413 lines
12 KiB
C
413 lines
12 KiB
C
#ifndef __LINUX_DCACHE_H
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#define __LINUX_DCACHE_H
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#include <linux/atomic.h>
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#include <linux/list.h>
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#include <linux/rculist.h>
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#include <linux/rculist_bl.h>
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#include <linux/spinlock.h>
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#include <linux/seqlock.h>
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#include <linux/cache.h>
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#include <linux/rcupdate.h>
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struct nameidata;
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struct path;
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struct vfsmount;
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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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/* The hash is always the low bits of hash_len */
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#ifdef __LITTLE_ENDIAN
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#define HASH_LEN_DECLARE u32 hash; u32 len;
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#else
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#define HASH_LEN_DECLARE u32 len; u32 hash;
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#endif
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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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* hash comes first so it snuggles against d_parent in the
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* dentry.
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*/
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struct qstr {
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union {
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struct {
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HASH_LEN_DECLARE;
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};
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u64 hash_len;
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};
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const unsigned char *name;
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};
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#define QSTR_INIT(n,l) { { { .len = l } }, .name = n }
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#define hashlen_hash(hashlen) ((u32) (hashlen))
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#define hashlen_len(hashlen) ((u32)((hashlen) >> 32))
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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
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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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/*
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* Finally: cut down the number of bits to a int value (and try to avoid
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* losing bits)
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*/
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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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extern unsigned int full_name_hash(const unsigned char *, unsigned int);
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/*
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* Try to keep struct dentry aligned on 64 byte cachelines (this will
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* give reasonable cacheline footprint with larger lines without the
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* large memory footprint increase).
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*/
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#ifdef CONFIG_64BIT
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# define DNAME_INLINE_LEN 32 /* 192 bytes */
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#else
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# ifdef CONFIG_SMP
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# define DNAME_INLINE_LEN 36 /* 128 bytes */
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# else
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# define DNAME_INLINE_LEN 40 /* 128 bytes */
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# endif
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#endif
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struct dentry {
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/* RCU lookup touched fields */
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unsigned int d_flags; /* protected by d_lock */
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seqcount_t d_seq; /* per dentry seqlock */
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struct hlist_bl_node d_hash; /* lookup hash list */
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struct dentry *d_parent; /* parent directory */
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struct qstr d_name;
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struct inode *d_inode; /* Where the name belongs to - NULL is
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* negative */
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unsigned char d_iname[DNAME_INLINE_LEN]; /* small names */
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/* Ref lookup also touches following */
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unsigned int d_count; /* protected by d_lock */
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spinlock_t d_lock; /* per dentry lock */
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const 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_time; /* used by d_revalidate */
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void *d_fsdata; /* fs-specific data */
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struct list_head d_lru; /* LRU list */
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/*
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* d_child and d_rcu can share memory
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*/
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union {
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struct list_head d_child; /* child of parent list */
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struct rcu_head d_rcu;
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} d_u;
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struct list_head d_subdirs; /* our children */
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struct hlist_node d_alias; /* inode alias list */
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};
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/*
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* dentry->d_lock spinlock nesting subclasses:
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*
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* 0: normal
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* 1: nested
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*/
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enum dentry_d_lock_class
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{
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DENTRY_D_LOCK_NORMAL, /* implicitly used by plain spin_lock() APIs. */
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DENTRY_D_LOCK_NESTED
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};
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struct dentry_operations {
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int (*d_revalidate)(struct dentry *, unsigned int);
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int (*d_hash)(const struct dentry *, const struct inode *,
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struct qstr *);
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int (*d_compare)(const struct dentry *, const struct inode *,
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const struct dentry *, const struct inode *,
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unsigned int, const char *, const struct qstr *);
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int (*d_delete)(const struct dentry *);
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void (*d_release)(struct dentry *);
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void (*d_prune)(struct dentry *);
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void (*d_iput)(struct dentry *, struct inode *);
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char *(*d_dname)(struct dentry *, char *, int);
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struct vfsmount *(*d_automount)(struct path *);
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int (*d_manage)(struct dentry *, bool);
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} ____cacheline_aligned;
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/*
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* Locking rules for dentry_operations callbacks are to be found in
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* Documentation/filesystems/Locking. Keep it updated!
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*
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* FUrther descriptions are found in Documentation/filesystems/vfs.txt.
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* Keep it updated too!
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*/
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/* d_flags entries */
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#define DCACHE_OP_HASH 0x0001
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#define DCACHE_OP_COMPARE 0x0002
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#define DCACHE_OP_REVALIDATE 0x0004
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#define DCACHE_OP_DELETE 0x0008
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#define DCACHE_OP_PRUNE 0x0010
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#define DCACHE_DISCONNECTED 0x0020
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/* This dentry is possibly not currently connected to the dcache tree, in
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* which case its parent will either be itself, or will have this flag as
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* well. nfsd will not use a dentry with this bit set, but will first
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* endeavour to clear the bit either by discovering that it is connected,
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* or by performing lookup operations. Any filesystem which supports
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* nfsd_operations MUST have a lookup function which, if it finds a
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* directory inode with a DCACHE_DISCONNECTED dentry, will d_move that
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* dentry into place and return that dentry rather than the passed one,
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* typically using d_splice_alias. */
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#define DCACHE_REFERENCED 0x0040 /* Recently used, don't discard. */
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#define DCACHE_RCUACCESS 0x0080 /* Entry has ever been RCU-visible */
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#define DCACHE_CANT_MOUNT 0x0100
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#define DCACHE_GENOCIDE 0x0200
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#define DCACHE_SHRINK_LIST 0x0400
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#define DCACHE_NFSFS_RENAMED 0x1000
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/* this dentry has been "silly renamed" and has to be deleted on the last
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* dput() */
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#define DCACHE_COOKIE 0x2000 /* For use by dcookie subsystem */
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#define DCACHE_FSNOTIFY_PARENT_WATCHED 0x4000
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/* Parent inode is watched by some fsnotify listener */
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#define DCACHE_MOUNTED 0x10000 /* is a mountpoint */
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#define DCACHE_NEED_AUTOMOUNT 0x20000 /* handle automount on this dir */
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#define DCACHE_MANAGE_TRANSIT 0x40000 /* manage transit from this dirent */
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#define DCACHE_MANAGED_DENTRY \
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(DCACHE_MOUNTED|DCACHE_NEED_AUTOMOUNT|DCACHE_MANAGE_TRANSIT)
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#define DCACHE_DENTRY_KILLED 0x100000
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extern seqlock_t rename_lock;
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static inline int dname_external(struct dentry *dentry)
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{
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return dentry->d_name.name != dentry->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 struct dentry * d_instantiate_unique(struct dentry *, struct inode *);
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extern struct dentry * d_materialise_unique(struct dentry *, struct inode *);
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extern void __d_drop(struct dentry *dentry);
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extern void d_drop(struct dentry *dentry);
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extern void d_delete(struct dentry *);
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extern void d_set_d_op(struct dentry *dentry, const struct dentry_operations *op);
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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 struct dentry * d_alloc_pseudo(struct super_block *, const struct qstr *);
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extern struct dentry * d_splice_alias(struct inode *, struct dentry *);
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extern struct dentry * d_add_ci(struct dentry *, struct inode *, struct qstr *);
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extern struct dentry *d_find_any_alias(struct inode *inode);
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extern struct dentry * d_obtain_alias(struct inode *);
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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 void shrink_dcache_for_umount(struct super_block *);
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extern int d_invalidate(struct dentry *);
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/* only used at mount-time */
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extern struct dentry * d_make_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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/**
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* d_add_unique - add dentry to hash queues without aliasing
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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 struct dentry *d_add_unique(struct dentry *entry, struct inode *inode)
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{
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struct dentry *res;
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res = d_instantiate_unique(entry, inode);
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d_rehash(res != NULL ? res : entry);
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return res;
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}
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extern void dentry_update_name_case(struct dentry *, struct qstr *);
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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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extern struct dentry *d_ancestor(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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extern struct dentry *d_hash_and_lookup(struct dentry *, struct qstr *);
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extern struct dentry *__d_lookup(struct dentry *, struct qstr *);
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extern struct dentry *__d_lookup_rcu(const struct dentry *parent,
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const struct qstr *name,
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unsigned *seq, struct inode *inode);
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/**
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* __d_rcu_to_refcount - take a refcount on dentry if sequence check is ok
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* @dentry: dentry to take a ref on
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* @seq: seqcount to verify against
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* Returns: 0 on failure, else 1.
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*
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* __d_rcu_to_refcount operates on a dentry,seq pair that was returned
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* by __d_lookup_rcu, to get a reference on an rcu-walk dentry.
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*/
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static inline int __d_rcu_to_refcount(struct dentry *dentry, unsigned seq)
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{
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int ret = 0;
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assert_spin_locked(&dentry->d_lock);
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if (!read_seqcount_retry(&dentry->d_seq, seq)) {
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ret = 1;
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dentry->d_count++;
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}
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return ret;
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}
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/* validate "insecure" dentry pointer */
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extern int d_validate(struct dentry *, struct dentry *);
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/*
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* helper function for dentry_operations.d_dname() members
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*/
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extern char *dynamic_dname(struct dentry *, char *, int, const char *, ...);
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extern char *__d_path(const struct path *, const struct path *, char *, int);
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extern char *d_absolute_path(const struct path *, char *, int);
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extern char *d_path(const struct path *, char *, int);
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extern char *d_path_with_unreachable(const struct path *, char *, int);
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extern char *dentry_path_raw(struct dentry *, char *, int);
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extern char *dentry_path(struct dentry *, char *, int);
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/* Allocation counts.. */
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/**
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* dget, dget_dlock - 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.
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*/
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static inline struct dentry *dget_dlock(struct dentry *dentry)
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{
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if (dentry)
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dentry->d_count++;
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return dentry;
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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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spin_lock(&dentry->d_lock);
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dget_dlock(dentry);
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spin_unlock(&dentry->d_lock);
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}
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return dentry;
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}
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extern struct dentry *dget_parent(struct dentry *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 hlist_bl_unhashed(&dentry->d_hash);
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}
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static inline int d_unlinked(struct dentry *dentry)
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{
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return d_unhashed(dentry) && !IS_ROOT(dentry);
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}
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static inline int cant_mount(struct dentry *dentry)
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{
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return (dentry->d_flags & DCACHE_CANT_MOUNT);
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}
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static inline void dont_mount(struct dentry *dentry)
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{
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spin_lock(&dentry->d_lock);
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dentry->d_flags |= DCACHE_CANT_MOUNT;
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spin_unlock(&dentry->d_lock);
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}
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extern void dput(struct dentry *);
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static inline bool d_managed(struct dentry *dentry)
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{
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return dentry->d_flags & DCACHE_MANAGED_DENTRY;
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}
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static inline bool d_mountpoint(struct dentry *dentry)
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{
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return dentry->d_flags & DCACHE_MOUNTED;
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}
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extern int sysctl_vfs_cache_pressure;
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#endif /* __LINUX_DCACHE_H */
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