377 lines
11 KiB
C
377 lines
11 KiB
C
#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 */
|
|
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 */
|
|
|
|
#define DCACHE_COOKIE 0x0040 /* For use by dcookie subsystem */
|
|
|
|
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 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 vfsmount *, struct dentry *);
|
|
extern struct dentry *lookup_create(struct nameidata *nd, int is_dir);
|
|
|
|
extern int sysctl_vfs_cache_pressure;
|
|
|
|
#endif /* __LINUX_DCACHE_H */
|