| #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 */ |