[deliverable/linux.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>

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 */
#ifdef CONFIG_PROFILING
	struct dcookie_struct *d_cookie; /* cookie, if any */
#endif
	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>
1da177e4 LT	11
	12	struct nameidata;
	13	struct vfsmount;
	14
	15	/*
	16	* linux/include/linux/dcache.h
	17	*
	18	* Dirent cache data structures
	19	*
	20	* (C) Copyright 1997 Thomas Schoebel-Theuer,
	21	* with heavy changes by Linus Torvalds
	22	*/
	23
	24	#define IS_ROOT(x) ((x) == (x)->d_parent)
	25
	26	/*
	27	* "quick string" -- eases parameter passing, but more importantly
	28	* saves "metadata" about the string (ie length and the hash).
	29	*
	30	* hash comes first so it snuggles against d_parent in the
	31	* dentry.
	32	*/
	33	struct qstr {
	34	unsigned int hash;
	35	unsigned int len;
	36	const unsigned char *name;
	37	};
	38
	39	struct dentry_stat_t {
	40	int nr_dentry;
	41	int nr_unused;
	42	int age_limit; /* age in seconds */
	43	int want_pages; /* pages requested by system */
	44	int dummy[2];
	45	};
	46	extern struct dentry_stat_t dentry_stat;
	47
	48	/* Name hashing routines. Initial hash value */
	49	/* Hash courtesy of the R5 hash in reiserfs modulo sign bits */
	50	#define init_name_hash() 0
	51
	52	/* partial hash update function. Assume roughly 4 bits per character */
	53	static inline unsigned long
	54	partial_name_hash(unsigned long c, unsigned long prevhash)
	55	{
	56	return (prevhash + (c << 4) + (c >> 4)) * 11;
	57	}
	58
	59	/*
	60	* Finally: cut down the number of bits to a int value (and try to avoid
	61	* losing bits)
	62	*/
	63	static inline unsigned long end_name_hash(unsigned long hash)
	64	{
	65	return (unsigned int) hash;
	66	}
	67
	68	/* Compute the hash for a name string. */
	69	static inline unsigned int
	70	full_name_hash(const unsigned char *name, unsigned int len)
	71	{
	72	unsigned long hash = init_name_hash();
	73	while (len--)
	74	hash = partial_name_hash(*name++, hash);
75	return end_name_hash(hash);
76	}
77
78	struct dcookie_struct;
79
80	#define DNAME_INLINE_LEN_MIN 36
81
82	struct dentry {
83	atomic_t d_count;
84	unsigned int d_flags; /* protected by d_lock */
85	spinlock_t d_lock; /* per dentry lock */
86	struct inode d_inode; / Where the name belongs to - NULL is
87	* negative */
88	/*
89	* The next three fields are touched by __d_lookup. Place them here
3f4bb1f4	90	* so they all fit in a cache line.
1da177e4	91	*/
3f4bb1f4	92	struct hlist_node d_hash; /* lookup hash list */
1da177e4 LT	93	struct dentry d_parent; / parent directory */
	94	struct qstr d_name;
	95
	96	struct list_head d_lru; /* LRU list */
5160ee6f ED	97	/*
	98	* d_child and d_rcu can share memory
	99	*/
	100	union {
	101	struct list_head d_child; /* child of parent list */
	102	struct rcu_head d_rcu;
	103	} d_u;
1da177e4 LT	104	struct list_head d_subdirs; /* our children */
	105	struct list_head d_alias; /* inode alias list */
	106	unsigned long d_time; /* used by d_revalidate */
	107	struct dentry_operations *d_op;
	108	struct super_block d_sb; / The root of the dentry tree */
	109	void d_fsdata; / fs-specific data */
47ba87e0	110	#ifdef CONFIG_PROFILING
1da177e4	111	struct dcookie_struct d_cookie; / cookie, if any */
47ba87e0	112	#endif
1da177e4 LT	113	int d_mounted;
	114	unsigned char d_iname[DNAME_INLINE_LEN_MIN]; /* small names */
	115	};
	116
	117	struct dentry_operations {
	118	int (d_revalidate)(struct dentry , struct nameidata *);
	119	int (d_hash) (struct dentry , struct qstr *);
	120	int (d_compare) (struct dentry , struct qstr , struct qstr );
	121	int (d_delete)(struct dentry );
	122	void (d_release)(struct dentry );
	123	void (d_iput)(struct dentry , struct inode *);
	124	};
	125
	126	/* the dentry parameter passed to d_hash and d_compare is the parent
	127	* directory of the entries to be compared. It is used in case these
	128	* functions need any directory specific information for determining
	129	* equivalency classes. Using the dentry itself might not work, as it
	130	* might be a negative dentry which has no information associated with
	131	* it */
	132
	133	/*
	134	locking rules:
	135	big lock dcache_lock d_lock may block
	136	d_revalidate: no no no yes
	137	d_hash no no no yes
	138	d_compare: no yes yes no
	139	d_delete: no yes no no
	140	d_release: no no no yes
	141	d_iput: no no no yes
	142	*/
	143
	144	/* d_flags entries */
	145	#define DCACHE_AUTOFS_PENDING 0x0001 /* autofs: "under construction" */
	146	#define DCACHE_NFSFS_RENAMED 0x0002 /* this dentry has been "silly
	147	* renamed" and has to be
	148	* deleted on the last dput()
	149	*/
	150	#define DCACHE_DISCONNECTED 0x0004
	151	/* This dentry is possibly not currently connected to the dcache tree,
	152	* in which case its parent will either be itself, or will have this
	153	* flag as well. nfsd will not use a dentry with this bit set, but will
	154	* first endeavour to clear the bit either by discovering that it is
	155	* connected, or by performing lookup operations. Any filesystem which
	156	* supports nfsd_operations MUST have a lookup function which, if it finds
	157	* a directory inode with a DCACHE_DISCONNECTED dentry, will d_move
	158	* that dentry into place and return that dentry rather than the passed one,
	159	* typically using d_splice_alias.
	160	*/
	161
	162	#define DCACHE_REFERENCED 0x0008 /* Recently used, don't discard. */
	163	#define DCACHE_UNHASHED 0x0010
	164
	165	extern spinlock_t dcache_lock;
	166
	167	/**
	168	* d_drop - drop a dentry
	169	* @dentry: dentry to drop
	170	*
	171	* d_drop() unhashes the entry from the parent dentry hashes, so that it won't
	172	* be found through a VFS lookup any more. Note that this is different from
	173	* deleting the dentry - d_delete will try to mark the dentry negative if
	174	* possible, giving a successful _negative_ lookup, while d_drop will
	175	* just make the cache lookup fail.
	176	*
177	* d_drop() is used mainly for stuff that wants to invalidate a dentry for some
178	* reason (NFS timeouts or autofs deletes).
179	*
180	* __d_drop requires dentry->d_lock.
181	*/
182
183	static inline void __d_drop(struct dentry *dentry)
184	{
185	if (!(dentry->d_flags & DCACHE_UNHASHED)) {
186	dentry->d_flags \|= DCACHE_UNHASHED;
187	hlist_del_rcu(&dentry->d_hash);
188	}
189	}
190
191	static inline void d_drop(struct dentry *dentry)
192	{
193	spin_lock(&dcache_lock);
194	spin_lock(&dentry->d_lock);
195	__d_drop(dentry);
196	spin_unlock(&dentry->d_lock);
197	spin_unlock(&dcache_lock);
198	}
199
200	static inline int dname_external(struct dentry *dentry)
201	{
202	return dentry->d_name.name != dentry->d_iname;
203	}
204
205	/*
206	* These are the low-level FS interfaces to the dcache..
207	*/
208	extern void d_instantiate(struct dentry , struct inode );
209	extern struct dentry * d_instantiate_unique(struct dentry , struct inode );
210	extern void d_delete(struct dentry *);
211
212	/* allocate/de-allocate */
213	extern struct dentry * d_alloc(struct dentry , const struct qstr );
214	extern struct dentry * d_alloc_anon(struct inode *);
215	extern struct dentry * d_splice_alias(struct inode , struct dentry );
216	extern void shrink_dcache_sb(struct super_block *);
217	extern void shrink_dcache_parent(struct dentry *);
218	extern void shrink_dcache_anon(struct hlist_head *);
219	extern int d_invalidate(struct dentry *);
220
221	/* only used at mount-time */
222	extern struct dentry * d_alloc_root(struct inode *);
223
224	/* <clickety>-<click> the ramfs-type tree */
225	extern void d_genocide(struct dentry *);
226
227	extern struct dentry d_find_alias(struct inode );
228	extern void d_prune_aliases(struct inode *);
229
230	/* test whether we have any submounts in a subdir tree */
231	extern int have_submounts(struct dentry *);
232
233	/*
234	* This adds the entry to the hash queues.
235	*/
236	extern void d_rehash(struct dentry *);
237
238	/**
239	* d_add - add dentry to hash queues
240	* @entry: dentry to add
241	* @inode: The inode to attach to this dentry
242	*
243	* This adds the entry to the hash queues and initializes @inode.
244	* The entry was actually filled in earlier during d_alloc().
245	*/
246
247	static inline void d_add(struct dentry entry, struct inode inode)
248	{
249	d_instantiate(entry, inode);
250	d_rehash(entry);
251	}
252
253	/**
254	* d_add_unique - add dentry to hash queues without aliasing
255	* @entry: dentry to add
256	* @inode: The inode to attach to this dentry
257	*
258	* This adds the entry to the hash queues and initializes @inode.
259	* The entry was actually filled in earlier during d_alloc().
260	*/
261	static inline struct dentry d_add_unique(struct dentry entry, struct inode *inode)
262	{
263	struct dentry *res;
264
265	res = d_instantiate_unique(entry, inode);
266	d_rehash(res != NULL ? res : entry);
267	return res;
268	}
269
270	/* used for rename() and baskets */
271	extern void d_move(struct dentry , struct dentry );
272
273	/* appendix may either be NULL or be used for transname suffixes */
274	extern struct dentry * d_lookup(struct dentry , struct qstr );
275	extern struct dentry * __d_lookup(struct dentry , struct qstr );
276
277	/* validate "insecure" dentry pointer */
278	extern int d_validate(struct dentry , struct dentry );
279
280	extern char * d_path(struct dentry , struct vfsmount , char *, int);
281
282	/* Allocation counts.. */
283
284	/**
285	* dget, dget_locked - get a reference to a dentry
286	* @dentry: dentry to get a reference to
287	*
288	* Given a dentry or %NULL pointer increment the reference count
289	* if appropriate and return the dentry. A dentry will not be
290	* destroyed when it has references. dget() should never be
291	* called for dentries with zero reference counter. For these cases
292	* (preferably none, functions in dcache.c are sufficient for normal
293	* needs and they take necessary precautions) you should hold dcache_lock
294	* and call dget_locked() instead of dget().
295	*/
296
297	static inline struct dentry dget(struct dentry dentry)
298	{
299	if (dentry) {
300	BUG_ON(!atomic_read(&dentry->d_count));
301	atomic_inc(&dentry->d_count);
302	}
303	return dentry;
304	}
305
306	extern struct dentry * dget_locked(struct dentry *);
307
308	/**
309	* d_unhashed - is dentry hashed
310	* @dentry: entry to check
311	*
312	* Returns true if the dentry passed is not currently hashed.
313	*/
314
315	static inline int d_unhashed(struct dentry *dentry)
316	{
317	return (dentry->d_flags & DCACHE_UNHASHED);
318	}
319
320	static inline struct dentry dget_parent(struct dentry dentry)
321	{
322	struct dentry *ret;
323
324	spin_lock(&dentry->d_lock);
325	ret = dget(dentry->d_parent);
326	spin_unlock(&dentry->d_lock);
327	return ret;
328	}
329
330	extern void dput(struct dentry *);
331
332	static inline int d_mountpoint(struct dentry *dentry)
333	{
334	return dentry->d_mounted;
335	}
336
337	extern struct vfsmount lookup_mnt(struct vfsmount , struct dentry *);
a05964f3	338	extern struct vfsmount __lookup_mnt(struct vfsmount , struct dentry *, int);
1da177e4 LT	339	extern struct dentry lookup_create(struct nameidata nd, int is_dir);
	340
	341	extern int sysctl_vfs_cache_pressure;
	342
	343	#endif /* __KERNEL__ */
	344
	345	#endif /* __LINUX_DCACHE_H */