#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/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 longpartial_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 intfull_name_hash(const unsigned char *name, unsigned int len){ unsigned long hash = init_name_hash(); while (len--) hash = partial_name_hash(*name++, hash); return end_name_hash(hash);} /* * Try to keep struct dentry aligned on 64 byte cachelines (this will * give reasonable cacheline footprint with larger lines without the * large memory footprint increase). */#ifdef CONFIG_64BIT#define DNAME_INLINE_LEN_MIN 32 /* 192 bytes */#else#define DNAME_INLINE_LEN_MIN 40 /* 128 bytes */#endif struct dentry { atomic_t d_count; unsigned int d_flags; /* protected by d_lock */ spinlock_t d_lock; /* per dentry lock */ int d_mounted; struct inode *d_inode; /* Where the name belongs to - NULL is * negative */ /* * The next three fields are touched by __d_lookup. Place them here * so they all fit in a cache line. */ struct hlist_node d_hash; /* lookup hash list */ struct dentry *d_parent; /* parent directory */ struct qstr d_name; struct list_head d_lru; /* LRU list */ /* * d_child and d_rcu can share memory */ union { struct list_head d_child; /* child of parent list */ struct rcu_head d_rcu; } d_u; struct list_head d_subdirs; /* our children */ struct list_head d_alias; /* inode alias list */ unsigned long d_time; /* used by d_revalidate */ const struct dentry_operations *d_op; struct super_block *d_sb; /* The root of the dentry tree */ void *d_fsdata; /* fs-specific data */ unsigned char d_iname[DNAME_INLINE_LEN_MIN]; /* small names */}; /* * dentry->d_lock spinlock nesting subclasses: * * 0: normal * 1: nested */enum dentry_d_lock_class{ DENTRY_D_LOCK_NORMAL, /* implicitly used by plain spin_lock() APIs. */ DENTRY_D_LOCK_NESTED}; struct dentry_operations { int (*d_revalidate)(struct dentry *, struct nameidata *); int (*d_hash) (struct dentry *, struct qstr *); int (*d_compare) (struct dentry *, struct qstr *, struct qstr *); int (*d_delete)(struct dentry *); void (*d_release)(struct dentry *); void (*d_iput)(struct dentry *, struct inode *); char *(*d_dname)(struct dentry *, char *, int);}; /* the dentry parameter passed to d_hash and d_compare is the parent * directory of the entries to be compared. It is used in case these * functions need any directory specific information for determining * equivalency classes. Using the dentry itself might not work, as it * might be a negative dentry which has no information associated with * it */ /*locking rules: big lock dcache_lock d_lock may blockd_revalidate: no no no yesd_hash no no no yesd_compare: no yes yes nod_delete: no yes no nod_release: no no no yesd_iput: no no no yes */ /* 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 */ extern spinlock_t dcache_lock;extern seqlock_t rename_lock; /** * d_drop - drop a dentry * @dentry: dentry to drop * * d_drop() unhashes the entry from the parent dentry hashes, so that it won't * be found through a VFS lookup any more. Note that this is different from * deleting the dentry - d_delete will try to mark the dentry negative if * possible, giving a successful _negative_ lookup, while d_drop will * just make the cache lookup fail. * * d_drop() is used mainly for stuff that wants to invalidate a dentry for some * reason (NFS timeouts or autofs deletes). * * __d_drop requires dentry->d_lock. */ static inline void __d_drop(struct dentry *dentry){ if (!(dentry->d_flags & DCACHE_UNHASHED)) { dentry->d_flags |= DCACHE_UNHASHED; hlist_del_rcu(&dentry->d_hash); }} static inline void d_drop(struct dentry *dentry){ spin_lock(&dcache_lock); spin_lock(&dentry->d_lock); __d_drop(dentry); spin_unlock(&dentry->d_lock); spin_unlock(&dcache_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_delete(struct dentry *); /* allocate/de-allocate */extern struct dentry * d_alloc(struct dentry *, const struct qstr *);extern struct dentry * d_splice_alias(struct inode *, struct dentry *);extern struct dentry * d_add_ci(struct dentry *, struct inode *, struct qstr *);extern struct dentry * d_obtain_alias(struct inode *);extern void shrink_dcache_sb(struct super_block *);extern void shrink_dcache_parent(struct dentry *);extern void shrink_dcache_for_umount(struct super_block *);extern int d_invalidate(struct dentry *); /* only used at mount-time */extern struct dentry * d_alloc_root(struct inode *); /* <clickety>-<click> the ramfs-type tree */extern void d_genocide(struct dentry *); extern struct dentry *d_find_alias(struct inode *);extern void d_prune_aliases(struct inode *); /* test whether we have any submounts in a subdir tree */extern int have_submounts(struct dentry *); /* * This adds the entry to the hash queues. */extern void d_rehash(struct dentry *); /** * d_add - add dentry to hash queues * @entry: dentry to add * @inode: The inode to attach to this dentry * * This adds the entry to the hash queues and initializes @inode. * The entry was actually filled in earlier during d_alloc(). */ static inline void d_add(struct dentry *entry, struct inode *inode){ d_instantiate(entry, inode); d_rehash(entry);} /** * d_add_unique - add dentry to hash queues without aliasing * @entry: dentry to add * @inode: The inode to attach to this dentry * * This adds the entry to the hash queues and initializes @inode. * The entry was actually filled in earlier during d_alloc(). */static inline struct dentry *d_add_unique(struct dentry *entry, struct inode *inode){ struct dentry *res; res = d_instantiate_unique(entry, inode); d_rehash(res != NULL ? res : entry); return res;} /* 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_lookup(struct dentry *, struct qstr *);extern struct dentry * d_hash_and_lookup(struct dentry *, struct qstr *); /* 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 *dentry_path(struct dentry *, char *, int); /* Allocation counts.. */ /** * dget, dget_locked - 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. dget() should never be * called for dentries with zero reference counter. For these cases * (preferably none, functions in dcache.c are sufficient for normal * needs and they take necessary precautions) you should hold dcache_lock * and call dget_locked() instead of dget(). */ static inline struct dentry *dget(struct dentry *dentry){ if (dentry) { BUG_ON(!atomic_read(&dentry->d_count)); atomic_inc(&dentry->d_count); } return dentry;} extern struct dentry * dget_locked(struct 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 struct dentry *dget_parent(struct dentry *dentry){ struct dentry *ret; spin_lock(&dentry->d_lock); ret = dget(dentry->d_parent); spin_unlock(&dentry->d_lock); return ret;} extern void dput(struct dentry *); static inline int d_mountpoint(struct dentry *dentry){ return dentry->d_mounted;} extern struct vfsmount *lookup_mnt(struct path *);extern struct dentry *lookup_create(struct nameidata *nd, int is_dir); extern int sysctl_vfs_cache_pressure; #endif /* __LINUX_DCACHE_H */
#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/cache.h>
#include <linux/rcupdate.h>
struct nameidata;
struct path;
struct vfsmount;
/*
* linux/include/linux/dcache.h
*
* Dirent cache data structures
*
* (C) Copyright 1997 Thomas Schoebel-Theuer,
* with heavy changes by Linus Torvalds
*/
#define IS_ROOT(x) ((x) == (x)->d_parent)
/*
* "quick string" -- eases parameter passing, but more importantly
* saves "metadata" about the string (ie length and the hash).
*
* hash comes first so it snuggles against d_parent in the
* dentry.
*/
struct qstr {
unsigned int hash;
unsigned int len;
const unsigned char *name;
};
struct dentry_stat_t {
int nr_dentry;
int nr_unused;
int age_limit; /* age in seconds */
int want_pages; /* pages requested by system */
int dummy[2];
};
extern struct dentry_stat_t dentry_stat;
/* Name hashing routines. Initial hash value */
/* Hash courtesy of the R5 hash in reiserfs modulo sign bits */
#define init_name_hash() 0
/* partial hash update function. Assume roughly 4 bits per character */
static inline unsigned long
partial_name_hash(unsigned long c, unsigned long prevhash)
{
return (prevhash + (c << 4) + (c >> 4)) * 11;
}
/*
* Finally: cut down the number of bits to a int value (and try to avoid
* losing bits)
*/
static inline unsigned long end_name_hash(unsigned long hash)
{
return (unsigned int) hash;
}
/* Compute the hash for a name string. */
static inline unsigned int
full_name_hash(const unsigned char *name, unsigned int len)
{
unsigned long hash = init_name_hash();
while (len--)
hash = partial_name_hash(*name++, hash);
return end_name_hash(hash);
}
/*
* Try to keep struct dentry aligned on 64 byte cachelines (this will
* give reasonable cacheline footprint with larger lines without the
* large memory footprint increase).
*/
#ifdef CONFIG_64BIT
#define DNAME_INLINE_LEN_MIN 32 /* 192 bytes */
#else
#define DNAME_INLINE_LEN_MIN 40 /* 128 bytes */
#endif
struct dentry {
atomic_t d_count;
unsigned int d_flags; /* protected by d_lock */
spinlock_t d_lock; /* per dentry lock */
int d_mounted;
struct inode *d_inode; /* Where the name belongs to - NULL is
* negative */
/*
* The next three fields are touched by __d_lookup. Place them here
* so they all fit in a cache line.
*/
struct hlist_node d_hash; /* lookup hash list */
struct dentry *d_parent; /* parent directory */
struct qstr d_name;
struct list_head d_lru; /* LRU list */
/*
* d_child and d_rcu can share memory
*/
union {
struct list_head d_child; /* child of parent list */
struct rcu_head d_rcu;
} d_u;
struct list_head d_subdirs; /* our children */
struct list_head d_alias; /* inode alias list */
unsigned long d_time; /* used by d_revalidate */
const struct dentry_operations *d_op;
struct super_block *d_sb; /* The root of the dentry tree */
void *d_fsdata; /* fs-specific data */
unsigned char d_iname[DNAME_INLINE_LEN_MIN]; /* small names */
};
/*
* dentry->d_lock spinlock nesting subclasses:
*
* 0: normal
* 1: nested
*/
enum dentry_d_lock_class
{
DENTRY_D_LOCK_NORMAL, /* implicitly used by plain spin_lock() APIs. */
DENTRY_D_LOCK_NESTED
};
struct dentry_operations {
int (*d_revalidate)(struct dentry *, struct nameidata *);
int (*d_hash) (struct dentry *, struct qstr *);
int (*d_compare) (struct dentry *, struct qstr *, struct qstr *);
int (*d_delete)(struct dentry *);
void (*d_release)(struct dentry *);
void (*d_iput)(struct dentry *, struct inode *);
char *(*d_dname)(struct dentry *, char *, int);
};
/* the dentry parameter passed to d_hash and d_compare is the parent
* directory of the entries to be compared. It is used in case these
* functions need any directory specific information for determining
* equivalency classes. Using the dentry itself might not work, as it
* might be a negative dentry which has no information associated with
* it */
/*
locking rules:
big lock dcache_lock d_lock may block
d_revalidate: no no no yes
d_hash no no no yes
d_compare: no yes yes no
d_delete: no yes no no
d_release: no no no yes
d_iput: no no no yes
*/
/* 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 */
extern spinlock_t dcache_lock;
extern seqlock_t rename_lock;
/**
* d_drop - drop a dentry
* @dentry: dentry to drop
*
* d_drop() unhashes the entry from the parent dentry hashes, so that it won't
* be found through a VFS lookup any more. Note that this is different from
* deleting the dentry - d_delete will try to mark the dentry negative if
* possible, giving a successful _negative_ lookup, while d_drop will
* just make the cache lookup fail.
*
* d_drop() is used mainly for stuff that wants to invalidate a dentry for some
* reason (NFS timeouts or autofs deletes).
*
* __d_drop requires dentry->d_lock.
*/
static inline void __d_drop(struct dentry *dentry)
{
if (!(dentry->d_flags & DCACHE_UNHASHED)) {
dentry->d_flags |= DCACHE_UNHASHED;
hlist_del_rcu(&dentry->d_hash);
}
}
static inline void d_drop(struct dentry *dentry)
{
spin_lock(&dcache_lock);
spin_lock(&dentry->d_lock);
__d_drop(dentry);
spin_unlock(&dentry->d_lock);
spin_unlock(&dcache_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_delete(struct dentry *);
/* allocate/de-allocate */
extern struct dentry * d_alloc(struct dentry *, const struct qstr *);
extern struct dentry * d_splice_alias(struct inode *, struct dentry *);
extern struct dentry * d_add_ci(struct dentry *, struct inode *, struct qstr *);
extern struct dentry * d_obtain_alias(struct inode *);
extern void shrink_dcache_sb(struct super_block *);
extern void shrink_dcache_parent(struct dentry *);
extern void shrink_dcache_for_umount(struct super_block *);
extern int d_invalidate(struct dentry *);
/* only used at mount-time */
extern struct dentry * d_alloc_root(struct inode *);
/* <clickety>-<click> the ramfs-type tree */
extern void d_genocide(struct dentry *);
extern struct dentry *d_find_alias(struct inode *);
extern void d_prune_aliases(struct inode *);
/* test whether we have any submounts in a subdir tree */
extern int have_submounts(struct dentry *);
/*
* This adds the entry to the hash queues.
*/
extern void d_rehash(struct dentry *);
/**
* d_add - add dentry to hash queues
* @entry: dentry to add
* @inode: The inode to attach to this dentry
*
* This adds the entry to the hash queues and initializes @inode.
* The entry was actually filled in earlier during d_alloc().
*/
static inline void d_add(struct dentry *entry, struct inode *inode)
{
d_instantiate(entry, inode);
d_rehash(entry);
}
/**
* d_add_unique - add dentry to hash queues without aliasing
* @entry: dentry to add
* @inode: The inode to attach to this dentry
*
* This adds the entry to the hash queues and initializes @inode.
* The entry was actually filled in earlier during d_alloc().
*/
static inline struct dentry *d_add_unique(struct dentry *entry, struct inode *inode)
{
struct dentry *res;
res = d_instantiate_unique(entry, inode);
d_rehash(res != NULL ? res : entry);
return res;
}
/* 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_lookup(struct dentry *, struct qstr *);
extern struct dentry * d_hash_and_lookup(struct dentry *, struct qstr *);
/* 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 *dentry_path(struct dentry *, char *, int);
/* Allocation counts.. */
/**
* dget, dget_locked - 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. dget() should never be
* called for dentries with zero reference counter. For these cases
* (preferably none, functions in dcache.c are sufficient for normal
* needs and they take necessary precautions) you should hold dcache_lock
* and call dget_locked() instead of dget().
*/
static inline struct dentry *dget(struct dentry *dentry)
{
if (dentry) {
BUG_ON(!atomic_read(&dentry->d_count));
atomic_inc(&dentry->d_count);
}
return dentry;
}
extern struct dentry * dget_locked(struct 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 struct dentry *dget_parent(struct dentry *dentry)
{
struct dentry *ret;
spin_lock(&dentry->d_lock);
ret = dget(dentry->d_parent);
spin_unlock(&dentry->d_lock);
return ret;
}
extern void dput(struct dentry *);
static inline int d_mountpoint(struct dentry *dentry)
{
return dentry->d_mounted;
}
extern struct vfsmount *lookup_mnt(struct path *);
extern struct dentry *lookup_create(struct nameidata *nd, int is_dir);
extern int sysctl_vfs_cache_pressure;
#endif /* __LINUX_DCACHE_H */