#ifndef __LINUX_DCACHE_H #define __LINUX_DCACHE_H #ifdef __KERNEL__ #include #include /* * 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). */ struct qstr { const unsigned char * name; unsigned int len; unsigned int hash; }; 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); } #define DNAME_INLINE_LEN 16 struct dentry { atomic_t d_count; unsigned int d_flags; struct inode * d_inode; /* Where the name belongs to - NULL is negative */ struct dentry * d_parent; /* parent directory */ struct list_head d_hash; /* lookup hash list */ struct list_head d_lru; /* d_count = 0 LRU list */ struct list_head d_child; /* child of parent list */ struct list_head d_subdirs; /* our children */ struct list_head d_alias; /* inode alias list */ int d_mounted; struct qstr d_name; unsigned long d_time; /* used by d_revalidate */ struct dentry_operations *d_op; struct super_block * d_sb; /* The root of the dentry tree */ unsigned long d_vfs_flags; void * d_fsdata; /* fs-specific data */ unsigned char d_iname[DNAME_INLINE_LEN]; /* small names */ }; struct dentry_operations { int (*d_revalidate)(struct dentry *, int); 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 *); }; /* 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 may block d_revalidate: no no yes d_hash no no yes d_compare: no yes no d_delete: no yes no d_release: no no yes d_iput: 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_NFSD_DISCONNECTED 0x0004 /* This dentry is not currently connected to the * dcache tree. Its parent will either be itself, * or will have this flag as well. * If this dentry points to a directory, then * s_nfsd_free_path semaphore will be down */ #define DCACHE_REFERENCED 0x0008 /* Recently used, don't discard. */ extern spinlock_t dcache_lock; static __inline__ int dname_external(struct dentry *d) { return d->d_name.name != d->d_iname; } /* * These are the low-level FS interfaces to the dcache.. */ extern void d_instantiate(struct dentry *, struct inode *); extern void d_delete(struct dentry *); /* allocate/de-allocate */ extern struct dentry * d_alloc(struct dentry *, const struct qstr *); extern void shrink_dcache_sb(struct super_block *); extern void shrink_dcache_parent(struct dentry *); extern int d_invalidate(struct dentry *); #define shrink_dcache() prune_dcache(0) struct zone_struct; /* dcache memory management */ extern int shrink_dcache_memory(int, unsigned int); extern void prune_dcache(int); /* icache memory management (defined in linux/fs/inode.c) */ extern int shrink_icache_memory(int, int); extern void prune_icache(int); /* quota cache memory management (defined in linux/fs/dquot.c) */ extern int shrink_dqcache_memory(int, unsigned int); /* only used at mount-time */ extern struct dentry * d_alloc_root(struct inode *); /* - 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); } /* used for rename() and baskets */ extern void d_move(struct dentry *, struct dentry *); /* appendix may either be NULL or be used for transname suffixes */ extern struct dentry * d_lookup(struct dentry *, struct qstr *); /* validate "insecure" dentry pointer */ extern int d_validate(struct dentry *, struct dentry *); extern char * __d_path(struct dentry *, struct vfsmount *, struct dentry *, struct vfsmount *, 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) { if (!atomic_read(&dentry->d_count)) BUG(); 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 list_empty(&dentry->d_hash); } 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 *); #endif /* __KERNEL__ */ #endif /* __LINUX_DCACHE_H */ #if !defined(__LINUX_DCACHE_H_INLINES) && defined(_TASK_STRUCT_DEFINED) #define __LINUX_DCACHE_H_INLINES #ifdef __KERNEL__ /** * 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). */ static __inline__ void d_drop(struct dentry * dentry) { spin_lock(&dcache_lock); list_del(&dentry->d_hash); INIT_LIST_HEAD(&dentry->d_hash); spin_unlock(&dcache_lock); } #endif #endif