// SPDX-License-Identifier: GPL-2.0-or-later
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/* FS-Cache worker operation management routines
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*
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* Copyright (C) 2008 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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*
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* See Documentation/filesystems/caching/operations.rst
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*/
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#define FSCACHE_DEBUG_LEVEL OPERATION
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#include <linux/module.h>
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#include <linux/seq_file.h>
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#include <linux/slab.h>
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#include "internal.h"
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atomic_t fscache_op_debug_id;
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EXPORT_SYMBOL(fscache_op_debug_id);
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static void fscache_operation_dummy_cancel(struct fscache_operation *op)
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{
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}
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/**
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* fscache_operation_init - Do basic initialisation of an operation
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* @op: The operation to initialise
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* @release: The release function to assign
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*
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* Do basic initialisation of an operation. The caller must still set flags,
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* object and processor if needed.
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*/
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void fscache_operation_init(struct fscache_cookie *cookie,
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struct fscache_operation *op,
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fscache_operation_processor_t processor,
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fscache_operation_cancel_t cancel,
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fscache_operation_release_t release)
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{
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INIT_WORK(&op->work, fscache_op_work_func);
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atomic_set(&op->usage, 1);
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op->state = FSCACHE_OP_ST_INITIALISED;
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op->debug_id = atomic_inc_return(&fscache_op_debug_id);
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op->processor = processor;
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op->cancel = cancel ?: fscache_operation_dummy_cancel;
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op->release = release;
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INIT_LIST_HEAD(&op->pend_link);
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fscache_stat(&fscache_n_op_initialised);
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trace_fscache_op(cookie, op, fscache_op_init);
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}
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EXPORT_SYMBOL(fscache_operation_init);
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/**
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* fscache_enqueue_operation - Enqueue an operation for processing
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* @op: The operation to enqueue
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*
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* Enqueue an operation for processing by the FS-Cache thread pool.
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*
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* This will get its own ref on the object.
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*/
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void fscache_enqueue_operation(struct fscache_operation *op)
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{
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struct fscache_cookie *cookie = op->object->cookie;
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_enter("{OBJ%x OP%x,%u}",
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op->object->debug_id, op->debug_id, atomic_read(&op->usage));
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ASSERT(list_empty(&op->pend_link));
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ASSERT(op->processor != NULL);
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ASSERT(fscache_object_is_available(op->object));
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ASSERTCMP(atomic_read(&op->usage), >, 0);
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ASSERTIFCMP(op->state != FSCACHE_OP_ST_IN_PROGRESS,
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op->state, ==, FSCACHE_OP_ST_CANCELLED);
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fscache_stat(&fscache_n_op_enqueue);
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switch (op->flags & FSCACHE_OP_TYPE) {
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case FSCACHE_OP_ASYNC:
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trace_fscache_op(cookie, op, fscache_op_enqueue_async);
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_debug("queue async");
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atomic_inc(&op->usage);
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if (!queue_work(fscache_op_wq, &op->work))
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fscache_put_operation(op);
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break;
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case FSCACHE_OP_MYTHREAD:
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trace_fscache_op(cookie, op, fscache_op_enqueue_mythread);
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_debug("queue for caller's attention");
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break;
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default:
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pr_err("Unexpected op type %lx", op->flags);
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BUG();
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break;
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}
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}
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EXPORT_SYMBOL(fscache_enqueue_operation);
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/*
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* start an op running
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*/
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static void fscache_run_op(struct fscache_object *object,
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struct fscache_operation *op)
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{
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ASSERTCMP(op->state, ==, FSCACHE_OP_ST_PENDING);
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op->state = FSCACHE_OP_ST_IN_PROGRESS;
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object->n_in_progress++;
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if (test_and_clear_bit(FSCACHE_OP_WAITING, &op->flags))
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wake_up_bit(&op->flags, FSCACHE_OP_WAITING);
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if (op->processor)
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fscache_enqueue_operation(op);
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else
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trace_fscache_op(object->cookie, op, fscache_op_run);
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fscache_stat(&fscache_n_op_run);
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}
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/*
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* report an unexpected submission
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*/
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static void fscache_report_unexpected_submission(struct fscache_object *object,
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struct fscache_operation *op,
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const struct fscache_state *ostate)
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{
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static bool once_only;
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struct fscache_operation *p;
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unsigned n;
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if (once_only)
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return;
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once_only = true;
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kdebug("unexpected submission OP%x [OBJ%x %s]",
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op->debug_id, object->debug_id, object->state->name);
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kdebug("objstate=%s [%s]", object->state->name, ostate->name);
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kdebug("objflags=%lx", object->flags);
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kdebug("objevent=%lx [%lx]", object->events, object->event_mask);
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kdebug("ops=%u inp=%u exc=%u",
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object->n_ops, object->n_in_progress, object->n_exclusive);
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if (!list_empty(&object->pending_ops)) {
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n = 0;
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list_for_each_entry(p, &object->pending_ops, pend_link) {
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ASSERTCMP(p->object, ==, object);
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kdebug("%p %p", op->processor, op->release);
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n++;
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}
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kdebug("n=%u", n);
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}
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dump_stack();
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}
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/*
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* submit an exclusive operation for an object
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* - other ops are excluded from running simultaneously with this one
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* - this gets any extra refs it needs on an op
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*/
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int fscache_submit_exclusive_op(struct fscache_object *object,
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struct fscache_operation *op)
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{
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const struct fscache_state *ostate;
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unsigned long flags;
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int ret;
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_enter("{OBJ%x OP%x},", object->debug_id, op->debug_id);
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trace_fscache_op(object->cookie, op, fscache_op_submit_ex);
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ASSERTCMP(op->state, ==, FSCACHE_OP_ST_INITIALISED);
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ASSERTCMP(atomic_read(&op->usage), >, 0);
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spin_lock(&object->lock);
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ASSERTCMP(object->n_ops, >=, object->n_in_progress);
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ASSERTCMP(object->n_ops, >=, object->n_exclusive);
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ASSERT(list_empty(&op->pend_link));
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ostate = object->state;
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smp_rmb();
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op->state = FSCACHE_OP_ST_PENDING;
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flags = READ_ONCE(object->flags);
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if (unlikely(!(flags & BIT(FSCACHE_OBJECT_IS_LIVE)))) {
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fscache_stat(&fscache_n_op_rejected);
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op->cancel(op);
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op->state = FSCACHE_OP_ST_CANCELLED;
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ret = -ENOBUFS;
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} else if (unlikely(fscache_cache_is_broken(object))) {
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op->cancel(op);
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op->state = FSCACHE_OP_ST_CANCELLED;
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ret = -EIO;
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} else if (flags & BIT(FSCACHE_OBJECT_IS_AVAILABLE)) {
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op->object = object;
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object->n_ops++;
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object->n_exclusive++; /* reads and writes must wait */
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if (object->n_in_progress > 0) {
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atomic_inc(&op->usage);
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list_add_tail(&op->pend_link, &object->pending_ops);
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fscache_stat(&fscache_n_op_pend);
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} else if (!list_empty(&object->pending_ops)) {
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atomic_inc(&op->usage);
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list_add_tail(&op->pend_link, &object->pending_ops);
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fscache_stat(&fscache_n_op_pend);
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fscache_start_operations(object);
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} else {
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ASSERTCMP(object->n_in_progress, ==, 0);
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fscache_run_op(object, op);
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}
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/* need to issue a new write op after this */
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clear_bit(FSCACHE_OBJECT_PENDING_WRITE, &object->flags);
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ret = 0;
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} else if (flags & BIT(FSCACHE_OBJECT_IS_LOOKED_UP)) {
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op->object = object;
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object->n_ops++;
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object->n_exclusive++; /* reads and writes must wait */
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atomic_inc(&op->usage);
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list_add_tail(&op->pend_link, &object->pending_ops);
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fscache_stat(&fscache_n_op_pend);
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ret = 0;
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} else if (flags & BIT(FSCACHE_OBJECT_KILLED_BY_CACHE)) {
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op->cancel(op);
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op->state = FSCACHE_OP_ST_CANCELLED;
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ret = -ENOBUFS;
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} else {
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fscache_report_unexpected_submission(object, op, ostate);
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op->cancel(op);
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op->state = FSCACHE_OP_ST_CANCELLED;
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ret = -ENOBUFS;
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}
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spin_unlock(&object->lock);
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return ret;
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}
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/*
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* submit an operation for an object
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* - objects may be submitted only in the following states:
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* - during object creation (write ops may be submitted)
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* - whilst the object is active
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* - after an I/O error incurred in one of the two above states (op rejected)
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* - this gets any extra refs it needs on an op
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*/
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int fscache_submit_op(struct fscache_object *object,
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struct fscache_operation *op)
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{
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const struct fscache_state *ostate;
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unsigned long flags;
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int ret;
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_enter("{OBJ%x OP%x},{%u}",
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object->debug_id, op->debug_id, atomic_read(&op->usage));
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trace_fscache_op(object->cookie, op, fscache_op_submit);
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ASSERTCMP(op->state, ==, FSCACHE_OP_ST_INITIALISED);
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ASSERTCMP(atomic_read(&op->usage), >, 0);
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spin_lock(&object->lock);
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ASSERTCMP(object->n_ops, >=, object->n_in_progress);
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ASSERTCMP(object->n_ops, >=, object->n_exclusive);
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ASSERT(list_empty(&op->pend_link));
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ostate = object->state;
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smp_rmb();
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op->state = FSCACHE_OP_ST_PENDING;
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flags = READ_ONCE(object->flags);
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if (unlikely(!(flags & BIT(FSCACHE_OBJECT_IS_LIVE)))) {
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fscache_stat(&fscache_n_op_rejected);
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op->cancel(op);
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op->state = FSCACHE_OP_ST_CANCELLED;
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ret = -ENOBUFS;
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} else if (unlikely(fscache_cache_is_broken(object))) {
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op->cancel(op);
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op->state = FSCACHE_OP_ST_CANCELLED;
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ret = -EIO;
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} else if (flags & BIT(FSCACHE_OBJECT_IS_AVAILABLE)) {
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op->object = object;
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object->n_ops++;
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if (object->n_exclusive > 0) {
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atomic_inc(&op->usage);
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list_add_tail(&op->pend_link, &object->pending_ops);
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fscache_stat(&fscache_n_op_pend);
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} else if (!list_empty(&object->pending_ops)) {
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atomic_inc(&op->usage);
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list_add_tail(&op->pend_link, &object->pending_ops);
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fscache_stat(&fscache_n_op_pend);
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fscache_start_operations(object);
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} else {
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ASSERTCMP(object->n_exclusive, ==, 0);
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fscache_run_op(object, op);
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}
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ret = 0;
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} else if (flags & BIT(FSCACHE_OBJECT_IS_LOOKED_UP)) {
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op->object = object;
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object->n_ops++;
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atomic_inc(&op->usage);
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list_add_tail(&op->pend_link, &object->pending_ops);
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fscache_stat(&fscache_n_op_pend);
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ret = 0;
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} else if (flags & BIT(FSCACHE_OBJECT_KILLED_BY_CACHE)) {
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op->cancel(op);
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op->state = FSCACHE_OP_ST_CANCELLED;
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ret = -ENOBUFS;
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} else {
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fscache_report_unexpected_submission(object, op, ostate);
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ASSERT(!fscache_object_is_active(object));
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op->cancel(op);
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op->state = FSCACHE_OP_ST_CANCELLED;
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ret = -ENOBUFS;
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}
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spin_unlock(&object->lock);
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return ret;
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}
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/*
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* queue an object for withdrawal on error, aborting all following asynchronous
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* operations
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*/
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void fscache_abort_object(struct fscache_object *object)
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{
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_enter("{OBJ%x}", object->debug_id);
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fscache_raise_event(object, FSCACHE_OBJECT_EV_ERROR);
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}
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/*
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* Jump start the operation processing on an object. The caller must hold
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* object->lock.
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*/
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void fscache_start_operations(struct fscache_object *object)
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{
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struct fscache_operation *op;
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bool stop = false;
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while (!list_empty(&object->pending_ops) && !stop) {
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op = list_entry(object->pending_ops.next,
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struct fscache_operation, pend_link);
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if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags)) {
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if (object->n_in_progress > 0)
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break;
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stop = true;
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}
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list_del_init(&op->pend_link);
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fscache_run_op(object, op);
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/* the pending queue was holding a ref on the object */
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fscache_put_operation(op);
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}
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ASSERTCMP(object->n_in_progress, <=, object->n_ops);
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_debug("woke %d ops on OBJ%x",
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object->n_in_progress, object->debug_id);
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}
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/*
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* cancel an operation that's pending on an object
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*/
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int fscache_cancel_op(struct fscache_operation *op,
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bool cancel_in_progress_op)
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{
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struct fscache_object *object = op->object;
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bool put = false;
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int ret;
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_enter("OBJ%x OP%x}", op->object->debug_id, op->debug_id);
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trace_fscache_op(object->cookie, op, fscache_op_cancel);
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ASSERTCMP(op->state, >=, FSCACHE_OP_ST_PENDING);
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ASSERTCMP(op->state, !=, FSCACHE_OP_ST_CANCELLED);
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ASSERTCMP(atomic_read(&op->usage), >, 0);
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spin_lock(&object->lock);
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ret = -EBUSY;
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if (op->state == FSCACHE_OP_ST_PENDING) {
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ASSERT(!list_empty(&op->pend_link));
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list_del_init(&op->pend_link);
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put = true;
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fscache_stat(&fscache_n_op_cancelled);
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op->cancel(op);
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op->state = FSCACHE_OP_ST_CANCELLED;
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if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags))
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object->n_exclusive--;
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if (test_and_clear_bit(FSCACHE_OP_WAITING, &op->flags))
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wake_up_bit(&op->flags, FSCACHE_OP_WAITING);
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ret = 0;
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} else if (op->state == FSCACHE_OP_ST_IN_PROGRESS && cancel_in_progress_op) {
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ASSERTCMP(object->n_in_progress, >, 0);
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if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags))
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object->n_exclusive--;
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object->n_in_progress--;
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if (object->n_in_progress == 0)
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fscache_start_operations(object);
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fscache_stat(&fscache_n_op_cancelled);
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op->cancel(op);
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op->state = FSCACHE_OP_ST_CANCELLED;
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if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags))
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object->n_exclusive--;
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if (test_and_clear_bit(FSCACHE_OP_WAITING, &op->flags))
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wake_up_bit(&op->flags, FSCACHE_OP_WAITING);
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ret = 0;
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}
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if (put)
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fscache_put_operation(op);
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spin_unlock(&object->lock);
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_leave(" = %d", ret);
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return ret;
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}
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/*
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* Cancel all pending operations on an object
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*/
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void fscache_cancel_all_ops(struct fscache_object *object)
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{
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struct fscache_operation *op;
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_enter("OBJ%x", object->debug_id);
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spin_lock(&object->lock);
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|
while (!list_empty(&object->pending_ops)) {
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op = list_entry(object->pending_ops.next,
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struct fscache_operation, pend_link);
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fscache_stat(&fscache_n_op_cancelled);
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list_del_init(&op->pend_link);
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trace_fscache_op(object->cookie, op, fscache_op_cancel_all);
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ASSERTCMP(op->state, ==, FSCACHE_OP_ST_PENDING);
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op->cancel(op);
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op->state = FSCACHE_OP_ST_CANCELLED;
|
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if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags))
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object->n_exclusive--;
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if (test_and_clear_bit(FSCACHE_OP_WAITING, &op->flags))
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wake_up_bit(&op->flags, FSCACHE_OP_WAITING);
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fscache_put_operation(op);
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cond_resched_lock(&object->lock);
|
}
|
|
spin_unlock(&object->lock);
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_leave("");
|
}
|
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/*
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* Record the completion or cancellation of an in-progress operation.
|
*/
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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) {
|
trace_fscache_op(object->cookie, op, fscache_op_completed);
|
op->state = FSCACHE_OP_ST_COMPLETE;
|
} else {
|
op->cancel(op);
|
trace_fscache_op(object->cookie, op, fscache_op_cancelled);
|
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 ? op->object->debug_id : 0,
|
op->debug_id, atomic_read(&op->usage));
|
|
ASSERTCMP(atomic_read(&op->usage), >, 0);
|
|
if (!atomic_dec_and_test(&op->usage))
|
return;
|
|
trace_fscache_op(op->object ? op->object->cookie : NULL, op, fscache_op_put);
|
|
_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;
|
trace_fscache_op(object->cookie, op, fscache_op_gc);
|
|
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));
|
|
trace_fscache_op(op->object->cookie, op, fscache_op_work);
|
|
ASSERT(op->processor != NULL);
|
start = jiffies;
|
op->processor(op);
|
fscache_hist(fscache_ops_histogram, start);
|
fscache_put_operation(op);
|
|
_leave("");
|
}
|
