| /* SPDX-License-Identifier: GPL-2.0 */ |
| #ifndef __LINUX_DCACHE_H |
| #define __LINUX_DCACHE_H |
| |
| #include <linux/atomic.h> |
| #include <linux/list.h> |
| #include <linux/math.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> |
| #include <linux/stringhash.h> |
| #include <linux/wait.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 } |
| |
| extern const struct qstr empty_name; |
| extern const struct qstr slash_name; |
| |
| struct dentry_stat_t { |
| long nr_dentry; |
| long nr_unused; |
| long age_limit; /* age in seconds */ |
| long want_pages; /* pages requested by system */ |
| long nr_negative; /* # of unused negative dentries */ |
| long dummy; /* Reserved for future use */ |
| }; |
| extern struct dentry_stat_t dentry_stat; |
| |
| /* |
| * 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_spinlock_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 */ |
| |
| union { |
| struct list_head d_lru; /* LRU list */ |
| wait_queue_head_t *d_wait; /* in-lookup ones only */ |
| }; |
| 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 hlist_bl_node d_in_lookup_hash; /* only for in-lookup ones */ |
| struct rcu_head d_rcu; |
| } d_u; |
| } __randomize_layout; |
| |
| /* |
| * 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 *, |
| unsigned int, const char *, const struct qstr *); |
| int (*d_delete)(const struct dentry *); |
| int (*d_init)(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)(const struct path *, bool); |
| struct dentry *(*d_real)(struct dentry *, const struct inode *); |
| } ____cacheline_aligned; |
| |
| /* |
| * Locking rules for dentry_operations callbacks are to be found in |
| * Documentation/filesystems/locking.rst. Keep it updated! |
| * |
| * FUrther descriptions are found in Documentation/filesystems/vfs.rst. |
| * 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_DONTCACHE 0x00000080 /* Purge from memory on final dput() */ |
| |
| #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 */ |
| #define DCACHE_NOKEY_NAME 0x02000000 /* Encrypted name encoded without key */ |
| #define DCACHE_OP_REAL 0x04000000 |
| |
| #define DCACHE_PAR_LOOKUP 0x10000000 /* being looked up (with parent locked shared) */ |
| #define DCACHE_DENTRY_CURSOR 0x20000000 |
| #define DCACHE_NORCU 0x40000000 /* No RCU delay for freeing */ |
| |
| extern seqlock_t rename_lock; |
| |
| /* |
| * These are the low-level FS interfaces to the dcache.. |
| */ |
| extern void d_instantiate(struct dentry *, struct inode *); |
| extern void d_instantiate_new(struct dentry *, struct inode *); |
| extern struct dentry * d_instantiate_unique(struct dentry *, struct inode *); |
| extern struct dentry * d_instantiate_anon(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_anon(struct super_block *); |
| extern struct dentry * d_alloc_parallel(struct dentry *, const struct qstr *, |
| wait_queue_head_t *); |
| 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_exact_alias(struct dentry *, struct inode *); |
| 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 *); |
| |
| extern struct dentry *d_find_alias_rcu(struct inode *); |
| |
| /* test whether we have any submounts in a subdir tree */ |
| extern int path_has_submounts(const struct path *); |
| |
| /* |
| * This adds the entry to the hash queues. |
| */ |
| extern void d_rehash(struct dentry *); |
| |
| extern void d_add(struct dentry *, struct inode *); |
| |
| /* 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 __printf(4, 5) |
| 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 *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 __d_lookup_done(struct dentry *); |
| |
| static inline int d_in_lookup(const struct dentry *dentry) |
| { |
| return dentry->d_flags & DCACHE_PAR_LOOKUP; |
| } |
| |
| static inline void d_lookup_done(struct dentry *dentry) |
| { |
| if (unlikely(d_in_lookup(dentry))) { |
| spin_lock(&dentry->d_lock); |
| __d_lookup_done(dentry); |
| 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) |
| { |
| return dentry->d_flags & 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_flags_negative(unsigned flags) |
| { |
| return (flags & DCACHE_ENTRY_TYPE) == DCACHE_MISS_TYPE; |
| } |
| |
| 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; |
| } |
| |
| static inline int simple_positive(const struct dentry *dentry) |
| { |
| return d_really_is_positive(dentry) && !d_unhashed(dentry); |
| } |
| |
| 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 READ_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 READ_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; |
| } |
| |
| /** |
| * d_real - Return the real dentry |
| * @dentry: the dentry to query |
| * @inode: inode to select the dentry from multiple layers (can be NULL) |
| * |
| * If dentry is on a union/overlay, then return the underlying, real dentry. |
| * Otherwise return the dentry itself. |
| * |
| * See also: Documentation/filesystems/vfs.rst |
| */ |
| static inline struct dentry *d_real(struct dentry *dentry, |
| const struct inode *inode) |
| { |
| if (unlikely(dentry->d_flags & DCACHE_OP_REAL)) |
| return dentry->d_op->d_real(dentry, inode); |
| else |
| return dentry; |
| } |
| |
| /** |
| * d_real_inode - Return the real inode |
| * @dentry: The dentry to query |
| * |
| * If dentry is on a union/overlay, then return the underlying, real inode. |
| * Otherwise return d_inode(). |
| */ |
| static inline struct inode *d_real_inode(const struct dentry *dentry) |
| { |
| /* This usage of d_real() results in const dentry */ |
| return d_backing_inode(d_real((struct dentry *) dentry, NULL)); |
| } |
| |
| struct name_snapshot { |
| struct qstr name; |
| unsigned char inline_name[DNAME_INLINE_LEN]; |
| }; |
| void take_dentry_name_snapshot(struct name_snapshot *, struct dentry *); |
| void release_dentry_name_snapshot(struct name_snapshot *); |
| |
| #endif /* __LINUX_DCACHE_H */ |