[mirror_ubuntu-artful-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);

static void fscache_operation_dummy_cancel(struct fscache_operation *op)
{
}

/**
 * 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_cancel_t cancel,
			    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->cancel = cancel ?: fscache_operation_dummy_cancel;
	op->release = release;
	INIT_LIST_HEAD(&op->pend_link);
	fscache_stat(&fscache_n_op_initialised);
}
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->cancel(op);
		op->state = FSCACHE_OP_ST_CANCELLED;
		ret = -ENOBUFS;
	} else if (unlikely(fscache_cache_is_broken(object))) {
		op->cancel(op);
		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->cancel(op);
		op->state = FSCACHE_OP_ST_CANCELLED;
		ret = -ENOBUFS;
	} else {
		fscache_report_unexpected_submission(object, op, ostate);
		op->cancel(op);
		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->cancel(op);
		op->state = FSCACHE_OP_ST_CANCELLED;
		ret = -ENOBUFS;
	} else if (unlikely(fscache_cache_is_broken(object))) {
		op->cancel(op);
		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->cancel(op);
		op->state = FSCACHE_OP_ST_CANCELLED;
		ret = -ENOBUFS;
	} else {
		fscache_report_unexpected_submission(object, op, ostate);
		ASSERT(!fscache_object_is_active(object));
		op->cancel(op);
		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,
		      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);
		op->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) {
		ASSERTCMP(object->n_in_progress, >, 0);
		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);

		fscache_stat(&fscache_n_op_cancelled);
		op->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->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);
		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);

	if (!cancelled) {
		op->state = FSCACHE_OP_ST_COMPLETE;
	} else {
		op->cancel(op);
		op->state = FSCACHE_OP_ST_CANCELLED;
	}

	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_INITIALISED &&
		    op->state != FSCACHE_OP_ST_COMPLETE,
		    op->state, ==, FSCACHE_OP_ST_CANCELLED);

	fscache_stat(&fscache_n_op_release);

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

	object = op->object;
	if (likely(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
d3b97ca4 DH	23	static void fscache_operation_dummy_cancel(struct fscache_operation *op)
	24	{
	25	}
	26
1339ec98 DH	27	/**
	28	* fscache_operation_init - Do basic initialisation of an operation
	29	* @op: The operation to initialise
	30	* @release: The release function to assign
	31	*
	32	* Do basic initialisation of an operation. The caller must still set flags,
	33	* object and processor if needed.
	34	*/
	35	void fscache_operation_init(struct fscache_operation *op,
	36	fscache_operation_processor_t processor,
d3b97ca4	37	fscache_operation_cancel_t cancel,
1339ec98 DH	38	fscache_operation_release_t release)
	39	{
	40	INIT_WORK(&op->work, fscache_op_work_func);
	41	atomic_set(&op->usage, 1);
	42	op->state = FSCACHE_OP_ST_INITIALISED;
	43	op->debug_id = atomic_inc_return(&fscache_op_debug_id);
	44	op->processor = processor;
d3b97ca4	45	op->cancel = cancel ?: fscache_operation_dummy_cancel;
1339ec98 DH	46	op->release = release;
1339ec98 DH	47	INIT_LIST_HEAD(&op->pend_link);
03cdd0e4	48	fscache_stat(&fscache_n_op_initialised);
1339ec98 DH	49	}
	50	EXPORT_SYMBOL(fscache_operation_init);
	51
952efe7b DH	52	/**
	53	* fscache_enqueue_operation - Enqueue an operation for processing
	54	* @op: The operation to enqueue
	55	*
	56	* Enqueue an operation for processing by the FS-Cache thread pool.
	57	*
	58	* This will get its own ref on the object.
	59	*/
	60	void fscache_enqueue_operation(struct fscache_operation *op)
	61	{
	62	_enter("{OBJ%x OP%x,%u}",
	63	op->object->debug_id, op->debug_id, atomic_read(&op->usage));
	64
5753c441	65	ASSERT(list_empty(&op->pend_link));
952efe7b	66	ASSERT(op->processor != NULL);
493f7bc1	67	ASSERT(fscache_object_is_available(op->object));
952efe7b	68	ASSERTCMP(atomic_read(&op->usage), >, 0);
9f10523f	69	ASSERTCMP(op->state, ==, FSCACHE_OP_ST_IN_PROGRESS);
952efe7b	70
5753c441 DH	71	fscache_stat(&fscache_n_op_enqueue);
5753c441 DH	72	switch (op->flags & FSCACHE_OP_TYPE) {
8af7c124 TH	73	case FSCACHE_OP_ASYNC:
8af7c124 TH	74	_debug("queue async");
5753c441	75	atomic_inc(&op->usage);
8af7c124	76	if (!queue_work(fscache_op_wq, &op->work))
5753c441 DH	77	fscache_put_operation(op);
5753c441 DH	78	break;
5753c441 DH	79	case FSCACHE_OP_MYTHREAD:
	80	_debug("queue for caller's attention");
	81	break;
	82	default:
36dfd116	83	pr_err("Unexpected op type %lx", op->flags);
5753c441 DH	84	BUG();
5753c441 DH	85	break;
952efe7b DH	86	}
	87	}
	88	EXPORT_SYMBOL(fscache_enqueue_operation);
	89
	90	/*
	91	* start an op running
	92	*/
	93	static void fscache_run_op(struct fscache_object *object,
	94	struct fscache_operation *op)
	95	{
9f10523f DH	96	ASSERTCMP(op->state, ==, FSCACHE_OP_ST_PENDING);
	97
	98	op->state = FSCACHE_OP_ST_IN_PROGRESS;
952efe7b DH	99	object->n_in_progress++;
	100	if (test_and_clear_bit(FSCACHE_OP_WAITING, &op->flags))
	101	wake_up_bit(&op->flags, FSCACHE_OP_WAITING);
	102	if (op->processor)
	103	fscache_enqueue_operation(op);
	104	fscache_stat(&fscache_n_op_run);
	105	}
	106
3c305984 DH	107	/*
	108	* report an unexpected submission
	109	*/
	110	static void fscache_report_unexpected_submission(struct fscache_object *object,
	111	struct fscache_operation *op,
	112	const struct fscache_state *ostate)
	113	{
	114	static bool once_only;
	115	struct fscache_operation *p;
	116	unsigned n;
	117
	118	if (once_only)
	119	return;
	120	once_only = true;
	121
	122	kdebug("unexpected submission OP%x [OBJ%x %s]",
	123	op->debug_id, object->debug_id, object->state->name);
	124	kdebug("objstate=%s [%s]", object->state->name, ostate->name);
	125	kdebug("objflags=%lx", object->flags);
	126	kdebug("objevent=%lx [%lx]", object->events, object->event_mask);
	127	kdebug("ops=%u inp=%u exc=%u",
	128	object->n_ops, object->n_in_progress, object->n_exclusive);
	129
	130	if (!list_empty(&object->pending_ops)) {
	131	n = 0;
	132	list_for_each_entry(p, &object->pending_ops, pend_link) {
	133	ASSERTCMP(p->object, ==, object);
	134	kdebug("%p %p", op->processor, op->release);
	135	n++;
	136	}
	137
	138	kdebug("n=%u", n);
	139	}
	140
	141	dump_stack();
	142	}
	143
952efe7b DH	144	/*
	145	* submit an exclusive operation for an object
	146	* - other ops are excluded from running simultaneously with this one
	147	* - this gets any extra refs it needs on an op
	148	*/
	149	int fscache_submit_exclusive_op(struct fscache_object *object,
	150	struct fscache_operation *op)
	151	{
30ceec62 DH	152	const struct fscache_state *ostate;
30ceec62 DH	153	unsigned long flags;
8d76349d DH	154	int ret;
8d76349d DH	155
952efe7b DH	156	_enter("{OBJ%x OP%x},", object->debug_id, op->debug_id);
952efe7b DH	157
9f10523f DH	158	ASSERTCMP(op->state, ==, FSCACHE_OP_ST_INITIALISED);
	159	ASSERTCMP(atomic_read(&op->usage), >, 0);
	160
952efe7b DH	161	spin_lock(&object->lock);
	162	ASSERTCMP(object->n_ops, >=, object->n_in_progress);
	163	ASSERTCMP(object->n_ops, >=, object->n_exclusive);
5753c441	164	ASSERT(list_empty(&op->pend_link));
952efe7b	165
30ceec62 DH	166	ostate = object->state;
	167	smp_rmb();
	168
9f10523f	169	op->state = FSCACHE_OP_ST_PENDING;
30ceec62 DH	170	flags = READ_ONCE(object->flags);
	171	if (unlikely(!(flags & BIT(FSCACHE_OBJECT_IS_LIVE)))) {
	172	fscache_stat(&fscache_n_op_rejected);
d3b97ca4	173	op->cancel(op);
30ceec62 DH	174	op->state = FSCACHE_OP_ST_CANCELLED;
	175	ret = -ENOBUFS;
	176	} else if (unlikely(fscache_cache_is_broken(object))) {
d3b97ca4	177	op->cancel(op);
30ceec62 DH	178	op->state = FSCACHE_OP_ST_CANCELLED;
	179	ret = -EIO;
	180	} else if (flags & BIT(FSCACHE_OBJECT_IS_AVAILABLE)) {
952efe7b DH	181	op->object = object;
	182	object->n_ops++;
	183	object->n_exclusive++; /* reads and writes must wait */
	184
9f10523f	185	if (object->n_in_progress > 0) {
952efe7b DH	186	atomic_inc(&op->usage);
	187	list_add_tail(&op->pend_link, &object->pending_ops);
	188	fscache_stat(&fscache_n_op_pend);
	189	} else if (!list_empty(&object->pending_ops)) {
	190	atomic_inc(&op->usage);
	191	list_add_tail(&op->pend_link, &object->pending_ops);
	192	fscache_stat(&fscache_n_op_pend);
	193	fscache_start_operations(object);
	194	} else {
	195	ASSERTCMP(object->n_in_progress, ==, 0);
	196	fscache_run_op(object, op);
	197	}
	198
	199	/* need to issue a new write op after this */
	200	clear_bit(FSCACHE_OBJECT_PENDING_WRITE, &object->flags);
8d76349d	201	ret = 0;
30ceec62	202	} else if (flags & BIT(FSCACHE_OBJECT_IS_LOOKED_UP)) {
952efe7b DH	203	op->object = object;
	204	object->n_ops++;
	205	object->n_exclusive++; /* reads and writes must wait */
	206	atomic_inc(&op->usage);
	207	list_add_tail(&op->pend_link, &object->pending_ops);
	208	fscache_stat(&fscache_n_op_pend);
8d76349d	209	ret = 0;
6515d1db	210	} else if (flags & BIT(FSCACHE_OBJECT_KILLED_BY_CACHE)) {
d3b97ca4	211	op->cancel(op);
6515d1db DH	212	op->state = FSCACHE_OP_ST_CANCELLED;
6515d1db DH	213	ret = -ENOBUFS;
952efe7b	214	} else {
30ceec62	215	fscache_report_unexpected_submission(object, op, ostate);
d3b97ca4	216	op->cancel(op);
30ceec62 DH	217	op->state = FSCACHE_OP_ST_CANCELLED;
30ceec62 DH	218	ret = -ENOBUFS;
952efe7b DH	219	}
	220
	221	spin_unlock(&object->lock);
8d76349d	222	return ret;
952efe7b DH	223	}
952efe7b DH	224
952efe7b DH	225	/*
	226	* submit an operation for an object
	227	* - objects may be submitted only in the following states:
	228	* - during object creation (write ops may be submitted)
	229	* - whilst the object is active
	230	* - after an I/O error incurred in one of the two above states (op rejected)
	231	* - this gets any extra refs it needs on an op
	232	*/
	233	int fscache_submit_op(struct fscache_object *object,
	234	struct fscache_operation *op)
	235	{
caaef690	236	const struct fscache_state *ostate;
30ceec62	237	unsigned long flags;
952efe7b DH	238	int ret;
	239
	240	_enter("{OBJ%x OP%x},{%u}",
	241	object->debug_id, op->debug_id, atomic_read(&op->usage));
	242
9f10523f	243	ASSERTCMP(op->state, ==, FSCACHE_OP_ST_INITIALISED);
952efe7b DH	244	ASSERTCMP(atomic_read(&op->usage), >, 0);
	245
	246	spin_lock(&object->lock);
	247	ASSERTCMP(object->n_ops, >=, object->n_in_progress);
	248	ASSERTCMP(object->n_ops, >=, object->n_exclusive);
5753c441	249	ASSERT(list_empty(&op->pend_link));
952efe7b DH	250
	251	ostate = object->state;
	252	smp_rmb();
	253
9f10523f	254	op->state = FSCACHE_OP_ST_PENDING;
30ceec62 DH	255	flags = READ_ONCE(object->flags);
	256	if (unlikely(!(flags & BIT(FSCACHE_OBJECT_IS_LIVE)))) {
	257	fscache_stat(&fscache_n_op_rejected);
d3b97ca4	258	op->cancel(op);
30ceec62 DH	259	op->state = FSCACHE_OP_ST_CANCELLED;
	260	ret = -ENOBUFS;
	261	} else if (unlikely(fscache_cache_is_broken(object))) {
d3b97ca4	262	op->cancel(op);
30ceec62 DH	263	op->state = FSCACHE_OP_ST_CANCELLED;
	264	ret = -EIO;
	265	} else if (flags & BIT(FSCACHE_OBJECT_IS_AVAILABLE)) {
952efe7b DH	266	op->object = object;
	267	object->n_ops++;
	268
	269	if (object->n_exclusive > 0) {
	270	atomic_inc(&op->usage);
	271	list_add_tail(&op->pend_link, &object->pending_ops);
	272	fscache_stat(&fscache_n_op_pend);
	273	} else if (!list_empty(&object->pending_ops)) {
	274	atomic_inc(&op->usage);
	275	list_add_tail(&op->pend_link, &object->pending_ops);
	276	fscache_stat(&fscache_n_op_pend);
	277	fscache_start_operations(object);
	278	} else {
	279	ASSERTCMP(object->n_exclusive, ==, 0);
	280	fscache_run_op(object, op);
	281	}
	282	ret = 0;
30ceec62	283	} else if (flags & BIT(FSCACHE_OBJECT_IS_LOOKED_UP)) {
952efe7b DH	284	op->object = object;
	285	object->n_ops++;
	286	atomic_inc(&op->usage);
	287	list_add_tail(&op->pend_link, &object->pending_ops);
	288	fscache_stat(&fscache_n_op_pend);
	289	ret = 0;
6515d1db	290	} else if (flags & BIT(FSCACHE_OBJECT_KILLED_BY_CACHE)) {
d3b97ca4	291	op->cancel(op);
6515d1db DH	292	op->state = FSCACHE_OP_ST_CANCELLED;
6515d1db DH	293	ret = -ENOBUFS;
30ceec62	294	} else {
952efe7b DH	295	fscache_report_unexpected_submission(object, op, ostate);
952efe7b DH	296	ASSERT(!fscache_object_is_active(object));
d3b97ca4	297	op->cancel(op);
9f10523f	298	op->state = FSCACHE_OP_ST_CANCELLED;
952efe7b	299	ret = -ENOBUFS;
952efe7b DH	300	}
	301
	302	spin_unlock(&object->lock);
	303	return ret;
	304	}
	305
	306	/*
	307	* queue an object for withdrawal on error, aborting all following asynchronous
	308	* operations
	309	*/
	310	void fscache_abort_object(struct fscache_object *object)
	311	{
	312	_enter("{OBJ%x}", object->debug_id);
	313
	314	fscache_raise_event(object, FSCACHE_OBJECT_EV_ERROR);
	315	}
	316
	317	/*
dcfae32f DH	318	* Jump start the operation processing on an object. The caller must hold
dcfae32f DH	319	* object->lock.
952efe7b DH	320	*/
	321	void fscache_start_operations(struct fscache_object *object)
	322	{
	323	struct fscache_operation *op;
	324	bool stop = false;
	325
	326	while (!list_empty(&object->pending_ops) && !stop) {
	327	op = list_entry(object->pending_ops.next,
	328	struct fscache_operation, pend_link);
	329
	330	if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags)) {
	331	if (object->n_in_progress > 0)
	332	break;
	333	stop = true;
	334	}
	335	list_del_init(&op->pend_link);
5753c441	336	fscache_run_op(object, op);
952efe7b DH	337
	338	/* the pending queue was holding a ref on the object */
	339	fscache_put_operation(op);
	340	}
	341
	342	ASSERTCMP(object->n_in_progress, <=, object->n_ops);
	343
	344	_debug("woke %d ops on OBJ%x",
	345	object->n_in_progress, object->debug_id);
	346	}
	347
5753c441 DH	348	/*
	349	* cancel an operation that's pending on an object
	350	*/
91c7fbbf	351	int fscache_cancel_op(struct fscache_operation *op,
418b7eb9	352	bool cancel_in_progress_op)
5753c441 DH	353	{
5753c441 DH	354	struct fscache_object *object = op->object;
418b7eb9	355	bool put = false;
5753c441 DH	356	int ret;
	357
	358	_enter("OBJ%x OP%x}", op->object->debug_id, op->debug_id);
	359
9f10523f DH	360	ASSERTCMP(op->state, >=, FSCACHE_OP_ST_PENDING);
	361	ASSERTCMP(op->state, !=, FSCACHE_OP_ST_CANCELLED);
	362	ASSERTCMP(atomic_read(&op->usage), >, 0);
	363
5753c441 DH	364	spin_lock(&object->lock);
	365
	366	ret = -EBUSY;
9f10523f DH	367	if (op->state == FSCACHE_OP_ST_PENDING) {
9f10523f DH	368	ASSERT(!list_empty(&op->pend_link));
5753c441	369	list_del_init(&op->pend_link);
418b7eb9	370	put = true;
d3b97ca4	371
418b7eb9	372	fscache_stat(&fscache_n_op_cancelled);
d3b97ca4	373	op->cancel(op);
418b7eb9 DH	374	op->state = FSCACHE_OP_ST_CANCELLED;
	375	if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags))
	376	object->n_exclusive--;
	377	if (test_and_clear_bit(FSCACHE_OP_WAITING, &op->flags))
	378	wake_up_bit(&op->flags, FSCACHE_OP_WAITING);
	379	ret = 0;
	380	} else if (op->state == FSCACHE_OP_ST_IN_PROGRESS && cancel_in_progress_op) {
73c04a47 DH	381	ASSERTCMP(object->n_in_progress, >, 0);
	382	if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags))
	383	object->n_exclusive--;
	384	object->n_in_progress--;
	385	if (object->n_in_progress == 0)
	386	fscache_start_operations(object);
	387
418b7eb9	388	fscache_stat(&fscache_n_op_cancelled);
d3b97ca4	389	op->cancel(op);
9f10523f	390	op->state = FSCACHE_OP_ST_CANCELLED;
5753c441 DH	391	if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags))
	392	object->n_exclusive--;
	393	if (test_and_clear_bit(FSCACHE_OP_WAITING, &op->flags))
	394	wake_up_bit(&op->flags, FSCACHE_OP_WAITING);
5753c441 DH	395	ret = 0;
	396	}
	397
418b7eb9 DH	398	if (put)
418b7eb9 DH	399	fscache_put_operation(op);
5753c441 DH	400	spin_unlock(&object->lock);
	401	_leave(" = %d", ret);
	402	return ret;
	403	}
	404
ef778e7a DH	405	/*
	406	* Cancel all pending operations on an object
	407	*/
	408	void fscache_cancel_all_ops(struct fscache_object *object)
	409	{
	410	struct fscache_operation *op;
	411
	412	_enter("OBJ%x", object->debug_id);
	413
	414	spin_lock(&object->lock);
	415
	416	while (!list_empty(&object->pending_ops)) {
	417	op = list_entry(object->pending_ops.next,
	418	struct fscache_operation, pend_link);
	419	fscache_stat(&fscache_n_op_cancelled);
	420	list_del_init(&op->pend_link);
	421
	422	ASSERTCMP(op->state, ==, FSCACHE_OP_ST_PENDING);
d3b97ca4	423	op->cancel(op);
ef778e7a DH	424	op->state = FSCACHE_OP_ST_CANCELLED;
	425
	426	if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags))
	427	object->n_exclusive--;
	428	if (test_and_clear_bit(FSCACHE_OP_WAITING, &op->flags))
	429	wake_up_bit(&op->flags, FSCACHE_OP_WAITING);
	430	fscache_put_operation(op);
	431	cond_resched_lock(&object->lock);
	432	}
	433
	434	spin_unlock(&object->lock);
	435	_leave("");
	436	}
	437
9f10523f	438	/*
1f372dff	439	* Record the completion or cancellation of an in-progress operation.
9f10523f	440	*/
1f372dff	441	void fscache_op_complete(struct fscache_operation *op, bool cancelled)
9f10523f DH	442	{
	443	struct fscache_object *object = op->object;
	444
	445	_enter("OBJ%x", object->debug_id);
	446
	447	ASSERTCMP(op->state, ==, FSCACHE_OP_ST_IN_PROGRESS);
	448	ASSERTCMP(object->n_in_progress, >, 0);
	449	ASSERTIFCMP(test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags),
	450	object->n_exclusive, >, 0);
	451	ASSERTIFCMP(test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags),
	452	object->n_in_progress, ==, 1);
	453
	454	spin_lock(&object->lock);
	455
d3b97ca4 DH	456	if (!cancelled) {
	457	op->state = FSCACHE_OP_ST_COMPLETE;
	458	} else {
	459	op->cancel(op);
	460	op->state = FSCACHE_OP_ST_CANCELLED;
	461	}
9f10523f DH	462
	463	if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags))
	464	object->n_exclusive--;
	465	object->n_in_progress--;
	466	if (object->n_in_progress == 0)
	467	fscache_start_operations(object);
	468
	469	spin_unlock(&object->lock);
	470	_leave("");
	471	}
	472	EXPORT_SYMBOL(fscache_op_complete);
	473
952efe7b DH	474	/*
	475	* release an operation
	476	* - queues pending ops if this is the last in-progress op
	477	*/
	478	void fscache_put_operation(struct fscache_operation *op)
	479	{
	480	struct fscache_object *object;
	481	struct fscache_cache *cache;
	482
	483	_enter("{OBJ%x OP%x,%d}",
	484	op->object->debug_id, op->debug_id, atomic_read(&op->usage));
	485
	486	ASSERTCMP(atomic_read(&op->usage), >, 0);
	487
	488	if (!atomic_dec_and_test(&op->usage))
	489	return;
	490
	491	_debug("PUT OP");
a39caadf DH	492	ASSERTIFCMP(op->state != FSCACHE_OP_ST_INITIALISED &&
a39caadf DH	493	op->state != FSCACHE_OP_ST_COMPLETE,
9f10523f	494	op->state, ==, FSCACHE_OP_ST_CANCELLED);
952efe7b DH	495
	496	fscache_stat(&fscache_n_op_release);
	497
	498	if (op->release) {
	499	op->release(op);
	500	op->release = NULL;
	501	}
4a47132f	502	op->state = FSCACHE_OP_ST_DEAD;
952efe7b DH	503
952efe7b DH	504	object = op->object;
a39caadf DH	505	if (likely(object)) {
	506	if (test_bit(FSCACHE_OP_DEC_READ_CNT, &op->flags))
	507	atomic_dec(&object->n_reads);
	508	if (test_bit(FSCACHE_OP_UNUSE_COOKIE, &op->flags))
	509	fscache_unuse_cookie(object);
	510
	511	/* now... we may get called with the object spinlock held, so we
	512	* complete the cleanup here only if we can immediately acquire the
	513	* lock, and defer it otherwise */
	514	if (!spin_trylock(&object->lock)) {
	515	_debug("defer put");
	516	fscache_stat(&fscache_n_op_deferred_release);
	517
	518	cache = object->cache;
	519	spin_lock(&cache->op_gc_list_lock);
	520	list_add_tail(&op->pend_link, &cache->op_gc_list);
	521	spin_unlock(&cache->op_gc_list_lock);
	522	schedule_work(&cache->op_gc);
	523	_leave(" [defer]");
	524	return;
	525	}
952efe7b	526
a39caadf DH	527	ASSERTCMP(object->n_ops, >, 0);
	528	object->n_ops--;
	529	if (object->n_ops == 0)
	530	fscache_raise_event(object, FSCACHE_OBJECT_EV_CLEARED);
952efe7b	531
a39caadf	532	spin_unlock(&object->lock);
952efe7b DH	533	}
952efe7b DH	534
952efe7b DH	535	kfree(op);
	536	_leave(" [done]");
	537	}
	538	EXPORT_SYMBOL(fscache_put_operation);
	539
	540	/*
	541	* garbage collect operations that have had their release deferred
	542	*/
	543	void fscache_operation_gc(struct work_struct *work)
	544	{
	545	struct fscache_operation *op;
	546	struct fscache_object *object;
	547	struct fscache_cache *cache =
	548	container_of(work, struct fscache_cache, op_gc);
	549	int count = 0;
	550
	551	_enter("");
	552
	553	do {
	554	spin_lock(&cache->op_gc_list_lock);
	555	if (list_empty(&cache->op_gc_list)) {
	556	spin_unlock(&cache->op_gc_list_lock);
	557	break;
	558	}
	559
	560	op = list_entry(cache->op_gc_list.next,
	561	struct fscache_operation, pend_link);
	562	list_del(&op->pend_link);
	563	spin_unlock(&cache->op_gc_list_lock);
	564
	565	object = op->object;
9f10523f	566	spin_lock(&object->lock);
952efe7b DH	567
	568	_debug("GC DEFERRED REL OBJ%x OP%x",
	569	object->debug_id, op->debug_id);
	570	fscache_stat(&fscache_n_op_gc);
	571
	572	ASSERTCMP(atomic_read(&op->usage), ==, 0);
9f10523f	573	ASSERTCMP(op->state, ==, FSCACHE_OP_ST_DEAD);
952efe7b DH	574
	575	ASSERTCMP(object->n_ops, >, 0);
	576	object->n_ops--;
	577	if (object->n_ops == 0)
	578	fscache_raise_event(object, FSCACHE_OBJECT_EV_CLEARED);
	579
	580	spin_unlock(&object->lock);
9f10523f	581	kfree(op);
952efe7b DH	582
	583	} while (count++ < 20);
	584
	585	if (!list_empty(&cache->op_gc_list))
	586	schedule_work(&cache->op_gc);
	587
	588	_leave("");
	589	}
	590
	591	/*
8af7c124 TH	592	* execute an operation using fs_op_wq to provide processing context -
8af7c124 TH	593	* the caller holds a ref to this object, so we don't need to hold one
952efe7b	594	*/
8af7c124	595	void fscache_op_work_func(struct work_struct *work)
952efe7b DH	596	{
952efe7b DH	597	struct fscache_operation *op =
8af7c124	598	container_of(work, struct fscache_operation, work);
952efe7b DH	599	unsigned long start;
	600
	601	_enter("{OBJ%x OP%x,%d}",
	602	op->object->debug_id, op->debug_id, atomic_read(&op->usage));
	603
	604	ASSERT(op->processor != NULL);
	605	start = jiffies;
	606	op->processor(op);
	607	fscache_hist(fscache_ops_histogram, start);
8af7c124	608	fscache_put_operation(op);
952efe7b DH	609
	610	_leave("");
	611	}