[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)

/*
 * "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;

/*
 * Compare 2 name strings, return 0 if they match, otherwise non-zero.
 * The strings are both count bytes long, and count is non-zero.
 */
static inline int dentry_cmp(const unsigned char *cs, size_t scount,
				const unsigned char *ct, size_t tcount)
{
	int ret;
	if (scount != tcount)
		return 1;
	do {
		ret = (*cs != *ct);
		if (ret)
			break;
		cs++;
		ct++;
		tcount--;
	} while (tcount);
	return ret;
}

/* 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 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 list_head 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 *, 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_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_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)

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_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 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
1da177e4 LT	1	#ifndef __LINUX_DCACHE_H
	2	#define __LINUX_DCACHE_H
	3
60063497	4	#include <linux/atomic.h>
1da177e4	5	#include <linux/list.h>
82524746	6	#include <linux/rculist.h>
ceb5bdc2	7	#include <linux/rculist_bl.h>
1da177e4	8	#include <linux/spinlock.h>
31e6b01f	9	#include <linux/seqlock.h>
1da177e4 LT	10	#include <linux/cache.h>
1da177e4 LT	11	#include <linux/rcupdate.h>
1da177e4 LT	12
1da177e4 LT	13	struct nameidata;
cf28b486	14	struct path;
1da177e4 LT	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	/*
	29	* "quick string" -- eases parameter passing, but more importantly
	30	* saves "metadata" about the string (ie length and the hash).
	31	*
	32	* hash comes first so it snuggles against d_parent in the
	33	* dentry.
	34	*/
	35	struct qstr {
	36	unsigned int hash;
	37	unsigned int len;
	38	const unsigned char *name;
	39	};
	40
	41	struct dentry_stat_t {
	42	int nr_dentry;
	43	int nr_unused;
	44	int age_limit; /* age in seconds */
	45	int want_pages; /* pages requested by system */
	46	int dummy[2];
	47	};
	48	extern struct dentry_stat_t dentry_stat;
	49
9d55c369 NP	50	/*
	51	* Compare 2 name strings, return 0 if they match, otherwise non-zero.
	52	* The strings are both count bytes long, and count is non-zero.
	53	*/
	54	static inline int dentry_cmp(const unsigned char *cs, size_t scount,
	55	const unsigned char *ct, size_t tcount)
	56	{
	57	int ret;
	58	if (scount != tcount)
	59	return 1;
	60	do {
	61	ret = (cs != ct);
	62	if (ret)
	63	break;
	64	cs++;
	65	ct++;
	66	tcount--;
	67	} while (tcount);
	68	return ret;
	69	}
	70
1da177e4 LT	71	/* Name hashing routines. Initial hash value */
	72	/* Hash courtesy of the R5 hash in reiserfs modulo sign bits */
	73	#define init_name_hash() 0
	74
	75	/* partial hash update function. Assume roughly 4 bits per character */
	76	static inline unsigned long
	77	partial_name_hash(unsigned long c, unsigned long prevhash)
	78	{
	79	return (prevhash + (c << 4) + (c >> 4)) * 11;
	80	}
	81
	82	/*
	83	* Finally: cut down the number of bits to a int value (and try to avoid
	84	* losing bits)
	85	*/
	86	static inline unsigned long end_name_hash(unsigned long hash)
	87	{
	88	return (unsigned int) hash;
	89	}
	90
	91	/* Compute the hash for a name string. */
	92	static inline unsigned int
	93	full_name_hash(const unsigned char *name, unsigned int len)
	94	{
	95	unsigned long hash = init_name_hash();
	96	while (len--)
	97	hash = partial_name_hash(*name++, hash);
	98	return end_name_hash(hash);
	99	}
	100
c2452f32 NP	101	/*
	102	* Try to keep struct dentry aligned on 64 byte cachelines (this will
	103	* give reasonable cacheline footprint with larger lines without the
	104	* large memory footprint increase).
	105	*/
	106	#ifdef CONFIG_64BIT
44a7d7a8	107	# define DNAME_INLINE_LEN 32 /* 192 bytes */
c2452f32	108	#else
44a7d7a8 NP	109	# ifdef CONFIG_SMP
	110	# define DNAME_INLINE_LEN 36 /* 128 bytes */
	111	# else
	112	# define DNAME_INLINE_LEN 40 /* 128 bytes */
	113	# endif
c2452f32	114	#endif
1da177e4 LT	115
1da177e4 LT	116	struct dentry {
44a7d7a8	117	/* RCU lookup touched fields */
1da177e4	118	unsigned int d_flags; /* protected by d_lock */
31e6b01f	119	seqcount_t d_seq; /* per dentry seqlock */
ceb5bdc2	120	struct hlist_bl_node d_hash; /* lookup hash list */
1da177e4 LT	121	struct dentry d_parent; / parent directory */
1da177e4 LT	122	struct qstr d_name;
44a7d7a8 NP	123	struct inode d_inode; / Where the name belongs to - NULL is
	124	* negative */
	125	unsigned char d_iname[DNAME_INLINE_LEN]; /* small names */
	126
	127	/* Ref lookup also touches following */
	128	unsigned int d_count; /* protected by d_lock */
	129	spinlock_t d_lock; /* per dentry lock */
	130	const struct dentry_operations *d_op;
	131	struct super_block d_sb; / The root of the dentry tree */
	132	unsigned long d_time; /* used by d_revalidate */
	133	void d_fsdata; / fs-specific data */
1da177e4 LT	134
1da177e4 LT	135	struct list_head d_lru; /* LRU list */
5160ee6f ED	136	/*
	137	* d_child and d_rcu can share memory
	138	*/
	139	union {
	140	struct list_head d_child; /* child of parent list */
	141	struct rcu_head d_rcu;
	142	} d_u;
1da177e4 LT	143	struct list_head d_subdirs; /* our children */
1da177e4 LT	144	struct list_head d_alias; /* inode alias list */
1da177e4 LT	145	};
1da177e4 LT	146
a90b9c05 IM	147	/*
	148	* dentry->d_lock spinlock nesting subclasses:
	149	*
	150	* 0: normal
	151	* 1: nested
	152	*/
	153	enum dentry_d_lock_class
	154	{
	155	DENTRY_D_LOCK_NORMAL, /* implicitly used by plain spin_lock() APIs. */
	156	DENTRY_D_LOCK_NESTED
	157	};
	158
1da177e4 LT	159	struct dentry_operations {
1da177e4 LT	160	int (d_revalidate)(struct dentry , struct nameidata *);
b1e6a015 NP	161	int (d_hash)(const struct dentry , const struct inode *,
b1e6a015 NP	162	struct qstr *);
621e155a NP	163	int (d_compare)(const struct dentry , const struct inode *,
	164	const struct dentry , const struct inode ,
	165	unsigned int, const char , const struct qstr );
fe15ce44	166	int (d_delete)(const struct dentry );
1da177e4	167	void (d_release)(struct dentry );
f0023bc6	168	void (d_prune)(struct dentry );
1da177e4	169	void (d_iput)(struct dentry , struct inode *);
c23fbb6b	170	char (d_dname)(struct dentry , char , int);
9875cf80	171	struct vfsmount (d_automount)(struct path *);
1aed3e42	172	int (d_manage)(struct dentry , bool);
44a7d7a8	173	} ____cacheline_aligned;
1da177e4	174
5eef7fa9 NP	175	/*
	176	* Locking rules for dentry_operations callbacks are to be found in
	177	* Documentation/filesystems/Locking. Keep it updated!
	178	*
621e155a NP	179	* FUrther descriptions are found in Documentation/filesystems/vfs.txt.
621e155a NP	180	* Keep it updated too!
1da177e4 LT	181	*/
	182
	183	/* d_flags entries */
830c0f0e LT	184	#define DCACHE_OP_HASH 0x0001
	185	#define DCACHE_OP_COMPARE 0x0002
	186	#define DCACHE_OP_REVALIDATE 0x0004
	187	#define DCACHE_OP_DELETE 0x0008
f0023bc6	188	#define DCACHE_OP_PRUNE 0x0010
5f57cbcc	189
f0023bc6	190	#define DCACHE_DISCONNECTED 0x0020
5f57cbcc NP	191	/* This dentry is possibly not currently connected to the dcache tree, in
	192	* which case its parent will either be itself, or will have this flag as
	193	* well. nfsd will not use a dentry with this bit set, but will first
	194	* endeavour to clear the bit either by discovering that it is connected,
	195	* or by performing lookup operations. Any filesystem which supports
	196	* nfsd_operations MUST have a lookup function which, if it finds a
	197	* directory inode with a DCACHE_DISCONNECTED dentry, will d_move that
	198	* dentry into place and return that dentry rather than the passed one,
	199	* typically using d_splice_alias. */
1da177e4	200
f0023bc6 SW	201	#define DCACHE_REFERENCED 0x0040 /* Recently used, don't discard. */
f0023bc6 SW	202	#define DCACHE_RCUACCESS 0x0080 /* Entry has ever been RCU-visible */
c28f7e56	203
d83c49f3	204	#define DCACHE_CANT_MOUNT 0x0100
949854d0	205	#define DCACHE_GENOCIDE 0x0200
5f57cbcc	206
830c0f0e LT	207	#define DCACHE_NFSFS_RENAMED 0x1000
	208	/* this dentry has been "silly renamed" and has to be deleted on the last
	209	* dput() */
	210	#define DCACHE_COOKIE 0x2000 /* For use by dcookie subsystem */
	211	#define DCACHE_FSNOTIFY_PARENT_WATCHED 0x4000
	212	/* Parent inode is watched by some fsnotify listener */
fb045adb	213
9875cf80 DH	214	#define DCACHE_MOUNTED 0x10000 /* is a mountpoint */
9875cf80 DH	215	#define DCACHE_NEED_AUTOMOUNT 0x20000 /* handle automount on this dir */
cc53ce53	216	#define DCACHE_MANAGE_TRANSIT 0x40000 /* manage transit from this dirent */
44396f4b	217	#define DCACHE_NEED_LOOKUP 0x80000 /* dentry requires i_op->lookup */
9875cf80	218	#define DCACHE_MANAGED_DENTRY \
cc53ce53	219	(DCACHE_MOUNTED\|DCACHE_NEED_AUTOMOUNT\|DCACHE_MANAGE_TRANSIT)
9875cf80	220
74c3cbe3	221	extern seqlock_t rename_lock;
1da177e4	222
1da177e4 LT	223	static inline int dname_external(struct dentry *dentry)
	224	{
	225	return dentry->d_name.name != dentry->d_iname;
	226	}
	227
	228	/*
	229	* These are the low-level FS interfaces to the dcache..
	230	*/
	231	extern void d_instantiate(struct dentry , struct inode );
	232	extern struct dentry * d_instantiate_unique(struct dentry , struct inode );
770bfad8	233	extern struct dentry * d_materialise_unique(struct dentry , struct inode );
789680d1 NP	234	extern void __d_drop(struct dentry *dentry);
789680d1 NP	235	extern void d_drop(struct dentry *dentry);
1da177e4	236	extern void d_delete(struct dentry *);
fb045adb	237	extern void d_set_d_op(struct dentry dentry, const struct dentry_operations op);
1da177e4 LT	238
	239	/* allocate/de-allocate */
	240	extern struct dentry * d_alloc(struct dentry , const struct qstr );
4b936885	241	extern struct dentry * d_alloc_pseudo(struct super_block , const struct qstr );
1da177e4	242	extern struct dentry * d_splice_alias(struct inode , struct dentry );
e45b590b	243	extern struct dentry * d_add_ci(struct dentry , struct inode , struct qstr *);
4ea3ada2	244	extern struct dentry * d_obtain_alias(struct inode *);
1da177e4 LT	245	extern void shrink_dcache_sb(struct super_block *);
1da177e4 LT	246	extern void shrink_dcache_parent(struct dentry *);
c636ebdb	247	extern void shrink_dcache_for_umount(struct super_block *);
1da177e4 LT	248	extern int d_invalidate(struct dentry *);
	249
	250	/* only used at mount-time */
	251	extern struct dentry * d_alloc_root(struct inode *);
	252
	253	/* <clickety>-<click> the ramfs-type tree */
	254	extern void d_genocide(struct dentry *);
	255
	256	extern struct dentry d_find_alias(struct inode );
	257	extern void d_prune_aliases(struct inode *);
	258
	259	/* test whether we have any submounts in a subdir tree */
	260	extern int have_submounts(struct dentry *);
	261
	262	/*
	263	* This adds the entry to the hash queues.
	264	*/
	265	extern void d_rehash(struct dentry *);
	266
	267	/**
	268	* d_add - add dentry to hash queues
	269	* @entry: dentry to add
	270	* @inode: The inode to attach to this dentry
	271	*
	272	* This adds the entry to the hash queues and initializes @inode.
	273	* The entry was actually filled in earlier during d_alloc().
	274	*/
	275
	276	static inline void d_add(struct dentry entry, struct inode inode)
	277	{
	278	d_instantiate(entry, inode);
	279	d_rehash(entry);
	280	}
	281
	282	/**
	283	* d_add_unique - add dentry to hash queues without aliasing
	284	* @entry: dentry to add
	285	* @inode: The inode to attach to this dentry
	286	*
	287	* This adds the entry to the hash queues and initializes @inode.
	288	* The entry was actually filled in earlier during d_alloc().
	289	*/
	290	static inline struct dentry d_add_unique(struct dentry entry, struct inode *inode)
	291	{
	292	struct dentry *res;
	293
	294	res = d_instantiate_unique(entry, inode);
	295	d_rehash(res != NULL ? res : entry);
	296	return res;
	297	}
	298
fb2d5b86 NP	299	extern void dentry_update_name_case(struct dentry , struct qstr );
fb2d5b86 NP	300
1da177e4 LT	301	/* used for rename() and baskets */
1da177e4 LT	302	extern void d_move(struct dentry , struct dentry );
e2761a11	303	extern struct dentry d_ancestor(struct dentry , struct dentry *);
1da177e4 LT	304
1da177e4 LT	305	/* appendix may either be NULL or be used for transname suffixes */
31e6b01f NP	306	extern struct dentry d_lookup(struct dentry , struct qstr *);
	307	extern struct dentry d_hash_and_lookup(struct dentry , struct qstr *);
	308	extern struct dentry __d_lookup(struct dentry , struct qstr *);
	309	extern struct dentry __d_lookup_rcu(struct dentry parent, struct qstr *name,
	310	unsigned seq, struct inode *inode);
	311
	312	/**
	313	* __d_rcu_to_refcount - take a refcount on dentry if sequence check is ok
	314	* @dentry: dentry to take a ref on
	315	* @seq: seqcount to verify against
2a8c0c68	316	* Returns: 0 on failure, else 1.
31e6b01f NP	317	*
	318	* __d_rcu_to_refcount operates on a dentry,seq pair that was returned
	319	* by __d_lookup_rcu, to get a reference on an rcu-walk dentry.
	320	*/
	321	static inline int __d_rcu_to_refcount(struct dentry *dentry, unsigned seq)
	322	{
	323	int ret = 0;
	324
	325	assert_spin_locked(&dentry->d_lock);
	326	if (!read_seqcount_retry(&dentry->d_seq, seq)) {
	327	ret = 1;
	328	dentry->d_count++;
	329	}
	330
	331	return ret;
	332	}
1da177e4 LT	333
	334	/* validate "insecure" dentry pointer */
	335	extern int d_validate(struct dentry , struct dentry );
	336
c23fbb6b ED	337	/*
	338	* helper function for dentry_operations.d_dname() members
	339	*/
	340	extern char dynamic_dname(struct dentry , char , int, const char , ...);
	341
9d1bc601	342	extern char __d_path(const struct path path, struct path root, char , int);
20d4fdc1	343	extern char d_path(const struct path , char *, int);
8df9d1a4	344	extern char d_path_with_unreachable(const struct path , char *, int);
ec2447c2	345	extern char dentry_path_raw(struct dentry , char *, int);
6092d048	346	extern char dentry_path(struct dentry , char *, int);
cf28b486	347
1da177e4 LT	348	/* Allocation counts.. */
	349
	350	/**
dc0474be	351	* dget, dget_dlock - get a reference to a dentry
1da177e4 LT	352	* @dentry: dentry to get a reference to
	353	*
	354	* Given a dentry or %NULL pointer increment the reference count
	355	* if appropriate and return the dentry. A dentry will not be
dc0474be	356	* destroyed when it has references.
1da177e4	357	*/
b7ab39f6 NP	358	static inline struct dentry dget_dlock(struct dentry dentry)
b7ab39f6 NP	359	{
dc0474be	360	if (dentry)
b7ab39f6	361	dentry->d_count++;
b7ab39f6 NP	362	return dentry;
b7ab39f6 NP	363	}
2fd6b7f5	364
1da177e4 LT	365	static inline struct dentry dget(struct dentry dentry)
	366	{
	367	if (dentry) {
b7ab39f6 NP	368	spin_lock(&dentry->d_lock);
	369	dget_dlock(dentry);
	370	spin_unlock(&dentry->d_lock);
1da177e4 LT	371	}
	372	return dentry;
	373	}
	374
b7ab39f6	375	extern struct dentry dget_parent(struct dentry dentry);
1da177e4 LT	376
	377	/**
	378	* d_unhashed - is dentry hashed
	379	* @dentry: entry to check
	380	*
	381	* Returns true if the dentry passed is not currently hashed.
	382	*/
	383
	384	static inline int d_unhashed(struct dentry *dentry)
	385	{
dea3667b	386	return hlist_bl_unhashed(&dentry->d_hash);
1da177e4 LT	387	}
1da177e4 LT	388
f3da392e AD	389	static inline int d_unlinked(struct dentry *dentry)
	390	{
	391	return d_unhashed(dentry) && !IS_ROOT(dentry);
	392	}
	393
d83c49f3 AV	394	static inline int cant_mount(struct dentry *dentry)
	395	{
	396	return (dentry->d_flags & DCACHE_CANT_MOUNT);
	397	}
	398
	399	static inline void dont_mount(struct dentry *dentry)
	400	{
	401	spin_lock(&dentry->d_lock);
	402	dentry->d_flags \|= DCACHE_CANT_MOUNT;
	403	spin_unlock(&dentry->d_lock);
	404	}
	405
1da177e4 LT	406	extern void dput(struct dentry *);
1da177e4 LT	407
cc53ce53 DH	408	static inline bool d_managed(struct dentry *dentry)
	409	{
	410	return dentry->d_flags & DCACHE_MANAGED_DENTRY;
	411	}
	412
	413	static inline bool d_mountpoint(struct dentry *dentry)
1da177e4	414	{
5f57cbcc	415	return dentry->d_flags & DCACHE_MOUNTED;
1da177e4 LT	416	}
1da177e4 LT	417
44396f4b JB	418	static inline bool d_need_lookup(struct dentry *dentry)
	419	{
	420	return dentry->d_flags & DCACHE_NEED_LOOKUP;
	421	}
	422
	423	extern void d_clear_need_lookup(struct dentry *dentry);
1da177e4 LT	424
	425	extern int sysctl_vfs_cache_pressure;
	426
1da177e4	427	#endif /* __LINUX_DCACHE_H */