diff options
Diffstat (limited to 'include/linux/dcache.h')
| -rw-r--r-- | include/linux/dcache.h | 243 |
1 files changed, 128 insertions, 115 deletions
diff --git a/include/linux/dcache.h b/include/linux/dcache.h index 6a4aea30aa09..bd07758943e0 100644 --- a/include/linux/dcache.h +++ b/include/linux/dcache.h @@ -4,7 +4,9 @@ #include <asm/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> @@ -45,6 +47,27 @@ struct dentry_stat_t { }; extern struct dentry_stat_t dentry_stat; +/* + * Compare 2 name strings, return 0 if they match, otherwise non-zero. + * The strings are both count bytes long, and count is non-zero. + */ +static inline int dentry_cmp(const unsigned char *cs, size_t scount, + const unsigned char *ct, size_t tcount) +{ + int ret; + if (scount != tcount) + return 1; + do { + ret = (*cs != *ct); + if (ret) + break; + cs++; + ct++; + tcount--; + } while (tcount); + return ret; +} + /* Name hashing routines. Initial hash value */ /* Hash courtesy of the R5 hash in reiserfs modulo sign bits */ #define init_name_hash() 0 @@ -81,25 +104,33 @@ full_name_hash(const unsigned char *name, unsigned int len) * large memory footprint increase). */ #ifdef CONFIG_64BIT -#define DNAME_INLINE_LEN_MIN 32 /* 192 bytes */ +# define DNAME_INLINE_LEN 32 /* 192 bytes */ #else -#define DNAME_INLINE_LEN_MIN 40 /* 128 bytes */ +# ifdef CONFIG_SMP +# define DNAME_INLINE_LEN 36 /* 128 bytes */ +# else +# define DNAME_INLINE_LEN 40 /* 128 bytes */ +# endif #endif struct dentry { - atomic_t d_count; + /* RCU lookup touched fields */ 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 */ + 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 */ /* @@ -111,12 +142,6 @@ struct dentry { } 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 */ }; /* @@ -133,96 +158,61 @@ enum dentry_d_lock_class 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 *); + 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_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 */ +} ____cacheline_aligned; /* -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 + * 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_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_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_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 */ +#define DCACHE_FSNOTIFY_PARENT_WATCHED 0x0080 + /* Parent inode is watched by some fsnotify listener */ #define DCACHE_CANT_MOUNT 0x0100 +#define DCACHE_GENOCIDE 0x0200 +#define DCACHE_MOUNTED 0x0400 /* is a mountpoint */ -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); - } -} +#define DCACHE_OP_HASH 0x1000 +#define DCACHE_OP_COMPARE 0x2000 +#define DCACHE_OP_REVALIDATE 0x4000 +#define DCACHE_OP_DELETE 0x8000 -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); -} +extern seqlock_t rename_lock; static inline int dname_external(struct dentry *dentry) { @@ -235,10 +225,14 @@ static inline int dname_external(struct dentry *dentry) 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_obtain_alias(struct inode *); @@ -296,14 +290,40 @@ static inline struct dentry *d_add_unique(struct dentry *entry, struct inode *in 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_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_hash_and_lookup(struct dentry *, struct qstr *); +extern struct dentry *__d_lookup(struct dentry *, struct qstr *); +extern struct dentry *__d_lookup_rcu(struct dentry *parent, 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 *); @@ -316,34 +336,37 @@ 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 *d_path_with_unreachable(const struct path *, char *, int); -extern char *__dentry_path(struct dentry *, char *, int); +extern char *dentry_path_raw(struct dentry *, char *, int); extern char *dentry_path(struct dentry *, char *, int); /* Allocation counts.. */ /** - * dget, dget_locked - get a reference to a dentry + * 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. 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(). + * 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) { - BUG_ON(!atomic_read(&dentry->d_count)); - atomic_inc(&dentry->d_count); + spin_lock(&dentry->d_lock); + dget_dlock(dentry); + spin_unlock(&dentry->d_lock); } return dentry; } -extern struct dentry * dget_locked(struct dentry *); +extern struct dentry *dget_parent(struct dentry *dentry); /** * d_unhashed - is dentry hashed @@ -374,21 +397,11 @@ static inline void dont_mount(struct dentry *dentry) spin_unlock(&dentry->d_lock); } -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; + return dentry->d_flags & DCACHE_MOUNTED; } extern struct vfsmount *lookup_mnt(struct path *); |