names */
116 };
117
118 /*
119 * dentry->d_lock spinlock nesting subclasses:
120 *
121 * 0: normal
122 * 1: nested
123 */
124 enum dentry_d_lock_class
125 {
126 DENTRY_D_LOCK_NORMAL, /* implicitly used by plain spin_lock() APIs. */
127 DENTRY_D_LOCK_NESTED
128 };
129
130 struct dentry_operations {
131 int (*d_revalidate)(struct dentry *, struct nameidata *);
132 int (*d_hash) (struct dentry *, struct qstr *);
133 int (*d_compare) (struct dentry *, struct qstr *, struct qstr *);
134 int (*d_delete)(struct dentry *);
135 void (*d_release)(struct dentry *);
136 void (*d_iput)(struct dentry *, struct inode *);
137 char *(*d_dname)(struct dentry *, char *, int);
138 };
139
140 /* the dentry parameter passed to d_hash and d_compare is the parent
141 * directory of the entries to be compared. It is used in case these
142 * functions need any directory specific information for determining
143 * equivalency classes. Using the dentry itself might not work, as it
144 * might be a negative dentry which has no information associated with
145 * it */
146
147 /*
148 locking rules:
149 big lock dcache_lock d_lock may block
150 d_revalidate: no no no yes
151 d_hash no no no yes
152 d_compare: no yes yes no
153 d_delete: no yes no no
154 d_release: no no no yes
155 d_iput: no no no yes
156 */
157
158 /* d_flags entries */
159 #define DCACHE_AUTOFS_PENDING 0x0001 /* autofs: "under construction" */
160 #define DCACHE_NFSFS_RENAMED 0x0002 /* this dentry has been "silly
161 * renamed" and has to be
162 * deleted on the last dput()
163 */
164 #define DCACHE_DISCONNECTED 0x0004
165 /* This dentry is possibly not currently connected to the dcache tree,
166 * in which case its parent will either be itself, or will have this
167 * flag as well. nfsd will not use a dentry with this bit set, but will
168 * first endeavour to clear the bit either by discovering that it is
169 * connected, or by performing lookup operations. Any filesystem which
170 * supports nfsd_operations MUST have a lookup function which, if it finds
171 * a directory inode with a DCACHE_DISCONNECTED dentry, will d_move
172 * that dentry into place and return that dentry rather than the passed one,
173 * typically using d_splice_alias.
174 */
175
176 #define DCACHE_REFERENCED 0x0008 /* Recently used, don't discard. */
177 #define DCACHE_UNHASHED 0x0010
178
179 #define DCACHE_INOTIFY_PARENT_WATCHED 0x0020 /* Parent inode is watched */
180
181 extern spinlock_t dcache_lock;
182 extern seqlock_t rename_lock;
183
184 /**
185 * d_drop - drop a dentry
186 * @dentry: dentry to drop
187 *
188 * d_drop() unhashes the entry from the parent dentry hashes, so that it won't
189 * be found through a VFS lookup any more. Note that this is different from
190 * deleting the dentry - d_delete will try to mark the dentry negative if
191 * possible, giving a successful _negative_ lookup, while d_drop will
192 * just make the cache lookup fail.
193 *
194 * d_drop() is used mainly for stuff that wants to invalidate a dentry for some
195 * reason (NFS timeouts or autofs deletes).
196 *
197 * __d_drop requires dentry->d_lock.
198 */
199
200 static inline void __d_drop(struct dentry *dentry)
201 {
202 if (!(dentry->d_flags & DCACHE_UNHASHED)) {
203 dentry->d_flags |= DCACHE_UNHASHED;
204 hlist_del_rcu(&dentry->d_hash);
205 }
206 }
207
208 static inline void d_drop(struct dentry *dentry)
209 {
210 spin_lock(&dcache_lock);
211 spin_lock(&dentry->d_lock);
212 __d_drop(dentry);
213 spin_unlock(&dentry->d_lock);
214 spin_unlock(&dcache_lock);
215 }
216
217 static inline int dname_external(struct dentry *dentry)
218 {
219 return dentry->d_name.name != dentry->d_iname;
220 }
221
222 /*
223 * These are the low-level FS interfaces to the dcache..
224 */
225 extern void d_instantiate(struct dentry *, struct inode *);
226 extern struct dentry * d_instantiate_unique(struct dentry *, struct inode *);
227 extern struct dentry * d_materialise_unique(struct dentry *, struct inode *);
228 extern void d_delete(struct dentry *);
229
230 /* allocate/de-allocate */
231 extern struct dentry * d_alloc(struct dentry *, const struct qstr *);
232 extern struct dentry * d_alloc_anon(struct inode *);
233 extern struct dentry * d_splice_alias(struct inode *, struct dentry *);
234 extern void shrink_dcache_sb(struct super_block *);
235 extern void shrink_dcache_parent(struct dentry *);
236 extern void shrink_dcache_for_umount(struct super_block *);
237 extern int d_invalidate(struct dentry *);
238
239 /* only used at mount-time */
240 extern struct dentry * d_alloc_root(struct inode *);
241
242 /* <clickety>-<click> the ramfs-type tree */
243 extern void d_genocide(struct dentry *);
244
245 extern struct dentry *d_find_alias(struct inode *);
246 extern void d_prune_aliases(struct inode *);
247
248 /* test whether we have any submounts in a subdir tree */
249 extern int have_submounts(struct dentry *);
250
251 /*
252 * This adds the entry to the hash queues.
253 */
254 extern void d_rehash(struct dentry *);
255
256 /**
257 * d_add - add dentry to hash queues
258 * @entry: dentry to add
259 * @inode: The inode to attach to this dentry
260 *
261 * This adds the entry to the hash queues and initializes @inode.
262 * The entry was actually filled in earlier during d_alloc().
263 */
264
265 static inline void d_add(struct dentry *entry, struct inode *inode)
266 {
267 d_instantiate(entry, inode);
268 d_rehash(entry);
269 }
270
271 /**
272 * d_add_unique - add dentry to hash queues without aliasing
273 * @entry: dentry to add
274 * @inode: The inode to attach to this dentry
275 *
276 * This adds the entry to the hash queues and initializes @inode.
277 * The entry was actually filled in earlier during d_alloc().
278 */
279 static inline struct dentry *d_add_unique(struct dentry *entry, struct inode *inode)
280 {
281 struct dentry *res;
282
283 res = d_instantiate_unique(entry, inode);
284 d_rehash(res != NULL ? res : entry);
285 return res;
286 }
287
288 /* used for rename() and baskets */
289 extern void d_move(struct dentry *, struct dentry *);
290
291 /* appendix may either be NULL or be used for transname suffixes */
292 extern struct dentry * d_lookup(struct dentry *, struct qstr *);
293 extern struct dentry * __d_lookup(struct dentry *, struct qstr *);
294 extern struct dentry * d_hash_and_lookup(struct dentry *, struct qstr *);
295
296 /* validate "insecure" dentry pointer */
297 extern int d_validate(struct dentry *, struct dentry *);
298
299 /*
300 * helper function for dentry_operations.d_dname() members
301 */
302 extern char *dynamic_dname(struct dentry *, char *, int, const char *, ...);
303
304 extern char *d_path(struct path *, char *, int);
305
306 /* Allocation counts.. */
307
308 /**
309 * dget, dget_locked - get a reference to a dentry
310 * @dentry: dentry to get a reference to
311 *
312 * Given a dentry or %NULL pointer increment the reference count
313 * if appropriate and return the dentry. A dentry will not be
314 * destroyed when it has references. dget() should never be
315 * called for dentries with zero reference counter. For these cases
316 * (preferably none, functions in dcache.c are sufficient for normal
317 * needs and they take necessary precautions) you should hold dcache_lock
318 * and call dget_locked() instead of dget().
319 */
320
321 static inline struct dentry *dget(struct dentry *dentry)
322 {
323 if (dentry) {
324 BUG_ON(!atomic_read(&dentry->d_count));
325 atomic_inc(&dentry->d_count);
326 }
327 return dentry;
328 }
329
330 extern struct dentry * dget_locked(struct dentry *);
331
332 /**
333 * d_unhashed - is dentry hashed
334 * @dentry: entry to check
335 *
336 * Returns true if the dentry passed is not currently hashed.
337 */
338
339 static inline int d_unhashed(struct dentry *dentry)
340 {
341 return (dentry->d_flags & DCACHE_UNHASHED);
342 }
343
344 static inline struct dentry *dget_parent(struct dentry *dentry)
345 {
346 struct dentry *ret;
347
348 spin_lock(&dentry->d_lock);
349 ret = dget(dentry->d_parent);
350 spin_unlock(&dentry->d_lock);
351 return ret;
352 }
353
354 extern void dput(struct dentry *);
355
356 static inline int d_mountpoint(struct dentry *dentry)
357 {
358 return dentry->d_mounted;
359 }
360
361 extern struct vfsmount *lookup_mnt(struct vfsmount *, struct dentry *);
362 extern struct vfsmount *__lookup_mnt(struct vfsmount *, struct dentry *, int);
363 extern struct dentry *lookup_create(struct nameidata *nd, int is_dir);
364
365 extern int sysctl_vfs_cache_pressure;
366
367 #endif /* __KERNEL__ */
368
369 #endif /* __LINUX_DCACHE_H */