1 #ifndef __LINUX_DCACHE_H
2 #define __LINUX_DCACHE_H
3 
4 #include <linux/atomic.h>
5 #include <linux/list.h>
6 #include <linux/rculist.h>
7 #include <linux/rculist_bl.h>
8 #include <linux/spinlock.h>
9 #include <linux/seqlock.h>
10 #include <linux/cache.h>
11 #include <linux/rcupdate.h>
12 #include <linux/lockref.h>
13 
14 struct path;
15 struct vfsmount;
16 
17 /*
18  * linux/include/linux/dcache.h
19  *
20  * Dirent cache data structures
21  *
22  * (C) Copyright 1997 Thomas Schoebel-Theuer,
23  * with heavy changes by Linus Torvalds
24  */
25 
26 #define IS_ROOT(x) ((x) == (x)->d_parent)
27 
28 /* The hash is always the low bits of hash_len */
29 #ifdef __LITTLE_ENDIAN
30  #define HASH_LEN_DECLARE u32 hash; u32 len;
31  #define bytemask_from_count(cnt)	(~(~0ul << (cnt)*8))
32 #else
33  #define HASH_LEN_DECLARE u32 len; u32 hash;
34  #define bytemask_from_count(cnt)	(~(~0ul >> (cnt)*8))
35 #endif
36 
37 /*
38  * "quick string" -- eases parameter passing, but more importantly
39  * saves "metadata" about the string (ie length and the hash).
40  *
41  * hash comes first so it snuggles against d_parent in the
42  * dentry.
43  */
44 struct qstr {
45 	union {
46 		struct {
47 			HASH_LEN_DECLARE;
48 		};
49 		u64 hash_len;
50 	};
51 	const unsigned char *name;
52 };
53 
54 #define QSTR_INIT(n,l) { { { .len = l } }, .name = n }
55 #define hashlen_hash(hashlen) ((u32) (hashlen))
56 #define hashlen_len(hashlen)  ((u32)((hashlen) >> 32))
57 #define hashlen_create(hash,len) (((u64)(len)<<32)|(u32)(hash))
58 
59 struct dentry_stat_t {
60 	long nr_dentry;
61 	long nr_unused;
62 	long age_limit;          /* age in seconds */
63 	long want_pages;         /* pages requested by system */
64 	long dummy[2];
65 };
66 extern struct dentry_stat_t dentry_stat;
67 
68 /* Name hashing routines. Initial hash value */
69 /* Hash courtesy of the R5 hash in reiserfs modulo sign bits */
70 #define init_name_hash()		0
71 
72 /* partial hash update function. Assume roughly 4 bits per character */
73 static inline unsigned long
partial_name_hash(unsigned long c,unsigned long prevhash)74 partial_name_hash(unsigned long c, unsigned long prevhash)
75 {
76 	return (prevhash + (c << 4) + (c >> 4)) * 11;
77 }
78 
79 /*
80  * Finally: cut down the number of bits to a int value (and try to avoid
81  * losing bits)
82  */
end_name_hash(unsigned long hash)83 static inline unsigned long end_name_hash(unsigned long hash)
84 {
85 	return (unsigned int) hash;
86 }
87 
88 /* Compute the hash for a name string. */
89 extern unsigned int full_name_hash(const unsigned char *, unsigned int);
90 
91 /*
92  * Try to keep struct dentry aligned on 64 byte cachelines (this will
93  * give reasonable cacheline footprint with larger lines without the
94  * large memory footprint increase).
95  */
96 #ifdef CONFIG_64BIT
97 # define DNAME_INLINE_LEN 32 /* 192 bytes */
98 #else
99 # ifdef CONFIG_SMP
100 #  define DNAME_INLINE_LEN 36 /* 128 bytes */
101 # else
102 #  define DNAME_INLINE_LEN 40 /* 128 bytes */
103 # endif
104 #endif
105 
106 #define d_lock	d_lockref.lock
107 
108 struct dentry {
109 	/* RCU lookup touched fields */
110 	unsigned int d_flags;		/* protected by d_lock */
111 	seqcount_t d_seq;		/* per dentry seqlock */
112 	struct hlist_bl_node d_hash;	/* lookup hash list */
113 	struct dentry *d_parent;	/* parent directory */
114 	struct qstr d_name;
115 	struct inode *d_inode;		/* Where the name belongs to - NULL is
116 					 * negative */
117 	unsigned char d_iname[DNAME_INLINE_LEN];	/* small names */
118 
119 	/* Ref lookup also touches following */
120 	struct lockref d_lockref;	/* per-dentry lock and refcount */
121 	const struct dentry_operations *d_op;
122 	struct super_block *d_sb;	/* The root of the dentry tree */
123 	unsigned long d_time;		/* used by d_revalidate */
124 	void *d_fsdata;			/* fs-specific data */
125 
126 	struct list_head d_lru;		/* LRU list */
127 	struct list_head d_child;	/* child of parent list */
128 	struct list_head d_subdirs;	/* our children */
129 	/*
130 	 * d_alias and d_rcu can share memory
131 	 */
132 	union {
133 		struct hlist_node d_alias;	/* inode alias list */
134 	 	struct rcu_head d_rcu;
135 	} d_u;
136 };
137 
138 /*
139  * dentry->d_lock spinlock nesting subclasses:
140  *
141  * 0: normal
142  * 1: nested
143  */
144 enum dentry_d_lock_class
145 {
146 	DENTRY_D_LOCK_NORMAL, /* implicitly used by plain spin_lock() APIs. */
147 	DENTRY_D_LOCK_NESTED
148 };
149 
150 struct dentry_operations {
151 	int (*d_revalidate)(struct dentry *, unsigned int);
152 	int (*d_weak_revalidate)(struct dentry *, unsigned int);
153 	int (*d_hash)(const struct dentry *, struct qstr *);
154 	int (*d_compare)(const struct dentry *, const struct dentry *,
155 			unsigned int, const char *, const struct qstr *);
156 	int (*d_delete)(const struct dentry *);
157 	void (*d_release)(struct dentry *);
158 	void (*d_prune)(struct dentry *);
159 	void (*d_iput)(struct dentry *, struct inode *);
160 	char *(*d_dname)(struct dentry *, char *, int);
161 	struct vfsmount *(*d_automount)(struct path *);
162 	int (*d_manage)(struct dentry *, bool);
163 	struct inode *(*d_select_inode)(struct dentry *, unsigned);
164 	struct dentry *(*d_real)(struct dentry *, struct inode *);
165 } ____cacheline_aligned;
166 
167 /*
168  * Locking rules for dentry_operations callbacks are to be found in
169  * Documentation/filesystems/Locking. Keep it updated!
170  *
171  * FUrther descriptions are found in Documentation/filesystems/vfs.txt.
172  * Keep it updated too!
173  */
174 
175 /* d_flags entries */
176 #define DCACHE_OP_HASH			0x00000001
177 #define DCACHE_OP_COMPARE		0x00000002
178 #define DCACHE_OP_REVALIDATE		0x00000004
179 #define DCACHE_OP_DELETE		0x00000008
180 #define DCACHE_OP_PRUNE			0x00000010
181 
182 #define	DCACHE_DISCONNECTED		0x00000020
183      /* This dentry is possibly not currently connected to the dcache tree, in
184       * which case its parent will either be itself, or will have this flag as
185       * well.  nfsd will not use a dentry with this bit set, but will first
186       * endeavour to clear the bit either by discovering that it is connected,
187       * or by performing lookup operations.   Any filesystem which supports
188       * nfsd_operations MUST have a lookup function which, if it finds a
189       * directory inode with a DCACHE_DISCONNECTED dentry, will d_move that
190       * dentry into place and return that dentry rather than the passed one,
191       * typically using d_splice_alias. */
192 
193 #define DCACHE_REFERENCED		0x00000040 /* Recently used, don't discard. */
194 #define DCACHE_RCUACCESS		0x00000080 /* Entry has ever been RCU-visible */
195 
196 #define DCACHE_CANT_MOUNT		0x00000100
197 #define DCACHE_GENOCIDE			0x00000200
198 #define DCACHE_SHRINK_LIST		0x00000400
199 
200 #define DCACHE_OP_WEAK_REVALIDATE	0x00000800
201 
202 #define DCACHE_NFSFS_RENAMED		0x00001000
203      /* this dentry has been "silly renamed" and has to be deleted on the last
204       * dput() */
205 #define DCACHE_COOKIE			0x00002000 /* For use by dcookie subsystem */
206 #define DCACHE_FSNOTIFY_PARENT_WATCHED	0x00004000
207      /* Parent inode is watched by some fsnotify listener */
208 
209 #define DCACHE_DENTRY_KILLED		0x00008000
210 
211 #define DCACHE_MOUNTED			0x00010000 /* is a mountpoint */
212 #define DCACHE_NEED_AUTOMOUNT		0x00020000 /* handle automount on this dir */
213 #define DCACHE_MANAGE_TRANSIT		0x00040000 /* manage transit from this dirent */
214 #define DCACHE_MANAGED_DENTRY \
215 	(DCACHE_MOUNTED|DCACHE_NEED_AUTOMOUNT|DCACHE_MANAGE_TRANSIT)
216 
217 #define DCACHE_LRU_LIST			0x00080000
218 
219 #define DCACHE_ENTRY_TYPE		0x00700000
220 #define DCACHE_MISS_TYPE		0x00000000 /* Negative dentry (maybe fallthru to nowhere) */
221 #define DCACHE_WHITEOUT_TYPE		0x00100000 /* Whiteout dentry (stop pathwalk) */
222 #define DCACHE_DIRECTORY_TYPE		0x00200000 /* Normal directory */
223 #define DCACHE_AUTODIR_TYPE		0x00300000 /* Lookupless directory (presumed automount) */
224 #define DCACHE_REGULAR_TYPE		0x00400000 /* Regular file type (or fallthru to such) */
225 #define DCACHE_SPECIAL_TYPE		0x00500000 /* Other file type (or fallthru to such) */
226 #define DCACHE_SYMLINK_TYPE		0x00600000 /* Symlink (or fallthru to such) */
227 
228 #define DCACHE_MAY_FREE			0x00800000
229 #define DCACHE_FALLTHRU			0x01000000 /* Fall through to lower layer */
230 #define DCACHE_OP_SELECT_INODE		0x02000000 /* Unioned entry: dcache op selects inode */
231 #define DCACHE_OP_REAL			0x08000000
232 
233 extern seqlock_t rename_lock;
234 
235 /*
236  * These are the low-level FS interfaces to the dcache..
237  */
238 extern void d_instantiate(struct dentry *, struct inode *);
239 extern struct dentry * d_instantiate_unique(struct dentry *, struct inode *);
240 extern int d_instantiate_no_diralias(struct dentry *, struct inode *);
241 extern void __d_drop(struct dentry *dentry);
242 extern void d_drop(struct dentry *dentry);
243 extern void d_delete(struct dentry *);
244 extern void d_set_d_op(struct dentry *dentry, const struct dentry_operations *op);
245 
246 /* allocate/de-allocate */
247 extern struct dentry * d_alloc(struct dentry *, const struct qstr *);
248 extern struct dentry * d_alloc_pseudo(struct super_block *, const struct qstr *);
249 extern struct dentry * d_splice_alias(struct inode *, struct dentry *);
250 extern struct dentry * d_add_ci(struct dentry *, struct inode *, struct qstr *);
251 extern struct dentry *d_find_any_alias(struct inode *inode);
252 extern struct dentry * d_obtain_alias(struct inode *);
253 extern struct dentry * d_obtain_root(struct inode *);
254 extern void shrink_dcache_sb(struct super_block *);
255 extern void shrink_dcache_parent(struct dentry *);
256 extern void shrink_dcache_for_umount(struct super_block *);
257 extern void d_invalidate(struct dentry *);
258 
259 /* only used at mount-time */
260 extern struct dentry * d_make_root(struct inode *);
261 
262 /* <clickety>-<click> the ramfs-type tree */
263 extern void d_genocide(struct dentry *);
264 
265 extern void d_tmpfile(struct dentry *, struct inode *);
266 
267 extern struct dentry *d_find_alias(struct inode *);
268 extern void d_prune_aliases(struct inode *);
269 
270 /* test whether we have any submounts in a subdir tree */
271 extern int have_submounts(struct dentry *);
272 
273 /*
274  * This adds the entry to the hash queues.
275  */
276 extern void d_rehash(struct dentry *);
277 
278 /**
279  * d_add - add dentry to hash queues
280  * @entry: dentry to add
281  * @inode: The inode to attach to this dentry
282  *
283  * This adds the entry to the hash queues and initializes @inode.
284  * The entry was actually filled in earlier during d_alloc().
285  */
286 
d_add(struct dentry * entry,struct inode * inode)287 static inline void d_add(struct dentry *entry, struct inode *inode)
288 {
289 	d_instantiate(entry, inode);
290 	d_rehash(entry);
291 }
292 
293 /**
294  * d_add_unique - add dentry to hash queues without aliasing
295  * @entry: dentry to add
296  * @inode: The inode to attach to this dentry
297  *
298  * This adds the entry to the hash queues and initializes @inode.
299  * The entry was actually filled in earlier during d_alloc().
300  */
d_add_unique(struct dentry * entry,struct inode * inode)301 static inline struct dentry *d_add_unique(struct dentry *entry, struct inode *inode)
302 {
303 	struct dentry *res;
304 
305 	res = d_instantiate_unique(entry, inode);
306 	d_rehash(res != NULL ? res : entry);
307 	return res;
308 }
309 
310 extern void dentry_update_name_case(struct dentry *, struct qstr *);
311 
312 /* used for rename() and baskets */
313 extern void d_move(struct dentry *, struct dentry *);
314 extern void d_exchange(struct dentry *, struct dentry *);
315 extern struct dentry *d_ancestor(struct dentry *, struct dentry *);
316 
317 /* appendix may either be NULL or be used for transname suffixes */
318 extern struct dentry *d_lookup(const struct dentry *, const struct qstr *);
319 extern struct dentry *d_hash_and_lookup(struct dentry *, struct qstr *);
320 extern struct dentry *__d_lookup(const struct dentry *, const struct qstr *);
321 extern struct dentry *__d_lookup_rcu(const struct dentry *parent,
322 				const struct qstr *name, unsigned *seq);
323 
d_count(const struct dentry * dentry)324 static inline unsigned d_count(const struct dentry *dentry)
325 {
326 	return dentry->d_lockref.count;
327 }
328 
329 /*
330  * helper function for dentry_operations.d_dname() members
331  */
332 extern __printf(4, 5)
333 char *dynamic_dname(struct dentry *, char *, int, const char *, ...);
334 extern char *simple_dname(struct dentry *, char *, int);
335 
336 extern char *__d_path(const struct path *, const struct path *, char *, int);
337 extern char *d_absolute_path(const struct path *, char *, int);
338 extern char *d_path(const struct path *, char *, int);
339 extern char *dentry_path_raw(struct dentry *, char *, int);
340 extern char *dentry_path(struct dentry *, char *, int);
341 
342 /* Allocation counts.. */
343 
344 /**
345  *	dget, dget_dlock -	get a reference to a dentry
346  *	@dentry: dentry to get a reference to
347  *
348  *	Given a dentry or %NULL pointer increment the reference count
349  *	if appropriate and return the dentry. A dentry will not be
350  *	destroyed when it has references.
351  */
dget_dlock(struct dentry * dentry)352 static inline struct dentry *dget_dlock(struct dentry *dentry)
353 {
354 	if (dentry)
355 		dentry->d_lockref.count++;
356 	return dentry;
357 }
358 
dget(struct dentry * dentry)359 static inline struct dentry *dget(struct dentry *dentry)
360 {
361 	if (dentry)
362 		lockref_get(&dentry->d_lockref);
363 	return dentry;
364 }
365 
366 extern struct dentry *dget_parent(struct dentry *dentry);
367 
368 /**
369  *	d_unhashed -	is dentry hashed
370  *	@dentry: entry to check
371  *
372  *	Returns true if the dentry passed is not currently hashed.
373  */
374 
d_unhashed(const struct dentry * dentry)375 static inline int d_unhashed(const struct dentry *dentry)
376 {
377 	return hlist_bl_unhashed(&dentry->d_hash);
378 }
379 
d_unlinked(const struct dentry * dentry)380 static inline int d_unlinked(const struct dentry *dentry)
381 {
382 	return d_unhashed(dentry) && !IS_ROOT(dentry);
383 }
384 
cant_mount(const struct dentry * dentry)385 static inline int cant_mount(const struct dentry *dentry)
386 {
387 	return (dentry->d_flags & DCACHE_CANT_MOUNT);
388 }
389 
dont_mount(struct dentry * dentry)390 static inline void dont_mount(struct dentry *dentry)
391 {
392 	spin_lock(&dentry->d_lock);
393 	dentry->d_flags |= DCACHE_CANT_MOUNT;
394 	spin_unlock(&dentry->d_lock);
395 }
396 
397 extern void dput(struct dentry *);
398 
d_managed(const struct dentry * dentry)399 static inline bool d_managed(const struct dentry *dentry)
400 {
401 	return dentry->d_flags & DCACHE_MANAGED_DENTRY;
402 }
403 
d_mountpoint(const struct dentry * dentry)404 static inline bool d_mountpoint(const struct dentry *dentry)
405 {
406 	return dentry->d_flags & DCACHE_MOUNTED;
407 }
408 
409 /*
410  * Directory cache entry type accessor functions.
411  */
__d_entry_type(const struct dentry * dentry)412 static inline unsigned __d_entry_type(const struct dentry *dentry)
413 {
414 	return dentry->d_flags & DCACHE_ENTRY_TYPE;
415 }
416 
d_is_miss(const struct dentry * dentry)417 static inline bool d_is_miss(const struct dentry *dentry)
418 {
419 	return __d_entry_type(dentry) == DCACHE_MISS_TYPE;
420 }
421 
d_is_whiteout(const struct dentry * dentry)422 static inline bool d_is_whiteout(const struct dentry *dentry)
423 {
424 	return __d_entry_type(dentry) == DCACHE_WHITEOUT_TYPE;
425 }
426 
d_can_lookup(const struct dentry * dentry)427 static inline bool d_can_lookup(const struct dentry *dentry)
428 {
429 	return __d_entry_type(dentry) == DCACHE_DIRECTORY_TYPE;
430 }
431 
d_is_autodir(const struct dentry * dentry)432 static inline bool d_is_autodir(const struct dentry *dentry)
433 {
434 	return __d_entry_type(dentry) == DCACHE_AUTODIR_TYPE;
435 }
436 
d_is_dir(const struct dentry * dentry)437 static inline bool d_is_dir(const struct dentry *dentry)
438 {
439 	return d_can_lookup(dentry) || d_is_autodir(dentry);
440 }
441 
d_is_symlink(const struct dentry * dentry)442 static inline bool d_is_symlink(const struct dentry *dentry)
443 {
444 	return __d_entry_type(dentry) == DCACHE_SYMLINK_TYPE;
445 }
446 
d_is_reg(const struct dentry * dentry)447 static inline bool d_is_reg(const struct dentry *dentry)
448 {
449 	return __d_entry_type(dentry) == DCACHE_REGULAR_TYPE;
450 }
451 
d_is_special(const struct dentry * dentry)452 static inline bool d_is_special(const struct dentry *dentry)
453 {
454 	return __d_entry_type(dentry) == DCACHE_SPECIAL_TYPE;
455 }
456 
d_is_file(const struct dentry * dentry)457 static inline bool d_is_file(const struct dentry *dentry)
458 {
459 	return d_is_reg(dentry) || d_is_special(dentry);
460 }
461 
d_is_negative(const struct dentry * dentry)462 static inline bool d_is_negative(const struct dentry *dentry)
463 {
464 	// TODO: check d_is_whiteout(dentry) also.
465 	return d_is_miss(dentry);
466 }
467 
d_is_positive(const struct dentry * dentry)468 static inline bool d_is_positive(const struct dentry *dentry)
469 {
470 	return !d_is_negative(dentry);
471 }
472 
473 /**
474  * d_really_is_negative - Determine if a dentry is really negative (ignoring fallthroughs)
475  * @dentry: The dentry in question
476  *
477  * Returns true if the dentry represents either an absent name or a name that
478  * doesn't map to an inode (ie. ->d_inode is NULL).  The dentry could represent
479  * a true miss, a whiteout that isn't represented by a 0,0 chardev or a
480  * fallthrough marker in an opaque directory.
481  *
482  * Note!  (1) This should be used *only* by a filesystem to examine its own
483  * dentries.  It should not be used to look at some other filesystem's
484  * dentries.  (2) It should also be used in combination with d_inode() to get
485  * the inode.  (3) The dentry may have something attached to ->d_lower and the
486  * type field of the flags may be set to something other than miss or whiteout.
487  */
d_really_is_negative(const struct dentry * dentry)488 static inline bool d_really_is_negative(const struct dentry *dentry)
489 {
490 	return dentry->d_inode == NULL;
491 }
492 
493 /**
494  * d_really_is_positive - Determine if a dentry is really positive (ignoring fallthroughs)
495  * @dentry: The dentry in question
496  *
497  * Returns true if the dentry represents a name that maps to an inode
498  * (ie. ->d_inode is not NULL).  The dentry might still represent a whiteout if
499  * that is represented on medium as a 0,0 chardev.
500  *
501  * Note!  (1) This should be used *only* by a filesystem to examine its own
502  * dentries.  It should not be used to look at some other filesystem's
503  * dentries.  (2) It should also be used in combination with d_inode() to get
504  * the inode.
505  */
d_really_is_positive(const struct dentry * dentry)506 static inline bool d_really_is_positive(const struct dentry *dentry)
507 {
508 	return dentry->d_inode != NULL;
509 }
510 
simple_positive(struct dentry * dentry)511 static inline int simple_positive(struct dentry *dentry)
512 {
513 	return d_really_is_positive(dentry) && !d_unhashed(dentry);
514 }
515 
516 extern void d_set_fallthru(struct dentry *dentry);
517 
d_is_fallthru(const struct dentry * dentry)518 static inline bool d_is_fallthru(const struct dentry *dentry)
519 {
520 	return dentry->d_flags & DCACHE_FALLTHRU;
521 }
522 
523 
524 extern int sysctl_vfs_cache_pressure;
525 
vfs_pressure_ratio(unsigned long val)526 static inline unsigned long vfs_pressure_ratio(unsigned long val)
527 {
528 	return mult_frac(val, sysctl_vfs_cache_pressure, 100);
529 }
530 
531 /**
532  * d_inode - Get the actual inode of this dentry
533  * @dentry: The dentry to query
534  *
535  * This is the helper normal filesystems should use to get at their own inodes
536  * in their own dentries and ignore the layering superimposed upon them.
537  */
d_inode(const struct dentry * dentry)538 static inline struct inode *d_inode(const struct dentry *dentry)
539 {
540 	return dentry->d_inode;
541 }
542 
543 /**
544  * d_inode_rcu - Get the actual inode of this dentry with ACCESS_ONCE()
545  * @dentry: The dentry to query
546  *
547  * This is the helper normal filesystems should use to get at their own inodes
548  * in their own dentries and ignore the layering superimposed upon them.
549  */
d_inode_rcu(const struct dentry * dentry)550 static inline struct inode *d_inode_rcu(const struct dentry *dentry)
551 {
552 	return ACCESS_ONCE(dentry->d_inode);
553 }
554 
555 /**
556  * d_backing_inode - Get upper or lower inode we should be using
557  * @upper: The upper layer
558  *
559  * This is the helper that should be used to get at the inode that will be used
560  * if this dentry were to be opened as a file.  The inode may be on the upper
561  * dentry or it may be on a lower dentry pinned by the upper.
562  *
563  * Normal filesystems should not use this to access their own inodes.
564  */
d_backing_inode(const struct dentry * upper)565 static inline struct inode *d_backing_inode(const struct dentry *upper)
566 {
567 	struct inode *inode = upper->d_inode;
568 
569 	return inode;
570 }
571 
572 /**
573  * d_backing_dentry - Get upper or lower dentry we should be using
574  * @upper: The upper layer
575  *
576  * This is the helper that should be used to get the dentry of the inode that
577  * will be used if this dentry were opened as a file.  It may be the upper
578  * dentry or it may be a lower dentry pinned by the upper.
579  *
580  * Normal filesystems should not use this to access their own dentries.
581  */
d_backing_dentry(struct dentry * upper)582 static inline struct dentry *d_backing_dentry(struct dentry *upper)
583 {
584 	return upper;
585 }
586 
d_real(struct dentry * dentry)587 static inline struct dentry *d_real(struct dentry *dentry)
588 {
589 	if (unlikely(dentry->d_flags & DCACHE_OP_REAL))
590 		return dentry->d_op->d_real(dentry, NULL);
591 	else
592 		return dentry;
593 }
594 
vfs_select_inode(struct dentry * dentry,unsigned open_flags)595 static inline struct inode *vfs_select_inode(struct dentry *dentry,
596 					     unsigned open_flags)
597 {
598 	struct inode *inode = d_inode(dentry);
599 
600 	if (inode && unlikely(dentry->d_flags & DCACHE_OP_SELECT_INODE))
601 		inode = dentry->d_op->d_select_inode(dentry, open_flags);
602 
603 	return inode;
604 }
605 
606 
607 #endif	/* __LINUX_DCACHE_H */
608