278 lines
7.9 KiB
C
Executable File
278 lines
7.9 KiB
C
Executable File
#ifndef __LINUX_DCACHE_H
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#define __LINUX_DCACHE_H
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#ifdef __KERNEL__
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#include <asm/atomic.h>
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#include <linux/mount.h>
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/*
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* linux/include/linux/dcache.h
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*
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* Dirent cache data structures
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*
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* (C) Copyright 1997 Thomas Schoebel-Theuer,
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* with heavy changes by Linus Torvalds
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*/
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#define IS_ROOT(x) ((x) == (x)->d_parent)
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/*
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* "quick string" -- eases parameter passing, but more importantly
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* saves "metadata" about the string (ie length and the hash).
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*/
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struct qstr {
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const unsigned char * name;
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unsigned int len;
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unsigned int hash;
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};
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struct dentry_stat_t {
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int nr_dentry;
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int nr_unused;
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int age_limit; /* age in seconds */
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int want_pages; /* pages requested by system */
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int dummy[2];
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};
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extern struct dentry_stat_t dentry_stat;
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/* Name hashing routines. Initial hash value */
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/* Hash courtesy of the R5 hash in reiserfs modulo sign bits */
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#define init_name_hash() 0
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/* partial hash update function. Assume roughly 4 bits per character */
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static __inline__ unsigned long partial_name_hash(unsigned long c, unsigned long prevhash)
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{
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return (prevhash + (c << 4) + (c >> 4)) * 11;
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}
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/* Finally: cut down the number of bits to a int value (and try to avoid losing bits) */
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static __inline__ unsigned long end_name_hash(unsigned long hash)
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{
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return (unsigned int) hash;
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}
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/* Compute the hash for a name string. */
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static __inline__ unsigned int full_name_hash(const unsigned char * name, unsigned int len)
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{
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unsigned long hash = init_name_hash();
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while (len--)
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hash = partial_name_hash(*name++, hash);
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return end_name_hash(hash);
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}
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#define DNAME_INLINE_LEN 16
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struct dentry {
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atomic_t d_count;
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unsigned int d_flags;
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struct inode * d_inode; /* Where the name belongs to - NULL is negative */
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struct dentry * d_parent; /* parent directory */
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struct list_head d_hash; /* lookup hash list */
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struct list_head d_lru; /* d_count = 0 LRU list */
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struct list_head d_child; /* child of parent list */
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struct list_head d_subdirs; /* our children */
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struct list_head d_alias; /* inode alias list */
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int d_mounted;
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struct qstr d_name;
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unsigned long d_time; /* used by d_revalidate */
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struct dentry_operations *d_op;
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struct super_block * d_sb; /* The root of the dentry tree */
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unsigned long d_vfs_flags;
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void * d_fsdata; /* fs-specific data */
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unsigned char d_iname[DNAME_INLINE_LEN]; /* small names */
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};
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struct dentry_operations {
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int (*d_revalidate)(struct dentry *, int);
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int (*d_hash) (struct dentry *, struct qstr *);
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int (*d_compare) (struct dentry *, struct qstr *, struct qstr *);
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int (*d_delete)(struct dentry *);
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void (*d_release)(struct dentry *);
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void (*d_iput)(struct dentry *, struct inode *);
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};
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/* the dentry parameter passed to d_hash and d_compare is the parent
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* directory of the entries to be compared. It is used in case these
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* functions need any directory specific information for determining
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* equivalency classes. Using the dentry itself might not work, as it
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* might be a negative dentry which has no information associated with
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* it */
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/*
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locking rules:
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big lock dcache_lock may block
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d_revalidate: no no yes
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d_hash no no yes
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d_compare: no yes no
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d_delete: no yes no
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d_release: no no yes
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d_iput: no no yes
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*/
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/* d_flags entries */
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#define DCACHE_AUTOFS_PENDING 0x0001 /* autofs: "under construction" */
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#define DCACHE_NFSFS_RENAMED 0x0002 /* this dentry has been "silly
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* renamed" and has to be
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* deleted on the last dput()
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*/
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#define DCACHE_NFSD_DISCONNECTED 0x0004 /* This dentry is not currently connected to the
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* dcache tree. Its parent will either be itself,
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* or will have this flag as well.
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* If this dentry points to a directory, then
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* s_nfsd_free_path semaphore will be down
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*/
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#define DCACHE_REFERENCED 0x0008 /* Recently used, don't discard. */
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extern spinlock_t dcache_lock;
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/**
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* d_drop - drop a dentry
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* @dentry: dentry to drop
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*
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* d_drop() unhashes the entry from the parent
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* dentry hashes, so that it won't be found through
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* a VFS lookup any more. Note that this is different
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* from deleting the dentry - d_delete will try to
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* mark the dentry negative if possible, giving a
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* successful _negative_ lookup, while d_drop will
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* just make the cache lookup fail.
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*
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* d_drop() is used mainly for stuff that wants
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* to invalidate a dentry for some reason (NFS
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* timeouts or autofs deletes).
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*/
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static __inline__ void d_drop(struct dentry * dentry)
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{
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spin_lock(&dcache_lock);
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list_del(&dentry->d_hash);
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INIT_LIST_HEAD(&dentry->d_hash);
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spin_unlock(&dcache_lock);
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}
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static __inline__ int dname_external(struct dentry *d)
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{
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return d->d_name.name != d->d_iname;
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}
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/*
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* These are the low-level FS interfaces to the dcache..
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*/
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extern void d_instantiate(struct dentry *, struct inode *);
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extern void d_delete(struct dentry *);
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/* allocate/de-allocate */
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extern struct dentry * d_alloc(struct dentry *, const struct qstr *);
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extern void shrink_dcache_sb(struct super_block *);
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extern void shrink_dcache_parent(struct dentry *);
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extern int d_invalidate(struct dentry *);
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#define shrink_dcache() prune_dcache(0)
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struct zone_struct;
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/* dcache memory management */
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extern int shrink_dcache_memory(int, unsigned int);
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extern void prune_dcache(int);
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/* icache memory management (defined in linux/fs/inode.c) */
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extern int shrink_icache_memory(int, int);
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extern void prune_icache(int);
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/* quota cache memory management (defined in linux/fs/dquot.c) */
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extern int shrink_dqcache_memory(int, unsigned int);
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/* only used at mount-time */
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extern struct dentry * d_alloc_root(struct inode *);
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/* <clickety>-<click> the ramfs-type tree */
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extern void d_genocide(struct dentry *);
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extern struct dentry *d_find_alias(struct inode *);
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extern void d_prune_aliases(struct inode *);
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/* test whether we have any submounts in a subdir tree */
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extern int have_submounts(struct dentry *);
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/*
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* This adds the entry to the hash queues.
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*/
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extern void d_rehash(struct dentry *);
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/**
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* d_add - add dentry to hash queues
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* @entry: dentry to add
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* @inode: The inode to attach to this dentry
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*
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* This adds the entry to the hash queues and initializes @inode.
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* The entry was actually filled in earlier during d_alloc().
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*/
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static __inline__ void d_add(struct dentry * entry, struct inode * inode)
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{
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d_instantiate(entry, inode);
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d_rehash(entry);
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}
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/* used for rename() and baskets */
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extern void d_move(struct dentry *, struct dentry *);
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/* appendix may either be NULL or be used for transname suffixes */
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extern struct dentry * d_lookup(struct dentry *, struct qstr *);
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/* validate "insecure" dentry pointer */
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extern int d_validate(struct dentry *, struct dentry *);
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extern char * __d_path(struct dentry *, struct vfsmount *, struct dentry *,
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struct vfsmount *, char *, int);
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/* Allocation counts.. */
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/**
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* dget, dget_locked - get a reference to a dentry
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* @dentry: dentry to get a reference to
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*
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* Given a dentry or %NULL pointer increment the reference count
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* if appropriate and return the dentry. A dentry will not be
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* destroyed when it has references. dget() should never be
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* called for dentries with zero reference counter. For these cases
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* (preferably none, functions in dcache.c are sufficient for normal
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* needs and they take necessary precautions) you should hold dcache_lock
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* and call dget_locked() instead of dget().
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*/
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static __inline__ struct dentry * dget(struct dentry *dentry)
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{
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if (dentry) {
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if (!atomic_read(&dentry->d_count))
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BUG();
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atomic_inc(&dentry->d_count);
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}
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return dentry;
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}
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extern struct dentry * dget_locked(struct dentry *);
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/**
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* d_unhashed - is dentry hashed
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* @dentry: entry to check
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*
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* Returns true if the dentry passed is not currently hashed.
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*/
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static __inline__ int d_unhashed(struct dentry *dentry)
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{
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return list_empty(&dentry->d_hash);
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}
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extern void dput(struct dentry *);
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static __inline__ int d_mountpoint(struct dentry *dentry)
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{
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return dentry->d_mounted;
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}
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extern struct vfsmount *lookup_mnt(struct vfsmount *, struct dentry *);
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#endif /* __KERNEL__ */
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#endif /* __LINUX_DCACHE_H */
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