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Diffstat (limited to 'include/linux/dcache.h')
| -rw-r--r-- | include/linux/dcache.h | 579 |
1 files changed, 579 insertions, 0 deletions
diff --git a/include/linux/dcache.h b/include/linux/dcache.h new file mode 100644 index 000000000..df334cbac --- /dev/null +++ b/include/linux/dcache.h @@ -0,0 +1,579 @@ +#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> +#include <linux/lockref.h> + +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) + +/* The hash is always the low bits of hash_len */ +#ifdef __LITTLE_ENDIAN + #define HASH_LEN_DECLARE u32 hash; u32 len; + #define bytemask_from_count(cnt) (~(~0ul << (cnt)*8)) +#else + #define HASH_LEN_DECLARE u32 len; u32 hash; + #define bytemask_from_count(cnt) (~(~0ul >> (cnt)*8)) +#endif + +/* + * "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 { + union { + struct { + HASH_LEN_DECLARE; + }; + u64 hash_len; + }; + const unsigned char *name; +}; + +#define QSTR_INIT(n,l) { { { .len = l } }, .name = n } +#define hashlen_hash(hashlen) ((u32) (hashlen)) +#define hashlen_len(hashlen) ((u32)((hashlen) >> 32)) +#define hashlen_create(hash,len) (((u64)(len)<<32)|(u32)(hash)) + +struct dentry_stat_t { + long nr_dentry; + long nr_unused; + long age_limit; /* age in seconds */ + long want_pages; /* pages requested by system */ + long 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 + +#define d_lock d_lockref.lock + +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 */ + struct lockref d_lockref; /* per-dentry lock and refcount */ + 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 */ + struct list_head d_child; /* child of parent list */ + struct list_head d_subdirs; /* our children */ + /* + * d_alias and d_rcu can share memory + */ + union { + struct hlist_node d_alias; /* inode alias list */ + struct rcu_head d_rcu; + } d_u; +}; + +/* + * 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 *, unsigned int); + int (*d_weak_revalidate)(struct dentry *, unsigned int); + int (*d_hash)(const struct dentry *, struct qstr *); + int (*d_compare)(const struct dentry *, const struct dentry *, + 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 0x00000001 +#define DCACHE_OP_COMPARE 0x00000002 +#define DCACHE_OP_REVALIDATE 0x00000004 +#define DCACHE_OP_DELETE 0x00000008 +#define DCACHE_OP_PRUNE 0x00000010 + +#define DCACHE_DISCONNECTED 0x00000020 + /* 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 0x00000040 /* Recently used, don't discard. */ +#define DCACHE_RCUACCESS 0x00000080 /* Entry has ever been RCU-visible */ + +#define DCACHE_CANT_MOUNT 0x00000100 +#define DCACHE_GENOCIDE 0x00000200 +#define DCACHE_SHRINK_LIST 0x00000400 + +#define DCACHE_OP_WEAK_REVALIDATE 0x00000800 + +#define DCACHE_NFSFS_RENAMED 0x00001000 + /* this dentry has been "silly renamed" and has to be deleted on the last + * dput() */ +#define DCACHE_COOKIE 0x00002000 /* For use by dcookie subsystem */ +#define DCACHE_FSNOTIFY_PARENT_WATCHED 0x00004000 + /* Parent inode is watched by some fsnotify listener */ + +#define DCACHE_DENTRY_KILLED 0x00008000 + +#define DCACHE_MOUNTED 0x00010000 /* is a mountpoint */ +#define DCACHE_NEED_AUTOMOUNT 0x00020000 /* handle automount on this dir */ +#define DCACHE_MANAGE_TRANSIT 0x00040000 /* manage transit from this dirent */ +#define DCACHE_MANAGED_DENTRY \ + (DCACHE_MOUNTED|DCACHE_NEED_AUTOMOUNT|DCACHE_MANAGE_TRANSIT) + +#define DCACHE_LRU_LIST 0x00080000 + +#define DCACHE_ENTRY_TYPE 0x00700000 +#define DCACHE_MISS_TYPE 0x00000000 /* Negative dentry (maybe fallthru to nowhere) */ +#define DCACHE_WHITEOUT_TYPE 0x00100000 /* Whiteout dentry (stop pathwalk) */ +#define DCACHE_DIRECTORY_TYPE 0x00200000 /* Normal directory */ +#define DCACHE_AUTODIR_TYPE 0x00300000 /* Lookupless directory (presumed automount) */ +#define DCACHE_REGULAR_TYPE 0x00400000 /* Regular file type (or fallthru to such) */ +#define DCACHE_SPECIAL_TYPE 0x00500000 /* Other file type (or fallthru to such) */ +#define DCACHE_SYMLINK_TYPE 0x00600000 /* Symlink (or fallthru to such) */ + +#define DCACHE_MAY_FREE 0x00800000 +#define DCACHE_FALLTHRU 0x01000000 /* Fall through to lower layer */ + +extern seqlock_t rename_lock; + +/* + * 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 int d_instantiate_no_diralias(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 struct dentry * d_obtain_root(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 void 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 void d_tmpfile(struct dentry *, struct inode *); + +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 void d_exchange(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(const struct dentry *, const struct qstr *); +extern struct dentry *d_hash_and_lookup(struct dentry *, struct qstr *); +extern struct dentry *__d_lookup(const struct dentry *, const struct qstr *); +extern struct dentry *__d_lookup_rcu(const struct dentry *parent, + const struct qstr *name, unsigned *seq); + +static inline unsigned d_count(const struct dentry *dentry) +{ + return dentry->d_lockref.count; +} + +/* + * helper function for dentry_operations.d_dname() members + */ +extern char *dynamic_dname(struct dentry *, char *, int, const char *, ...); +extern char *simple_dname(struct dentry *, char *, int); + +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 *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_lockref.count++; + return dentry; +} + +static inline struct dentry *dget(struct dentry *dentry) +{ + if (dentry) + lockref_get(&dentry->d_lockref); + 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(const struct dentry *dentry) +{ + return hlist_bl_unhashed(&dentry->d_hash); +} + +static inline int d_unlinked(const struct dentry *dentry) +{ + return d_unhashed(dentry) && !IS_ROOT(dentry); +} + +static inline int cant_mount(const 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(const struct dentry *dentry) +{ + return dentry->d_flags & DCACHE_MANAGED_DENTRY; +} + +static inline bool d_mountpoint(const struct dentry *dentry) +{ + return dentry->d_flags & DCACHE_MOUNTED; +} + +/* + * Directory cache entry type accessor functions. + */ +static inline unsigned __d_entry_type(const struct dentry *dentry) +{ + unsigned type = READ_ONCE(dentry->d_flags); + smp_rmb(); + return type & DCACHE_ENTRY_TYPE; +} + +static inline bool d_is_miss(const struct dentry *dentry) +{ + return __d_entry_type(dentry) == DCACHE_MISS_TYPE; +} + +static inline bool d_is_whiteout(const struct dentry *dentry) +{ + return __d_entry_type(dentry) == DCACHE_WHITEOUT_TYPE; +} + +static inline bool d_can_lookup(const struct dentry *dentry) +{ + return __d_entry_type(dentry) == DCACHE_DIRECTORY_TYPE; +} + +static inline bool d_is_autodir(const struct dentry *dentry) +{ + return __d_entry_type(dentry) == DCACHE_AUTODIR_TYPE; +} + +static inline bool d_is_dir(const struct dentry *dentry) +{ + return d_can_lookup(dentry) || d_is_autodir(dentry); +} + +static inline bool d_is_symlink(const struct dentry *dentry) +{ + return __d_entry_type(dentry) == DCACHE_SYMLINK_TYPE; +} + +static inline bool d_is_reg(const struct dentry *dentry) +{ + return __d_entry_type(dentry) == DCACHE_REGULAR_TYPE; +} + +static inline bool d_is_special(const struct dentry *dentry) +{ + return __d_entry_type(dentry) == DCACHE_SPECIAL_TYPE; +} + +static inline bool d_is_file(const struct dentry *dentry) +{ + return d_is_reg(dentry) || d_is_special(dentry); +} + +static inline bool d_is_negative(const struct dentry *dentry) +{ + // TODO: check d_is_whiteout(dentry) also. + return d_is_miss(dentry); +} + +static inline bool d_is_positive(const struct dentry *dentry) +{ + return !d_is_negative(dentry); +} + +/** + * d_really_is_negative - Determine if a dentry is really negative (ignoring fallthroughs) + * @dentry: The dentry in question + * + * Returns true if the dentry represents either an absent name or a name that + * doesn't map to an inode (ie. ->d_inode is NULL). The dentry could represent + * a true miss, a whiteout that isn't represented by a 0,0 chardev or a + * fallthrough marker in an opaque directory. + * + * Note! (1) This should be used *only* by a filesystem to examine its own + * dentries. It should not be used to look at some other filesystem's + * dentries. (2) It should also be used in combination with d_inode() to get + * the inode. (3) The dentry may have something attached to ->d_lower and the + * type field of the flags may be set to something other than miss or whiteout. + */ +static inline bool d_really_is_negative(const struct dentry *dentry) +{ + return dentry->d_inode == NULL; +} + +/** + * d_really_is_positive - Determine if a dentry is really positive (ignoring fallthroughs) + * @dentry: The dentry in question + * + * Returns true if the dentry represents a name that maps to an inode + * (ie. ->d_inode is not NULL). The dentry might still represent a whiteout if + * that is represented on medium as a 0,0 chardev. + * + * Note! (1) This should be used *only* by a filesystem to examine its own + * dentries. It should not be used to look at some other filesystem's + * dentries. (2) It should also be used in combination with d_inode() to get + * the inode. + */ +static inline bool d_really_is_positive(const struct dentry *dentry) +{ + return dentry->d_inode != NULL; +} + +extern void d_set_fallthru(struct dentry *dentry); + +static inline bool d_is_fallthru(const struct dentry *dentry) +{ + return dentry->d_flags & DCACHE_FALLTHRU; +} + + +extern int sysctl_vfs_cache_pressure; + +static inline unsigned long vfs_pressure_ratio(unsigned long val) +{ + return mult_frac(val, sysctl_vfs_cache_pressure, 100); +} + +/** + * d_inode - Get the actual inode of this dentry + * @dentry: The dentry to query + * + * This is the helper normal filesystems should use to get at their own inodes + * in their own dentries and ignore the layering superimposed upon them. + */ +static inline struct inode *d_inode(const struct dentry *dentry) +{ + return dentry->d_inode; +} + +/** + * d_inode_rcu - Get the actual inode of this dentry with ACCESS_ONCE() + * @dentry: The dentry to query + * + * This is the helper normal filesystems should use to get at their own inodes + * in their own dentries and ignore the layering superimposed upon them. + */ +static inline struct inode *d_inode_rcu(const struct dentry *dentry) +{ + return ACCESS_ONCE(dentry->d_inode); +} + +/** + * d_backing_inode - Get upper or lower inode we should be using + * @upper: The upper layer + * + * This is the helper that should be used to get at the inode that will be used + * if this dentry were to be opened as a file. The inode may be on the upper + * dentry or it may be on a lower dentry pinned by the upper. + * + * Normal filesystems should not use this to access their own inodes. + */ +static inline struct inode *d_backing_inode(const struct dentry *upper) +{ + struct inode *inode = upper->d_inode; + + return inode; +} + +/** + * d_backing_dentry - Get upper or lower dentry we should be using + * @upper: The upper layer + * + * This is the helper that should be used to get the dentry of the inode that + * will be used if this dentry were opened as a file. It may be the upper + * dentry or it may be a lower dentry pinned by the upper. + * + * Normal filesystems should not use this to access their own dentries. + */ +static inline struct dentry *d_backing_dentry(struct dentry *upper) +{ + return upper; +} + +#endif /* __LINUX_DCACHE_H */ |