[net-next-2.6.git] / fs / fscache / operation.c

/* FS-Cache worker operation management routines
 *
 * Copyright (C) 2008 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.
 *
 * See Documentation/filesystems/caching/operations.txt
 */

#define FSCACHE_DEBUG_LEVEL OPERATION
#include <linux/module.h>
#include <linux/seq_file.h>
#include <linux/slab.h>
#include "internal.h"

atomic_t fscache_op_debug_id;
EXPORT_SYMBOL(fscache_op_debug_id);

/**
 * fscache_enqueue_operation - Enqueue an operation for processing
 * @op: The operation to enqueue
 *
 * Enqueue an operation for processing by the FS-Cache thread pool.
 *
 * This will get its own ref on the object.
 */
void fscache_enqueue_operation(struct fscache_operation *op)
{
	_enter("{OBJ%x OP%x,%u}",
	       op->object->debug_id, op->debug_id, atomic_read(&op->usage));

	fscache_set_op_state(op, "EnQ");

	ASSERT(list_empty(&op->pend_link));
	ASSERT(op->processor != NULL);
	ASSERTCMP(op->object->state, >=, FSCACHE_OBJECT_AVAILABLE);
	ASSERTCMP(atomic_read(&op->usage), >, 0);

	fscache_stat(&fscache_n_op_enqueue);
	switch (op->flags & FSCACHE_OP_TYPE) {
	case FSCACHE_OP_ASYNC:
		_debug("queue async");
		atomic_inc(&op->usage);
		if (!queue_work(fscache_op_wq, &op->work))
			fscache_put_operation(op);
		break;
	case FSCACHE_OP_MYTHREAD:
		_debug("queue for caller's attention");
		break;
	default:
		printk(KERN_ERR "FS-Cache: Unexpected op type %lx",
		       op->flags);
		BUG();
		break;
	}
}
EXPORT_SYMBOL(fscache_enqueue_operation);

/*
 * start an op running
 */
static void fscache_run_op(struct fscache_object *object,
			   struct fscache_operation *op)
{
	fscache_set_op_state(op, "Run");

	object->n_in_progress++;
	if (test_and_clear_bit(FSCACHE_OP_WAITING, &op->flags))
		wake_up_bit(&op->flags, FSCACHE_OP_WAITING);
	if (op->processor)
		fscache_enqueue_operation(op);
	fscache_stat(&fscache_n_op_run);
}

/*
 * submit an exclusive operation for an object
 * - other ops are excluded from running simultaneously with this one
 * - this gets any extra refs it needs on an op
 */
int fscache_submit_exclusive_op(struct fscache_object *object,
				struct fscache_operation *op)
{
	int ret;

	_enter("{OBJ%x OP%x},", object->debug_id, op->debug_id);

	fscache_set_op_state(op, "SubmitX");

	spin_lock(&object->lock);
	ASSERTCMP(object->n_ops, >=, object->n_in_progress);
	ASSERTCMP(object->n_ops, >=, object->n_exclusive);
	ASSERT(list_empty(&op->pend_link));

	ret = -ENOBUFS;
	if (fscache_object_is_active(object)) {
		op->object = object;
		object->n_ops++;
		object->n_exclusive++;	/* reads and writes must wait */

		if (object->n_ops > 0) {
			atomic_inc(&op->usage);
			list_add_tail(&op->pend_link, &object->pending_ops);
			fscache_stat(&fscache_n_op_pend);
		} else if (!list_empty(&object->pending_ops)) {
			atomic_inc(&op->usage);
			list_add_tail(&op->pend_link, &object->pending_ops);
			fscache_stat(&fscache_n_op_pend);
			fscache_start_operations(object);
		} else {
			ASSERTCMP(object->n_in_progress, ==, 0);
			fscache_run_op(object, op);
		}

		/* need to issue a new write op after this */
		clear_bit(FSCACHE_OBJECT_PENDING_WRITE, &object->flags);
		ret = 0;
	} else if (object->state == FSCACHE_OBJECT_CREATING) {
		op->object = object;
		object->n_ops++;
		object->n_exclusive++;	/* reads and writes must wait */
		atomic_inc(&op->usage);
		list_add_tail(&op->pend_link, &object->pending_ops);
		fscache_stat(&fscache_n_op_pend);
		ret = 0;
	} else {
		/* not allowed to submit ops in any other state */
		BUG();
	}

	spin_unlock(&object->lock);
	return ret;
}

/*
 * report an unexpected submission
 */
static void fscache_report_unexpected_submission(struct fscache_object *object,
						 struct fscache_operation *op,
						 unsigned long ostate)
{
	static bool once_only;
	struct fscache_operation *p;
	unsigned n;

	if (once_only)
		return;
	once_only = true;

	kdebug("unexpected submission OP%x [OBJ%x %s]",
	       op->debug_id, object->debug_id,
	       fscache_object_states[object->state]);
	kdebug("objstate=%s [%s]",
	       fscache_object_states[object->state],
	       fscache_object_states[ostate]);
	kdebug("objflags=%lx", object->flags);
	kdebug("objevent=%lx [%lx]", object->events, object->event_mask);
	kdebug("ops=%u inp=%u exc=%u",
	       object->n_ops, object->n_in_progress, object->n_exclusive);

	if (!list_empty(&object->pending_ops)) {
		n = 0;
		list_for_each_entry(p, &object->pending_ops, pend_link) {
			ASSERTCMP(p->object, ==, object);
			kdebug("%p %p", op->processor, op->release);
			n++;
		}

		kdebug("n=%u", n);
	}

	dump_stack();
}

/*
 * submit an operation for an object
 * - objects may be submitted only in the following states:
 *   - during object creation (write ops may be submitted)
 *   - whilst the object is active
 *   - after an I/O error incurred in one of the two above states (op rejected)
 * - this gets any extra refs it needs on an op
 */
int fscache_submit_op(struct fscache_object *object,
		      struct fscache_operation *op)
{
	unsigned long ostate;
	int ret;

	_enter("{OBJ%x OP%x},{%u}",
	       object->debug_id, op->debug_id, atomic_read(&op->usage));

	ASSERTCMP(atomic_read(&op->usage), >, 0);

	fscache_set_op_state(op, "Submit");

	spin_lock(&object->lock);
	ASSERTCMP(object->n_ops, >=, object->n_in_progress);
	ASSERTCMP(object->n_ops, >=, object->n_exclusive);
	ASSERT(list_empty(&op->pend_link));

	ostate = object->state;
	smp_rmb();

	if (fscache_object_is_active(object)) {
		op->object = object;
		object->n_ops++;

		if (object->n_exclusive > 0) {
			atomic_inc(&op->usage);
			list_add_tail(&op->pend_link, &object->pending_ops);
			fscache_stat(&fscache_n_op_pend);
		} else if (!list_empty(&object->pending_ops)) {
			atomic_inc(&op->usage);
			list_add_tail(&op->pend_link, &object->pending_ops);
			fscache_stat(&fscache_n_op_pend);
			fscache_start_operations(object);
		} else {
			ASSERTCMP(object->n_exclusive, ==, 0);
			fscache_run_op(object, op);
		}
		ret = 0;
	} else if (object->state == FSCACHE_OBJECT_CREATING) {
		op->object = object;
		object->n_ops++;
		atomic_inc(&op->usage);
		list_add_tail(&op->pend_link, &object->pending_ops);
		fscache_stat(&fscache_n_op_pend);
		ret = 0;
	} else if (object->state == FSCACHE_OBJECT_DYING ||
		   object->state == FSCACHE_OBJECT_LC_DYING ||
		   object->state == FSCACHE_OBJECT_WITHDRAWING) {
		fscache_stat(&fscache_n_op_rejected);
		ret = -ENOBUFS;
	} else if (!test_bit(FSCACHE_IOERROR, &object->cache->flags)) {
		fscache_report_unexpected_submission(object, op, ostate);
		ASSERT(!fscache_object_is_active(object));
		ret = -ENOBUFS;
	} else {
		ret = -ENOBUFS;
	}

	spin_unlock(&object->lock);
	return ret;
}

/*
 * queue an object for withdrawal on error, aborting all following asynchronous
 * operations
 */
void fscache_abort_object(struct fscache_object *object)
{
	_enter("{OBJ%x}", object->debug_id);

	fscache_raise_event(object, FSCACHE_OBJECT_EV_ERROR);
}

/*
 * jump start the operation processing on an object
 * - caller must hold object->lock
 */
void fscache_start_operations(struct fscache_object *object)
{
	struct fscache_operation *op;
	bool stop = false;

	while (!list_empty(&object->pending_ops) && !stop) {
		op = list_entry(object->pending_ops.next,
				struct fscache_operation, pend_link);

		if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags)) {
			if (object->n_in_progress > 0)
				break;
			stop = true;
		}
		list_del_init(&op->pend_link);
		fscache_run_op(object, op);

		/* the pending queue was holding a ref on the object */
		fscache_put_operation(op);
	}

	ASSERTCMP(object->n_in_progress, <=, object->n_ops);

	_debug("woke %d ops on OBJ%x",
	       object->n_in_progress, object->debug_id);
}

/*
 * cancel an operation that's pending on an object
 */
int fscache_cancel_op(struct fscache_operation *op)
{
	struct fscache_object *object = op->object;
	int ret;

	_enter("OBJ%x OP%x}", op->object->debug_id, op->debug_id);

	spin_lock(&object->lock);

	ret = -EBUSY;
	if (!list_empty(&op->pend_link)) {
		fscache_stat(&fscache_n_op_cancelled);
		list_del_init(&op->pend_link);
		object->n_ops--;
		if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags))
			object->n_exclusive--;
		if (test_and_clear_bit(FSCACHE_OP_WAITING, &op->flags))
			wake_up_bit(&op->flags, FSCACHE_OP_WAITING);
		fscache_put_operation(op);
		ret = 0;
	}

	spin_unlock(&object->lock);
	_leave(" = %d", ret);
	return ret;
}

/*
 * release an operation
 * - queues pending ops if this is the last in-progress op
 */
void fscache_put_operation(struct fscache_operation *op)
{
	struct fscache_object *object;
	struct fscache_cache *cache;

	_enter("{OBJ%x OP%x,%d}",
	       op->object->debug_id, op->debug_id, atomic_read(&op->usage));

	ASSERTCMP(atomic_read(&op->usage), >, 0);

	if (!atomic_dec_and_test(&op->usage))
		return;

	fscache_set_op_state(op, "Put");

	_debug("PUT OP");
	if (test_and_set_bit(FSCACHE_OP_DEAD, &op->flags))
		BUG();

	fscache_stat(&fscache_n_op_release);

	if (op->release) {
		op->release(op);
		op->release = NULL;
	}

	object = op->object;

	if (test_bit(FSCACHE_OP_DEC_READ_CNT, &op->flags))
		atomic_dec(&object->n_reads);

	/* now... we may get called with the object spinlock held, so we
	 * complete the cleanup here only if we can immediately acquire the
	 * lock, and defer it otherwise */
	if (!spin_trylock(&object->lock)) {
		_debug("defer put");
		fscache_stat(&fscache_n_op_deferred_release);

		cache = object->cache;
		spin_lock(&cache->op_gc_list_lock);
		list_add_tail(&op->pend_link, &cache->op_gc_list);
		spin_unlock(&cache->op_gc_list_lock);
		schedule_work(&cache->op_gc);
		_leave(" [defer]");
		return;
	}

	if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags)) {
		ASSERTCMP(object->n_exclusive, >, 0);
		object->n_exclusive--;
	}

	ASSERTCMP(object->n_in_progress, >, 0);
	object->n_in_progress--;
	if (object->n_in_progress == 0)
		fscache_start_operations(object);

	ASSERTCMP(object->n_ops, >, 0);
	object->n_ops--;
	if (object->n_ops == 0)
		fscache_raise_event(object, FSCACHE_OBJECT_EV_CLEARED);

	spin_unlock(&object->lock);

	kfree(op);
	_leave(" [done]");
}
EXPORT_SYMBOL(fscache_put_operation);

/*
 * garbage collect operations that have had their release deferred
 */
void fscache_operation_gc(struct work_struct *work)
{
	struct fscache_operation *op;
	struct fscache_object *object;
	struct fscache_cache *cache =
		container_of(work, struct fscache_cache, op_gc);
	int count = 0;

	_enter("");

	do {
		spin_lock(&cache->op_gc_list_lock);
		if (list_empty(&cache->op_gc_list)) {
			spin_unlock(&cache->op_gc_list_lock);
			break;
		}

		op = list_entry(cache->op_gc_list.next,
				struct fscache_operation, pend_link);
		list_del(&op->pend_link);
		spin_unlock(&cache->op_gc_list_lock);

		object = op->object;

		_debug("GC DEFERRED REL OBJ%x OP%x",
		       object->debug_id, op->debug_id);
		fscache_stat(&fscache_n_op_gc);

		ASSERTCMP(atomic_read(&op->usage), ==, 0);

		spin_lock(&object->lock);
		if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags)) {
			ASSERTCMP(object->n_exclusive, >, 0);
			object->n_exclusive--;
		}

		ASSERTCMP(object->n_in_progress, >, 0);
		object->n_in_progress--;
		if (object->n_in_progress == 0)
			fscache_start_operations(object);

		ASSERTCMP(object->n_ops, >, 0);
		object->n_ops--;
		if (object->n_ops == 0)
			fscache_raise_event(object, FSCACHE_OBJECT_EV_CLEARED);

		spin_unlock(&object->lock);

	} while (count++ < 20);

	if (!list_empty(&cache->op_gc_list))
		schedule_work(&cache->op_gc);

	_leave("");
}

/*
 * execute an operation using fs_op_wq to provide processing context -
 * the caller holds a ref to this object, so we don't need to hold one
 */
void fscache_op_work_func(struct work_struct *work)
{
	struct fscache_operation *op =
		container_of(work, struct fscache_operation, work);
	unsigned long start;

	_enter("{OBJ%x OP%x,%d}",
	       op->object->debug_id, op->debug_id, atomic_read(&op->usage));

	ASSERT(op->processor != NULL);
	start = jiffies;
	op->processor(op);
	fscache_hist(fscache_ops_histogram, start);
	fscache_put_operation(op);

	_leave("");
}
Commit	Line	Data
952efe7b DH	1	/* FS-Cache worker operation management routines
	2	*
	3	* Copyright (C) 2008 Red Hat, Inc. All Rights Reserved.
	4	* Written by David Howells (dhowells@redhat.com)
	5	*
	6	* This program is free software; you can redistribute it and/or
	7	* modify it under the terms of the GNU General Public License
	8	* as published by the Free Software Foundation; either version
	9	* 2 of the License, or (at your option) any later version.
	10	*
	11	* See Documentation/filesystems/caching/operations.txt
	12	*/
	13
	14	#define FSCACHE_DEBUG_LEVEL OPERATION
	15	#include <linux/module.h>
440f0aff	16	#include <linux/seq_file.h>
5a0e3ad6	17	#include <linux/slab.h>
952efe7b DH	18	#include "internal.h"
	19
	20	atomic_t fscache_op_debug_id;
	21	EXPORT_SYMBOL(fscache_op_debug_id);
	22
	23	/**
	24	* fscache_enqueue_operation - Enqueue an operation for processing
	25	* @op: The operation to enqueue
	26	*
	27	* Enqueue an operation for processing by the FS-Cache thread pool.
	28	*
	29	* This will get its own ref on the object.
	30	*/
	31	void fscache_enqueue_operation(struct fscache_operation *op)
	32	{
	33	_enter("{OBJ%x OP%x,%u}",
	34	op->object->debug_id, op->debug_id, atomic_read(&op->usage));
	35
440f0aff DH	36	fscache_set_op_state(op, "EnQ");
440f0aff DH	37
5753c441	38	ASSERT(list_empty(&op->pend_link));
952efe7b DH	39	ASSERT(op->processor != NULL);
	40	ASSERTCMP(op->object->state, >=, FSCACHE_OBJECT_AVAILABLE);
	41	ASSERTCMP(atomic_read(&op->usage), >, 0);
	42
5753c441 DH	43	fscache_stat(&fscache_n_op_enqueue);
5753c441 DH	44	switch (op->flags & FSCACHE_OP_TYPE) {
8af7c124 TH	45	case FSCACHE_OP_ASYNC:
8af7c124 TH	46	_debug("queue async");
5753c441	47	atomic_inc(&op->usage);
8af7c124	48	if (!queue_work(fscache_op_wq, &op->work))
5753c441 DH	49	fscache_put_operation(op);
5753c441 DH	50	break;
5753c441 DH	51	case FSCACHE_OP_MYTHREAD:
	52	_debug("queue for caller's attention");
	53	break;
	54	default:
	55	printk(KERN_ERR "FS-Cache: Unexpected op type %lx",
	56	op->flags);
	57	BUG();
	58	break;
952efe7b DH	59	}
	60	}
	61	EXPORT_SYMBOL(fscache_enqueue_operation);
	62
	63	/*
	64	* start an op running
	65	*/
	66	static void fscache_run_op(struct fscache_object *object,
	67	struct fscache_operation *op)
	68	{
440f0aff DH	69	fscache_set_op_state(op, "Run");
440f0aff DH	70
952efe7b DH	71	object->n_in_progress++;
	72	if (test_and_clear_bit(FSCACHE_OP_WAITING, &op->flags))
	73	wake_up_bit(&op->flags, FSCACHE_OP_WAITING);
	74	if (op->processor)
	75	fscache_enqueue_operation(op);
	76	fscache_stat(&fscache_n_op_run);
	77	}
	78
	79	/*
	80	* submit an exclusive operation for an object
	81	* - other ops are excluded from running simultaneously with this one
	82	* - this gets any extra refs it needs on an op
	83	*/
	84	int fscache_submit_exclusive_op(struct fscache_object *object,
	85	struct fscache_operation *op)
	86	{
	87	int ret;
	88
	89	_enter("{OBJ%x OP%x},", object->debug_id, op->debug_id);
	90
440f0aff DH	91	fscache_set_op_state(op, "SubmitX");
440f0aff DH	92
952efe7b DH	93	spin_lock(&object->lock);
	94	ASSERTCMP(object->n_ops, >=, object->n_in_progress);
	95	ASSERTCMP(object->n_ops, >=, object->n_exclusive);
5753c441	96	ASSERT(list_empty(&op->pend_link));
952efe7b DH	97
	98	ret = -ENOBUFS;
	99	if (fscache_object_is_active(object)) {
	100	op->object = object;
	101	object->n_ops++;
	102	object->n_exclusive++; /* reads and writes must wait */
	103
	104	if (object->n_ops > 0) {
	105	atomic_inc(&op->usage);
	106	list_add_tail(&op->pend_link, &object->pending_ops);
	107	fscache_stat(&fscache_n_op_pend);
	108	} else if (!list_empty(&object->pending_ops)) {
	109	atomic_inc(&op->usage);
	110	list_add_tail(&op->pend_link, &object->pending_ops);
	111	fscache_stat(&fscache_n_op_pend);
	112	fscache_start_operations(object);
	113	} else {
	114	ASSERTCMP(object->n_in_progress, ==, 0);
	115	fscache_run_op(object, op);
	116	}
	117
	118	/* need to issue a new write op after this */
	119	clear_bit(FSCACHE_OBJECT_PENDING_WRITE, &object->flags);
	120	ret = 0;
	121	} else if (object->state == FSCACHE_OBJECT_CREATING) {
	122	op->object = object;
	123	object->n_ops++;
	124	object->n_exclusive++; /* reads and writes must wait */
	125	atomic_inc(&op->usage);
	126	list_add_tail(&op->pend_link, &object->pending_ops);
	127	fscache_stat(&fscache_n_op_pend);
	128	ret = 0;
	129	} else {
	130	/* not allowed to submit ops in any other state */
	131	BUG();
	132	}
	133
	134	spin_unlock(&object->lock);
	135	return ret;
	136	}
	137
	138	/*
	139	* report an unexpected submission
	140	*/
	141	static void fscache_report_unexpected_submission(struct fscache_object *object,
	142	struct fscache_operation *op,
	143	unsigned long ostate)
	144	{
	145	static bool once_only;
	146	struct fscache_operation *p;
	147	unsigned n;
	148
	149	if (once_only)
	150	return;
	151	once_only = true;
	152
	153	kdebug("unexpected submission OP%x [OBJ%x %s]",
	154	op->debug_id, object->debug_id,
	155	fscache_object_states[object->state]);
	156	kdebug("objstate=%s [%s]",
	157	fscache_object_states[object->state],
	158	fscache_object_states[ostate]);
	159	kdebug("objflags=%lx", object->flags);
	160	kdebug("objevent=%lx [%lx]", object->events, object->event_mask);
161	kdebug("ops=%u inp=%u exc=%u",
162	object->n_ops, object->n_in_progress, object->n_exclusive);
163
164	if (!list_empty(&object->pending_ops)) {
165	n = 0;
166	list_for_each_entry(p, &object->pending_ops, pend_link) {
167	ASSERTCMP(p->object, ==, object);
168	kdebug("%p %p", op->processor, op->release);
169	n++;
170	}
171
172	kdebug("n=%u", n);
173	}
174
175	dump_stack();
176	}
177
178	/*
179	* submit an operation for an object
180	* - objects may be submitted only in the following states:
181	* - during object creation (write ops may be submitted)
182	* - whilst the object is active
183	* - after an I/O error incurred in one of the two above states (op rejected)
184	* - this gets any extra refs it needs on an op
185	*/
186	int fscache_submit_op(struct fscache_object *object,
187	struct fscache_operation *op)
188	{
189	unsigned long ostate;
190	int ret;
191
192	_enter("{OBJ%x OP%x},{%u}",
193	object->debug_id, op->debug_id, atomic_read(&op->usage));
194
195	ASSERTCMP(atomic_read(&op->usage), >, 0);
196
440f0aff DH	197	fscache_set_op_state(op, "Submit");
440f0aff DH	198
952efe7b DH	199	spin_lock(&object->lock);
	200	ASSERTCMP(object->n_ops, >=, object->n_in_progress);
	201	ASSERTCMP(object->n_ops, >=, object->n_exclusive);
5753c441	202	ASSERT(list_empty(&op->pend_link));
952efe7b DH	203
	204	ostate = object->state;
	205	smp_rmb();
	206
	207	if (fscache_object_is_active(object)) {
	208	op->object = object;
	209	object->n_ops++;
	210
	211	if (object->n_exclusive > 0) {
	212	atomic_inc(&op->usage);
	213	list_add_tail(&op->pend_link, &object->pending_ops);
	214	fscache_stat(&fscache_n_op_pend);
	215	} else if (!list_empty(&object->pending_ops)) {
	216	atomic_inc(&op->usage);
	217	list_add_tail(&op->pend_link, &object->pending_ops);
	218	fscache_stat(&fscache_n_op_pend);
	219	fscache_start_operations(object);
	220	} else {
	221	ASSERTCMP(object->n_exclusive, ==, 0);
	222	fscache_run_op(object, op);
	223	}
	224	ret = 0;
	225	} else if (object->state == FSCACHE_OBJECT_CREATING) {
	226	op->object = object;
	227	object->n_ops++;
	228	atomic_inc(&op->usage);
	229	list_add_tail(&op->pend_link, &object->pending_ops);
	230	fscache_stat(&fscache_n_op_pend);
	231	ret = 0;
e3d4d28b DH	232	} else if (object->state == FSCACHE_OBJECT_DYING \|\|
	233	object->state == FSCACHE_OBJECT_LC_DYING \|\|
	234	object->state == FSCACHE_OBJECT_WITHDRAWING) {
	235	fscache_stat(&fscache_n_op_rejected);
	236	ret = -ENOBUFS;
952efe7b DH	237	} else if (!test_bit(FSCACHE_IOERROR, &object->cache->flags)) {
	238	fscache_report_unexpected_submission(object, op, ostate);
	239	ASSERT(!fscache_object_is_active(object));
	240	ret = -ENOBUFS;
	241	} else {
	242	ret = -ENOBUFS;
	243	}
	244
	245	spin_unlock(&object->lock);
	246	return ret;
	247	}
	248
	249	/*
	250	* queue an object for withdrawal on error, aborting all following asynchronous
	251	* operations
	252	*/
	253	void fscache_abort_object(struct fscache_object *object)
	254	{
	255	_enter("{OBJ%x}", object->debug_id);
	256
	257	fscache_raise_event(object, FSCACHE_OBJECT_EV_ERROR);
	258	}
	259
	260	/*
	261	* jump start the operation processing on an object
	262	* - caller must hold object->lock
	263	*/
	264	void fscache_start_operations(struct fscache_object *object)
	265	{
	266	struct fscache_operation *op;
	267	bool stop = false;
	268
	269	while (!list_empty(&object->pending_ops) && !stop) {
	270	op = list_entry(object->pending_ops.next,
	271	struct fscache_operation, pend_link);
	272
	273	if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags)) {
	274	if (object->n_in_progress > 0)
	275	break;
	276	stop = true;
	277	}
	278	list_del_init(&op->pend_link);
5753c441	279	fscache_run_op(object, op);
952efe7b DH	280
	281	/* the pending queue was holding a ref on the object */
	282	fscache_put_operation(op);
	283	}
	284
	285	ASSERTCMP(object->n_in_progress, <=, object->n_ops);
	286
	287	_debug("woke %d ops on OBJ%x",
	288	object->n_in_progress, object->debug_id);
	289	}
	290
5753c441 DH	291	/*
	292	* cancel an operation that's pending on an object
	293	*/
	294	int fscache_cancel_op(struct fscache_operation *op)
	295	{
	296	struct fscache_object *object = op->object;
	297	int ret;
	298
	299	_enter("OBJ%x OP%x}", op->object->debug_id, op->debug_id);
	300
	301	spin_lock(&object->lock);
	302
	303	ret = -EBUSY;
	304	if (!list_empty(&op->pend_link)) {
	305	fscache_stat(&fscache_n_op_cancelled);
	306	list_del_init(&op->pend_link);
	307	object->n_ops--;
	308	if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags))
	309	object->n_exclusive--;
	310	if (test_and_clear_bit(FSCACHE_OP_WAITING, &op->flags))
	311	wake_up_bit(&op->flags, FSCACHE_OP_WAITING);
	312	fscache_put_operation(op);
	313	ret = 0;
	314	}
	315
	316	spin_unlock(&object->lock);
	317	_leave(" = %d", ret);
	318	return ret;
	319	}
	320
952efe7b DH	321	/*
	322	* release an operation
	323	* - queues pending ops if this is the last in-progress op
	324	*/
	325	void fscache_put_operation(struct fscache_operation *op)
	326	{
	327	struct fscache_object *object;
	328	struct fscache_cache *cache;
	329
	330	_enter("{OBJ%x OP%x,%d}",
	331	op->object->debug_id, op->debug_id, atomic_read(&op->usage));
	332
	333	ASSERTCMP(atomic_read(&op->usage), >, 0);
	334
	335	if (!atomic_dec_and_test(&op->usage))
	336	return;
	337
440f0aff DH	338	fscache_set_op_state(op, "Put");
440f0aff DH	339
952efe7b DH	340	_debug("PUT OP");
	341	if (test_and_set_bit(FSCACHE_OP_DEAD, &op->flags))
	342	BUG();
	343
	344	fscache_stat(&fscache_n_op_release);
	345
	346	if (op->release) {
	347	op->release(op);
	348	op->release = NULL;
	349	}
	350
	351	object = op->object;
	352
4fbf4291 DH	353	if (test_bit(FSCACHE_OP_DEC_READ_CNT, &op->flags))
	354	atomic_dec(&object->n_reads);
	355
952efe7b DH	356	/* now... we may get called with the object spinlock held, so we
	357	* complete the cleanup here only if we can immediately acquire the
	358	* lock, and defer it otherwise */
	359	if (!spin_trylock(&object->lock)) {
	360	_debug("defer put");
	361	fscache_stat(&fscache_n_op_deferred_release);
	362
	363	cache = object->cache;
	364	spin_lock(&cache->op_gc_list_lock);
	365	list_add_tail(&op->pend_link, &cache->op_gc_list);
	366	spin_unlock(&cache->op_gc_list_lock);
	367	schedule_work(&cache->op_gc);
	368	_leave(" [defer]");
	369	return;
	370	}
	371
	372	if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags)) {
	373	ASSERTCMP(object->n_exclusive, >, 0);
	374	object->n_exclusive--;
	375	}
	376
	377	ASSERTCMP(object->n_in_progress, >, 0);
	378	object->n_in_progress--;
	379	if (object->n_in_progress == 0)
	380	fscache_start_operations(object);
	381
	382	ASSERTCMP(object->n_ops, >, 0);
	383	object->n_ops--;
	384	if (object->n_ops == 0)
	385	fscache_raise_event(object, FSCACHE_OBJECT_EV_CLEARED);
	386
	387	spin_unlock(&object->lock);
	388
	389	kfree(op);
	390	_leave(" [done]");
	391	}
	392	EXPORT_SYMBOL(fscache_put_operation);
	393
	394	/*
	395	* garbage collect operations that have had their release deferred
	396	*/
	397	void fscache_operation_gc(struct work_struct *work)
	398	{
	399	struct fscache_operation *op;
	400	struct fscache_object *object;
	401	struct fscache_cache *cache =
	402	container_of(work, struct fscache_cache, op_gc);
	403	int count = 0;
	404
	405	_enter("");
	406
	407	do {
	408	spin_lock(&cache->op_gc_list_lock);
	409	if (list_empty(&cache->op_gc_list)) {
	410	spin_unlock(&cache->op_gc_list_lock);
	411	break;
	412	}
	413
	414	op = list_entry(cache->op_gc_list.next,
	415	struct fscache_operation, pend_link);
	416	list_del(&op->pend_link);
	417	spin_unlock(&cache->op_gc_list_lock);
	418
	419	object = op->object;
420
421	_debug("GC DEFERRED REL OBJ%x OP%x",
422	object->debug_id, op->debug_id);
423	fscache_stat(&fscache_n_op_gc);
424
425	ASSERTCMP(atomic_read(&op->usage), ==, 0);
426
427	spin_lock(&object->lock);
428	if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags)) {
429	ASSERTCMP(object->n_exclusive, >, 0);
430	object->n_exclusive--;
431	}
432
433	ASSERTCMP(object->n_in_progress, >, 0);
434	object->n_in_progress--;
435	if (object->n_in_progress == 0)
436	fscache_start_operations(object);
437
438	ASSERTCMP(object->n_ops, >, 0);
439	object->n_ops--;
440	if (object->n_ops == 0)
441	fscache_raise_event(object, FSCACHE_OBJECT_EV_CLEARED);
442
443	spin_unlock(&object->lock);
444
445	} while (count++ < 20);
446
447	if (!list_empty(&cache->op_gc_list))
448	schedule_work(&cache->op_gc);
449
450	_leave("");
451	}
452
453	/*
8af7c124 TH	454	* execute an operation using fs_op_wq to provide processing context -
8af7c124 TH	455	* the caller holds a ref to this object, so we don't need to hold one
952efe7b	456	*/
8af7c124	457	void fscache_op_work_func(struct work_struct *work)
952efe7b DH	458	{
952efe7b DH	459	struct fscache_operation *op =
8af7c124	460	container_of(work, struct fscache_operation, work);
952efe7b DH	461	unsigned long start;
	462
	463	_enter("{OBJ%x OP%x,%d}",
	464	op->object->debug_id, op->debug_id, atomic_read(&op->usage));
	465
	466	ASSERT(op->processor != NULL);
	467	start = jiffies;
	468	op->processor(op);
	469	fscache_hist(fscache_ops_histogram, start);
8af7c124	470	fscache_put_operation(op);
952efe7b DH	471
	472	_leave("");
	473	}