[mirror_ubuntu-artful-kernel.git] / include / linux / dcache.h

#ifndef __LINUX_DCACHE_H
#define __LINUX_DCACHE_H

#ifdef __KERNEL__

#include <asm/atomic.h>
#include <linux/list.h>
#include <linux/spinlock.h>
#include <linux/cache.h>
#include <linux/rcupdate.h>
#include <asm/bug.h>

struct nameidata;
struct vfsmount;

/*
 * linux/include/linux/dcache.h
 *
 * Dirent cache data structures
 *
 * (C) Copyright 1997 Thomas Schoebel-Theuer,
 * with heavy changes by Linus Torvalds
 */

#define IS_ROOT(x) ((x) == (x)->d_parent)

/*
 * "quick string" -- eases parameter passing, but more importantly
 * saves "metadata" about the string (ie length and the hash).
 *
 * hash comes first so it snuggles against d_parent in the
 * dentry.
 */
struct qstr {
	unsigned int hash;
	unsigned int len;
	const unsigned char *name;
};

struct dentry_stat_t {
	int nr_dentry;
	int nr_unused;
	int age_limit;          /* age in seconds */
	int want_pages;         /* pages requested by system */
	int dummy[2];
};
extern struct dentry_stat_t dentry_stat;

/* Name hashing routines. Initial hash value */
/* Hash courtesy of the R5 hash in reiserfs modulo sign bits */
#define init_name_hash()		0

/* partial hash update function. Assume roughly 4 bits per character */
static inline unsigned long
partial_name_hash(unsigned long c, unsigned long prevhash)
{
	return (prevhash + (c << 4) + (c >> 4)) * 11;
}

/*
 * Finally: cut down the number of bits to a int value (and try to avoid
 * losing bits)
 */
static inline unsigned long end_name_hash(unsigned long hash)
{
	return (unsigned int) hash;
}

/* Compute the hash for a name string. */
static inline unsigned int
full_name_hash(const unsigned char *name, unsigned int len)
{
	unsigned long hash = init_name_hash();
	while (len--)
		hash = partial_name_hash(*name++, hash);
	return end_name_hash(hash);
}

struct dcookie_struct;

#define DNAME_INLINE_LEN_MIN 36

struct dentry {
	atomic_t d_count;
	unsigned int d_flags;		/* protected by d_lock */
	spinlock_t d_lock;		/* per dentry lock */
	struct inode *d_inode;		/* Where the name belongs to - NULL is
					 * negative */
	/*
	 * The next three fields are touched by __d_lookup.  Place them here
	 * so they all fit in a cache line.
	 */
	struct hlist_node d_hash;	/* lookup hash list */
	struct dentry *d_parent;	/* parent directory */
	struct qstr d_name;

	struct list_head d_lru;		/* LRU list */
	/*
	 * d_child and d_rcu can share memory
	 */
	union {
		struct list_head d_child;	/* child of parent list */
	 	struct rcu_head d_rcu;
	} d_u;
	struct list_head d_subdirs;	/* our children */
	struct list_head d_alias;	/* inode alias list */
	unsigned long d_time;		/* used by d_revalidate */
	struct dentry_operations *d_op;
	struct super_block *d_sb;	/* The root of the dentry tree */
	void *d_fsdata;			/* fs-specific data */
	struct dcookie_struct *d_cookie; /* cookie, if any */
	int d_mounted;
	unsigned char d_iname[DNAME_INLINE_LEN_MIN];	/* small names */
};

struct dentry_operations {
	int (*d_revalidate)(struct dentry *, struct nameidata *);
	int (*d_hash) (struct dentry *, struct qstr *);
	int (*d_compare) (struct dentry *, struct qstr *, struct qstr *);
	int (*d_delete)(struct dentry *);
	void (*d_release)(struct dentry *);
	void (*d_iput)(struct dentry *, struct inode *);
};

/* the dentry parameter passed to d_hash and d_compare is the parent
 * directory of the entries to be compared. It is used in case these
 * functions need any directory specific information for determining
 * equivalency classes.  Using the dentry itself might not work, as it
 * might be a negative dentry which has no information associated with
 * it */

/*
locking rules:
		big lock	dcache_lock	d_lock   may block
d_revalidate:	no		no		no       yes
d_hash		no		no		no       yes
d_compare:	no		yes		yes      no
d_delete:	no		yes		no       no
d_release:	no		no		no       yes
d_iput:		no		no		no       yes
 */

/* d_flags entries */
#define DCACHE_AUTOFS_PENDING 0x0001    /* autofs: "under construction" */
#define DCACHE_NFSFS_RENAMED  0x0002    /* this dentry has been "silly
					 * renamed" and has to be
					 * deleted on the last dput()
					 */
#define	DCACHE_DISCONNECTED 0x0004
     /* This dentry is possibly not currently connected to the dcache tree,
      * in which case its parent will either be itself, or will have this
      * flag as well.  nfsd will not use a dentry with this bit set, but will
      * first endeavour to clear the bit either by discovering that it is
      * connected, or by performing lookup operations.   Any filesystem which
      * supports nfsd_operations MUST have a lookup function which, if it finds
      * a directory inode with a DCACHE_DISCONNECTED dentry, will d_move
      * that dentry into place and return that dentry rather than the passed one,
      * typically using d_splice_alias.
      */

#define DCACHE_REFERENCED	0x0008  /* Recently used, don't discard. */
#define DCACHE_UNHASHED		0x0010	

extern spinlock_t dcache_lock;

/**
 * d_drop - drop a dentry
 * @dentry: dentry to drop
 *
 * d_drop() unhashes the entry from the parent dentry hashes, so that it won't
 * be found through a VFS lookup any more. Note that this is different from
 * deleting the dentry - d_delete will try to mark the dentry negative if
 * possible, giving a successful _negative_ lookup, while d_drop will
 * just make the cache lookup fail.
 *
 * d_drop() is used mainly for stuff that wants to invalidate a dentry for some
 * reason (NFS timeouts or autofs deletes).
 *
 * __d_drop requires dentry->d_lock.
 */

static inline void __d_drop(struct dentry *dentry)
{
	if (!(dentry->d_flags & DCACHE_UNHASHED)) {
		dentry->d_flags |= DCACHE_UNHASHED;
		hlist_del_rcu(&dentry->d_hash);
	}
}

static inline void d_drop(struct dentry *dentry)
{
	spin_lock(&dcache_lock);
	spin_lock(&dentry->d_lock);
 	__d_drop(dentry);
	spin_unlock(&dentry->d_lock);
	spin_unlock(&dcache_lock);
}

static inline int dname_external(struct dentry *dentry)
{
	return dentry->d_name.name != dentry->d_iname;
}

/*
 * These are the low-level FS interfaces to the dcache..
 */
extern void d_instantiate(struct dentry *, struct inode *);
extern struct dentry * d_instantiate_unique(struct dentry *, struct inode *);
extern void d_delete(struct dentry *);

/* allocate/de-allocate */
extern struct dentry * d_alloc(struct dentry *, const struct qstr *);
extern struct dentry * d_alloc_anon(struct inode *);
extern struct dentry * d_splice_alias(struct inode *, struct dentry *);
extern void shrink_dcache_sb(struct super_block *);
extern void shrink_dcache_parent(struct dentry *);
extern void shrink_dcache_anon(struct hlist_head *);
extern int d_invalidate(struct dentry *);

/* only used at mount-time */
extern struct dentry * d_alloc_root(struct inode *);

/* <clickety>-<click> the ramfs-type tree */
extern void d_genocide(struct dentry *);

extern struct dentry *d_find_alias(struct inode *);
extern void d_prune_aliases(struct inode *);

/* test whether we have any submounts in a subdir tree */
extern int have_submounts(struct dentry *);

/*
 * This adds the entry to the hash queues.
 */
extern void d_rehash(struct dentry *);

/**
 * d_add - add dentry to hash queues
 * @entry: dentry to add
 * @inode: The inode to attach to this dentry
 *
 * This adds the entry to the hash queues and initializes @inode.
 * The entry was actually filled in earlier during d_alloc().
 */
 
static inline void d_add(struct dentry *entry, struct inode *inode)
{
	d_instantiate(entry, inode);
	d_rehash(entry);
}

/**
 * d_add_unique - add dentry to hash queues without aliasing
 * @entry: dentry to add
 * @inode: The inode to attach to this dentry
 *
 * This adds the entry to the hash queues and initializes @inode.
 * The entry was actually filled in earlier during d_alloc().
 */
static inline struct dentry *d_add_unique(struct dentry *entry, struct inode *inode)
{
	struct dentry *res;

	res = d_instantiate_unique(entry, inode);
	d_rehash(res != NULL ? res : entry);
	return res;
}

/* used for rename() and baskets */
extern void d_move(struct dentry *, struct dentry *);

/* appendix may either be NULL or be used for transname suffixes */
extern struct dentry * d_lookup(struct dentry *, struct qstr *);
extern struct dentry * __d_lookup(struct dentry *, struct qstr *);

/* validate "insecure" dentry pointer */
extern int d_validate(struct dentry *, struct dentry *);

extern char * d_path(struct dentry *, struct vfsmount *, char *, int);
  
/* Allocation counts.. */

/**
 *	dget, dget_locked	-	get a reference to a dentry
 *	@dentry: dentry to get a reference to
 *
 *	Given a dentry or %NULL pointer increment the reference count
 *	if appropriate and return the dentry. A dentry will not be 
 *	destroyed when it has references. dget() should never be
 *	called for dentries with zero reference counter. For these cases
 *	(preferably none, functions in dcache.c are sufficient for normal
 *	needs and they take necessary precautions) you should hold dcache_lock
 *	and call dget_locked() instead of dget().
 */
 
static inline struct dentry *dget(struct dentry *dentry)
{
	if (dentry) {
		BUG_ON(!atomic_read(&dentry->d_count));
		atomic_inc(&dentry->d_count);
	}
	return dentry;
}

extern struct dentry * dget_locked(struct dentry *);

/**
 *	d_unhashed -	is dentry hashed
 *	@dentry: entry to check
 *
 *	Returns true if the dentry passed is not currently hashed.
 */
 
static inline int d_unhashed(struct dentry *dentry)
{
	return (dentry->d_flags & DCACHE_UNHASHED);
}

static inline struct dentry *dget_parent(struct dentry *dentry)
{
	struct dentry *ret;

	spin_lock(&dentry->d_lock);
	ret = dget(dentry->d_parent);
	spin_unlock(&dentry->d_lock);
	return ret;
}

extern void dput(struct dentry *);

static inline int d_mountpoint(struct dentry *dentry)
{
	return dentry->d_mounted;
}

extern struct vfsmount *lookup_mnt(struct vfsmount *, struct dentry *);
extern struct vfsmount *__lookup_mnt(struct vfsmount *, struct dentry *, int);
extern struct dentry *lookup_create(struct nameidata *nd, int is_dir);

extern int sysctl_vfs_cache_pressure;

#endif /* __KERNEL__ */

#endif	/* __LINUX_DCACHE_H */
Commit	Line	Data
1da177e4 LT	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	#include <asm/bug.h>
	12
	13	struct nameidata;
	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
3f4bb1f4	91	* so they all fit in a cache line.
1da177e4	92	*/
3f4bb1f4	93	struct hlist_node d_hash; /* lookup hash list */
1da177e4 LT	94	struct dentry d_parent; / parent directory */
	95	struct qstr d_name;
	96
	97	struct list_head d_lru; /* LRU list */
5160ee6f ED	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;
1da177e4 LT	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 */
1da177e4	111	struct dcookie_struct d_cookie; / cookie, if any */
1da177e4 LT	112	int d_mounted;
	113	unsigned char d_iname[DNAME_INLINE_LEN_MIN]; /* small names */
	114	};
	115
	116	struct dentry_operations {
	117	int (d_revalidate)(struct dentry , struct nameidata *);
	118	int (d_hash) (struct dentry , struct qstr *);
	119	int (d_compare) (struct dentry , struct qstr , struct qstr );
	120	int (d_delete)(struct dentry );
	121	void (d_release)(struct dentry );
	122	void (d_iput)(struct dentry , struct inode *);
	123	};
	124
	125	/* the dentry parameter passed to d_hash and d_compare is the parent
	126	* directory of the entries to be compared. It is used in case these
	127	* functions need any directory specific information for determining
	128	* equivalency classes. Using the dentry itself might not work, as it
	129	* might be a negative dentry which has no information associated with
	130	* it */
	131
	132	/*
	133	locking rules:
	134	big lock dcache_lock d_lock may block
	135	d_revalidate: no no no yes
	136	d_hash no no no yes
	137	d_compare: no yes yes no
	138	d_delete: no yes no no
	139	d_release: no no no yes
	140	d_iput: no no no yes
	141	*/
	142
	143	/* d_flags entries */
	144	#define DCACHE_AUTOFS_PENDING 0x0001 /* autofs: "under construction" */
	145	#define DCACHE_NFSFS_RENAMED 0x0002 /* this dentry has been "silly
	146	* renamed" and has to be
	147	* deleted on the last dput()
	148	*/
	149	#define DCACHE_DISCONNECTED 0x0004
	150	/* This dentry is possibly not currently connected to the dcache tree,
	151	* in which case its parent will either be itself, or will have this
	152	* flag as well. nfsd will not use a dentry with this bit set, but will
	153	* first endeavour to clear the bit either by discovering that it is
	154	* connected, or by performing lookup operations. Any filesystem which
	155	* supports nfsd_operations MUST have a lookup function which, if it finds
	156	* a directory inode with a DCACHE_DISCONNECTED dentry, will d_move
	157	* that dentry into place and return that dentry rather than the passed one,
	158	* typically using d_splice_alias.
	159	*/
	160
	161	#define DCACHE_REFERENCED 0x0008 /* Recently used, don't discard. */
	162	#define DCACHE_UNHASHED 0x0010
	163
	164	extern spinlock_t dcache_lock;
	165
	166	/**
	167	* d_drop - drop a dentry
	168	* @dentry: dentry to drop
	169	*
	170	* d_drop() unhashes the entry from the parent dentry hashes, so that it won't
	171	* be found through a VFS lookup any more. Note that this is different from
	172	* deleting the dentry - d_delete will try to mark the dentry negative if
	173	* possible, giving a successful _negative_ lookup, while d_drop will
	174	* just make the cache lookup fail.
	175	*
176	* d_drop() is used mainly for stuff that wants to invalidate a dentry for some
177	* reason (NFS timeouts or autofs deletes).
178	*
179	* __d_drop requires dentry->d_lock.
180	*/
181
182	static inline void __d_drop(struct dentry *dentry)
183	{
184	if (!(dentry->d_flags & DCACHE_UNHASHED)) {
185	dentry->d_flags \|= DCACHE_UNHASHED;
186	hlist_del_rcu(&dentry->d_hash);
187	}
188	}
189
190	static inline void d_drop(struct dentry *dentry)
191	{
192	spin_lock(&dcache_lock);
193	spin_lock(&dentry->d_lock);
194	__d_drop(dentry);
195	spin_unlock(&dentry->d_lock);
196	spin_unlock(&dcache_lock);
197	}
198
199	static inline int dname_external(struct dentry *dentry)
200	{
201	return dentry->d_name.name != dentry->d_iname;
202	}
203
204	/*
205	* These are the low-level FS interfaces to the dcache..
206	*/
207	extern void d_instantiate(struct dentry , struct inode );
208	extern struct dentry * d_instantiate_unique(struct dentry , struct inode );
209	extern void d_delete(struct dentry *);
210
211	/* allocate/de-allocate */
212	extern struct dentry * d_alloc(struct dentry , const struct qstr );
213	extern struct dentry * d_alloc_anon(struct inode *);
214	extern struct dentry * d_splice_alias(struct inode , struct dentry );
215	extern void shrink_dcache_sb(struct super_block *);
216	extern void shrink_dcache_parent(struct dentry *);
217	extern void shrink_dcache_anon(struct hlist_head *);
218	extern int d_invalidate(struct dentry *);
219
220	/* only used at mount-time */
221	extern struct dentry * d_alloc_root(struct inode *);
222
223	/* <clickety>-<click> the ramfs-type tree */
224	extern void d_genocide(struct dentry *);
225
226	extern struct dentry d_find_alias(struct inode );
227	extern void d_prune_aliases(struct inode *);
228
229	/* test whether we have any submounts in a subdir tree */
230	extern int have_submounts(struct dentry *);
231
232	/*
233	* This adds the entry to the hash queues.
234	*/
235	extern void d_rehash(struct dentry *);
236
237	/**
238	* d_add - add dentry to hash queues
239	* @entry: dentry to add
240	* @inode: The inode to attach to this dentry
241	*
242	* This adds the entry to the hash queues and initializes @inode.
243	* The entry was actually filled in earlier during d_alloc().
244	*/
245
246	static inline void d_add(struct dentry entry, struct inode inode)
247	{
248	d_instantiate(entry, inode);
249	d_rehash(entry);
250	}
251
252	/**
253	* d_add_unique - add dentry to hash queues without aliasing
254	* @entry: dentry to add
255	* @inode: The inode to attach to this dentry
256	*
257	* This adds the entry to the hash queues and initializes @inode.
258	* The entry was actually filled in earlier during d_alloc().
259	*/
260	static inline struct dentry d_add_unique(struct dentry entry, struct inode *inode)
261	{
262	struct dentry *res;
263
264	res = d_instantiate_unique(entry, inode);
265	d_rehash(res != NULL ? res : entry);
266	return res;
267	}
268
269	/* used for rename() and baskets */
270	extern void d_move(struct dentry , struct dentry );
271
272	/* appendix may either be NULL or be used for transname suffixes */
273	extern struct dentry * d_lookup(struct dentry , struct qstr );
274	extern struct dentry * __d_lookup(struct dentry , struct qstr );
275
276	/* validate "insecure" dentry pointer */
277	extern int d_validate(struct dentry , struct dentry );
278
279	extern char * d_path(struct dentry , struct vfsmount , char *, int);
280
281	/* Allocation counts.. */
282
283	/**
284	* dget, dget_locked - get a reference to a dentry
285	* @dentry: dentry to get a reference to
286	*
287	* Given a dentry or %NULL pointer increment the reference count
288	* if appropriate and return the dentry. A dentry will not be
289	* destroyed when it has references. dget() should never be
290	* called for dentries with zero reference counter. For these cases
291	* (preferably none, functions in dcache.c are sufficient for normal
292	* needs and they take necessary precautions) you should hold dcache_lock
293	* and call dget_locked() instead of dget().
294	*/
295
296	static inline struct dentry dget(struct dentry dentry)
297	{
298	if (dentry) {
299	BUG_ON(!atomic_read(&dentry->d_count));
300	atomic_inc(&dentry->d_count);
301	}
302	return dentry;
303	}
304
305	extern struct dentry * dget_locked(struct dentry *);
306
307	/**
308	* d_unhashed - is dentry hashed
309	* @dentry: entry to check
310	*
311	* Returns true if the dentry passed is not currently hashed.
312	*/
313
314	static inline int d_unhashed(struct dentry *dentry)
315	{
316	return (dentry->d_flags & DCACHE_UNHASHED);
317	}
318
319	static inline struct dentry dget_parent(struct dentry dentry)
320	{
321	struct dentry *ret;
322
323	spin_lock(&dentry->d_lock);
324	ret = dget(dentry->d_parent);
325	spin_unlock(&dentry->d_lock);
326	return ret;
327	}
328
329	extern void dput(struct dentry *);
330
331	static inline int d_mountpoint(struct dentry *dentry)
332	{
333	return dentry->d_mounted;
334	}
335
336	extern struct vfsmount lookup_mnt(struct vfsmount , struct dentry *);
a05964f3	337	extern struct vfsmount __lookup_mnt(struct vfsmount , struct dentry *, int);
1da177e4 LT	338	extern struct dentry lookup_create(struct nameidata nd, int is_dir);
	339
	340	extern int sysctl_vfs_cache_pressure;
	341
	342	#endif /* __KERNEL__ */
	343
	344	#endif /* __LINUX_DCACHE_H */