[linux.git] / fs / fscache / operation.c

/* FS-Cache worker operation management routines
 *
 * Copyright (C) 2008 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells ([email protected])
 *
 * 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));

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

	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:
		pr_err("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)
{
	ASSERTCMP(op->state, ==, FSCACHE_OP_ST_PENDING);

	op->state = FSCACHE_OP_ST_IN_PROGRESS;
	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);

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

	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));

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

		if (object->n_in_progress > 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 (test_bit(FSCACHE_OBJECT_IS_LOOKED_UP, &object->flags)) {
		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 {
		/* If we're in any other state, there must have been an I/O
		 * error of some nature.
		 */
		ASSERT(test_bit(FSCACHE_IOERROR, &object->cache->flags));
		ret = -EIO;
	}

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

/*
 * report an unexpected submission
 */
static void fscache_report_unexpected_submission(struct fscache_object *object,
						 struct fscache_operation *op,
						 const struct fscache_state *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, object->state->name);
	kdebug("objstate=%s [%s]", object->state->name, ostate->name);
	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)
{
	const struct fscache_state *ostate;
	int ret;

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

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

	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();

	op->state = FSCACHE_OP_ST_PENDING;
	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 (test_bit(FSCACHE_OBJECT_IS_LOOKED_UP, &object->flags)) {
		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 (fscache_object_is_dying(object)) {
		fscache_stat(&fscache_n_op_rejected);
		op->state = FSCACHE_OP_ST_CANCELLED;
		ret = -ENOBUFS;
	} else if (!test_bit(FSCACHE_IOERROR, &object->cache->flags)) {
		fscache_report_unexpected_submission(object, op, ostate);
		ASSERT(!fscache_object_is_active(object));
		op->state = FSCACHE_OP_ST_CANCELLED;
		ret = -ENOBUFS;
	} else {
		op->state = FSCACHE_OP_ST_CANCELLED;
		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.  The 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,
		      void (*do_cancel)(struct fscache_operation *))
{
	struct fscache_object *object = op->object;
	int ret;

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

	ASSERTCMP(op->state, >=, FSCACHE_OP_ST_PENDING);
	ASSERTCMP(op->state, !=, FSCACHE_OP_ST_CANCELLED);
	ASSERTCMP(atomic_read(&op->usage), >, 0);

	spin_lock(&object->lock);

	ret = -EBUSY;
	if (op->state == FSCACHE_OP_ST_PENDING) {
		ASSERT(!list_empty(&op->pend_link));
		fscache_stat(&fscache_n_op_cancelled);
		list_del_init(&op->pend_link);
		if (do_cancel)
			do_cancel(op);
		op->state = FSCACHE_OP_ST_CANCELLED;
		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;
}

/*
 * Cancel all pending operations on an object
 */
void fscache_cancel_all_ops(struct fscache_object *object)
{
	struct fscache_operation *op;

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

	spin_lock(&object->lock);

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

		ASSERTCMP(op->state, ==, FSCACHE_OP_ST_PENDING);
		op->state = FSCACHE_OP_ST_CANCELLED;

		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);
		cond_resched_lock(&object->lock);
	}

	spin_unlock(&object->lock);
	_leave("");
}

/*
 * Record the completion or cancellation of an in-progress operation.
 */
void fscache_op_complete(struct fscache_operation *op, bool cancelled)
{
	struct fscache_object *object = op->object;

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

	ASSERTCMP(op->state, ==, FSCACHE_OP_ST_IN_PROGRESS);
	ASSERTCMP(object->n_in_progress, >, 0);
	ASSERTIFCMP(test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags),
		    object->n_exclusive, >, 0);
	ASSERTIFCMP(test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags),
		    object->n_in_progress, ==, 1);

	spin_lock(&object->lock);

	op->state = cancelled ?
		FSCACHE_OP_ST_CANCELLED : FSCACHE_OP_ST_COMPLETE;

	if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags))
		object->n_exclusive--;
	object->n_in_progress--;
	if (object->n_in_progress == 0)
		fscache_start_operations(object);

	spin_unlock(&object->lock);
	_leave("");
}
EXPORT_SYMBOL(fscache_op_complete);

/*
 * 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;

	_debug("PUT OP");
	ASSERTIFCMP(op->state != FSCACHE_OP_ST_COMPLETE,
		    op->state, ==, FSCACHE_OP_ST_CANCELLED);
	op->state = FSCACHE_OP_ST_DEAD;

	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);
	if (test_bit(FSCACHE_OP_UNUSE_COOKIE, &op->flags))
		fscache_unuse_cookie(object);

	/* 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;
	}

	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;
		spin_lock(&object->lock);

		_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);
		ASSERTCMP(op->state, ==, FSCACHE_OP_ST_DEAD);

		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);

	} 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 ([email protected])
	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
5753c441	36	ASSERT(list_empty(&op->pend_link));
952efe7b	37	ASSERT(op->processor != NULL);
493f7bc1	38	ASSERT(fscache_object_is_available(op->object));
952efe7b	39	ASSERTCMP(atomic_read(&op->usage), >, 0);
9f10523f	40	ASSERTCMP(op->state, ==, FSCACHE_OP_ST_IN_PROGRESS);
952efe7b	41
5753c441 DH	42	fscache_stat(&fscache_n_op_enqueue);
5753c441 DH	43	switch (op->flags & FSCACHE_OP_TYPE) {
8af7c124 TH	44	case FSCACHE_OP_ASYNC:
8af7c124 TH	45	_debug("queue async");
5753c441	46	atomic_inc(&op->usage);
8af7c124	47	if (!queue_work(fscache_op_wq, &op->work))
5753c441 DH	48	fscache_put_operation(op);
5753c441 DH	49	break;
5753c441 DH	50	case FSCACHE_OP_MYTHREAD:
	51	_debug("queue for caller's attention");
	52	break;
	53	default:
36dfd116	54	pr_err("Unexpected op type %lx", op->flags);
5753c441 DH	55	BUG();
5753c441 DH	56	break;
952efe7b DH	57	}
	58	}
	59	EXPORT_SYMBOL(fscache_enqueue_operation);
	60
	61	/*
	62	* start an op running
	63	*/
	64	static void fscache_run_op(struct fscache_object *object,
	65	struct fscache_operation *op)
	66	{
9f10523f DH	67	ASSERTCMP(op->state, ==, FSCACHE_OP_ST_PENDING);
	68
	69	op->state = FSCACHE_OP_ST_IN_PROGRESS;
952efe7b DH	70	object->n_in_progress++;
	71	if (test_and_clear_bit(FSCACHE_OP_WAITING, &op->flags))
	72	wake_up_bit(&op->flags, FSCACHE_OP_WAITING);
	73	if (op->processor)
	74	fscache_enqueue_operation(op);
	75	fscache_stat(&fscache_n_op_run);
	76	}
	77
	78	/*
	79	* submit an exclusive operation for an object
	80	* - other ops are excluded from running simultaneously with this one
	81	* - this gets any extra refs it needs on an op
	82	*/
	83	int fscache_submit_exclusive_op(struct fscache_object *object,
	84	struct fscache_operation *op)
	85	{
8d76349d DH	86	int ret;
8d76349d DH	87
952efe7b DH	88	_enter("{OBJ%x OP%x},", object->debug_id, op->debug_id);
952efe7b DH	89
9f10523f DH	90	ASSERTCMP(op->state, ==, FSCACHE_OP_ST_INITIALISED);
	91	ASSERTCMP(atomic_read(&op->usage), >, 0);
	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	97
9f10523f	98	op->state = FSCACHE_OP_ST_PENDING;
952efe7b DH	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
9f10523f	104	if (object->n_in_progress > 0) {
952efe7b DH	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);
8d76349d	120	ret = 0;
caaef690	121	} else if (test_bit(FSCACHE_OBJECT_IS_LOOKED_UP, &object->flags)) {
952efe7b DH	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);
8d76349d	128	ret = 0;
952efe7b	129	} else {
8d76349d DH	130	/* If we're in any other state, there must have been an I/O
	131	* error of some nature.
	132	*/
	133	ASSERT(test_bit(FSCACHE_IOERROR, &object->cache->flags));
	134	ret = -EIO;
952efe7b DH	135	}
	136
	137	spin_unlock(&object->lock);
8d76349d	138	return ret;
952efe7b DH	139	}
	140
	141	/*
	142	* report an unexpected submission
	143	*/
	144	static void fscache_report_unexpected_submission(struct fscache_object *object,
	145	struct fscache_operation *op,
caaef690	146	const struct fscache_state *ostate)
952efe7b DH	147	{
	148	static bool once_only;
	149	struct fscache_operation *p;
	150	unsigned n;
	151
	152	if (once_only)
	153	return;
	154	once_only = true;
	155
	156	kdebug("unexpected submission OP%x [OBJ%x %s]",
caaef690 DH	157	op->debug_id, object->debug_id, object->state->name);
caaef690 DH	158	kdebug("objstate=%s [%s]", object->state->name, ostate->name);
952efe7b DH	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	{
caaef690	189	const struct fscache_state *ostate;
952efe7b DH	190	int ret;
	191
	192	_enter("{OBJ%x OP%x},{%u}",
	193	object->debug_id, op->debug_id, atomic_read(&op->usage));
	194
9f10523f	195	ASSERTCMP(op->state, ==, FSCACHE_OP_ST_INITIALISED);
952efe7b DH	196	ASSERTCMP(atomic_read(&op->usage), >, 0);
	197
	198	spin_lock(&object->lock);
	199	ASSERTCMP(object->n_ops, >=, object->n_in_progress);
	200	ASSERTCMP(object->n_ops, >=, object->n_exclusive);
5753c441	201	ASSERT(list_empty(&op->pend_link));
952efe7b DH	202
	203	ostate = object->state;
	204	smp_rmb();
	205
9f10523f	206	op->state = FSCACHE_OP_ST_PENDING;
952efe7b DH	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;
caaef690	225	} else if (test_bit(FSCACHE_OBJECT_IS_LOOKED_UP, &object->flags)) {
952efe7b DH	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;
caaef690	232	} else if (fscache_object_is_dying(object)) {
e3d4d28b	233	fscache_stat(&fscache_n_op_rejected);
9f10523f	234	op->state = FSCACHE_OP_ST_CANCELLED;
e3d4d28b	235	ret = -ENOBUFS;
952efe7b DH	236	} else if (!test_bit(FSCACHE_IOERROR, &object->cache->flags)) {
	237	fscache_report_unexpected_submission(object, op, ostate);
	238	ASSERT(!fscache_object_is_active(object));
9f10523f	239	op->state = FSCACHE_OP_ST_CANCELLED;
952efe7b DH	240	ret = -ENOBUFS;
952efe7b DH	241	} else {
9f10523f	242	op->state = FSCACHE_OP_ST_CANCELLED;
952efe7b DH	243	ret = -ENOBUFS;
	244	}
	245
	246	spin_unlock(&object->lock);
	247	return ret;
	248	}
	249
	250	/*
	251	* queue an object for withdrawal on error, aborting all following asynchronous
	252	* operations
	253	*/
	254	void fscache_abort_object(struct fscache_object *object)
	255	{
	256	_enter("{OBJ%x}", object->debug_id);
	257
	258	fscache_raise_event(object, FSCACHE_OBJECT_EV_ERROR);
	259	}
	260
	261	/*
dcfae32f DH	262	* Jump start the operation processing on an object. The caller must hold
dcfae32f DH	263	* object->lock.
952efe7b DH	264	*/
	265	void fscache_start_operations(struct fscache_object *object)
	266	{
	267	struct fscache_operation *op;
	268	bool stop = false;
	269
	270	while (!list_empty(&object->pending_ops) && !stop) {
	271	op = list_entry(object->pending_ops.next,
	272	struct fscache_operation, pend_link);
	273
	274	if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags)) {
	275	if (object->n_in_progress > 0)
	276	break;
	277	stop = true;
	278	}
	279	list_del_init(&op->pend_link);
5753c441	280	fscache_run_op(object, op);
952efe7b DH	281
	282	/* the pending queue was holding a ref on the object */
	283	fscache_put_operation(op);
	284	}
	285
	286	ASSERTCMP(object->n_in_progress, <=, object->n_ops);
	287
	288	_debug("woke %d ops on OBJ%x",
	289	object->n_in_progress, object->debug_id);
	290	}
	291
5753c441 DH	292	/*
	293	* cancel an operation that's pending on an object
	294	*/
91c7fbbf DH	295	int fscache_cancel_op(struct fscache_operation *op,
91c7fbbf DH	296	void (do_cancel)(struct fscache_operation ))
5753c441 DH	297	{
	298	struct fscache_object *object = op->object;
	299	int ret;
	300
	301	_enter("OBJ%x OP%x}", op->object->debug_id, op->debug_id);
	302
9f10523f DH	303	ASSERTCMP(op->state, >=, FSCACHE_OP_ST_PENDING);
	304	ASSERTCMP(op->state, !=, FSCACHE_OP_ST_CANCELLED);
	305	ASSERTCMP(atomic_read(&op->usage), >, 0);
	306
5753c441 DH	307	spin_lock(&object->lock);
	308
	309	ret = -EBUSY;
9f10523f DH	310	if (op->state == FSCACHE_OP_ST_PENDING) {
9f10523f DH	311	ASSERT(!list_empty(&op->pend_link));
5753c441 DH	312	fscache_stat(&fscache_n_op_cancelled);
5753c441 DH	313	list_del_init(&op->pend_link);
91c7fbbf DH	314	if (do_cancel)
91c7fbbf DH	315	do_cancel(op);
9f10523f	316	op->state = FSCACHE_OP_ST_CANCELLED;
5753c441 DH	317	if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags))
	318	object->n_exclusive--;
	319	if (test_and_clear_bit(FSCACHE_OP_WAITING, &op->flags))
	320	wake_up_bit(&op->flags, FSCACHE_OP_WAITING);
	321	fscache_put_operation(op);
	322	ret = 0;
	323	}
	324
	325	spin_unlock(&object->lock);
	326	_leave(" = %d", ret);
	327	return ret;
	328	}
	329
ef778e7a DH	330	/*
	331	* Cancel all pending operations on an object
	332	*/
	333	void fscache_cancel_all_ops(struct fscache_object *object)
	334	{
	335	struct fscache_operation *op;
	336
	337	_enter("OBJ%x", object->debug_id);
	338
	339	spin_lock(&object->lock);
	340
	341	while (!list_empty(&object->pending_ops)) {
	342	op = list_entry(object->pending_ops.next,
	343	struct fscache_operation, pend_link);
	344	fscache_stat(&fscache_n_op_cancelled);
	345	list_del_init(&op->pend_link);
	346
	347	ASSERTCMP(op->state, ==, FSCACHE_OP_ST_PENDING);
	348	op->state = FSCACHE_OP_ST_CANCELLED;
	349
	350	if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags))
	351	object->n_exclusive--;
	352	if (test_and_clear_bit(FSCACHE_OP_WAITING, &op->flags))
	353	wake_up_bit(&op->flags, FSCACHE_OP_WAITING);
	354	fscache_put_operation(op);
	355	cond_resched_lock(&object->lock);
	356	}
	357
	358	spin_unlock(&object->lock);
	359	_leave("");
	360	}
	361
9f10523f	362	/*
1f372dff	363	* Record the completion or cancellation of an in-progress operation.
9f10523f	364	*/
1f372dff	365	void fscache_op_complete(struct fscache_operation *op, bool cancelled)
9f10523f DH	366	{
	367	struct fscache_object *object = op->object;
	368
	369	_enter("OBJ%x", object->debug_id);
	370
	371	ASSERTCMP(op->state, ==, FSCACHE_OP_ST_IN_PROGRESS);
	372	ASSERTCMP(object->n_in_progress, >, 0);
	373	ASSERTIFCMP(test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags),
	374	object->n_exclusive, >, 0);
	375	ASSERTIFCMP(test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags),
	376	object->n_in_progress, ==, 1);
	377
	378	spin_lock(&object->lock);
	379
1f372dff DH	380	op->state = cancelled ?
1f372dff DH	381	FSCACHE_OP_ST_CANCELLED : FSCACHE_OP_ST_COMPLETE;
9f10523f DH	382
	383	if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags))
	384	object->n_exclusive--;
	385	object->n_in_progress--;
	386	if (object->n_in_progress == 0)
	387	fscache_start_operations(object);
	388
	389	spin_unlock(&object->lock);
	390	_leave("");
	391	}
	392	EXPORT_SYMBOL(fscache_op_complete);
	393
952efe7b DH	394	/*
	395	* release an operation
	396	* - queues pending ops if this is the last in-progress op
	397	*/
	398	void fscache_put_operation(struct fscache_operation *op)
	399	{
	400	struct fscache_object *object;
	401	struct fscache_cache *cache;
	402
	403	_enter("{OBJ%x OP%x,%d}",
	404	op->object->debug_id, op->debug_id, atomic_read(&op->usage));
	405
	406	ASSERTCMP(atomic_read(&op->usage), >, 0);
	407
	408	if (!atomic_dec_and_test(&op->usage))
	409	return;
	410
	411	_debug("PUT OP");
9f10523f DH	412	ASSERTIFCMP(op->state != FSCACHE_OP_ST_COMPLETE,
	413	op->state, ==, FSCACHE_OP_ST_CANCELLED);
	414	op->state = FSCACHE_OP_ST_DEAD;
952efe7b DH	415
	416	fscache_stat(&fscache_n_op_release);
	417
	418	if (op->release) {
	419	op->release(op);
	420	op->release = NULL;
	421	}
	422
	423	object = op->object;
	424
1362729b DH	425	if (test_bit(FSCACHE_OP_DEC_READ_CNT, &op->flags))
	426	atomic_dec(&object->n_reads);
	427	if (test_bit(FSCACHE_OP_UNUSE_COOKIE, &op->flags))
	428	fscache_unuse_cookie(object);
4fbf4291	429
952efe7b DH	430	/* now... we may get called with the object spinlock held, so we
	431	* complete the cleanup here only if we can immediately acquire the
	432	* lock, and defer it otherwise */
	433	if (!spin_trylock(&object->lock)) {
	434	_debug("defer put");
	435	fscache_stat(&fscache_n_op_deferred_release);
	436
	437	cache = object->cache;
	438	spin_lock(&cache->op_gc_list_lock);
	439	list_add_tail(&op->pend_link, &cache->op_gc_list);
	440	spin_unlock(&cache->op_gc_list_lock);
	441	schedule_work(&cache->op_gc);
	442	_leave(" [defer]");
	443	return;
	444	}
	445
952efe7b DH	446	ASSERTCMP(object->n_ops, >, 0);
	447	object->n_ops--;
	448	if (object->n_ops == 0)
	449	fscache_raise_event(object, FSCACHE_OBJECT_EV_CLEARED);
	450
	451	spin_unlock(&object->lock);
	452
	453	kfree(op);
	454	_leave(" [done]");
	455	}
	456	EXPORT_SYMBOL(fscache_put_operation);
	457
	458	/*
	459	* garbage collect operations that have had their release deferred
	460	*/
	461	void fscache_operation_gc(struct work_struct *work)
	462	{
	463	struct fscache_operation *op;
	464	struct fscache_object *object;
	465	struct fscache_cache *cache =
	466	container_of(work, struct fscache_cache, op_gc);
	467	int count = 0;
	468
	469	_enter("");
	470
	471	do {
	472	spin_lock(&cache->op_gc_list_lock);
	473	if (list_empty(&cache->op_gc_list)) {
	474	spin_unlock(&cache->op_gc_list_lock);
	475	break;
	476	}
	477
	478	op = list_entry(cache->op_gc_list.next,
	479	struct fscache_operation, pend_link);
	480	list_del(&op->pend_link);
	481	spin_unlock(&cache->op_gc_list_lock);
	482
	483	object = op->object;
9f10523f	484	spin_lock(&object->lock);
952efe7b DH	485
	486	_debug("GC DEFERRED REL OBJ%x OP%x",
	487	object->debug_id, op->debug_id);
	488	fscache_stat(&fscache_n_op_gc);
	489
	490	ASSERTCMP(atomic_read(&op->usage), ==, 0);
9f10523f	491	ASSERTCMP(op->state, ==, FSCACHE_OP_ST_DEAD);
952efe7b DH	492
	493	ASSERTCMP(object->n_ops, >, 0);
	494	object->n_ops--;
	495	if (object->n_ops == 0)
	496	fscache_raise_event(object, FSCACHE_OBJECT_EV_CLEARED);
	497
	498	spin_unlock(&object->lock);
9f10523f	499	kfree(op);
952efe7b DH	500
	501	} while (count++ < 20);
	502
	503	if (!list_empty(&cache->op_gc_list))
	504	schedule_work(&cache->op_gc);
	505
	506	_leave("");
	507	}
	508
	509	/*
8af7c124 TH	510	* execute an operation using fs_op_wq to provide processing context -
8af7c124 TH	511	* the caller holds a ref to this object, so we don't need to hold one
952efe7b	512	*/
8af7c124	513	void fscache_op_work_func(struct work_struct *work)
952efe7b DH	514	{
952efe7b DH	515	struct fscache_operation *op =
8af7c124	516	container_of(work, struct fscache_operation, work);
952efe7b DH	517	unsigned long start;
	518
	519	_enter("{OBJ%x OP%x,%d}",
	520	op->object->debug_id, op->debug_id, atomic_read(&op->usage));
	521
	522	ASSERT(op->processor != NULL);
	523	start = jiffies;
	524	op->processor(op);
	525	fscache_hist(fscache_ops_histogram, start);
8af7c124	526	fscache_put_operation(op);
952efe7b DH	527
	528	_leave("");
	529	}