/* Internal definitions for FS-Cache
 *
 * Copyright (C) 2004-2007 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */

/*
 * Lock order, in the order in which multiple locks should be obtained:
 * - fscache_addremove_sem
 * - cookie->lock
 * - cookie->parent->lock
 * - cache->object_list_lock
 * - object->lock
 * - object->parent->lock
 * - cookie->stores_lock
 * - fscache_thread_lock
 *
 */

#ifdef pr_fmt
#undef pr_fmt
#endif

#define pr_fmt(fmt) "FS-Cache: " fmt

#include <linux/fscache-cache.h>
#include <trace/events/fscache.h>
#include <linux/sched.h>
#include <linux/seq_file.h>

#define FSCACHE_MIN_THREADS	4
#define FSCACHE_MAX_THREADS	32

/*
 * cache.c
 */
extern struct list_head fscache_cache_list;
extern struct rw_semaphore fscache_addremove_sem;

extern struct fscache_cache *fscache_select_cache_for_object(
	struct fscache_cookie *);

/*
 * cookie.c
 */
extern struct kmem_cache *fscache_cookie_jar;

extern void fscache_free_cookie(struct fscache_cookie *);
extern struct fscache_cookie *fscache_alloc_cookie(struct fscache_cookie *,
						   const struct fscache_cookie_def *,
						   const void *, size_t,
						   const void *, size_t,
						   void *, loff_t);
extern struct fscache_cookie *fscache_hash_cookie(struct fscache_cookie *);
extern void fscache_cookie_put(struct fscache_cookie *,
			       enum fscache_cookie_trace);

/*
 * fsdef.c
 */
extern struct fscache_cookie fscache_fsdef_index;
extern struct fscache_cookie_def fscache_fsdef_netfs_def;

/*
 * histogram.c
 */
#ifdef CONFIG_FSCACHE_HISTOGRAM
extern atomic_t fscache_obj_instantiate_histogram[HZ];
extern atomic_t fscache_objs_histogram[HZ];
extern atomic_t fscache_ops_histogram[HZ];
extern atomic_t fscache_retrieval_delay_histogram[HZ];
extern atomic_t fscache_retrieval_histogram[HZ];

static inline void fscache_hist(atomic_t histogram[], unsigned long start_jif)
{
	unsigned long jif = jiffies - start_jif;
	if (jif >= HZ)
		jif = HZ - 1;
	atomic_inc(&histogram[jif]);
}

extern const struct seq_operations fscache_histogram_ops;

#else
#define fscache_hist(hist, start_jif) do {} while (0)
#endif

/*
 * main.c
 */
extern unsigned fscache_defer_lookup;
extern unsigned fscache_defer_create;
extern unsigned fscache_debug;
extern struct kobject *fscache_root;
extern struct workqueue_struct *fscache_object_wq;
extern struct workqueue_struct *fscache_op_wq;
DECLARE_PER_CPU(wait_queue_head_t, fscache_object_cong_wait);

static inline bool fscache_object_congested(void)
{
	return workqueue_congested(WORK_CPU_UNBOUND, fscache_object_wq);
}

/*
 * object.c
 */
extern void fscache_enqueue_object(struct fscache_object *);

/*
 * object-list.c
 */
#ifdef CONFIG_FSCACHE_OBJECT_LIST
extern const struct file_operations fscache_objlist_fops;

extern void fscache_objlist_add(struct fscache_object *);
extern void fscache_objlist_remove(struct fscache_object *);
#else
#define fscache_objlist_add(object) do {} while(0)
#define fscache_objlist_remove(object) do {} while(0)
#endif

/*
 * operation.c
 */
extern int fscache_submit_exclusive_op(struct fscache_object *,
				       struct fscache_operation *);
extern int fscache_submit_op(struct fscache_object *,
			     struct fscache_operation *);
extern int fscache_cancel_op(struct fscache_operation *, bool);
extern void fscache_cancel_all_ops(struct fscache_object *);
extern void fscache_abort_object(struct fscache_object *);
extern void fscache_start_operations(struct fscache_object *);
extern void fscache_operation_gc(struct work_struct *);

/*
 * page.c
 */
extern int fscache_wait_for_deferred_lookup(struct fscache_cookie *);
extern int fscache_wait_for_operation_activation(struct fscache_object *,
						 struct fscache_operation *,
						 atomic_t *,
						 atomic_t *);
extern void fscache_invalidate_writes(struct fscache_cookie *);

/*
 * proc.c
 */
#ifdef CONFIG_PROC_FS
extern int __init fscache_proc_init(void);
extern void fscache_proc_cleanup(void);
#else
#define fscache_proc_init()	(0)
#define fscache_proc_cleanup()	do {} while (0)
#endif

/*
 * stats.c
 */
#ifdef CONFIG_FSCACHE_STATS
extern atomic_t fscache_n_ops_processed[FSCACHE_MAX_THREADS];
extern atomic_t fscache_n_objs_processed[FSCACHE_MAX_THREADS];

extern atomic_t fscache_n_op_pend;
extern atomic_t fscache_n_op_run;
extern atomic_t fscache_n_op_enqueue;
extern atomic_t fscache_n_op_deferred_release;
extern atomic_t fscache_n_op_initialised;
extern atomic_t fscache_n_op_release;
extern atomic_t fscache_n_op_gc;
extern atomic_t fscache_n_op_cancelled;
extern atomic_t fscache_n_op_rejected;

extern atomic_t fscache_n_attr_changed;
extern atomic_t fscache_n_attr_changed_ok;
extern atomic_t fscache_n_attr_changed_nobufs;
extern atomic_t fscache_n_attr_changed_nomem;
extern atomic_t fscache_n_attr_changed_calls;

extern atomic_t fscache_n_allocs;
extern atomic_t fscache_n_allocs_ok;
extern atomic_t fscache_n_allocs_wait;
extern atomic_t fscache_n_allocs_nobufs;
extern atomic_t fscache_n_allocs_intr;
extern atomic_t fscache_n_allocs_object_dead;
extern atomic_t fscache_n_alloc_ops;
extern atomic_t fscache_n_alloc_op_waits;

extern atomic_t fscache_n_retrievals;
extern atomic_t fscache_n_retrievals_ok;
extern atomic_t fscache_n_retrievals_wait;
extern atomic_t fscache_n_retrievals_nodata;
extern atomic_t fscache_n_retrievals_nobufs;
extern atomic_t fscache_n_retrievals_intr;
extern atomic_t fscache_n_retrievals_nomem;
extern atomic_t fscache_n_retrievals_object_dead;
extern atomic_t fscache_n_retrieval_ops;
extern atomic_t fscache_n_retrieval_op_waits;

extern atomic_t fscache_n_stores;
extern atomic_t fscache_n_stores_ok;
extern atomic_t fscache_n_stores_again;
extern atomic_t fscache_n_stores_nobufs;
extern atomic_t fscache_n_stores_oom;
extern atomic_t fscache_n_store_ops;
extern atomic_t fscache_n_store_calls;
extern atomic_t fscache_n_store_pages;
extern atomic_t fscache_n_store_radix_deletes;
extern atomic_t fscache_n_store_pages_over_limit;

extern atomic_t fscache_n_store_vmscan_not_storing;
extern atomic_t fscache_n_store_vmscan_gone;
extern atomic_t fscache_n_store_vmscan_busy;
extern atomic_t fscache_n_store_vmscan_cancelled;
extern atomic_t fscache_n_store_vmscan_wait;

extern atomic_t fscache_n_marks;
extern atomic_t fscache_n_uncaches;

extern atomic_t fscache_n_acquires;
extern atomic_t fscache_n_acquires_null;
extern atomic_t fscache_n_acquires_no_cache;
extern atomic_t fscache_n_acquires_ok;
extern atomic_t fscache_n_acquires_nobufs;
extern atomic_t fscache_n_acquires_oom;

extern atomic_t fscache_n_invalidates;
extern atomic_t fscache_n_invalidates_run;

extern atomic_t fscache_n_updates;
extern atomic_t fscache_n_updates_null;
extern atomic_t fscache_n_updates_run;

extern atomic_t fscache_n_relinquishes;
extern atomic_t fscache_n_relinquishes_null;
extern atomic_t fscache_n_relinquishes_waitcrt;
extern atomic_t fscache_n_relinquishes_retire;

extern atomic_t fscache_n_cookie_index;
extern atomic_t fscache_n_cookie_data;
extern atomic_t fscache_n_cookie_special;

extern atomic_t fscache_n_object_alloc;
extern atomic_t fscache_n_object_no_alloc;
extern atomic_t fscache_n_object_lookups;
extern atomic_t fscache_n_object_lookups_negative;
extern atomic_t fscache_n_object_lookups_positive;
extern atomic_t fscache_n_object_lookups_timed_out;
extern atomic_t fscache_n_object_created;
extern atomic_t fscache_n_object_avail;
extern atomic_t fscache_n_object_dead;

extern atomic_t fscache_n_checkaux_none;
extern atomic_t fscache_n_checkaux_okay;
extern atomic_t fscache_n_checkaux_update;
extern atomic_t fscache_n_checkaux_obsolete;

extern atomic_t fscache_n_cop_alloc_object;
extern atomic_t fscache_n_cop_lookup_object;
extern atomic_t fscache_n_cop_lookup_complete;
extern atomic_t fscache_n_cop_grab_object;
extern atomic_t fscache_n_cop_invalidate_object;
extern atomic_t fscache_n_cop_update_object;
extern atomic_t fscache_n_cop_drop_object;
extern atomic_t fscache_n_cop_put_object;
extern atomic_t fscache_n_cop_sync_cache;
extern atomic_t fscache_n_cop_attr_changed;
extern atomic_t fscache_n_cop_read_or_alloc_page;
extern atomic_t fscache_n_cop_read_or_alloc_pages;
extern atomic_t fscache_n_cop_allocate_page;
extern atomic_t fscache_n_cop_allocate_pages;
extern atomic_t fscache_n_cop_write_page;
extern atomic_t fscache_n_cop_uncache_page;
extern atomic_t fscache_n_cop_dissociate_pages;

extern atomic_t fscache_n_cache_no_space_reject;
extern atomic_t fscache_n_cache_stale_objects;
extern atomic_t fscache_n_cache_retired_objects;
extern atomic_t fscache_n_cache_culled_objects;

static inline void fscache_stat(atomic_t *stat)
{
	atomic_inc(stat);
}

static inline void fscache_stat_d(atomic_t *stat)
{
	atomic_dec(stat);
}

#define __fscache_stat(stat) (stat)

int fscache_stats_show(struct seq_file *m, void *v);
#else

#define __fscache_stat(stat) (NULL)
#define fscache_stat(stat) do {} while (0)
#define fscache_stat_d(stat) do {} while (0)
#endif

/*
 * raise an event on an object
 * - if the event is not masked for that object, then the object is
 *   queued for attention by the thread pool.
 */
static inline void fscache_raise_event(struct fscache_object *object,
				       unsigned event)
{
	BUG_ON(event >= NR_FSCACHE_OBJECT_EVENTS);
#if 0
	printk("*** fscache_raise_event(OBJ%d{%lx},%x)\n",
	       object->debug_id, object->event_mask, (1 << event));
#endif
	if (!test_and_set_bit(event, &object->events) &&
	    test_bit(event, &object->event_mask))
		fscache_enqueue_object(object);
}

static inline void fscache_cookie_get(struct fscache_cookie *cookie,
				      enum fscache_cookie_trace where)
{
	int usage = atomic_inc_return(&cookie->usage);

	trace_fscache_cookie(cookie, where, usage);
}

/*
 * get an extra reference to a netfs retrieval context
 */
static inline
void *fscache_get_context(struct fscache_cookie *cookie, void *context)
{
	if (cookie->def->get_context)
		cookie->def->get_context(cookie->netfs_data, context);
	return context;
}

/*
 * release a reference to a netfs retrieval context
 */
static inline
void fscache_put_context(struct fscache_cookie *cookie, void *context)
{
	if (cookie->def->put_context)
		cookie->def->put_context(cookie->netfs_data, context);
}

/*
 * Update the auxiliary data on a cookie.
 */
static inline
void fscache_update_aux(struct fscache_cookie *cookie, const void *aux_data)
{
	void *p;

	if (!aux_data)
		return;
	if (cookie->aux_len <= sizeof(cookie->inline_aux))
		p = cookie->inline_aux;
	else
		p = cookie->aux;

	if (memcmp(p, aux_data, cookie->aux_len) != 0) {
		memcpy(p, aux_data, cookie->aux_len);
		set_bit(FSCACHE_COOKIE_AUX_UPDATED, &cookie->flags);
	}
}

/*****************************************************************************/
/*
 * debug tracing
 */
#define dbgprintk(FMT, ...) \
	printk(KERN_DEBUG "[%-6.6s] "FMT"\n", current->comm, ##__VA_ARGS__)

#define kenter(FMT, ...) dbgprintk("==> %s("FMT")", __func__, ##__VA_ARGS__)
#define kleave(FMT, ...) dbgprintk("<== %s()"FMT"", __func__, ##__VA_ARGS__)
#define kdebug(FMT, ...) dbgprintk(FMT, ##__VA_ARGS__)

#define kjournal(FMT, ...) no_printk(FMT, ##__VA_ARGS__)

#ifdef __KDEBUG
#define _enter(FMT, ...) kenter(FMT, ##__VA_ARGS__)
#define _leave(FMT, ...) kleave(FMT, ##__VA_ARGS__)
#define _debug(FMT, ...) kdebug(FMT, ##__VA_ARGS__)

#elif defined(CONFIG_FSCACHE_DEBUG)
#define _enter(FMT, ...)			\
do {						\
	if (__do_kdebug(ENTER))			\
		kenter(FMT, ##__VA_ARGS__);	\
} while (0)

#define _leave(FMT, ...)			\
do {						\
	if (__do_kdebug(LEAVE))			\
		kleave(FMT, ##__VA_ARGS__);	\
} while (0)

#define _debug(FMT, ...)			\
do {						\
	if (__do_kdebug(DEBUG))			\
		kdebug(FMT, ##__VA_ARGS__);	\
} while (0)

#else
#define _enter(FMT, ...) no_printk("==> %s("FMT")", __func__, ##__VA_ARGS__)
#define _leave(FMT, ...) no_printk("<== %s()"FMT"", __func__, ##__VA_ARGS__)
#define _debug(FMT, ...) no_printk(FMT, ##__VA_ARGS__)
#endif

/*
 * determine whether a particular optional debugging point should be logged
 * - we need to go through three steps to persuade cpp to correctly join the
 *   shorthand in FSCACHE_DEBUG_LEVEL with its prefix
 */
#define ____do_kdebug(LEVEL, POINT) \
	unlikely((fscache_debug & \
		  (FSCACHE_POINT_##POINT << (FSCACHE_DEBUG_ ## LEVEL * 3))))
#define ___do_kdebug(LEVEL, POINT) \
	____do_kdebug(LEVEL, POINT)
#define __do_kdebug(POINT) \
	___do_kdebug(FSCACHE_DEBUG_LEVEL, POINT)

#define FSCACHE_DEBUG_CACHE	0
#define FSCACHE_DEBUG_COOKIE	1
#define FSCACHE_DEBUG_PAGE	2
#define FSCACHE_DEBUG_OPERATION	3

#define FSCACHE_POINT_ENTER	1
#define FSCACHE_POINT_LEAVE	2
#define FSCACHE_POINT_DEBUG	4

#ifndef FSCACHE_DEBUG_LEVEL
#define FSCACHE_DEBUG_LEVEL CACHE
#endif

/*
 * assertions
 */
#if 1 /* defined(__KDEBUGALL) */

#define ASSERT(X)							\
do {									\
	if (unlikely(!(X))) {						\
		pr_err("\n");					\
		pr_err("Assertion failed\n");	\
		BUG();							\
	}								\
} while (0)

#define ASSERTCMP(X, OP, Y)						\
do {									\
	if (unlikely(!((X) OP (Y)))) {					\
		pr_err("\n");					\
		pr_err("Assertion failed\n");	\
		pr_err("%lx " #OP " %lx is false\n",		\
		       (unsigned long)(X), (unsigned long)(Y));		\
		BUG();							\
	}								\
} while (0)

#define ASSERTIF(C, X)							\
do {									\
	if (unlikely((C) && !(X))) {					\
		pr_err("\n");					\
		pr_err("Assertion failed\n");	\
		BUG();							\
	}								\
} while (0)

#define ASSERTIFCMP(C, X, OP, Y)					\
do {									\
	if (unlikely((C) && !((X) OP (Y)))) {				\
		pr_err("\n");					\
		pr_err("Assertion failed\n");	\
		pr_err("%lx " #OP " %lx is false\n",		\
		       (unsigned long)(X), (unsigned long)(Y));		\
		BUG();							\
	}								\
} while (0)

#else

#define ASSERT(X)			do {} while (0)
#define ASSERTCMP(X, OP, Y)		do {} while (0)
#define ASSERTIF(C, X)			do {} while (0)
#define ASSERTIFCMP(C, X, OP, Y)	do {} while (0)

#endif /* assert or not */
