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

#ifndef __LINUX_DCACHE_H
#define __LINUX_DCACHE_H

#include <linux/atomic.h>
#include <linux/list.h>
#include <linux/rculist.h>
#include <linux/rculist_bl.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)

/* The hash is always the low bits of hash_len */
#ifdef __LITTLE_ENDIAN
 #define HASH_LEN_DECLARE u32 hash; u32 len;
#else
 #define HASH_LEN_DECLARE u32 len; u32 hash;
#endif

/*
 * "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 {
	union {
		struct {
			HASH_LEN_DECLARE;
		};
		u64 hash_len;
	};
	const unsigned char *name;
};

#define QSTR_INIT(n,l) { { { .len = l } }, .name = n }
#define hashlen_hash(hashlen) ((u32) (hashlen))
#define hashlen_len(hashlen)  ((u32)((hashlen) >> 32))

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. */
extern unsigned int full_name_hash(const unsigned char *, unsigned int);

/*
 * 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 32 /* 192 bytes */
#else
# ifdef CONFIG_SMP
#  define DNAME_INLINE_LEN 36 /* 128 bytes */
# else
#  define DNAME_INLINE_LEN 40 /* 128 bytes */
# endif
#endif

struct dentry {
	/* RCU lookup touched fields */
	unsigned int d_flags;		/* protected by d_lock */
	seqcount_t d_seq;		/* per dentry seqlock */
	struct hlist_bl_node d_hash;	/* lookup hash list */
	struct dentry *d_parent;	/* parent directory */
	struct qstr d_name;
	struct inode *d_inode;		/* Where the name belongs to - NULL is
					 * negative */
	unsigned char d_iname[DNAME_INLINE_LEN];	/* small names */

	/* Ref lookup also touches following */
	unsigned int d_count;		/* protected by d_lock */
	spinlock_t d_lock;		/* per dentry lock */
	const struct dentry_operations *d_op;
	struct super_block *d_sb;	/* The root of the dentry tree */
	unsigned long d_time;		/* used by d_revalidate */
	void *d_fsdata;			/* fs-specific data */

	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 hlist_node d_alias;	/* inode alias list */
};

/*
 * 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 *, unsigned int);
	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_prune)(struct dentry *);
	void (*d_iput)(struct dentry *, struct inode *);
	char *(*d_dname)(struct dentry *, char *, int);
	struct vfsmount *(*d_automount)(struct path *);
	int (*d_manage)(struct dentry *, bool);
} ____cacheline_aligned;

/*
 * 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_OP_HASH		0x0001
#define DCACHE_OP_COMPARE	0x0002
#define DCACHE_OP_REVALIDATE	0x0004
#define DCACHE_OP_DELETE	0x0008
#define DCACHE_OP_PRUNE         0x0010

#define	DCACHE_DISCONNECTED	0x0020
     /* 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	0x0040  /* Recently used, don't discard. */
#define DCACHE_RCUACCESS	0x0080	/* Entry has ever been RCU-visible */

#define DCACHE_CANT_MOUNT	0x0100
#define DCACHE_GENOCIDE		0x0200
#define DCACHE_SHRINK_LIST	0x0400

#define DCACHE_NFSFS_RENAMED	0x1000
     /* this dentry has been "silly renamed" and has to be deleted on the last
      * dput() */
#define DCACHE_COOKIE		0x2000	/* For use by dcookie subsystem */
#define DCACHE_FSNOTIFY_PARENT_WATCHED 0x4000
     /* Parent inode is watched by some fsnotify listener */

#define DCACHE_MOUNTED		0x10000	/* is a mountpoint */
#define DCACHE_NEED_AUTOMOUNT	0x20000	/* handle automount on this dir */
#define DCACHE_MANAGE_TRANSIT	0x40000	/* manage transit from this dirent */
#define DCACHE_NEED_LOOKUP	0x80000 /* dentry requires i_op->lookup */
#define DCACHE_MANAGED_DENTRY \
	(DCACHE_MOUNTED|DCACHE_NEED_AUTOMOUNT|DCACHE_MANAGE_TRANSIT)

#define DCACHE_DENTRY_KILLED	0x100000

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 *);
extern void d_set_d_op(struct dentry *dentry, const struct dentry_operations *op);

/* allocate/de-allocate */
extern struct dentry * d_alloc(struct dentry *, const struct qstr *);
extern struct dentry * d_alloc_pseudo(struct super_block *, 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_find_any_alias(struct inode *inode);
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_make_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(const struct dentry *parent,
				const 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 *, const struct path *, char *, int);
extern char *d_absolute_path(const struct path *, 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 hlist_bl_unhashed(&dentry->d_hash);
}

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 bool d_managed(struct dentry *dentry)
{
	return dentry->d_flags & DCACHE_MANAGED_DENTRY;
}

static inline bool d_mountpoint(struct dentry *dentry)
{
	return dentry->d_flags & DCACHE_MOUNTED;
}

static inline bool d_need_lookup(struct dentry *dentry)
{
	return dentry->d_flags & DCACHE_NEED_LOOKUP;
}

extern void d_clear_need_lookup(struct dentry *dentry);

extern int sysctl_vfs_cache_pressure;

#endif	/* __LINUX_DCACHE_H */
Commit	Line	Data
	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
	13	struct nameidata;
	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	#else
	32	#define HASH_LEN_DECLARE u32 len; u32 hash;
	33	#endif
	34
	35	/*
	36	* "quick string" -- eases parameter passing, but more importantly
	37	* saves "metadata" about the string (ie length and the hash).
	38	*
	39	* hash comes first so it snuggles against d_parent in the
	40	* dentry.
	41	*/
	42	struct qstr {
	43	union {
	44	struct {
	45	HASH_LEN_DECLARE;
	46	};
	47	u64 hash_len;
	48	};
	49	const unsigned char *name;
	50	};
	51
	52	#define QSTR_INIT(n,l) { { { .len = l } }, .name = n }
	53	#define hashlen_hash(hashlen) ((u32) (hashlen))
	54	#define hashlen_len(hashlen) ((u32)((hashlen) >> 32))
	55
	56	struct dentry_stat_t {
	57	int nr_dentry;
	58	int nr_unused;
	59	int age_limit; /* age in seconds */
	60	int want_pages; /* pages requested by system */
	61	int dummy[2];
	62	};
	63	extern struct dentry_stat_t dentry_stat;
	64
	65	/* Name hashing routines. Initial hash value */
	66	/* Hash courtesy of the R5 hash in reiserfs modulo sign bits */
	67	#define init_name_hash() 0
	68
	69	/* partial hash update function. Assume roughly 4 bits per character */
	70	static inline unsigned long
	71	partial_name_hash(unsigned long c, unsigned long prevhash)
	72	{
	73	return (prevhash + (c << 4) + (c >> 4)) * 11;
	74	}
	75
	76	/*
	77	* Finally: cut down the number of bits to a int value (and try to avoid
	78	* losing bits)
	79	*/
	80	static inline unsigned long end_name_hash(unsigned long hash)
	81	{
	82	return (unsigned int) hash;
	83	}
	84
	85	/* Compute the hash for a name string. */
	86	extern unsigned int full_name_hash(const unsigned char *, unsigned int);
	87
	88	/*
	89	* Try to keep struct dentry aligned on 64 byte cachelines (this will
	90	* give reasonable cacheline footprint with larger lines without the
	91	* large memory footprint increase).
	92	*/
	93	#ifdef CONFIG_64BIT
	94	# define DNAME_INLINE_LEN 32 /* 192 bytes */
	95	#else
	96	# ifdef CONFIG_SMP
	97	# define DNAME_INLINE_LEN 36 /* 128 bytes */
	98	# else
	99	# define DNAME_INLINE_LEN 40 /* 128 bytes */
	100	# endif
	101	#endif
	102
	103	struct dentry {
	104	/* RCU lookup touched fields */
	105	unsigned int d_flags; /* protected by d_lock */
	106	seqcount_t d_seq; /* per dentry seqlock */
	107	struct hlist_bl_node d_hash; /* lookup hash list */
	108	struct dentry d_parent; / parent directory */
	109	struct qstr d_name;
	110	struct inode d_inode; / Where the name belongs to - NULL is
	111	* negative */
	112	unsigned char d_iname[DNAME_INLINE_LEN]; /* small names */
	113
	114	/* Ref lookup also touches following */
	115	unsigned int d_count; /* protected by d_lock */
	116	spinlock_t d_lock; /* per dentry lock */
	117	const struct dentry_operations *d_op;
	118	struct super_block d_sb; / The root of the dentry tree */
	119	unsigned long d_time; /* used by d_revalidate */
	120	void d_fsdata; / fs-specific data */
	121
	122	struct list_head d_lru; /* LRU list */
	123	/*
	124	* d_child and d_rcu can share memory
	125	*/
	126	union {
	127	struct list_head d_child; /* child of parent list */
	128	struct rcu_head d_rcu;
	129	} d_u;
	130	struct list_head d_subdirs; /* our children */
	131	struct hlist_node d_alias; /* inode alias list */
	132	};
	133
	134	/*
	135	* dentry->d_lock spinlock nesting subclasses:
	136	*
	137	* 0: normal
	138	* 1: nested
	139	*/
	140	enum dentry_d_lock_class
	141	{
	142	DENTRY_D_LOCK_NORMAL, /* implicitly used by plain spin_lock() APIs. */
	143	DENTRY_D_LOCK_NESTED
	144	};
	145
	146	struct dentry_operations {
	147	int (d_revalidate)(struct dentry , unsigned int);
	148	int (d_hash)(const struct dentry , const struct inode *,
	149	struct qstr *);
	150	int (d_compare)(const struct dentry , const struct inode *,
	151	const struct dentry , const struct inode ,
	152	unsigned int, const char , const struct qstr );
	153	int (d_delete)(const struct dentry );
	154	void (d_release)(struct dentry );
	155	void (d_prune)(struct dentry );
	156	void (d_iput)(struct dentry , struct inode *);
	157	char (d_dname)(struct dentry , char , int);
	158	struct vfsmount (d_automount)(struct path *);
	159	int (d_manage)(struct dentry , bool);
	160	} ____cacheline_aligned;
	161
	162	/*
	163	* Locking rules for dentry_operations callbacks are to be found in
	164	* Documentation/filesystems/Locking. Keep it updated!
	165	*
	166	* FUrther descriptions are found in Documentation/filesystems/vfs.txt.
	167	* Keep it updated too!
	168	*/
	169
	170	/* d_flags entries */
	171	#define DCACHE_OP_HASH 0x0001
	172	#define DCACHE_OP_COMPARE 0x0002
	173	#define DCACHE_OP_REVALIDATE 0x0004
	174	#define DCACHE_OP_DELETE 0x0008
	175	#define DCACHE_OP_PRUNE 0x0010
	176
	177	#define DCACHE_DISCONNECTED 0x0020
	178	/* This dentry is possibly not currently connected to the dcache tree, in
	179	* which case its parent will either be itself, or will have this flag as
	180	* well. nfsd will not use a dentry with this bit set, but will first
	181	* endeavour to clear the bit either by discovering that it is connected,
	182	* or by performing lookup operations. Any filesystem which supports
	183	* nfsd_operations MUST have a lookup function which, if it finds a
	184	* directory inode with a DCACHE_DISCONNECTED dentry, will d_move that
	185	* dentry into place and return that dentry rather than the passed one,
	186	* typically using d_splice_alias. */
	187
	188	#define DCACHE_REFERENCED 0x0040 /* Recently used, don't discard. */
	189	#define DCACHE_RCUACCESS 0x0080 /* Entry has ever been RCU-visible */
	190
	191	#define DCACHE_CANT_MOUNT 0x0100
	192	#define DCACHE_GENOCIDE 0x0200
	193	#define DCACHE_SHRINK_LIST 0x0400
	194
	195	#define DCACHE_NFSFS_RENAMED 0x1000
	196	/* this dentry has been "silly renamed" and has to be deleted on the last
	197	* dput() */
	198	#define DCACHE_COOKIE 0x2000 /* For use by dcookie subsystem */
	199	#define DCACHE_FSNOTIFY_PARENT_WATCHED 0x4000
	200	/* Parent inode is watched by some fsnotify listener */
	201
	202	#define DCACHE_MOUNTED 0x10000 /* is a mountpoint */
	203	#define DCACHE_NEED_AUTOMOUNT 0x20000 /* handle automount on this dir */
	204	#define DCACHE_MANAGE_TRANSIT 0x40000 /* manage transit from this dirent */
	205	#define DCACHE_NEED_LOOKUP 0x80000 /* dentry requires i_op->lookup */
	206	#define DCACHE_MANAGED_DENTRY \
	207	(DCACHE_MOUNTED\|DCACHE_NEED_AUTOMOUNT\|DCACHE_MANAGE_TRANSIT)
	208
	209	#define DCACHE_DENTRY_KILLED 0x100000
	210
	211	extern seqlock_t rename_lock;
	212
	213	static inline int dname_external(struct dentry *dentry)
	214	{
	215	return dentry->d_name.name != dentry->d_iname;
	216	}
	217
	218	/*
	219	* These are the low-level FS interfaces to the dcache..
	220	*/
	221	extern void d_instantiate(struct dentry , struct inode );
	222	extern struct dentry * d_instantiate_unique(struct dentry , struct inode );
	223	extern struct dentry * d_materialise_unique(struct dentry , struct inode );
	224	extern void __d_drop(struct dentry *dentry);
	225	extern void d_drop(struct dentry *dentry);
	226	extern void d_delete(struct dentry *);
	227	extern void d_set_d_op(struct dentry dentry, const struct dentry_operations op);
	228
	229	/* allocate/de-allocate */
	230	extern struct dentry * d_alloc(struct dentry , const struct qstr );
	231	extern struct dentry * d_alloc_pseudo(struct super_block , const struct qstr );
	232	extern struct dentry * d_splice_alias(struct inode , struct dentry );
	233	extern struct dentry * d_add_ci(struct dentry , struct inode , struct qstr *);
	234	extern struct dentry d_find_any_alias(struct inode inode);
	235	extern struct dentry * d_obtain_alias(struct inode *);
	236	extern void shrink_dcache_sb(struct super_block *);
	237	extern void shrink_dcache_parent(struct dentry *);
	238	extern void shrink_dcache_for_umount(struct super_block *);
	239	extern int d_invalidate(struct dentry *);
	240
	241	/* only used at mount-time */
	242	extern struct dentry * d_make_root(struct inode *);
	243
	244	/* <clickety>-<click> the ramfs-type tree */
	245	extern void d_genocide(struct dentry *);
	246
	247	extern struct dentry d_find_alias(struct inode );
	248	extern void d_prune_aliases(struct inode *);
	249
	250	/* test whether we have any submounts in a subdir tree */
	251	extern int have_submounts(struct dentry *);
	252
	253	/*
	254	* This adds the entry to the hash queues.
	255	*/
	256	extern void d_rehash(struct dentry *);
	257
	258	/**
	259	* d_add - add dentry to hash queues
	260	* @entry: dentry to add
	261	* @inode: The inode to attach to this dentry
	262	*
	263	* This adds the entry to the hash queues and initializes @inode.
	264	* The entry was actually filled in earlier during d_alloc().
	265	*/
	266
	267	static inline void d_add(struct dentry entry, struct inode inode)
	268	{
	269	d_instantiate(entry, inode);
	270	d_rehash(entry);
	271	}
	272
	273	/**
	274	* d_add_unique - add dentry to hash queues without aliasing
	275	* @entry: dentry to add
	276	* @inode: The inode to attach to this dentry
	277	*
	278	* This adds the entry to the hash queues and initializes @inode.
	279	* The entry was actually filled in earlier during d_alloc().
	280	*/
	281	static inline struct dentry d_add_unique(struct dentry entry, struct inode *inode)
	282	{
	283	struct dentry *res;
	284
	285	res = d_instantiate_unique(entry, inode);
	286	d_rehash(res != NULL ? res : entry);
	287	return res;
	288	}
	289
	290	extern void dentry_update_name_case(struct dentry , struct qstr );
	291
	292	/* used for rename() and baskets */
	293	extern void d_move(struct dentry , struct dentry );
	294	extern struct dentry d_ancestor(struct dentry , struct dentry *);
	295
	296	/* appendix may either be NULL or be used for transname suffixes */
	297	extern struct dentry d_lookup(struct dentry , struct qstr *);
	298	extern struct dentry d_hash_and_lookup(struct dentry , struct qstr *);
	299	extern struct dentry __d_lookup(struct dentry , struct qstr *);
	300	extern struct dentry __d_lookup_rcu(const struct dentry parent,
	301	const struct qstr *name,
	302	unsigned seq, struct inode inode);
	303
	304	/**
	305	* __d_rcu_to_refcount - take a refcount on dentry if sequence check is ok
	306	* @dentry: dentry to take a ref on
	307	* @seq: seqcount to verify against
	308	* Returns: 0 on failure, else 1.
	309	*
	310	* __d_rcu_to_refcount operates on a dentry,seq pair that was returned
	311	* by __d_lookup_rcu, to get a reference on an rcu-walk dentry.
	312	*/
	313	static inline int __d_rcu_to_refcount(struct dentry *dentry, unsigned seq)
	314	{
	315	int ret = 0;
	316
	317	assert_spin_locked(&dentry->d_lock);
	318	if (!read_seqcount_retry(&dentry->d_seq, seq)) {
	319	ret = 1;
	320	dentry->d_count++;
	321	}
	322
	323	return ret;
	324	}
	325
	326	/* validate "insecure" dentry pointer */
	327	extern int d_validate(struct dentry , struct dentry );
	328
	329	/*
	330	* helper function for dentry_operations.d_dname() members
	331	*/
	332	extern char dynamic_dname(struct dentry , char , int, const char , ...);
	333
	334	extern char __d_path(const struct path , const struct path , char , int);
	335	extern char d_absolute_path(const struct path , char *, int);
	336	extern char d_path(const struct path , char *, int);
	337	extern char d_path_with_unreachable(const struct path , char *, int);
	338	extern char dentry_path_raw(struct dentry , char *, int);
	339	extern char dentry_path(struct dentry , char *, int);
	340
	341	/* Allocation counts.. */
	342
	343	/**
	344	* dget, dget_dlock - get a reference to a dentry
	345	* @dentry: dentry to get a reference to
	346	*
	347	* Given a dentry or %NULL pointer increment the reference count
	348	* if appropriate and return the dentry. A dentry will not be
	349	* destroyed when it has references.
	350	*/
	351	static inline struct dentry dget_dlock(struct dentry dentry)
	352	{
	353	if (dentry)
	354	dentry->d_count++;
	355	return dentry;
	356	}
	357
	358	static inline struct dentry dget(struct dentry dentry)
	359	{
	360	if (dentry) {
	361	spin_lock(&dentry->d_lock);
	362	dget_dlock(dentry);
	363	spin_unlock(&dentry->d_lock);
	364	}
	365	return dentry;
	366	}
	367
	368	extern struct dentry dget_parent(struct dentry dentry);
	369
	370	/**
	371	* d_unhashed - is dentry hashed
	372	* @dentry: entry to check
	373	*
	374	* Returns true if the dentry passed is not currently hashed.
	375	*/
	376
	377	static inline int d_unhashed(struct dentry *dentry)
	378	{
	379	return hlist_bl_unhashed(&dentry->d_hash);
	380	}
	381
	382	static inline int d_unlinked(struct dentry *dentry)
	383	{
	384	return d_unhashed(dentry) && !IS_ROOT(dentry);
	385	}
	386
	387	static inline int cant_mount(struct dentry *dentry)
	388	{
	389	return (dentry->d_flags & DCACHE_CANT_MOUNT);
	390	}
	391
	392	static inline void dont_mount(struct dentry *dentry)
	393	{
	394	spin_lock(&dentry->d_lock);
	395	dentry->d_flags \|= DCACHE_CANT_MOUNT;
	396	spin_unlock(&dentry->d_lock);
	397	}
	398
	399	extern void dput(struct dentry *);
	400
	401	static inline bool d_managed(struct dentry *dentry)
	402	{
	403	return dentry->d_flags & DCACHE_MANAGED_DENTRY;
	404	}
	405
	406	static inline bool d_mountpoint(struct dentry *dentry)
	407	{
	408	return dentry->d_flags & DCACHE_MOUNTED;
	409	}
	410
	411	static inline bool d_need_lookup(struct dentry *dentry)
	412	{
	413	return dentry->d_flags & DCACHE_NEED_LOOKUP;
	414	}
	415
	416	extern void d_clear_need_lookup(struct dentry *dentry);
	417
	418	extern int sysctl_vfs_cache_pressure;
	419
	420	#endif /* __LINUX_DCACHE_H */