[deliverable/linux.git] / include / linux / dcache.h

#ifndef __LINUX_DCACHE_H
#define __LINUX_DCACHE_H

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

struct nameidata;
struct path;
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);
}

/*
 * Try to keep struct dentry aligned on 64 byte cachelines (this will
 * give reasonable cacheline footprint with larger lines without the
 * large memory footprint increase).
 */
#ifdef CONFIG_64BIT
#define DNAME_INLINE_LEN_MIN 32 /* 192 bytes */
#else
#define DNAME_INLINE_LEN_MIN 40 /* 128 bytes */
#endif

struct dentry {
	unsigned int d_count;		/* protected by d_lock */
	unsigned int d_flags;		/* protected by d_lock */
	spinlock_t d_lock;		/* per dentry lock */
	seqcount_t d_seq;		/* per dentry seqlock */
	int d_mounted;
	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 */
	const struct dentry_operations *d_op;
	struct super_block *d_sb;	/* The root of the dentry tree */
	void *d_fsdata;			/* fs-specific data */

	unsigned char d_iname[DNAME_INLINE_LEN_MIN];	/* small names */
};

/*
 * dentry->d_lock spinlock nesting subclasses:
 *
 * 0: normal
 * 1: nested
 */
enum dentry_d_lock_class
{
	DENTRY_D_LOCK_NORMAL, /* implicitly used by plain spin_lock() APIs. */
	DENTRY_D_LOCK_NESTED
};

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

/*
 * Locking rules for dentry_operations callbacks are to be found in
 * Documentation/filesystems/Locking. Keep it updated!
 *
 * FUrther descriptions are found in Documentation/filesystems/vfs.txt.
 * Keep it updated too!
 */

/* 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	

#define DCACHE_INOTIFY_PARENT_WATCHED	0x0020 /* Parent inode is watched by inotify */

#define DCACHE_COOKIE		0x0040	/* For use by dcookie subsystem */

#define DCACHE_FSNOTIFY_PARENT_WATCHED	0x0080 /* Parent inode is watched by some fsnotify listener */

#define DCACHE_CANT_MOUNT	0x0100
#define DCACHE_GENOCIDE		0x0200

extern spinlock_t dcache_inode_lock;
extern seqlock_t rename_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 struct dentry * d_materialise_unique(struct dentry *, struct inode *);
extern void __d_drop(struct dentry *dentry);
extern void d_drop(struct dentry *dentry);
extern void d_delete(struct dentry *);

/* allocate/de-allocate */
extern struct dentry * d_alloc(struct dentry *, const struct qstr *);
extern struct dentry * d_splice_alias(struct inode *, struct dentry *);
extern struct dentry * d_add_ci(struct dentry *, struct inode *, struct qstr *);
extern struct dentry * d_obtain_alias(struct inode *);
extern void shrink_dcache_sb(struct super_block *);
extern void shrink_dcache_parent(struct dentry *);
extern void shrink_dcache_for_umount(struct super_block *);
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;
}

extern void dentry_update_name_case(struct dentry *, struct qstr *);

/* used for rename() and baskets */
extern void d_move(struct dentry *, struct dentry *);
extern struct dentry *d_ancestor(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_hash_and_lookup(struct dentry *, struct qstr *);
extern struct dentry *__d_lookup(struct dentry *, struct qstr *);
extern struct dentry *__d_lookup_rcu(struct dentry *parent, struct qstr *name,
				unsigned *seq, struct inode **inode);

/**
 * __d_rcu_to_refcount - take a refcount on dentry if sequence check is ok
 * @dentry: dentry to take a ref on
 * @seq: seqcount to verify against
 * @Returns: 0 on failure, else 1.
 *
 * __d_rcu_to_refcount operates on a dentry,seq pair that was returned
 * by __d_lookup_rcu, to get a reference on an rcu-walk dentry.
 */
static inline int __d_rcu_to_refcount(struct dentry *dentry, unsigned seq)
{
	int ret = 0;

	assert_spin_locked(&dentry->d_lock);
	if (!read_seqcount_retry(&dentry->d_seq, seq)) {
		ret = 1;
		dentry->d_count++;
	}

	return ret;
}

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

/*
 * helper function for dentry_operations.d_dname() members
 */
extern char *dynamic_dname(struct dentry *, char *, int, const char *, ...);

extern char *__d_path(const struct path *path, struct path *root, char *, int);
extern char *d_path(const struct path *, char *, int);
extern char *d_path_with_unreachable(const struct path *, char *, int);
extern char *dentry_path_raw(struct dentry *, char *, int);
extern char *dentry_path(struct dentry *, char *, int);

/* Allocation counts.. */

/**
 *	dget, dget_dlock -	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.
 */
static inline struct dentry *dget_dlock(struct dentry *dentry)
{
	if (dentry)
		dentry->d_count++;
	return dentry;
}

static inline struct dentry *dget(struct dentry *dentry)
{
	if (dentry) {
		spin_lock(&dentry->d_lock);
		dget_dlock(dentry);
		spin_unlock(&dentry->d_lock);
	}
	return dentry;
}

extern struct dentry *dget_parent(struct dentry *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 int d_unlinked(struct dentry *dentry)
{
	return d_unhashed(dentry) && !IS_ROOT(dentry);
}

static inline int cant_mount(struct dentry *dentry)
{
	return (dentry->d_flags & DCACHE_CANT_MOUNT);
}

static inline void dont_mount(struct dentry *dentry)
{
	spin_lock(&dentry->d_lock);
	dentry->d_flags |= DCACHE_CANT_MOUNT;
	spin_unlock(&dentry->d_lock);
}

extern void dput(struct dentry *);

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

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

extern int sysctl_vfs_cache_pressure;

#endif	/* __LINUX_DCACHE_H */
Commit	Line	Data
1da177e4 LT	1	#ifndef __LINUX_DCACHE_H
	2	#define __LINUX_DCACHE_H
	3
1da177e4 LT	4	#include <asm/atomic.h>
1da177e4 LT	5	#include <linux/list.h>
82524746	6	#include <linux/rculist.h>
1da177e4	7	#include <linux/spinlock.h>
31e6b01f	8	#include <linux/seqlock.h>
1da177e4 LT	9	#include <linux/cache.h>
1da177e4 LT	10	#include <linux/rcupdate.h>
1da177e4 LT	11
1da177e4 LT	12	struct nameidata;
cf28b486	13	struct path;
1da177e4 LT	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
c2452f32 NP	79	/*
	80	* Try to keep struct dentry aligned on 64 byte cachelines (this will
	81	* give reasonable cacheline footprint with larger lines without the
	82	* large memory footprint increase).
	83	*/
	84	#ifdef CONFIG_64BIT
	85	#define DNAME_INLINE_LEN_MIN 32 /* 192 bytes */
	86	#else
	87	#define DNAME_INLINE_LEN_MIN 40 /* 128 bytes */
	88	#endif
1da177e4 LT	89
1da177e4 LT	90	struct dentry {
b7ab39f6	91	unsigned int d_count; /* protected by d_lock */
1da177e4 LT	92	unsigned int d_flags; /* protected by d_lock */
1da177e4 LT	93	spinlock_t d_lock; /* per dentry lock */
31e6b01f	94	seqcount_t d_seq; /* per dentry seqlock */
c2452f32	95	int d_mounted;
1da177e4 LT	96	struct inode d_inode; / Where the name belongs to - NULL is
	97	* negative */
	98	/*
	99	* The next three fields are touched by __d_lookup. Place them here
3f4bb1f4	100	* so they all fit in a cache line.
1da177e4	101	*/
3f4bb1f4	102	struct hlist_node d_hash; /* lookup hash list */
1da177e4 LT	103	struct dentry d_parent; / parent directory */
	104	struct qstr d_name;
	105
	106	struct list_head d_lru; /* LRU list */
5160ee6f ED	107	/*
	108	* d_child and d_rcu can share memory
	109	*/
	110	union {
	111	struct list_head d_child; /* child of parent list */
	112	struct rcu_head d_rcu;
	113	} d_u;
1da177e4 LT	114	struct list_head d_subdirs; /* our children */
	115	struct list_head d_alias; /* inode alias list */
	116	unsigned long d_time; /* used by d_revalidate */
e56980d4	117	const struct dentry_operations *d_op;
1da177e4 LT	118	struct super_block d_sb; / The root of the dentry tree */
1da177e4 LT	119	void d_fsdata; / fs-specific data */
c2452f32	120
1da177e4 LT	121	unsigned char d_iname[DNAME_INLINE_LEN_MIN]; /* small names */
	122	};
	123
a90b9c05 IM	124	/*
	125	* dentry->d_lock spinlock nesting subclasses:
	126	*
	127	* 0: normal
	128	* 1: nested
	129	*/
	130	enum dentry_d_lock_class
	131	{
	132	DENTRY_D_LOCK_NORMAL, /* implicitly used by plain spin_lock() APIs. */
	133	DENTRY_D_LOCK_NESTED
	134	};
	135
1da177e4 LT	136	struct dentry_operations {
1da177e4 LT	137	int (d_revalidate)(struct dentry , struct nameidata *);
b1e6a015 NP	138	int (d_hash)(const struct dentry , const struct inode *,
b1e6a015 NP	139	struct qstr *);
621e155a NP	140	int (d_compare)(const struct dentry , const struct inode *,
	141	const struct dentry , const struct inode ,
	142	unsigned int, const char , const struct qstr );
fe15ce44	143	int (d_delete)(const struct dentry );
1da177e4 LT	144	void (d_release)(struct dentry );
1da177e4 LT	145	void (d_iput)(struct dentry , struct inode *);
c23fbb6b	146	char (d_dname)(struct dentry , char , int);
1da177e4 LT	147	};
1da177e4 LT	148
5eef7fa9 NP	149	/*
	150	* Locking rules for dentry_operations callbacks are to be found in
	151	* Documentation/filesystems/Locking. Keep it updated!
	152	*
621e155a NP	153	* FUrther descriptions are found in Documentation/filesystems/vfs.txt.
621e155a NP	154	* Keep it updated too!
1da177e4 LT	155	*/
	156
	157	/* d_flags entries */
	158	#define DCACHE_AUTOFS_PENDING 0x0001 /* autofs: "under construction" */
	159	#define DCACHE_NFSFS_RENAMED 0x0002 /* this dentry has been "silly
	160	* renamed" and has to be
	161	* deleted on the last dput()
	162	*/
	163	#define DCACHE_DISCONNECTED 0x0004
	164	/* This dentry is possibly not currently connected to the dcache tree,
	165	* in which case its parent will either be itself, or will have this
	166	* flag as well. nfsd will not use a dentry with this bit set, but will
	167	* first endeavour to clear the bit either by discovering that it is
	168	* connected, or by performing lookup operations. Any filesystem which
	169	* supports nfsd_operations MUST have a lookup function which, if it finds
	170	* a directory inode with a DCACHE_DISCONNECTED dentry, will d_move
	171	* that dentry into place and return that dentry rather than the passed one,
	172	* typically using d_splice_alias.
	173	*/
	174
	175	#define DCACHE_REFERENCED 0x0008 /* Recently used, don't discard. */
	176	#define DCACHE_UNHASHED 0x0010
	177
c28f7e56	178	#define DCACHE_INOTIFY_PARENT_WATCHED 0x0020 /* Parent inode is watched by inotify */
c32ccd87	179
c2452f32 NP	180	#define DCACHE_COOKIE 0x0040 /* For use by dcookie subsystem */
c2452f32 NP	181
c28f7e56 EP	182	#define DCACHE_FSNOTIFY_PARENT_WATCHED 0x0080 /* Parent inode is watched by some fsnotify listener */
c28f7e56 EP	183
d83c49f3	184	#define DCACHE_CANT_MOUNT 0x0100
949854d0	185	#define DCACHE_GENOCIDE 0x0200
d83c49f3	186
b23fb0a6	187	extern spinlock_t dcache_inode_lock;
74c3cbe3	188	extern seqlock_t rename_lock;
1da177e4	189
1da177e4 LT	190	static inline int dname_external(struct dentry *dentry)
	191	{
	192	return dentry->d_name.name != dentry->d_iname;
	193	}
	194
	195	/*
	196	* These are the low-level FS interfaces to the dcache..
	197	*/
	198	extern void d_instantiate(struct dentry , struct inode );
	199	extern struct dentry * d_instantiate_unique(struct dentry , struct inode );
770bfad8	200	extern struct dentry * d_materialise_unique(struct dentry , struct inode );
789680d1 NP	201	extern void __d_drop(struct dentry *dentry);
789680d1 NP	202	extern void d_drop(struct dentry *dentry);
1da177e4 LT	203	extern void d_delete(struct dentry *);
	204
	205	/* allocate/de-allocate */
	206	extern struct dentry * d_alloc(struct dentry , const struct qstr );
1da177e4	207	extern struct dentry * d_splice_alias(struct inode , struct dentry );
e45b590b	208	extern struct dentry * d_add_ci(struct dentry , struct inode , struct qstr *);
4ea3ada2	209	extern struct dentry * d_obtain_alias(struct inode *);
1da177e4 LT	210	extern void shrink_dcache_sb(struct super_block *);
1da177e4 LT	211	extern void shrink_dcache_parent(struct dentry *);
c636ebdb	212	extern void shrink_dcache_for_umount(struct super_block *);
1da177e4 LT	213	extern int d_invalidate(struct dentry *);
	214
	215	/* only used at mount-time */
	216	extern struct dentry * d_alloc_root(struct inode *);
	217
	218	/* <clickety>-<click> the ramfs-type tree */
	219	extern void d_genocide(struct dentry *);
	220
	221	extern struct dentry d_find_alias(struct inode );
	222	extern void d_prune_aliases(struct inode *);
	223
	224	/* test whether we have any submounts in a subdir tree */
	225	extern int have_submounts(struct dentry *);
	226
	227	/*
	228	* This adds the entry to the hash queues.
	229	*/
	230	extern void d_rehash(struct dentry *);
	231
	232	/**
	233	* d_add - add dentry to hash queues
	234	* @entry: dentry to add
	235	* @inode: The inode to attach to this dentry
	236	*
	237	* This adds the entry to the hash queues and initializes @inode.
	238	* The entry was actually filled in earlier during d_alloc().
	239	*/
	240
	241	static inline void d_add(struct dentry entry, struct inode inode)
	242	{
	243	d_instantiate(entry, inode);
	244	d_rehash(entry);
	245	}
	246
	247	/**
	248	* d_add_unique - add dentry to hash queues without aliasing
	249	* @entry: dentry to add
	250	* @inode: The inode to attach to this dentry
	251	*
	252	* This adds the entry to the hash queues and initializes @inode.
	253	* The entry was actually filled in earlier during d_alloc().
	254	*/
	255	static inline struct dentry d_add_unique(struct dentry entry, struct inode *inode)
	256	{
	257	struct dentry *res;
	258
	259	res = d_instantiate_unique(entry, inode);
	260	d_rehash(res != NULL ? res : entry);
	261	return res;
	262	}
	263
fb2d5b86 NP	264	extern void dentry_update_name_case(struct dentry , struct qstr );
fb2d5b86 NP	265
1da177e4 LT	266	/* used for rename() and baskets */
1da177e4 LT	267	extern void d_move(struct dentry , struct dentry );
e2761a11	268	extern struct dentry d_ancestor(struct dentry , struct dentry *);
1da177e4 LT	269
1da177e4 LT	270	/* appendix may either be NULL or be used for transname suffixes */
31e6b01f NP	271	extern struct dentry d_lookup(struct dentry , struct qstr *);
	272	extern struct dentry d_hash_and_lookup(struct dentry , struct qstr *);
	273	extern struct dentry __d_lookup(struct dentry , struct qstr *);
	274	extern struct dentry __d_lookup_rcu(struct dentry parent, struct qstr *name,
	275	unsigned seq, struct inode *inode);
	276
	277	/**
	278	* __d_rcu_to_refcount - take a refcount on dentry if sequence check is ok
	279	* @dentry: dentry to take a ref on
	280	* @seq: seqcount to verify against
	281	* @Returns: 0 on failure, else 1.
	282	*
	283	* __d_rcu_to_refcount operates on a dentry,seq pair that was returned
	284	* by __d_lookup_rcu, to get a reference on an rcu-walk dentry.
	285	*/
	286	static inline int __d_rcu_to_refcount(struct dentry *dentry, unsigned seq)
	287	{
	288	int ret = 0;
	289
	290	assert_spin_locked(&dentry->d_lock);
	291	if (!read_seqcount_retry(&dentry->d_seq, seq)) {
	292	ret = 1;
	293	dentry->d_count++;
	294	}
	295
	296	return ret;
	297	}
1da177e4 LT	298
	299	/* validate "insecure" dentry pointer */
	300	extern int d_validate(struct dentry , struct dentry );
	301
c23fbb6b ED	302	/*
	303	* helper function for dentry_operations.d_dname() members
	304	*/
	305	extern char dynamic_dname(struct dentry , char , int, const char , ...);
	306
9d1bc601	307	extern char __d_path(const struct path path, struct path root, char , int);
20d4fdc1	308	extern char d_path(const struct path , char *, int);
8df9d1a4	309	extern char d_path_with_unreachable(const struct path , char *, int);
ec2447c2	310	extern char dentry_path_raw(struct dentry , char *, int);
6092d048	311	extern char dentry_path(struct dentry , char *, int);
cf28b486	312
1da177e4 LT	313	/* Allocation counts.. */
	314
	315	/**
dc0474be	316	* dget, dget_dlock - get a reference to a dentry
1da177e4 LT	317	* @dentry: dentry to get a reference to
	318	*
	319	* Given a dentry or %NULL pointer increment the reference count
	320	* if appropriate and return the dentry. A dentry will not be
dc0474be	321	* destroyed when it has references.
1da177e4	322	*/
b7ab39f6 NP	323	static inline struct dentry dget_dlock(struct dentry dentry)
b7ab39f6 NP	324	{
dc0474be	325	if (dentry)
b7ab39f6	326	dentry->d_count++;
b7ab39f6 NP	327	return dentry;
b7ab39f6 NP	328	}
2fd6b7f5	329
1da177e4 LT	330	static inline struct dentry dget(struct dentry dentry)
	331	{
	332	if (dentry) {
b7ab39f6 NP	333	spin_lock(&dentry->d_lock);
	334	dget_dlock(dentry);
	335	spin_unlock(&dentry->d_lock);
1da177e4 LT	336	}
	337	return dentry;
	338	}
	339
b7ab39f6	340	extern struct dentry dget_parent(struct dentry dentry);
1da177e4 LT	341
	342	/**
	343	* d_unhashed - is dentry hashed
	344	* @dentry: entry to check
	345	*
	346	* Returns true if the dentry passed is not currently hashed.
	347	*/
	348
	349	static inline int d_unhashed(struct dentry *dentry)
	350	{
	351	return (dentry->d_flags & DCACHE_UNHASHED);
	352	}
	353
f3da392e AD	354	static inline int d_unlinked(struct dentry *dentry)
	355	{
	356	return d_unhashed(dentry) && !IS_ROOT(dentry);
	357	}
	358
d83c49f3 AV	359	static inline int cant_mount(struct dentry *dentry)
	360	{
	361	return (dentry->d_flags & DCACHE_CANT_MOUNT);
	362	}
	363
	364	static inline void dont_mount(struct dentry *dentry)
	365	{
	366	spin_lock(&dentry->d_lock);
	367	dentry->d_flags \|= DCACHE_CANT_MOUNT;
	368	spin_unlock(&dentry->d_lock);
	369	}
	370
1da177e4 LT	371	extern void dput(struct dentry *);
	372
	373	static inline int d_mountpoint(struct dentry *dentry)
	374	{
	375	return dentry->d_mounted;
	376	}
	377
1c755af4	378	extern struct vfsmount lookup_mnt(struct path );
1da177e4 LT	379	extern struct dentry lookup_create(struct nameidata nd, int is_dir);
	380
	381	extern int sysctl_vfs_cache_pressure;
	382
1da177e4	383	#endif /* __LINUX_DCACHE_H */