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Diffstat (limited to 'include/linux/dcache.h')
| -rw-r--r-- | include/linux/dcache.h | 403 |
1 files changed, 403 insertions, 0 deletions
diff --git a/include/linux/dcache.h b/include/linux/dcache.h new file mode 100644 index 00000000..7e11f141 --- /dev/null +++ b/include/linux/dcache.h @@ -0,0 +1,403 @@ +#ifndef __LINUX_DCACHE_H +#define __LINUX_DCACHE_H + +#include <linux/atomic.h> +#include <linux/list.h> +#include <linux/rculist.h> +#include <linux/rculist_bl.h> +#include <linux/spinlock.h> +#include <linux/seqlock.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. */ +extern unsigned int full_name_hash(const unsigned char *, unsigned int); + +/* + * 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 32 /* 192 bytes */ +#else +# ifdef CONFIG_SMP +# define DNAME_INLINE_LEN 36 /* 128 bytes */ +# else +# define DNAME_INLINE_LEN 40 /* 128 bytes */ +# endif +#endif + +struct dentry { + /* RCU lookup touched fields */ + unsigned int d_flags; /* protected by d_lock */ + seqcount_t d_seq; /* per dentry seqlock */ + struct hlist_bl_node d_hash; /* lookup hash list */ + struct dentry *d_parent; /* parent directory */ + struct qstr d_name; + struct inode *d_inode; /* Where the name belongs to - NULL is + * negative */ + unsigned char d_iname[DNAME_INLINE_LEN]; /* small names */ + + /* Ref lookup also touches following */ + unsigned int d_count; /* protected by d_lock */ + spinlock_t d_lock; /* per dentry lock */ + const struct dentry_operations *d_op; + struct super_block *d_sb; /* The root of the dentry tree */ + unsigned long d_time; /* used by d_revalidate */ + void *d_fsdata; /* fs-specific data */ + + 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 */ +}; + +/* + * 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)(const struct dentry *, const struct inode *, + struct qstr *); + int (*d_compare)(const struct dentry *, const struct inode *, + const struct dentry *, const struct inode *, + unsigned int, const char *, const struct qstr *); + int (*d_delete)(const struct dentry *); + void (*d_release)(struct dentry *); + void (*d_prune)(struct dentry *); + void (*d_iput)(struct dentry *, struct inode *); + char *(*d_dname)(struct dentry *, char *, int); + struct vfsmount *(*d_automount)(struct path *); + int (*d_manage)(struct dentry *, bool); +} ____cacheline_aligned; + +/* + * Locking rules for dentry_operations callbacks are to be found in + * Documentation/filesystems/Locking. Keep it updated! + * + * FUrther descriptions are found in Documentation/filesystems/vfs.txt. + * Keep it updated too! + */ + +/* d_flags entries */ +#define DCACHE_OP_HASH 0x0001 +#define DCACHE_OP_COMPARE 0x0002 +#define DCACHE_OP_REVALIDATE 0x0004 +#define DCACHE_OP_DELETE 0x0008 +#define DCACHE_OP_PRUNE 0x0010 + +#define DCACHE_DISCONNECTED 0x0020 + /* 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 0x0040 /* Recently used, don't discard. */ +#define DCACHE_RCUACCESS 0x0080 /* Entry has ever been RCU-visible */ + +#define DCACHE_CANT_MOUNT 0x0100 +#define DCACHE_GENOCIDE 0x0200 +#define DCACHE_SHRINK_LIST 0x0400 + +#define DCACHE_NFSFS_RENAMED 0x1000 + /* this dentry has been "silly renamed" and has to be deleted on the last + * dput() */ +#define DCACHE_COOKIE 0x2000 /* For use by dcookie subsystem */ +#define DCACHE_FSNOTIFY_PARENT_WATCHED 0x4000 + /* Parent inode is watched by some fsnotify listener */ + +#define DCACHE_MOUNTED 0x10000 /* is a mountpoint */ +#define DCACHE_NEED_AUTOMOUNT 0x20000 /* handle automount on this dir */ +#define DCACHE_MANAGE_TRANSIT 0x40000 /* manage transit from this dirent */ +#define DCACHE_NEED_LOOKUP 0x80000 /* dentry requires i_op->lookup */ +#define DCACHE_MANAGED_DENTRY \ + (DCACHE_MOUNTED|DCACHE_NEED_AUTOMOUNT|DCACHE_MANAGE_TRANSIT) + +extern seqlock_t rename_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_drop(struct dentry *dentry); +extern void d_drop(struct dentry *dentry); +extern void d_delete(struct dentry *); +extern void d_set_d_op(struct dentry *dentry, const struct dentry_operations *op); + +/* allocate/de-allocate */ +extern struct dentry * d_alloc(struct dentry *, const struct qstr *); +extern struct dentry * d_alloc_pseudo(struct super_block *, 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_find_any_alias(struct inode *inode); +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_make_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; +} + +extern void dentry_update_name_case(struct dentry *, struct qstr *); + +/* 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_hash_and_lookup(struct dentry *, struct qstr *); +extern struct dentry *__d_lookup(struct dentry *, struct qstr *); +extern struct dentry *__d_lookup_rcu(const struct dentry *parent, + const struct qstr *name, + unsigned *seq, struct inode **inode); + +/** + * __d_rcu_to_refcount - take a refcount on dentry if sequence check is ok + * @dentry: dentry to take a ref on + * @seq: seqcount to verify against + * Returns: 0 on failure, else 1. + * + * __d_rcu_to_refcount operates on a dentry,seq pair that was returned + * by __d_lookup_rcu, to get a reference on an rcu-walk dentry. + */ +static inline int __d_rcu_to_refcount(struct dentry *dentry, unsigned seq) +{ + int ret = 0; + + assert_spin_locked(&dentry->d_lock); + if (!read_seqcount_retry(&dentry->d_seq, seq)) { + ret = 1; + dentry->d_count++; + } + + return ret; +} + +/* 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 *, const struct path *, char *, int); +extern char *d_absolute_path(const struct path *, char *, int); +extern char *d_path(const struct path *, char *, int); +extern char *d_path_with_unreachable(const struct path *, char *, int); +extern char *dentry_path_raw(struct dentry *, char *, int); +extern char *dentry_path(struct dentry *, char *, int); + +/* Allocation counts.. */ + +/** + * dget, dget_dlock - 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. + */ +static inline struct dentry *dget_dlock(struct dentry *dentry) +{ + if (dentry) + dentry->d_count++; + return dentry; +} + +static inline struct dentry *dget(struct dentry *dentry) +{ + if (dentry) { + spin_lock(&dentry->d_lock); + dget_dlock(dentry); + spin_unlock(&dentry->d_lock); + } + return dentry; +} + +extern struct dentry *dget_parent(struct dentry *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 hlist_bl_unhashed(&dentry->d_hash); +} + +static inline int d_unlinked(struct dentry *dentry) +{ + return d_unhashed(dentry) && !IS_ROOT(dentry); +} + +static inline int cant_mount(struct dentry *dentry) +{ + return (dentry->d_flags & DCACHE_CANT_MOUNT); +} + +static inline void dont_mount(struct dentry *dentry) +{ + spin_lock(&dentry->d_lock); + dentry->d_flags |= DCACHE_CANT_MOUNT; + spin_unlock(&dentry->d_lock); +} + +extern void dput(struct dentry *); + +static inline bool d_managed(struct dentry *dentry) +{ + return dentry->d_flags & DCACHE_MANAGED_DENTRY; +} + +static inline bool d_mountpoint(struct dentry *dentry) +{ + return dentry->d_flags & DCACHE_MOUNTED; +} + +static inline bool d_need_lookup(struct dentry *dentry) +{ + return dentry->d_flags & DCACHE_NEED_LOOKUP; +} + +extern void d_clear_need_lookup(struct dentry *dentry); + +extern int sysctl_vfs_cache_pressure; + +#endif /* __LINUX_DCACHE_H */ |