LU - Base Classes

struct lu_object {
        /**
         * Header for this object.
         */
        struct lu_object_header           *lo_header;
        /**
         * Device for this layer.
         */
        struct lu_device                  *lo_dev;
        /**
         * Operations for this object.
         */
        const struct lu_object_operations *lo_ops;
        /**
         * Linkage into list of all layers.
         */
        struct list_head                   lo_linkage;
        /**
         * Depth. Top level layer depth is 0.
         */
        int                                lo_depth;
        /**
         * Flags from enum lu_object_flags.
         */
        unsigned long                      lo_flags;
        /**
         * Link to the device, for debugging.
         */
        struct lu_ref_link                *lo_dev_ref;
};

int lu_object_init (struct lu_object *o,
                    struct lu_object_header *h, struct lu_device *d);

void lu_object_fini (struct lu_object *o);

void lu_object_add_top (struct lu_object_header *h, struct lu_object *o);

void lu_object_add (struct lu_object *before, struct lu_object *o);

struct lu_object_header {
        /**
         * Object flags from enum lu_object_header_flags. Set and checked
         * atomically.
         */
        unsigned long       loh_flags;
        /**
         * Object reference count. Protected by lu_site::ls_guard.
         */
        atomic_t            loh_ref;
        /**
         * Fid, uniquely identifying this object.
         */
        struct lu_fid       loh_fid;
        /**
         * Common object attributes, cached for efficiency. From enum
         * lu_object_header_attr.
         */
        __u32               loh_attr;
        /**
         * Linkage into per-site hash table. Protected by lu_site::ls_guard.
         */
        struct hlist_node   loh_hash;
        /**
         * Linkage into per-site LRU list. Protected by lu_site::ls_guard.
         */
        struct list_head    loh_lru;
        /**
         * Linkage into list of layers. Never modified once set (except lately
         * during object destruction). No locking is necessary.
         */
        struct list_head    loh_layers;
        /**
         * A list of references to this object, for debugging.
         */
        struct lu_ref       loh_reference;
};

int lu_object_header_init(struct lu_object_header *h);

void lu_object_header_fini(struct lu_object_header *h);

        /**
         * Allocate lower-layer parts of the object by calling
         * lu_device_operations::ldo_object_alloc() of the corresponding
         * underlying device.
         *
         * This method is called once for each object inserted into object
         * stack. It's responsibility of this method to insert lower-layer
         * object(s) it create into appropriate places of object stack.
         */
        int (*loo_object_init)(const struct lu_env *env,
                               struct lu_object *o,
                               const struct lu_object_conf *conf);

        /**
         * Called (in bottom-to-top order) during object allocation after all
         * layers were allocated and initialized. Can be used to perform
         * initialization depending on lower layers.
         */
        int (*loo_object_start)(const struct lu_env *env,
                                struct lu_object *o);

        /**
         * Called before lu_object_operations::loo_object_free() to signal
         * that object is being destroyed. Dual to
         * lu_object_operations::loo_object_init().
         */
        void (*loo_object_delete)(const struct lu_env *env,
                                  struct lu_object *o);

        /**
         * Dual to lu_device_operations::ldo_object_alloc(). Called when
         * object is removed from memory.
         */
        void (*loo_object_free)(const struct lu_env *env,
                                struct lu_object *o);

        /**
         * Called when last active reference to the object is released (and
         * object returns to the cache). This method is optional.
         */
        void (*loo_object_release)(const struct lu_env *env,
                                   struct lu_object *o);

        /**
         * Optional debugging helper. Print given object.
         */
        int (*loo_object_print)(const struct lu_env *env, void *cookie,
                                lu_printer_t p, const struct lu_object *o);

        /**
         * Optional debugging method. Returns true iff method is internally
         * consistent.
         */
        int (*loo_object_invariant)(const struct lu_object *o);

struct lu_device {
        /**
         * reference count. This is incremented, in particular, on each object
         * created at this layer.
         *
         * \todo XXX which means that atomic_t is probably too small.
         */
        atomic_t                           ld_ref;
        /**
         * Pointer to device type. Never modified once set.
         */
        struct lu_device_type       *ld_type;
        /**
         * Operation vector for this device.
         */
        const struct lu_device_operations *ld_ops;
        /**
         * Stack this device belongs to.
         */
        struct lu_site                    *ld_site;
        struct proc_dir_entry             *ld_proc_entry;

        /** \todo XXX: temporary back pointer into obd. */
        struct obd_device                 *ld_obd;
        /**
         * A list of references to this object, for debugging.
         */
        struct lu_ref                      ld_reference;
};

void lu_stack_fini (const struct lu_env *env, struct lu_device *top);

void lu_device_get (struct lu_device *d);

void lu_device_put (struct lu_device *d);

int  lu_device_init (struct lu_device *d, struct lu_device_type *t);

void lu_device_fini (struct lu_device *d);

        struct lu_object *(*ldo_object_alloc)(const struct lu_env *env,
                                              const struct lu_object_header *h,
                                              struct lu_device *d);

        int (*ldo_process_config)(const struct lu_env *env,
                                  struct lu_device *d, struct lustre_cfg *cfg);

        int (*ldo_recovery_complete)(const struct lu_env *env,
                                     struct lu_device *d);

        int (*ldo_prepare)(const struct lu_env *env,
                           struct lu_device *parent,
                           struct lu_device *dev);

struct lu_device_type {
        /**
         * Tag bits. Taken from enum lu_device_tag. Never modified once set.
         */
        __u32                                   ldt_tags;
        /**
         * Name of this class. Unique system-wide. Never modified once set.
         */
        char                                   *ldt_name;
        /**
         * Operations for this type.
         */
        const struct lu_device_type_operations *ldt_ops;
        /**
         * \todo XXX: temporary pointer to associated obd_type.
         */
        struct obd_type                        *ldt_obd_type;
        /**
         * \todo XXX: temporary: context tags used by obd_*() calls.
         */
        __u32                                   ldt_ctx_tags;
        /**
         * Number of existing device type instances.
         */
        unsigned                                ldt_device_nr;
        /**
         * Linkage into a global list of all device types.
         *
         * \see lu_device_types.
         */
        struct list_head                        ldt_linkage;
};

int lu_device_type_init(struct lu_device_type *ldt);

void lu_device_type_fini(struct lu_device_type *ldt);

void lu_types_stop(void);

        struct lu_device *(*ldto_device_alloc)(const struct lu_env *env,
                                               struct lu_device_type *t,
                                               struct lustre_cfg *lcfg);

        struct lu_device *(*ldto_device_free)(const struct lu_env *env,
                                              struct lu_device *d);

        int  (*ldto_device_init)(const struct lu_env *env,
                                 struct lu_device *d,
                                 const char *name,
                                 struct lu_device *next);

        struct lu_device *(*ldto_device_fini)(const struct lu_env *env,
                                              struct lu_device *d);

        int  (*ldto_init)(struct lu_device_type *t);

        void (*ldto_fini)(struct lu_device_type *t);

        void (*ldto_start)(struct lu_device_type *t);

        void (*ldto_stop)(struct lu_device_type *t);

/**
 * Common object attributes.
 */
struct lu_attr {
        /** size in bytes */
        __u64          la_size;
        /** modification time in seconds since Epoch */
        __u64          la_mtime;
        /** access time in seconds since Epoch */
        __u64          la_atime;
        /** change time in seconds since Epoch */
        __u64          la_ctime;
        /** 512-byte blocks allocated to object */
        __u64          la_blocks;
        /** permission bits and file type */
        __u32          la_mode;
        /** owner id */
        __u32          la_uid;
        /** group id */
        __u32          la_gid;
        /** object flags */
        __u32          la_flags;
        /** number of persistent references to this object */
        __u32          la_nlink;
        /** blk bits of the object*/
        __u32          la_blkbits;
        /** blk size of the object*/
        __u32          la_blksize;
        /** real device */
        __u32          la_rdev;
        /**
         * valid bits
         *
         * \see enum la_valid
         */
        __u64          la_valid;
};

/** Bit-mask of valid attributes */
enum la_valid {
        LA_ATIME = 1 << 0,
        LA_MTIME = 1 << 1,
        LA_CTIME = 1 << 2,
        LA_SIZE  = 1 << 3,
        LA_MODE  = 1 << 4,
        LA_UID   = 1 << 5,
        LA_GID   = 1 << 6,
        LA_BLOCKS = 1 << 7,
        LA_TYPE   = 1 << 8,
        LA_FLAGS  = 1 << 9,
        LA_NLINK  = 1 << 10,
        LA_RDEV   = 1 << 11,
        LA_BLKSIZE = 1 << 12,
};

struct lu_env {
        /**
         * "Local" context, used to store data instead of stack.
         */
        struct lu_context  le_ctx;
        /**
         * "Session" context for per-request data.
         */
        struct lu_context *le_ses;
};

int  lu_env_init  (struct lu_env *env, __u32 tags);

void lu_env_fini  (struct lu_env *env);

int  lu_env_refill(struct lu_env *env);

struct lu_context {
        /**
         * lu_context is used on the client side too. Yet we don't want to
         * allocate values of server-side keys for the client contexts and
         * vice versa.
         *
         * To achieve this, set of tags in introduced. Contexts and keys are
         * marked with tags. Key value are created only for context whose set
         * of tags has non-empty intersection with one for key. Tags are taken
         * from enum lu_context_tag.
         */
        __u32                  lc_tags;
        /**
         * Pointer to the home service thread. NULL for other execution
         * contexts.
         */
        struct ptlrpc_thread  *lc_thread;
        /**
         * Pointer to an array with key values. Internal implementation
         * detail.
         */
        void                 **lc_value;
        enum lu_context_state  lc_state;
        /**
         * Linkage into a list of all remembered contexts. Only
         * `non-transient' contexts, i.e., ones created for service threads
         * are placed here.
         */
        struct list_head       lc_remember;
        /**
         * Version counter used to skip calls to lu_context_refill() when no
         * keys were registered.
         */
        unsigned               lc_version;
        /**
         * Debugging cookie.
         */
        unsigned               lc_cookie;
};

int lu_context_init  (struct lu_context *ctx, __u32 tags);

void  lu_context_fini (struct lu_context *ctx);

void lu_context_enter (struct lu_context *ctx);

void lu_context_exit (struct lu_context *ctx);

int lu_context_refill (struct lu_context *ctx);

struct lu_context_key {
        /**
         * Set of tags for which values of this key are to be instantiated.
         */
        __u32 lct_tags;
        /**
         * Value constructor. This is called when new value is created for a
         * context. Returns pointer to new value of error pointer.
         */
        void  *(*lct_init)(const struct lu_context *ctx,
                           struct lu_context_key *key);
        /**
         * Value destructor. Called when context with previously allocated
         * value of this slot is destroyed. \a data is a value that was returned
         * by a matching call to lu_context_key::lct_init().
         */
        void   (*lct_fini)(const struct lu_context *ctx,
                           struct lu_context_key *key, void *data);
        /**
         * Optional method called on lu_context_exit() for all allocated
         * keys. Can be used by debugging code checking that locks are
         * released, etc.
         */
        void   (*lct_exit)(const struct lu_context *ctx,
                           struct lu_context_key *key, void *data);
        /**
         * Internal implementation detail: index within lu_context::lc_value[]
         * reserved for this key.
         */
        int      lct_index;
        /**
         * Internal implementation detail: number of values created for this
         * key.
         */
        atomic_t lct_used;
        /**
         * Internal implementation detail: module for this key.
         */
        struct module *lct_owner;
        /**
         * References to this key. For debugging.
         */
        struct lu_ref  lct_reference;
};

int lu_context_key_register(struct lu_context_key *key);

void  lu_context_key_degister(struct lu_context_key *key);

void *lu_context_key_get (const struct lu_context *ctx,
                          const struct lu_context_key *key);

void lu_context_key_quiesce (struct lu_context_key *key);

void lu_context_key_revive (struct lu_context_key *key);

struct lu_site {
        /**
         * Site-wide lock.
         *
         * lock protecting:
         *
         *        - lu_site::ls_hash hash table (and its linkages in objects);
         *
         *        - lu_site::ls_lru list (and its linkages in objects);
         *
         *        - 0/1 transitions of object lu_object_header::loh_ref
         *        reference count;
         *
         * yes, it's heavy.
         */
        rwlock_t              ls_guard;
        /**
         * Hash-table where objects are indexed by fid.
         */
        struct hlist_head    *ls_hash;
        /**
         * Bit-mask for hash-table size.
         */
        int                   ls_hash_mask;
        /**
         * Order of hash-table.
         */
        int                   ls_hash_bits;
        /**
         * Number of buckets in the hash-table.
         */
        int                   ls_hash_size;

        /**
         * LRU list, updated on each access to object. Protected by
         * lu_site::ls_guard.
         *
         * "Cold" end of LRU is lu_site::ls_lru.next. Accessed object are
         * moved to the lu_site::ls_lru.prev (this is due to the non-existence
         * of list_for_each_entry_safe_reverse()).
         */
        struct list_head      ls_lru;
        /**
         * Total number of objects in this site. Protected by
         * lu_site::ls_guard.
         */
        unsigned              ls_total;
        /**
         * Total number of objects in this site with reference counter greater
         * than 0. Protected by lu_site::ls_guard.
         */
        unsigned              ls_busy;

        /**
         * Top-level device for this stack.
         */
        struct lu_device     *ls_top_dev;

        /**
         * Wait-queue signaled when an object in this site is ultimately
         * destroyed (lu_object_free()). It is used by lu_object_find() to
         * wait before re-trying when object in the process of destruction is
         * found in the hash table.
         *
         * If having a single wait-queue turns out to be a problem, a
         * wait-queue per hash-table bucket can be easily implemented.
         *
         * \see htable_lookup().
         */
        cfs_waitq_t           ls_marche_funebre;

        /** statistical counters. Protected by nothing, races are accepted. */
        struct {
                __u32 s_created;
                __u32 s_cache_hit;
                __u32 s_cache_miss;
                /**
                 * Number of hash-table entry checks made.
                 *
                 *       ->s_cache_check / (->s_cache_miss + ->s_cache_hit)
                 *
                 * is an average number of hash slots inspected during single
                 * lookup.
                 */
                __u32 s_cache_check;
                /** Races with cache insertions. */
                __u32 s_cache_race;
                /**
                 * Races with object destruction.
                 *
                 * \see lu_site::ls_marche_funebre.
                 */
                __u32 s_cache_death_race;
                __u32 s_lru_purged;
        } ls_stats;

        /**
         * Linkage into global list of sites.
         */
        struct list_head      ls_linkage;
        struct lprocfs_stats *ls_time_stats;
};

int lu_site_init (struct lu_site *s, struct lu_device *d);

int lu_site_init_finish (struct lu_site *s);

void lu_site_fini (struct lu_site *s);