[mirror_ubuntu-zesty-kernel.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>
#include <linux/lockref.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;
 #define bytemask_from_count(cnt)	(~(~0ul << (cnt)*8))
#else
 #define HASH_LEN_DECLARE u32 len; u32 hash;
 #define bytemask_from_count(cnt)	(~(~0ul >> (cnt)*8))
#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 {
	long nr_dentry;
	long nr_unused;
	long age_limit;          /* age in seconds */
	long want_pages;         /* pages requested by system */
	long 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

#define d_lock	d_lockref.lock

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 */
	struct lockref d_lockref;	/* per-dentry lock and refcount */
	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_weak_revalidate)(struct dentry *, unsigned int);
	int (*d_hash)(const struct dentry *, struct qstr *);
	int (*d_compare)(const struct dentry *, const struct dentry *,
			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			0x00000001
#define DCACHE_OP_COMPARE		0x00000002
#define DCACHE_OP_REVALIDATE		0x00000004
#define DCACHE_OP_DELETE		0x00000008
#define DCACHE_OP_PRUNE			0x00000010

#define	DCACHE_DISCONNECTED		0x00000020
     /* 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		0x00000040 /* Recently used, don't discard. */
#define DCACHE_RCUACCESS		0x00000080 /* Entry has ever been RCU-visible */

#define DCACHE_CANT_MOUNT		0x00000100
#define DCACHE_GENOCIDE			0x00000200
#define DCACHE_SHRINK_LIST		0x00000400

#define DCACHE_OP_WEAK_REVALIDATE	0x00000800

#define DCACHE_NFSFS_RENAMED		0x00001000
     /* this dentry has been "silly renamed" and has to be deleted on the last
      * dput() */
#define DCACHE_COOKIE			0x00002000 /* For use by dcookie subsystem */
#define DCACHE_FSNOTIFY_PARENT_WATCHED	0x00004000
     /* Parent inode is watched by some fsnotify listener */

#define DCACHE_DENTRY_KILLED		0x00008000

#define DCACHE_MOUNTED			0x00010000 /* is a mountpoint */
#define DCACHE_NEED_AUTOMOUNT		0x00020000 /* handle automount on this dir */
#define DCACHE_MANAGE_TRANSIT		0x00040000 /* manage transit from this dirent */
#define DCACHE_MANAGED_DENTRY \
	(DCACHE_MOUNTED|DCACHE_NEED_AUTOMOUNT|DCACHE_MANAGE_TRANSIT)

#define DCACHE_LRU_LIST			0x00080000

#define DCACHE_ENTRY_TYPE		0x00700000
#define DCACHE_MISS_TYPE		0x00000000 /* Negative dentry */
#define DCACHE_DIRECTORY_TYPE		0x00100000 /* Normal directory */
#define DCACHE_AUTODIR_TYPE		0x00200000 /* Lookupless directory (presumed automount) */
#define DCACHE_SYMLINK_TYPE		0x00300000 /* Symlink */
#define DCACHE_FILE_TYPE		0x00400000 /* Other file type */

extern seqlock_t rename_lock;

static inline int dname_external(const 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 int d_instantiate_no_diralias(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 void d_tmpfile(struct dentry *, struct inode *);

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 *);
extern int check_submounts_and_drop(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 void d_exchange(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(const struct dentry *, const struct qstr *);
extern struct dentry *d_hash_and_lookup(struct dentry *, struct qstr *);
extern struct dentry *__d_lookup(const struct dentry *, const struct qstr *);
extern struct dentry *__d_lookup_rcu(const struct dentry *parent,
				const struct qstr *name, unsigned *seq);

static inline unsigned d_count(const struct dentry *dentry)
{
	return dentry->d_lockref.count;
}

/* 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 *simple_dname(struct dentry *, char *, int);

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 *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_lockref.count++;
	return dentry;
}

static inline struct dentry *dget(struct dentry *dentry)
{
	if (dentry)
		lockref_get(&dentry->d_lockref);
	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(const struct dentry *dentry)
{
	return hlist_bl_unhashed(&dentry->d_hash);
}

static inline int d_unlinked(const struct dentry *dentry)
{
	return d_unhashed(dentry) && !IS_ROOT(dentry);
}

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

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

/*
 * Directory cache entry type accessor functions.
 */
static inline void __d_set_type(struct dentry *dentry, unsigned type)
{
	dentry->d_flags = (dentry->d_flags & ~DCACHE_ENTRY_TYPE) | type;
}

static inline void __d_clear_type(struct dentry *dentry)
{
	__d_set_type(dentry, DCACHE_MISS_TYPE);
}

static inline void d_set_type(struct dentry *dentry, unsigned type)
{
	spin_lock(&dentry->d_lock);
	__d_set_type(dentry, type);
	spin_unlock(&dentry->d_lock);
}

static inline unsigned __d_entry_type(const struct dentry *dentry)
{
	return dentry->d_flags & DCACHE_ENTRY_TYPE;
}

static inline bool d_can_lookup(const struct dentry *dentry)
{
	return __d_entry_type(dentry) == DCACHE_DIRECTORY_TYPE;
}

static inline bool d_is_autodir(const struct dentry *dentry)
{
	return __d_entry_type(dentry) == DCACHE_AUTODIR_TYPE;
}

static inline bool d_is_dir(const struct dentry *dentry)
{
	return d_can_lookup(dentry) || d_is_autodir(dentry);
}

static inline bool d_is_symlink(const struct dentry *dentry)
{
	return __d_entry_type(dentry) == DCACHE_SYMLINK_TYPE;
}

static inline bool d_is_file(const struct dentry *dentry)
{
	return __d_entry_type(dentry) == DCACHE_FILE_TYPE;
}

static inline bool d_is_negative(const struct dentry *dentry)
{
	return __d_entry_type(dentry) == DCACHE_MISS_TYPE;
}

static inline bool d_is_positive(const struct dentry *dentry)
{
	return !d_is_negative(dentry);
}

extern int sysctl_vfs_cache_pressure;

static inline unsigned long vfs_pressure_ratio(unsigned long val)
{
	return mult_frac(val, sysctl_vfs_cache_pressure, 100);
}
#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>
98474236	12	#include <linux/lockref.h>
1da177e4 LT	13
1da177e4 LT	14	struct nameidata;
cf28b486	15	struct path;
1da177e4 LT	16	struct vfsmount;
	17
	18	/*
	19	* linux/include/linux/dcache.h
	20	*
	21	* Dirent cache data structures
	22	*
	23	* (C) Copyright 1997 Thomas Schoebel-Theuer,
	24	* with heavy changes by Linus Torvalds
	25	*/
	26
	27	#define IS_ROOT(x) ((x) == (x)->d_parent)
	28
26fe5750 LT	29	/* The hash is always the low bits of hash_len */
	30	#ifdef __LITTLE_ENDIAN
	31	#define HASH_LEN_DECLARE u32 hash; u32 len;
a5c21dce	32	#define bytemask_from_count(cnt) (~(~0ul << (cnt)*8))
26fe5750 LT	33	#else
26fe5750 LT	34	#define HASH_LEN_DECLARE u32 len; u32 hash;
a5c21dce	35	#define bytemask_from_count(cnt) (~(~0ul >> (cnt)*8))
26fe5750 LT	36	#endif
26fe5750 LT	37
1da177e4 LT	38	/*
	39	* "quick string" -- eases parameter passing, but more importantly
	40	* saves "metadata" about the string (ie length and the hash).
	41	*
	42	* hash comes first so it snuggles against d_parent in the
	43	* dentry.
	44	*/
	45	struct qstr {
26fe5750 LT	46	union {
	47	struct {
	48	HASH_LEN_DECLARE;
	49	};
	50	u64 hash_len;
	51	};
1da177e4 LT	52	const unsigned char *name;
	53	};
	54
26fe5750 LT	55	#define QSTR_INIT(n,l) { { { .len = l } }, .name = n }
	56	#define hashlen_hash(hashlen) ((u32) (hashlen))
	57	#define hashlen_len(hashlen) ((u32)((hashlen) >> 32))
	58
1da177e4	59	struct dentry_stat_t {
3942c07c GC	60	long nr_dentry;
	61	long nr_unused;
	62	long age_limit; /* age in seconds */
	63	long want_pages; /* pages requested by system */
	64	long dummy[2];
1da177e4 LT	65	};
	66	extern struct dentry_stat_t dentry_stat;
	67
	68	/* Name hashing routines. Initial hash value */
	69	/* Hash courtesy of the R5 hash in reiserfs modulo sign bits */
	70	#define init_name_hash() 0
	71
	72	/* partial hash update function. Assume roughly 4 bits per character */
	73	static inline unsigned long
	74	partial_name_hash(unsigned long c, unsigned long prevhash)
	75	{
	76	return (prevhash + (c << 4) + (c >> 4)) * 11;
	77	}
	78
	79	/*
	80	* Finally: cut down the number of bits to a int value (and try to avoid
	81	* losing bits)
	82	*/
	83	static inline unsigned long end_name_hash(unsigned long hash)
	84	{
	85	return (unsigned int) hash;
	86	}
	87
	88	/* Compute the hash for a name string. */
0145acc2	89	extern unsigned int full_name_hash(const unsigned char *, unsigned int);
1da177e4	90
c2452f32 NP	91	/*
	92	* Try to keep struct dentry aligned on 64 byte cachelines (this will
	93	* give reasonable cacheline footprint with larger lines without the
	94	* large memory footprint increase).
	95	*/
	96	#ifdef CONFIG_64BIT
44a7d7a8	97	# define DNAME_INLINE_LEN 32 /* 192 bytes */
c2452f32	98	#else
44a7d7a8 NP	99	# ifdef CONFIG_SMP
	100	# define DNAME_INLINE_LEN 36 /* 128 bytes */
	101	# else
	102	# define DNAME_INLINE_LEN 40 /* 128 bytes */
	103	# endif
c2452f32	104	#endif
1da177e4	105
98474236 WL	106	#define d_lock d_lockref.lock
98474236 WL	107
1da177e4	108	struct dentry {
44a7d7a8	109	/* RCU lookup touched fields */
1da177e4	110	unsigned int d_flags; /* protected by d_lock */
31e6b01f	111	seqcount_t d_seq; /* per dentry seqlock */
ceb5bdc2	112	struct hlist_bl_node d_hash; /* lookup hash list */
1da177e4 LT	113	struct dentry d_parent; / parent directory */
1da177e4 LT	114	struct qstr d_name;
44a7d7a8 NP	115	struct inode d_inode; / Where the name belongs to - NULL is
	116	* negative */
	117	unsigned char d_iname[DNAME_INLINE_LEN]; /* small names */
	118
	119	/* Ref lookup also touches following */
98474236	120	struct lockref d_lockref; /* per-dentry lock and refcount */
44a7d7a8 NP	121	const struct dentry_operations *d_op;
	122	struct super_block d_sb; / The root of the dentry tree */
	123	unsigned long d_time; /* used by d_revalidate */
	124	void d_fsdata; / fs-specific data */
1da177e4 LT	125
1da177e4 LT	126	struct list_head d_lru; /* LRU list */
5160ee6f ED	127	/*
	128	* d_child and d_rcu can share memory
	129	*/
	130	union {
	131	struct list_head d_child; /* child of parent list */
	132	struct rcu_head d_rcu;
	133	} d_u;
1da177e4	134	struct list_head d_subdirs; /* our children */
b3d9b7a3	135	struct hlist_node d_alias; /* inode alias list */
1da177e4 LT	136	};
1da177e4 LT	137
a90b9c05 IM	138	/*
	139	* dentry->d_lock spinlock nesting subclasses:
	140	*
	141	* 0: normal
	142	* 1: nested
	143	*/
	144	enum dentry_d_lock_class
	145	{
	146	DENTRY_D_LOCK_NORMAL, /* implicitly used by plain spin_lock() APIs. */
	147	DENTRY_D_LOCK_NESTED
	148	};
	149
1da177e4	150	struct dentry_operations {
0b728e19	151	int (d_revalidate)(struct dentry , unsigned int);
ecf3d1f1	152	int (d_weak_revalidate)(struct dentry , unsigned int);
da53be12 LT	153	int (d_hash)(const struct dentry , struct qstr *);
da53be12 LT	154	int (d_compare)(const struct dentry , const struct dentry *,
621e155a	155	unsigned int, const char , const struct qstr );
fe15ce44	156	int (d_delete)(const struct dentry );
1da177e4	157	void (d_release)(struct dentry );
f0023bc6	158	void (d_prune)(struct dentry );
1da177e4	159	void (d_iput)(struct dentry , struct inode *);
c23fbb6b	160	char (d_dname)(struct dentry , char , int);
9875cf80	161	struct vfsmount (d_automount)(struct path *);
1aed3e42	162	int (d_manage)(struct dentry , bool);
44a7d7a8	163	} ____cacheline_aligned;
1da177e4	164
5eef7fa9 NP	165	/*
	166	* Locking rules for dentry_operations callbacks are to be found in
	167	* Documentation/filesystems/Locking. Keep it updated!
	168	*
621e155a NP	169	* FUrther descriptions are found in Documentation/filesystems/vfs.txt.
621e155a NP	170	* Keep it updated too!
1da177e4 LT	171	*/
	172
	173	/* d_flags entries */
b18825a7 DH	174	#define DCACHE_OP_HASH 0x00000001
	175	#define DCACHE_OP_COMPARE 0x00000002
	176	#define DCACHE_OP_REVALIDATE 0x00000004
	177	#define DCACHE_OP_DELETE 0x00000008
	178	#define DCACHE_OP_PRUNE 0x00000010
5f57cbcc	179
b18825a7	180	#define DCACHE_DISCONNECTED 0x00000020
5f57cbcc NP	181	/* This dentry is possibly not currently connected to the dcache tree, in
	182	* which case its parent will either be itself, or will have this flag as
	183	* well. nfsd will not use a dentry with this bit set, but will first
	184	* endeavour to clear the bit either by discovering that it is connected,
	185	* or by performing lookup operations. Any filesystem which supports
	186	* nfsd_operations MUST have a lookup function which, if it finds a
	187	* directory inode with a DCACHE_DISCONNECTED dentry, will d_move that
	188	* dentry into place and return that dentry rather than the passed one,
	189	* typically using d_splice_alias. */
1da177e4	190
b18825a7 DH	191	#define DCACHE_REFERENCED 0x00000040 /* Recently used, don't discard. */
b18825a7 DH	192	#define DCACHE_RCUACCESS 0x00000080 /* Entry has ever been RCU-visible */
c28f7e56	193
b18825a7 DH	194	#define DCACHE_CANT_MOUNT 0x00000100
	195	#define DCACHE_GENOCIDE 0x00000200
	196	#define DCACHE_SHRINK_LIST 0x00000400
5f57cbcc	197
b18825a7	198	#define DCACHE_OP_WEAK_REVALIDATE 0x00000800
ecf3d1f1	199
b18825a7	200	#define DCACHE_NFSFS_RENAMED 0x00001000
830c0f0e LT	201	/* this dentry has been "silly renamed" and has to be deleted on the last
830c0f0e LT	202	* dput() */
b18825a7 DH	203	#define DCACHE_COOKIE 0x00002000 /* For use by dcookie subsystem */
b18825a7 DH	204	#define DCACHE_FSNOTIFY_PARENT_WATCHED 0x00004000
830c0f0e	205	/* Parent inode is watched by some fsnotify listener */
fb045adb	206
b18825a7 DH	207	#define DCACHE_DENTRY_KILLED 0x00008000
	208
	209	#define DCACHE_MOUNTED 0x00010000 /* is a mountpoint */
	210	#define DCACHE_NEED_AUTOMOUNT 0x00020000 /* handle automount on this dir */
	211	#define DCACHE_MANAGE_TRANSIT 0x00040000 /* manage transit from this dirent */
9875cf80	212	#define DCACHE_MANAGED_DENTRY \
cc53ce53	213	(DCACHE_MOUNTED\|DCACHE_NEED_AUTOMOUNT\|DCACHE_MANAGE_TRANSIT)
9875cf80	214
b18825a7 DH	215	#define DCACHE_LRU_LIST 0x00080000
	216
	217	#define DCACHE_ENTRY_TYPE 0x00700000
	218	#define DCACHE_MISS_TYPE 0x00000000 /* Negative dentry */
	219	#define DCACHE_DIRECTORY_TYPE 0x00100000 /* Normal directory */
	220	#define DCACHE_AUTODIR_TYPE 0x00200000 /* Lookupless directory (presumed automount) */
	221	#define DCACHE_SYMLINK_TYPE 0x00300000 /* Symlink */
	222	#define DCACHE_FILE_TYPE 0x00400000 /* Other file type */
b161dfa6	223
74c3cbe3	224	extern seqlock_t rename_lock;
1da177e4	225
f0d3b3de	226	static inline int dname_external(const struct dentry *dentry)
1da177e4 LT	227	{
	228	return dentry->d_name.name != dentry->d_iname;
	229	}
	230
	231	/*
	232	* These are the low-level FS interfaces to the dcache..
	233	*/
	234	extern void d_instantiate(struct dentry , struct inode );
	235	extern struct dentry * d_instantiate_unique(struct dentry , struct inode );
770bfad8	236	extern struct dentry * d_materialise_unique(struct dentry , struct inode );
b70a80e7	237	extern int d_instantiate_no_diralias(struct dentry , struct inode );
789680d1 NP	238	extern void __d_drop(struct dentry *dentry);
789680d1 NP	239	extern void d_drop(struct dentry *dentry);
1da177e4	240	extern void d_delete(struct dentry *);
fb045adb	241	extern void d_set_d_op(struct dentry dentry, const struct dentry_operations op);
1da177e4 LT	242
	243	/* allocate/de-allocate */
	244	extern struct dentry * d_alloc(struct dentry , const struct qstr );
4b936885	245	extern struct dentry * d_alloc_pseudo(struct super_block , const struct qstr );
1da177e4	246	extern struct dentry * d_splice_alias(struct inode , struct dentry );
e45b590b	247	extern struct dentry * d_add_ci(struct dentry , struct inode , struct qstr *);
46f72b34	248	extern struct dentry d_find_any_alias(struct inode inode);
4ea3ada2	249	extern struct dentry * d_obtain_alias(struct inode *);
1da177e4 LT	250	extern void shrink_dcache_sb(struct super_block *);
1da177e4 LT	251	extern void shrink_dcache_parent(struct dentry *);
c636ebdb	252	extern void shrink_dcache_for_umount(struct super_block *);
1da177e4 LT	253	extern int d_invalidate(struct dentry *);
	254
	255	/* only used at mount-time */
adc0e91a	256	extern struct dentry * d_make_root(struct inode *);
1da177e4 LT	257
	258	/* <clickety>-<click> the ramfs-type tree */
	259	extern void d_genocide(struct dentry *);
	260
60545d0d AV	261	extern void d_tmpfile(struct dentry , struct inode );
60545d0d AV	262
1da177e4 LT	263	extern struct dentry d_find_alias(struct inode );
	264	extern void d_prune_aliases(struct inode *);
	265
	266	/* test whether we have any submounts in a subdir tree */
	267	extern int have_submounts(struct dentry *);
848ac114	268	extern int check_submounts_and_drop(struct dentry *);
1da177e4 LT	269
	270	/*
	271	* This adds the entry to the hash queues.
	272	*/
	273	extern void d_rehash(struct dentry *);
	274
	275	/**
	276	* d_add - add dentry to hash queues
	277	* @entry: dentry to add
	278	* @inode: The inode to attach to this dentry
	279	*
	280	* This adds the entry to the hash queues and initializes @inode.
	281	* The entry was actually filled in earlier during d_alloc().
	282	*/
	283
	284	static inline void d_add(struct dentry entry, struct inode inode)
	285	{
	286	d_instantiate(entry, inode);
	287	d_rehash(entry);
	288	}
	289
	290	/**
	291	* d_add_unique - add dentry to hash queues without aliasing
	292	* @entry: dentry to add
	293	* @inode: The inode to attach to this dentry
	294	*
	295	* This adds the entry to the hash queues and initializes @inode.
	296	* The entry was actually filled in earlier during d_alloc().
	297	*/
	298	static inline struct dentry d_add_unique(struct dentry entry, struct inode *inode)
	299	{
	300	struct dentry *res;
	301
	302	res = d_instantiate_unique(entry, inode);
	303	d_rehash(res != NULL ? res : entry);
	304	return res;
	305	}
	306
fb2d5b86 NP	307	extern void dentry_update_name_case(struct dentry , struct qstr );
fb2d5b86 NP	308
1da177e4 LT	309	/* used for rename() and baskets */
1da177e4 LT	310	extern void d_move(struct dentry , struct dentry );
da1ce067	311	extern void d_exchange(struct dentry , struct dentry );
e2761a11	312	extern struct dentry d_ancestor(struct dentry , struct dentry *);
1da177e4 LT	313
1da177e4 LT	314	/* appendix may either be NULL or be used for transname suffixes */
da2d8455	315	extern struct dentry d_lookup(const struct dentry , const struct qstr *);
31e6b01f	316	extern struct dentry d_hash_and_lookup(struct dentry , struct qstr *);
a713ca2a	317	extern struct dentry __d_lookup(const struct dentry , const struct qstr *);
8966be90	318	extern struct dentry __d_lookup_rcu(const struct dentry parent,
da53be12	319	const struct qstr name, unsigned seq);
31e6b01f	320
24924a20	321	static inline unsigned d_count(const struct dentry *dentry)
84d08fa8	322	{
98474236	323	return dentry->d_lockref.count;
84d08fa8 AV	324	}
84d08fa8 AV	325
1da177e4 LT	326	/* validate "insecure" dentry pointer */
	327	extern int d_validate(struct dentry , struct dentry );
	328
c23fbb6b ED	329	/*
	330	* helper function for dentry_operations.d_dname() members
	331	*/
	332	extern char dynamic_dname(struct dentry , char , int, const char , ...);
118b2302	333	extern char simple_dname(struct dentry , char *, int);
c23fbb6b	334
02125a82 AV	335	extern char __d_path(const struct path , const struct path , char , int);
02125a82 AV	336	extern char d_absolute_path(const struct path , char *, int);
20d4fdc1	337	extern char d_path(const struct path , char *, int);
ec2447c2	338	extern char dentry_path_raw(struct dentry , char *, int);
6092d048	339	extern char dentry_path(struct dentry , char *, int);
cf28b486	340
1da177e4 LT	341	/* Allocation counts.. */
	342
	343	/**
dc0474be	344	* dget, dget_dlock - get a reference to a dentry
1da177e4 LT	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
dc0474be	349	* destroyed when it has references.
1da177e4	350	*/
b7ab39f6 NP	351	static inline struct dentry dget_dlock(struct dentry dentry)
b7ab39f6 NP	352	{
dc0474be	353	if (dentry)
98474236	354	dentry->d_lockref.count++;
b7ab39f6 NP	355	return dentry;
b7ab39f6 NP	356	}
2fd6b7f5	357
1da177e4 LT	358	static inline struct dentry dget(struct dentry dentry)
1da177e4 LT	359	{
98474236 WL	360	if (dentry)
98474236 WL	361	lockref_get(&dentry->d_lockref);
1da177e4 LT	362	return dentry;
	363	}
	364
b7ab39f6	365	extern struct dentry dget_parent(struct dentry dentry);
1da177e4 LT	366
	367	/**
	368	* d_unhashed - is dentry hashed
	369	* @dentry: entry to check
	370	*
	371	* Returns true if the dentry passed is not currently hashed.
	372	*/
	373
f0d3b3de	374	static inline int d_unhashed(const struct dentry *dentry)
1da177e4	375	{
dea3667b	376	return hlist_bl_unhashed(&dentry->d_hash);
1da177e4 LT	377	}
1da177e4 LT	378
f0d3b3de	379	static inline int d_unlinked(const struct dentry *dentry)
f3da392e AD	380	{
	381	return d_unhashed(dentry) && !IS_ROOT(dentry);
	382	}
	383
f0d3b3de	384	static inline int cant_mount(const struct dentry *dentry)
d83c49f3 AV	385	{
	386	return (dentry->d_flags & DCACHE_CANT_MOUNT);
	387	}
	388
	389	static inline void dont_mount(struct dentry *dentry)
	390	{
	391	spin_lock(&dentry->d_lock);
	392	dentry->d_flags \|= DCACHE_CANT_MOUNT;
	393	spin_unlock(&dentry->d_lock);
	394	}
	395
1da177e4 LT	396	extern void dput(struct dentry *);
1da177e4 LT	397
f0d3b3de	398	static inline bool d_managed(const struct dentry *dentry)
cc53ce53 DH	399	{
	400	return dentry->d_flags & DCACHE_MANAGED_DENTRY;
	401	}
	402
f0d3b3de	403	static inline bool d_mountpoint(const struct dentry *dentry)
1da177e4	404	{
5f57cbcc	405	return dentry->d_flags & DCACHE_MOUNTED;
1da177e4 LT	406	}
1da177e4 LT	407
b18825a7 DH	408	/*
	409	* Directory cache entry type accessor functions.
	410	*/
	411	static inline void __d_set_type(struct dentry *dentry, unsigned type)
	412	{
	413	dentry->d_flags = (dentry->d_flags & ~DCACHE_ENTRY_TYPE) \| type;
	414	}
	415
	416	static inline void __d_clear_type(struct dentry *dentry)
	417	{
	418	__d_set_type(dentry, DCACHE_MISS_TYPE);
	419	}
	420
	421	static inline void d_set_type(struct dentry *dentry, unsigned type)
	422	{
	423	spin_lock(&dentry->d_lock);
	424	__d_set_type(dentry, type);
	425	spin_unlock(&dentry->d_lock);
	426	}
	427
	428	static inline unsigned __d_entry_type(const struct dentry *dentry)
	429	{
	430	return dentry->d_flags & DCACHE_ENTRY_TYPE;
	431	}
	432
44b1d530	433	static inline bool d_can_lookup(const struct dentry *dentry)
b18825a7 DH	434	{
	435	return __d_entry_type(dentry) == DCACHE_DIRECTORY_TYPE;
	436	}
	437
	438	static inline bool d_is_autodir(const struct dentry *dentry)
	439	{
	440	return __d_entry_type(dentry) == DCACHE_AUTODIR_TYPE;
	441	}
	442
44b1d530 MS	443	static inline bool d_is_dir(const struct dentry *dentry)
	444	{
	445	return d_can_lookup(dentry) \|\| d_is_autodir(dentry);
	446	}
	447
b18825a7 DH	448	static inline bool d_is_symlink(const struct dentry *dentry)
	449	{
	450	return __d_entry_type(dentry) == DCACHE_SYMLINK_TYPE;
	451	}
	452
	453	static inline bool d_is_file(const struct dentry *dentry)
	454	{
	455	return __d_entry_type(dentry) == DCACHE_FILE_TYPE;
	456	}
	457
	458	static inline bool d_is_negative(const struct dentry *dentry)
	459	{
	460	return __d_entry_type(dentry) == DCACHE_MISS_TYPE;
	461	}
	462
	463	static inline bool d_is_positive(const struct dentry *dentry)
	464	{
	465	return !d_is_negative(dentry);
	466	}
	467
1da177e4 LT	468	extern int sysctl_vfs_cache_pressure;
1da177e4 LT	469
55f841ce GC	470	static inline unsigned long vfs_pressure_ratio(unsigned long val)
	471	{
	472	return mult_frac(val, sysctl_vfs_cache_pressure, 100);
	473	}
1da177e4	474	#endif /* __LINUX_DCACHE_H */