[mirror_ubuntu-zesty-kernel.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_operation_init - Do basic initialisation of an operation
 * @op: The operation to initialise
 * @release: The release function to assign
 *
 * Do basic initialisation of an operation.  The caller must still set flags,
 * object and processor if needed.
 */
void fscache_operation_init(struct fscache_operation *op,
			    fscache_operation_processor_t processor,
			    fscache_operation_release_t release)
{
	INIT_WORK(&op->work, fscache_op_work_func);
	atomic_set(&op->usage, 1);
	op->state = FSCACHE_OP_ST_INITIALISED;
	op->debug_id = atomic_inc_return(&fscache_op_debug_id);
	op->processor = processor;
	op->release = release;
	INIT_LIST_HEAD(&op->pend_link);
}
EXPORT_SYMBOL(fscache_operation_init);

/**
 * 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);
}

/*
 * 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 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)
{
	const struct fscache_state *ostate;
	unsigned long flags;
	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));

	ostate = object->state;
	smp_rmb();

	op->state = FSCACHE_OP_ST_PENDING;
	flags = READ_ONCE(object->flags);
	if (unlikely(!(flags & BIT(FSCACHE_OBJECT_IS_LIVE)))) {
		fscache_stat(&fscache_n_op_rejected);
		op->state = FSCACHE_OP_ST_CANCELLED;
		ret = -ENOBUFS;
	} else if (unlikely(fscache_cache_is_broken(object))) {
		op->state = FSCACHE_OP_ST_CANCELLED;
		ret = -EIO;
	} else if (flags & BIT(FSCACHE_OBJECT_IS_AVAILABLE)) {
		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 (flags & BIT(FSCACHE_OBJECT_IS_LOOKED_UP)) {
		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 (flags & BIT(FSCACHE_OBJECT_KILLED_BY_CACHE)) {
		op->state = FSCACHE_OP_ST_CANCELLED;
		ret = -ENOBUFS;
	} else {
		fscache_report_unexpected_submission(object, op, ostate);
		op->state = FSCACHE_OP_ST_CANCELLED;
		ret = -ENOBUFS;
	}

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

/*
 * 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;
	unsigned long flags;
	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;
	flags = READ_ONCE(object->flags);
	if (unlikely(!(flags & BIT(FSCACHE_OBJECT_IS_LIVE)))) {
		fscache_stat(&fscache_n_op_rejected);
		op->state = FSCACHE_OP_ST_CANCELLED;
		ret = -ENOBUFS;
	} else if (unlikely(fscache_cache_is_broken(object))) {
		op->state = FSCACHE_OP_ST_CANCELLED;
		ret = -EIO;
	} else if (flags & BIT(FSCACHE_OBJECT_IS_AVAILABLE)) {
		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 (flags & BIT(FSCACHE_OBJECT_IS_LOOKED_UP)) {
		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 (flags & BIT(FSCACHE_OBJECT_KILLED_BY_CACHE)) {
		op->state = FSCACHE_OP_ST_CANCELLED;
		ret = -ENOBUFS;
	} else {
		fscache_report_unexpected_submission(object, op, ostate);
		ASSERT(!fscache_object_is_active(object));
		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 *),
		      bool cancel_in_progress_op)
{
	struct fscache_object *object = op->object;
	bool put = false;
	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));
		list_del_init(&op->pend_link);
		put = true;
		fscache_stat(&fscache_n_op_cancelled);
		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);
		ret = 0;
	} else if (op->state == FSCACHE_OP_ST_IN_PROGRESS && cancel_in_progress_op) {
		fscache_stat(&fscache_n_op_cancelled);
		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);
		ret = 0;
	}

	if (put)
		fscache_put_operation(op);
	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 (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
1339ec98 DH	23	/**
	24	* fscache_operation_init - Do basic initialisation of an operation
	25	* @op: The operation to initialise
	26	* @release: The release function to assign
	27	*
	28	* Do basic initialisation of an operation. The caller must still set flags,
	29	* object and processor if needed.
	30	*/
	31	void fscache_operation_init(struct fscache_operation *op,
	32	fscache_operation_processor_t processor,
	33	fscache_operation_release_t release)
	34	{
	35	INIT_WORK(&op->work, fscache_op_work_func);
	36	atomic_set(&op->usage, 1);
	37	op->state = FSCACHE_OP_ST_INITIALISED;
	38	op->debug_id = atomic_inc_return(&fscache_op_debug_id);
	39	op->processor = processor;
	40	op->release = release;
	41	INIT_LIST_HEAD(&op->pend_link);
	42	}
	43	EXPORT_SYMBOL(fscache_operation_init);
	44
952efe7b DH	45	/**
	46	* fscache_enqueue_operation - Enqueue an operation for processing
	47	* @op: The operation to enqueue
	48	*
	49	* Enqueue an operation for processing by the FS-Cache thread pool.
	50	*
	51	* This will get its own ref on the object.
	52	*/
	53	void fscache_enqueue_operation(struct fscache_operation *op)
	54	{
	55	_enter("{OBJ%x OP%x,%u}",
	56	op->object->debug_id, op->debug_id, atomic_read(&op->usage));
	57
5753c441	58	ASSERT(list_empty(&op->pend_link));
952efe7b	59	ASSERT(op->processor != NULL);
493f7bc1	60	ASSERT(fscache_object_is_available(op->object));
952efe7b	61	ASSERTCMP(atomic_read(&op->usage), >, 0);
9f10523f	62	ASSERTCMP(op->state, ==, FSCACHE_OP_ST_IN_PROGRESS);
952efe7b	63
5753c441 DH	64	fscache_stat(&fscache_n_op_enqueue);
5753c441 DH	65	switch (op->flags & FSCACHE_OP_TYPE) {
8af7c124 TH	66	case FSCACHE_OP_ASYNC:
8af7c124 TH	67	_debug("queue async");
5753c441	68	atomic_inc(&op->usage);
8af7c124	69	if (!queue_work(fscache_op_wq, &op->work))
5753c441 DH	70	fscache_put_operation(op);
5753c441 DH	71	break;
5753c441 DH	72	case FSCACHE_OP_MYTHREAD:
	73	_debug("queue for caller's attention");
	74	break;
	75	default:
36dfd116	76	pr_err("Unexpected op type %lx", op->flags);
5753c441 DH	77	BUG();
5753c441 DH	78	break;
952efe7b DH	79	}
	80	}
	81	EXPORT_SYMBOL(fscache_enqueue_operation);
	82
	83	/*
	84	* start an op running
	85	*/
	86	static void fscache_run_op(struct fscache_object *object,
	87	struct fscache_operation *op)
	88	{
9f10523f DH	89	ASSERTCMP(op->state, ==, FSCACHE_OP_ST_PENDING);
	90
	91	op->state = FSCACHE_OP_ST_IN_PROGRESS;
952efe7b DH	92	object->n_in_progress++;
	93	if (test_and_clear_bit(FSCACHE_OP_WAITING, &op->flags))
	94	wake_up_bit(&op->flags, FSCACHE_OP_WAITING);
	95	if (op->processor)
	96	fscache_enqueue_operation(op);
	97	fscache_stat(&fscache_n_op_run);
	98	}
	99
3c305984 DH	100	/*
	101	* report an unexpected submission
	102	*/
	103	static void fscache_report_unexpected_submission(struct fscache_object *object,
	104	struct fscache_operation *op,
	105	const struct fscache_state *ostate)
	106	{
	107	static bool once_only;
	108	struct fscache_operation *p;
	109	unsigned n;
	110
	111	if (once_only)
	112	return;
	113	once_only = true;
	114
	115	kdebug("unexpected submission OP%x [OBJ%x %s]",
	116	op->debug_id, object->debug_id, object->state->name);
	117	kdebug("objstate=%s [%s]", object->state->name, ostate->name);
	118	kdebug("objflags=%lx", object->flags);
	119	kdebug("objevent=%lx [%lx]", object->events, object->event_mask);
	120	kdebug("ops=%u inp=%u exc=%u",
	121	object->n_ops, object->n_in_progress, object->n_exclusive);
	122
	123	if (!list_empty(&object->pending_ops)) {
	124	n = 0;
	125	list_for_each_entry(p, &object->pending_ops, pend_link) {
	126	ASSERTCMP(p->object, ==, object);
	127	kdebug("%p %p", op->processor, op->release);
	128	n++;
	129	}
	130
	131	kdebug("n=%u", n);
	132	}
	133
	134	dump_stack();
	135	}
	136
952efe7b DH	137	/*
	138	* submit an exclusive operation for an object
	139	* - other ops are excluded from running simultaneously with this one
	140	* - this gets any extra refs it needs on an op
	141	*/
	142	int fscache_submit_exclusive_op(struct fscache_object *object,
	143	struct fscache_operation *op)
	144	{
30ceec62 DH	145	const struct fscache_state *ostate;
30ceec62 DH	146	unsigned long flags;
8d76349d DH	147	int ret;
8d76349d DH	148
952efe7b DH	149	_enter("{OBJ%x OP%x},", object->debug_id, op->debug_id);
952efe7b DH	150
9f10523f DH	151	ASSERTCMP(op->state, ==, FSCACHE_OP_ST_INITIALISED);
	152	ASSERTCMP(atomic_read(&op->usage), >, 0);
	153
952efe7b DH	154	spin_lock(&object->lock);
	155	ASSERTCMP(object->n_ops, >=, object->n_in_progress);
	156	ASSERTCMP(object->n_ops, >=, object->n_exclusive);
5753c441	157	ASSERT(list_empty(&op->pend_link));
952efe7b	158
30ceec62 DH	159	ostate = object->state;
	160	smp_rmb();
	161
9f10523f	162	op->state = FSCACHE_OP_ST_PENDING;
30ceec62 DH	163	flags = READ_ONCE(object->flags);
	164	if (unlikely(!(flags & BIT(FSCACHE_OBJECT_IS_LIVE)))) {
	165	fscache_stat(&fscache_n_op_rejected);
	166	op->state = FSCACHE_OP_ST_CANCELLED;
	167	ret = -ENOBUFS;
	168	} else if (unlikely(fscache_cache_is_broken(object))) {
	169	op->state = FSCACHE_OP_ST_CANCELLED;
	170	ret = -EIO;
	171	} else if (flags & BIT(FSCACHE_OBJECT_IS_AVAILABLE)) {
952efe7b DH	172	op->object = object;
	173	object->n_ops++;
	174	object->n_exclusive++; /* reads and writes must wait */
	175
9f10523f	176	if (object->n_in_progress > 0) {
952efe7b DH	177	atomic_inc(&op->usage);
	178	list_add_tail(&op->pend_link, &object->pending_ops);
	179	fscache_stat(&fscache_n_op_pend);
	180	} else if (!list_empty(&object->pending_ops)) {
	181	atomic_inc(&op->usage);
	182	list_add_tail(&op->pend_link, &object->pending_ops);
	183	fscache_stat(&fscache_n_op_pend);
	184	fscache_start_operations(object);
	185	} else {
	186	ASSERTCMP(object->n_in_progress, ==, 0);
	187	fscache_run_op(object, op);
	188	}
	189
	190	/* need to issue a new write op after this */
	191	clear_bit(FSCACHE_OBJECT_PENDING_WRITE, &object->flags);
8d76349d	192	ret = 0;
30ceec62	193	} else if (flags & BIT(FSCACHE_OBJECT_IS_LOOKED_UP)) {
952efe7b DH	194	op->object = object;
	195	object->n_ops++;
	196	object->n_exclusive++; /* reads and writes must wait */
	197	atomic_inc(&op->usage);
	198	list_add_tail(&op->pend_link, &object->pending_ops);
	199	fscache_stat(&fscache_n_op_pend);
8d76349d	200	ret = 0;
6515d1db DH	201	} else if (flags & BIT(FSCACHE_OBJECT_KILLED_BY_CACHE)) {
	202	op->state = FSCACHE_OP_ST_CANCELLED;
	203	ret = -ENOBUFS;
952efe7b	204	} else {
30ceec62 DH	205	fscache_report_unexpected_submission(object, op, ostate);
	206	op->state = FSCACHE_OP_ST_CANCELLED;
	207	ret = -ENOBUFS;
952efe7b DH	208	}
	209
	210	spin_unlock(&object->lock);
8d76349d	211	return ret;
952efe7b DH	212	}
952efe7b DH	213
952efe7b DH	214	/*
	215	* submit an operation for an object
	216	* - objects may be submitted only in the following states:
	217	* - during object creation (write ops may be submitted)
	218	* - whilst the object is active
	219	* - after an I/O error incurred in one of the two above states (op rejected)
	220	* - this gets any extra refs it needs on an op
	221	*/
	222	int fscache_submit_op(struct fscache_object *object,
	223	struct fscache_operation *op)
	224	{
caaef690	225	const struct fscache_state *ostate;
30ceec62	226	unsigned long flags;
952efe7b DH	227	int ret;
	228
	229	_enter("{OBJ%x OP%x},{%u}",
	230	object->debug_id, op->debug_id, atomic_read(&op->usage));
	231
9f10523f	232	ASSERTCMP(op->state, ==, FSCACHE_OP_ST_INITIALISED);
952efe7b DH	233	ASSERTCMP(atomic_read(&op->usage), >, 0);
	234
	235	spin_lock(&object->lock);
	236	ASSERTCMP(object->n_ops, >=, object->n_in_progress);
	237	ASSERTCMP(object->n_ops, >=, object->n_exclusive);
5753c441	238	ASSERT(list_empty(&op->pend_link));
952efe7b DH	239
	240	ostate = object->state;
	241	smp_rmb();
	242
9f10523f	243	op->state = FSCACHE_OP_ST_PENDING;
30ceec62 DH	244	flags = READ_ONCE(object->flags);
	245	if (unlikely(!(flags & BIT(FSCACHE_OBJECT_IS_LIVE)))) {
	246	fscache_stat(&fscache_n_op_rejected);
	247	op->state = FSCACHE_OP_ST_CANCELLED;
	248	ret = -ENOBUFS;
	249	} else if (unlikely(fscache_cache_is_broken(object))) {
	250	op->state = FSCACHE_OP_ST_CANCELLED;
	251	ret = -EIO;
	252	} else if (flags & BIT(FSCACHE_OBJECT_IS_AVAILABLE)) {
952efe7b DH	253	op->object = object;
	254	object->n_ops++;
	255
	256	if (object->n_exclusive > 0) {
	257	atomic_inc(&op->usage);
	258	list_add_tail(&op->pend_link, &object->pending_ops);
	259	fscache_stat(&fscache_n_op_pend);
	260	} else if (!list_empty(&object->pending_ops)) {
	261	atomic_inc(&op->usage);
	262	list_add_tail(&op->pend_link, &object->pending_ops);
	263	fscache_stat(&fscache_n_op_pend);
	264	fscache_start_operations(object);
	265	} else {
	266	ASSERTCMP(object->n_exclusive, ==, 0);
	267	fscache_run_op(object, op);
	268	}
	269	ret = 0;
30ceec62	270	} else if (flags & BIT(FSCACHE_OBJECT_IS_LOOKED_UP)) {
952efe7b DH	271	op->object = object;
	272	object->n_ops++;
	273	atomic_inc(&op->usage);
	274	list_add_tail(&op->pend_link, &object->pending_ops);
	275	fscache_stat(&fscache_n_op_pend);
	276	ret = 0;
6515d1db DH	277	} else if (flags & BIT(FSCACHE_OBJECT_KILLED_BY_CACHE)) {
	278	op->state = FSCACHE_OP_ST_CANCELLED;
	279	ret = -ENOBUFS;
30ceec62	280	} else {
952efe7b DH	281	fscache_report_unexpected_submission(object, op, ostate);
952efe7b DH	282	ASSERT(!fscache_object_is_active(object));
9f10523f	283	op->state = FSCACHE_OP_ST_CANCELLED;
952efe7b	284	ret = -ENOBUFS;
952efe7b DH	285	}
	286
	287	spin_unlock(&object->lock);
	288	return ret;
	289	}
	290
	291	/*
	292	* queue an object for withdrawal on error, aborting all following asynchronous
	293	* operations
	294	*/
	295	void fscache_abort_object(struct fscache_object *object)
	296	{
	297	_enter("{OBJ%x}", object->debug_id);
	298
	299	fscache_raise_event(object, FSCACHE_OBJECT_EV_ERROR);
	300	}
	301
	302	/*
dcfae32f DH	303	* Jump start the operation processing on an object. The caller must hold
dcfae32f DH	304	* object->lock.
952efe7b DH	305	*/
	306	void fscache_start_operations(struct fscache_object *object)
	307	{
	308	struct fscache_operation *op;
	309	bool stop = false;
	310
	311	while (!list_empty(&object->pending_ops) && !stop) {
	312	op = list_entry(object->pending_ops.next,
	313	struct fscache_operation, pend_link);
	314
	315	if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags)) {
	316	if (object->n_in_progress > 0)
	317	break;
	318	stop = true;
	319	}
	320	list_del_init(&op->pend_link);
5753c441	321	fscache_run_op(object, op);
952efe7b DH	322
	323	/* the pending queue was holding a ref on the object */
	324	fscache_put_operation(op);
	325	}
	326
	327	ASSERTCMP(object->n_in_progress, <=, object->n_ops);
	328
	329	_debug("woke %d ops on OBJ%x",
	330	object->n_in_progress, object->debug_id);
	331	}
	332
5753c441 DH	333	/*
	334	* cancel an operation that's pending on an object
	335	*/
91c7fbbf	336	int fscache_cancel_op(struct fscache_operation *op,
418b7eb9 DH	337	void (do_cancel)(struct fscache_operation ),
418b7eb9 DH	338	bool cancel_in_progress_op)
5753c441 DH	339	{
5753c441 DH	340	struct fscache_object *object = op->object;
418b7eb9	341	bool put = false;
5753c441 DH	342	int ret;
	343
	344	_enter("OBJ%x OP%x}", op->object->debug_id, op->debug_id);
	345
9f10523f DH	346	ASSERTCMP(op->state, >=, FSCACHE_OP_ST_PENDING);
	347	ASSERTCMP(op->state, !=, FSCACHE_OP_ST_CANCELLED);
	348	ASSERTCMP(atomic_read(&op->usage), >, 0);
	349
5753c441 DH	350	spin_lock(&object->lock);
	351
	352	ret = -EBUSY;
9f10523f DH	353	if (op->state == FSCACHE_OP_ST_PENDING) {
9f10523f DH	354	ASSERT(!list_empty(&op->pend_link));
5753c441	355	list_del_init(&op->pend_link);
418b7eb9 DH	356	put = true;
	357	fscache_stat(&fscache_n_op_cancelled);
	358	if (do_cancel)
	359	do_cancel(op);
	360	op->state = FSCACHE_OP_ST_CANCELLED;
	361	if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags))
	362	object->n_exclusive--;
	363	if (test_and_clear_bit(FSCACHE_OP_WAITING, &op->flags))
	364	wake_up_bit(&op->flags, FSCACHE_OP_WAITING);
	365	ret = 0;
	366	} else if (op->state == FSCACHE_OP_ST_IN_PROGRESS && cancel_in_progress_op) {
	367	fscache_stat(&fscache_n_op_cancelled);
91c7fbbf DH	368	if (do_cancel)
91c7fbbf DH	369	do_cancel(op);
9f10523f	370	op->state = FSCACHE_OP_ST_CANCELLED;
5753c441 DH	371	if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags))
	372	object->n_exclusive--;
	373	if (test_and_clear_bit(FSCACHE_OP_WAITING, &op->flags))
	374	wake_up_bit(&op->flags, FSCACHE_OP_WAITING);
5753c441 DH	375	ret = 0;
	376	}
	377
418b7eb9 DH	378	if (put)
418b7eb9 DH	379	fscache_put_operation(op);
5753c441 DH	380	spin_unlock(&object->lock);
	381	_leave(" = %d", ret);
	382	return ret;
	383	}
	384
ef778e7a DH	385	/*
	386	* Cancel all pending operations on an object
	387	*/
	388	void fscache_cancel_all_ops(struct fscache_object *object)
	389	{
	390	struct fscache_operation *op;
	391
	392	_enter("OBJ%x", object->debug_id);
	393
	394	spin_lock(&object->lock);
	395
	396	while (!list_empty(&object->pending_ops)) {
	397	op = list_entry(object->pending_ops.next,
	398	struct fscache_operation, pend_link);
	399	fscache_stat(&fscache_n_op_cancelled);
	400	list_del_init(&op->pend_link);
	401
	402	ASSERTCMP(op->state, ==, FSCACHE_OP_ST_PENDING);
	403	op->state = FSCACHE_OP_ST_CANCELLED;
	404
	405	if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags))
	406	object->n_exclusive--;
	407	if (test_and_clear_bit(FSCACHE_OP_WAITING, &op->flags))
	408	wake_up_bit(&op->flags, FSCACHE_OP_WAITING);
	409	fscache_put_operation(op);
	410	cond_resched_lock(&object->lock);
	411	}
	412
	413	spin_unlock(&object->lock);
	414	_leave("");
	415	}
	416
9f10523f	417	/*
1f372dff	418	* Record the completion or cancellation of an in-progress operation.
9f10523f	419	*/
1f372dff	420	void fscache_op_complete(struct fscache_operation *op, bool cancelled)
9f10523f DH	421	{
	422	struct fscache_object *object = op->object;
	423
	424	_enter("OBJ%x", object->debug_id);
	425
	426	ASSERTCMP(op->state, ==, FSCACHE_OP_ST_IN_PROGRESS);
	427	ASSERTCMP(object->n_in_progress, >, 0);
	428	ASSERTIFCMP(test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags),
	429	object->n_exclusive, >, 0);
	430	ASSERTIFCMP(test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags),
	431	object->n_in_progress, ==, 1);
	432
	433	spin_lock(&object->lock);
	434
1f372dff DH	435	op->state = cancelled ?
1f372dff DH	436	FSCACHE_OP_ST_CANCELLED : FSCACHE_OP_ST_COMPLETE;
9f10523f DH	437
	438	if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags))
	439	object->n_exclusive--;
	440	object->n_in_progress--;
	441	if (object->n_in_progress == 0)
	442	fscache_start_operations(object);
	443
	444	spin_unlock(&object->lock);
	445	_leave("");
	446	}
	447	EXPORT_SYMBOL(fscache_op_complete);
	448
952efe7b DH	449	/*
	450	* release an operation
	451	* - queues pending ops if this is the last in-progress op
	452	*/
	453	void fscache_put_operation(struct fscache_operation *op)
	454	{
	455	struct fscache_object *object;
	456	struct fscache_cache *cache;
	457
	458	_enter("{OBJ%x OP%x,%d}",
	459	op->object->debug_id, op->debug_id, atomic_read(&op->usage));
	460
	461	ASSERTCMP(atomic_read(&op->usage), >, 0);
	462
	463	if (!atomic_dec_and_test(&op->usage))
	464	return;
	465
	466	_debug("PUT OP");
9f10523f DH	467	ASSERTIFCMP(op->state != FSCACHE_OP_ST_COMPLETE,
	468	op->state, ==, FSCACHE_OP_ST_CANCELLED);
	469	op->state = FSCACHE_OP_ST_DEAD;
952efe7b DH	470
	471	fscache_stat(&fscache_n_op_release);
	472
	473	if (op->release) {
	474	op->release(op);
	475	op->release = NULL;
	476	}
	477
	478	object = op->object;
	479
1362729b DH	480	if (test_bit(FSCACHE_OP_DEC_READ_CNT, &op->flags))
	481	atomic_dec(&object->n_reads);
	482	if (test_bit(FSCACHE_OP_UNUSE_COOKIE, &op->flags))
	483	fscache_unuse_cookie(object);
4fbf4291	484
952efe7b DH	485	/* now... we may get called with the object spinlock held, so we
	486	* complete the cleanup here only if we can immediately acquire the
	487	* lock, and defer it otherwise */
	488	if (!spin_trylock(&object->lock)) {
	489	_debug("defer put");
	490	fscache_stat(&fscache_n_op_deferred_release);
	491
	492	cache = object->cache;
	493	spin_lock(&cache->op_gc_list_lock);
	494	list_add_tail(&op->pend_link, &cache->op_gc_list);
	495	spin_unlock(&cache->op_gc_list_lock);
	496	schedule_work(&cache->op_gc);
	497	_leave(" [defer]");
	498	return;
	499	}
	500
952efe7b DH	501	ASSERTCMP(object->n_ops, >, 0);
	502	object->n_ops--;
	503	if (object->n_ops == 0)
	504	fscache_raise_event(object, FSCACHE_OBJECT_EV_CLEARED);
	505
	506	spin_unlock(&object->lock);
	507
	508	kfree(op);
	509	_leave(" [done]");
	510	}
	511	EXPORT_SYMBOL(fscache_put_operation);
	512
	513	/*
	514	* garbage collect operations that have had their release deferred
	515	*/
	516	void fscache_operation_gc(struct work_struct *work)
	517	{
	518	struct fscache_operation *op;
	519	struct fscache_object *object;
	520	struct fscache_cache *cache =
	521	container_of(work, struct fscache_cache, op_gc);
	522	int count = 0;
	523
	524	_enter("");
	525
	526	do {
	527	spin_lock(&cache->op_gc_list_lock);
	528	if (list_empty(&cache->op_gc_list)) {
	529	spin_unlock(&cache->op_gc_list_lock);
	530	break;
	531	}
	532
	533	op = list_entry(cache->op_gc_list.next,
	534	struct fscache_operation, pend_link);
	535	list_del(&op->pend_link);
	536	spin_unlock(&cache->op_gc_list_lock);
	537
	538	object = op->object;
9f10523f	539	spin_lock(&object->lock);
952efe7b DH	540
	541	_debug("GC DEFERRED REL OBJ%x OP%x",
	542	object->debug_id, op->debug_id);
	543	fscache_stat(&fscache_n_op_gc);
	544
	545	ASSERTCMP(atomic_read(&op->usage), ==, 0);
9f10523f	546	ASSERTCMP(op->state, ==, FSCACHE_OP_ST_DEAD);
952efe7b DH	547
	548	ASSERTCMP(object->n_ops, >, 0);
	549	object->n_ops--;
	550	if (object->n_ops == 0)
	551	fscache_raise_event(object, FSCACHE_OBJECT_EV_CLEARED);
	552
	553	spin_unlock(&object->lock);
9f10523f	554	kfree(op);
952efe7b DH	555
	556	} while (count++ < 20);
	557
	558	if (!list_empty(&cache->op_gc_list))
	559	schedule_work(&cache->op_gc);
	560
	561	_leave("");
	562	}
	563
	564	/*
8af7c124 TH	565	* execute an operation using fs_op_wq to provide processing context -
8af7c124 TH	566	* the caller holds a ref to this object, so we don't need to hold one
952efe7b	567	*/
8af7c124	568	void fscache_op_work_func(struct work_struct *work)
952efe7b DH	569	{
952efe7b DH	570	struct fscache_operation *op =
8af7c124	571	container_of(work, struct fscache_operation, work);
952efe7b DH	572	unsigned long start;
	573
	574	_enter("{OBJ%x OP%x,%d}",
	575	op->object->debug_id, op->debug_id, atomic_read(&op->usage));
	576
	577	ASSERT(op->processor != NULL);
	578	start = jiffies;
	579	op->processor(op);
	580	fscache_hist(fscache_ops_histogram, start);
8af7c124	581	fscache_put_operation(op);
952efe7b DH	582
	583	_leave("");
	584	}