[linux-2.6-block.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 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_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_iput)(struct dentry *, struct inode *);
	char *(*d_dname)(struct dentry *, char *, int);
} ____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_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
#define DCACHE_MOUNTED		0x0400	/* is a mountpoint */

#define DCACHE_OP_HASH		0x1000
#define DCACHE_OP_COMPARE	0x2000
#define DCACHE_OP_REVALIDATE	0x4000
#define DCACHE_OP_DELETE	0x8000

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 *);
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_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_flags & DCACHE_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
44a7d7a8	85	# define DNAME_INLINE_LEN 32 /* 192 bytes */
c2452f32	86	#else
44a7d7a8 NP	87	# ifdef CONFIG_SMP
	88	# define DNAME_INLINE_LEN 36 /* 128 bytes */
	89	# else
	90	# define DNAME_INLINE_LEN 40 /* 128 bytes */
	91	# endif
c2452f32	92	#endif
1da177e4 LT	93
1da177e4 LT	94	struct dentry {
44a7d7a8	95	/* RCU lookup touched fields */
1da177e4	96	unsigned int d_flags; /* protected by d_lock */
31e6b01f	97	seqcount_t d_seq; /* per dentry seqlock */
3f4bb1f4	98	struct hlist_node d_hash; /* lookup hash list */
1da177e4 LT	99	struct dentry d_parent; / parent directory */
1da177e4 LT	100	struct qstr d_name;
44a7d7a8 NP	101	struct inode d_inode; / Where the name belongs to - NULL is
	102	* negative */
	103	unsigned char d_iname[DNAME_INLINE_LEN]; /* small names */
	104
	105	/* Ref lookup also touches following */
	106	unsigned int d_count; /* protected by d_lock */
	107	spinlock_t d_lock; /* per dentry lock */
	108	const struct dentry_operations *d_op;
	109	struct super_block d_sb; / The root of the dentry tree */
	110	unsigned long d_time; /* used by d_revalidate */
	111	void d_fsdata; / fs-specific data */
1da177e4 LT	112
1da177e4 LT	113	struct list_head d_lru; /* LRU list */
5160ee6f ED	114	/*
	115	* d_child and d_rcu can share memory
	116	*/
	117	union {
	118	struct list_head d_child; /* child of parent list */
	119	struct rcu_head d_rcu;
	120	} d_u;
1da177e4 LT	121	struct list_head d_subdirs; /* our children */
1da177e4 LT	122	struct list_head d_alias; /* inode alias list */
1da177e4 LT	123	};
1da177e4 LT	124
a90b9c05 IM	125	/*
	126	* dentry->d_lock spinlock nesting subclasses:
	127	*
	128	* 0: normal
	129	* 1: nested
	130	*/
	131	enum dentry_d_lock_class
	132	{
	133	DENTRY_D_LOCK_NORMAL, /* implicitly used by plain spin_lock() APIs. */
	134	DENTRY_D_LOCK_NESTED
	135	};
	136
1da177e4 LT	137	struct dentry_operations {
1da177e4 LT	138	int (d_revalidate)(struct dentry , struct nameidata *);
b1e6a015 NP	139	int (d_hash)(const struct dentry , const struct inode *,
b1e6a015 NP	140	struct qstr *);
621e155a NP	141	int (d_compare)(const struct dentry , const struct inode *,
	142	const struct dentry , const struct inode ,
	143	unsigned int, const char , const struct qstr );
fe15ce44	144	int (d_delete)(const struct dentry );
1da177e4 LT	145	void (d_release)(struct dentry );
1da177e4 LT	146	void (d_iput)(struct dentry , struct inode *);
c23fbb6b	147	char (d_dname)(struct dentry , char , int);
44a7d7a8	148	} ____cacheline_aligned;
1da177e4	149
5eef7fa9 NP	150	/*
	151	* Locking rules for dentry_operations callbacks are to be found in
	152	* Documentation/filesystems/Locking. Keep it updated!
	153	*
621e155a NP	154	* FUrther descriptions are found in Documentation/filesystems/vfs.txt.
621e155a NP	155	* Keep it updated too!
1da177e4 LT	156	*/
	157
	158	/* d_flags entries */
	159	#define DCACHE_AUTOFS_PENDING 0x0001 /* autofs: "under construction" */
5f57cbcc NP	160	#define DCACHE_NFSFS_RENAMED 0x0002
	161	/* this dentry has been "silly renamed" and has to be deleted on the last
	162	* dput() */
	163
	164	#define DCACHE_DISCONNECTED 0x0004
	165	/* This dentry is possibly not currently connected to the dcache tree, in
	166	* which case its parent will either be itself, or will have this flag as
	167	* well. nfsd will not use a dentry with this bit set, but will first
	168	* endeavour to clear the bit either by discovering that it is connected,
	169	* or by performing lookup operations. Any filesystem which supports
	170	* nfsd_operations MUST have a lookup function which, if it finds a
	171	* directory inode with a DCACHE_DISCONNECTED dentry, will d_move that
	172	* dentry into place and return that dentry rather than the passed one,
	173	* typically using d_splice_alias. */
1da177e4 LT	174
	175	#define DCACHE_REFERENCED 0x0008 /* Recently used, don't discard. */
	176	#define DCACHE_UNHASHED 0x0010
5f57cbcc NP	177	#define DCACHE_INOTIFY_PARENT_WATCHED 0x0020
5f57cbcc NP	178	/* Parent inode is watched by inotify */
c32ccd87	179
c2452f32	180	#define DCACHE_COOKIE 0x0040 /* For use by dcookie subsystem */
5f57cbcc NP	181	#define DCACHE_FSNOTIFY_PARENT_WATCHED 0x0080
5f57cbcc NP	182	/* Parent inode is watched by some fsnotify listener */
c28f7e56	183
d83c49f3	184	#define DCACHE_CANT_MOUNT 0x0100
949854d0	185	#define DCACHE_GENOCIDE 0x0200
5f57cbcc NP	186	#define DCACHE_MOUNTED 0x0400 /* is a mountpoint */
5f57cbcc NP	187
fb045adb NP	188	#define DCACHE_OP_HASH 0x1000
	189	#define DCACHE_OP_COMPARE 0x2000
	190	#define DCACHE_OP_REVALIDATE 0x4000
	191	#define DCACHE_OP_DELETE 0x8000
	192
b23fb0a6	193	extern spinlock_t dcache_inode_lock;
74c3cbe3	194	extern seqlock_t rename_lock;
1da177e4	195
1da177e4 LT	196	static inline int dname_external(struct dentry *dentry)
	197	{
	198	return dentry->d_name.name != dentry->d_iname;
	199	}
	200
	201	/*
	202	* These are the low-level FS interfaces to the dcache..
	203	*/
	204	extern void d_instantiate(struct dentry , struct inode );
	205	extern struct dentry * d_instantiate_unique(struct dentry , struct inode );
770bfad8	206	extern struct dentry * d_materialise_unique(struct dentry , struct inode );
789680d1 NP	207	extern void __d_drop(struct dentry *dentry);
789680d1 NP	208	extern void d_drop(struct dentry *dentry);
1da177e4	209	extern void d_delete(struct dentry *);
fb045adb	210	extern void d_set_d_op(struct dentry dentry, const struct dentry_operations op);
1da177e4 LT	211
	212	/* allocate/de-allocate */
	213	extern struct dentry * d_alloc(struct dentry , const struct qstr );
1da177e4	214	extern struct dentry * d_splice_alias(struct inode , struct dentry );
e45b590b	215	extern struct dentry * d_add_ci(struct dentry , struct inode , struct qstr *);
4ea3ada2	216	extern struct dentry * d_obtain_alias(struct inode *);
1da177e4 LT	217	extern void shrink_dcache_sb(struct super_block *);
1da177e4 LT	218	extern void shrink_dcache_parent(struct dentry *);
c636ebdb	219	extern void shrink_dcache_for_umount(struct super_block *);
1da177e4 LT	220	extern int d_invalidate(struct dentry *);
	221
	222	/* only used at mount-time */
	223	extern struct dentry * d_alloc_root(struct inode *);
	224
	225	/* <clickety>-<click> the ramfs-type tree */
	226	extern void d_genocide(struct dentry *);
	227
	228	extern struct dentry d_find_alias(struct inode );
	229	extern void d_prune_aliases(struct inode *);
	230
	231	/* test whether we have any submounts in a subdir tree */
	232	extern int have_submounts(struct dentry *);
	233
	234	/*
	235	* This adds the entry to the hash queues.
	236	*/
	237	extern void d_rehash(struct dentry *);
	238
	239	/**
	240	* d_add - add dentry to hash queues
	241	* @entry: dentry to add
	242	* @inode: The inode to attach to this dentry
	243	*
	244	* This adds the entry to the hash queues and initializes @inode.
	245	* The entry was actually filled in earlier during d_alloc().
	246	*/
	247
	248	static inline void d_add(struct dentry entry, struct inode inode)
	249	{
	250	d_instantiate(entry, inode);
	251	d_rehash(entry);
	252	}
	253
	254	/**
	255	* d_add_unique - add dentry to hash queues without aliasing
	256	* @entry: dentry to add
	257	* @inode: The inode to attach to this dentry
	258	*
	259	* This adds the entry to the hash queues and initializes @inode.
	260	* The entry was actually filled in earlier during d_alloc().
	261	*/
	262	static inline struct dentry d_add_unique(struct dentry entry, struct inode *inode)
	263	{
	264	struct dentry *res;
	265
	266	res = d_instantiate_unique(entry, inode);
	267	d_rehash(res != NULL ? res : entry);
	268	return res;
	269	}
	270
fb2d5b86 NP	271	extern void dentry_update_name_case(struct dentry , struct qstr );
fb2d5b86 NP	272
1da177e4 LT	273	/* used for rename() and baskets */
1da177e4 LT	274	extern void d_move(struct dentry , struct dentry );
e2761a11	275	extern struct dentry d_ancestor(struct dentry , struct dentry *);
1da177e4 LT	276
1da177e4 LT	277	/* appendix may either be NULL or be used for transname suffixes */
31e6b01f NP	278	extern struct dentry d_lookup(struct dentry , struct qstr *);
	279	extern struct dentry d_hash_and_lookup(struct dentry , struct qstr *);
	280	extern struct dentry __d_lookup(struct dentry , struct qstr *);
	281	extern struct dentry __d_lookup_rcu(struct dentry parent, struct qstr *name,
	282	unsigned seq, struct inode *inode);
	283
	284	/**
	285	* __d_rcu_to_refcount - take a refcount on dentry if sequence check is ok
	286	* @dentry: dentry to take a ref on
	287	* @seq: seqcount to verify against
	288	* @Returns: 0 on failure, else 1.
	289	*
	290	* __d_rcu_to_refcount operates on a dentry,seq pair that was returned
	291	* by __d_lookup_rcu, to get a reference on an rcu-walk dentry.
	292	*/
	293	static inline int __d_rcu_to_refcount(struct dentry *dentry, unsigned seq)
	294	{
	295	int ret = 0;
	296
	297	assert_spin_locked(&dentry->d_lock);
	298	if (!read_seqcount_retry(&dentry->d_seq, seq)) {
	299	ret = 1;
	300	dentry->d_count++;
	301	}
	302
	303	return ret;
	304	}
1da177e4 LT	305
	306	/* validate "insecure" dentry pointer */
	307	extern int d_validate(struct dentry , struct dentry );
	308
c23fbb6b ED	309	/*
	310	* helper function for dentry_operations.d_dname() members
	311	*/
	312	extern char dynamic_dname(struct dentry , char , int, const char , ...);
	313
9d1bc601	314	extern char __d_path(const struct path path, struct path root, char , int);
20d4fdc1	315	extern char d_path(const struct path , char *, int);
8df9d1a4	316	extern char d_path_with_unreachable(const struct path , char *, int);
ec2447c2	317	extern char dentry_path_raw(struct dentry , char *, int);
6092d048	318	extern char dentry_path(struct dentry , char *, int);
cf28b486	319
1da177e4 LT	320	/* Allocation counts.. */
	321
	322	/**
dc0474be	323	* dget, dget_dlock - get a reference to a dentry
1da177e4 LT	324	* @dentry: dentry to get a reference to
	325	*
	326	* Given a dentry or %NULL pointer increment the reference count
	327	* if appropriate and return the dentry. A dentry will not be
dc0474be	328	* destroyed when it has references.
1da177e4	329	*/
b7ab39f6 NP	330	static inline struct dentry dget_dlock(struct dentry dentry)
b7ab39f6 NP	331	{
dc0474be	332	if (dentry)
b7ab39f6	333	dentry->d_count++;
b7ab39f6 NP	334	return dentry;
b7ab39f6 NP	335	}
2fd6b7f5	336
1da177e4 LT	337	static inline struct dentry dget(struct dentry dentry)
	338	{
	339	if (dentry) {
b7ab39f6 NP	340	spin_lock(&dentry->d_lock);
	341	dget_dlock(dentry);
	342	spin_unlock(&dentry->d_lock);
1da177e4 LT	343	}
	344	return dentry;
	345	}
	346
b7ab39f6	347	extern struct dentry dget_parent(struct dentry dentry);
1da177e4 LT	348
	349	/**
	350	* d_unhashed - is dentry hashed
	351	* @dentry: entry to check
	352	*
	353	* Returns true if the dentry passed is not currently hashed.
	354	*/
	355
	356	static inline int d_unhashed(struct dentry *dentry)
	357	{
	358	return (dentry->d_flags & DCACHE_UNHASHED);
	359	}
	360
f3da392e AD	361	static inline int d_unlinked(struct dentry *dentry)
	362	{
	363	return d_unhashed(dentry) && !IS_ROOT(dentry);
	364	}
	365
d83c49f3 AV	366	static inline int cant_mount(struct dentry *dentry)
	367	{
	368	return (dentry->d_flags & DCACHE_CANT_MOUNT);
	369	}
	370
	371	static inline void dont_mount(struct dentry *dentry)
	372	{
	373	spin_lock(&dentry->d_lock);
	374	dentry->d_flags \|= DCACHE_CANT_MOUNT;
	375	spin_unlock(&dentry->d_lock);
	376	}
	377
1da177e4 LT	378	extern void dput(struct dentry *);
	379
	380	static inline int d_mountpoint(struct dentry *dentry)
	381	{
5f57cbcc	382	return dentry->d_flags & DCACHE_MOUNTED;
1da177e4 LT	383	}
1da177e4 LT	384
1c755af4	385	extern struct vfsmount lookup_mnt(struct path );
1da177e4 LT	386	extern struct dentry lookup_create(struct nameidata nd, int is_dir);
	387
	388	extern int sysctl_vfs_cache_pressure;
	389
1da177e4	390	#endif /* __LINUX_DCACHE_H */