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@@ -0,0 +1,459 @@
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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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+ * This program is free software; you can redistribute it and/or
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+ * modify it under the terms of the GNU General Public License
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+ * as published by the Free Software Foundation; either version
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+ * 2 of the License, or (at your option) any later version.
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+ *
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+ * See Documentation/filesystems/caching/operations.txt
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+ */
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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 "internal.h"
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+
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+atomic_t fscache_op_debug_id;
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+EXPORT_SYMBOL(fscache_op_debug_id);
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+
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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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+ _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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+
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+ ASSERT(op->processor != NULL);
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+ ASSERTCMP(op->object->state, >=, FSCACHE_OBJECT_AVAILABLE);
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+ ASSERTCMP(atomic_read(&op->usage), >, 0);
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+
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+ if (list_empty(&op->pend_link)) {
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+ switch (op->flags & FSCACHE_OP_TYPE) {
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+ case FSCACHE_OP_FAST:
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+ _debug("queue fast");
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+ atomic_inc(&op->usage);
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+ if (!schedule_work(&op->fast_work))
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+ fscache_put_operation(op);
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+ break;
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+ case FSCACHE_OP_SLOW:
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+ _debug("queue slow");
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+ slow_work_enqueue(&op->slow_work);
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+ break;
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+ case FSCACHE_OP_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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+ printk(KERN_ERR "FS-Cache: Unexpected op type %lx",
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+ op->flags);
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+ BUG();
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+ break;
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+ }
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+ fscache_stat(&fscache_n_op_enqueue);
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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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+/*
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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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+ 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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+ fscache_stat(&fscache_n_op_run);
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+}
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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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+ int ret;
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+
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+ _enter("{OBJ%x OP%x},", object->debug_id, op->debug_id);
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+
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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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+
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+ ret = -ENOBUFS;
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+ if (fscache_object_is_active(object)) {
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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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+
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+ if (object->n_ops > 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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+
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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 (object->state == FSCACHE_OBJECT_CREATING) {
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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 {
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+ /* not allowed to submit ops in any other state */
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+ BUG();
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+ }
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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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+/*
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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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+ unsigned long 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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+
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+ if (once_only)
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+ return;
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+ once_only = true;
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+
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+ kdebug("unexpected submission OP%x [OBJ%x %s]",
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+ op->debug_id, object->debug_id,
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+ fscache_object_states[object->state]);
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+ kdebug("objstate=%s [%s]",
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+ fscache_object_states[object->state],
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+ fscache_object_states[ostate]);
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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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+
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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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+
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+ kdebug("n=%u", n);
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+ }
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+
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+ dump_stack();
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+}
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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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+ unsigned long ostate;
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+ int ret;
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+
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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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+
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+ ASSERTCMP(atomic_read(&op->usage), >, 0);
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+
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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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+
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+ ostate = object->state;
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+ smp_rmb();
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+
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+ if (fscache_object_is_active(object)) {
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+ op->object = object;
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+ object->n_ops++;
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+
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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 (object->state == FSCACHE_OBJECT_CREATING) {
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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 (!test_bit(FSCACHE_IOERROR, &object->cache->flags)) {
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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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+ ret = -ENOBUFS;
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+ } else {
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+ ret = -ENOBUFS;
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+ }
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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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+/*
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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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+
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+ fscache_raise_event(object, FSCACHE_OBJECT_EV_ERROR);
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+}
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+
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+/*
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+ * jump start the operation processing on an object
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+ * - caller must hold 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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+
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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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+
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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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+ object->n_in_progress++;
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+
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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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+
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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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+
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+ ASSERTCMP(object->n_in_progress, <=, object->n_ops);
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+
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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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+/*
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+ * release an operation
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+ * - queues pending ops if this is the last in-progress op
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+ */
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+void fscache_put_operation(struct fscache_operation *op)
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+{
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+ struct fscache_object *object;
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+ struct fscache_cache *cache;
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+
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+ _enter("{OBJ%x OP%x,%d}",
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+ op->object->debug_id, op->debug_id, atomic_read(&op->usage));
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+
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+ ASSERTCMP(atomic_read(&op->usage), >, 0);
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+
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+ if (!atomic_dec_and_test(&op->usage))
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+ return;
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+
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+ _debug("PUT OP");
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+ if (test_and_set_bit(FSCACHE_OP_DEAD, &op->flags))
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+ BUG();
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+
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+ fscache_stat(&fscache_n_op_release);
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+
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+ if (op->release) {
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+ op->release(op);
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+ op->release = NULL;
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+ }
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+
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+ object = op->object;
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+
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+ /* now... we may get called with the object spinlock held, so we
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+ * complete the cleanup here only if we can immediately acquire the
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+ * lock, and defer it otherwise */
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+ if (!spin_trylock(&object->lock)) {
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+ _debug("defer put");
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+ fscache_stat(&fscache_n_op_deferred_release);
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+
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+ cache = object->cache;
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+ spin_lock(&cache->op_gc_list_lock);
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+ list_add_tail(&op->pend_link, &cache->op_gc_list);
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+ spin_unlock(&cache->op_gc_list_lock);
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+ schedule_work(&cache->op_gc);
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+ _leave(" [defer]");
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+ return;
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+ }
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+
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+ if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags)) {
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+ ASSERTCMP(object->n_exclusive, >, 0);
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+ object->n_exclusive--;
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+ }
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+
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+ ASSERTCMP(object->n_in_progress, >, 0);
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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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+
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+ ASSERTCMP(object->n_ops, >, 0);
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+ object->n_ops--;
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+ if (object->n_ops == 0)
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+ fscache_raise_event(object, FSCACHE_OBJECT_EV_CLEARED);
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+
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+ spin_unlock(&object->lock);
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+
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+ kfree(op);
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+ _leave(" [done]");
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+}
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+EXPORT_SYMBOL(fscache_put_operation);
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+
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+/*
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+ * garbage collect operations that have had their release deferred
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+ */
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+void fscache_operation_gc(struct work_struct *work)
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+{
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+ struct fscache_operation *op;
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+ struct fscache_object *object;
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+ struct fscache_cache *cache =
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+ container_of(work, struct fscache_cache, op_gc);
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+ int count = 0;
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+
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+ _enter("");
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+
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+ do {
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+ spin_lock(&cache->op_gc_list_lock);
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+ if (list_empty(&cache->op_gc_list)) {
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+ spin_unlock(&cache->op_gc_list_lock);
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+ break;
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+ }
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+
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+ op = list_entry(cache->op_gc_list.next,
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+ struct fscache_operation, pend_link);
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+ list_del(&op->pend_link);
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+ spin_unlock(&cache->op_gc_list_lock);
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+
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+ object = op->object;
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+
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+ _debug("GC DEFERRED REL OBJ%x OP%x",
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+ object->debug_id, op->debug_id);
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+ fscache_stat(&fscache_n_op_gc);
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+
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+ ASSERTCMP(atomic_read(&op->usage), ==, 0);
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+
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+ spin_lock(&object->lock);
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+ if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags)) {
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+ ASSERTCMP(object->n_exclusive, >, 0);
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+ object->n_exclusive--;
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+ }
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+
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+ ASSERTCMP(object->n_in_progress, >, 0);
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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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+
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+ ASSERTCMP(object->n_ops, >, 0);
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+ object->n_ops--;
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+ if (object->n_ops == 0)
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+ fscache_raise_event(object, FSCACHE_OBJECT_EV_CLEARED);
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+
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+ spin_unlock(&object->lock);
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+
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+ } while (count++ < 20);
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+
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+ if (!list_empty(&cache->op_gc_list))
|
|
|
+ schedule_work(&cache->op_gc);
|
|
|
+
|
|
|
+ _leave("");
|
|
|
+}
|
|
|
+
|
|
|
+/*
|
|
|
+ * allow the slow work item processor to get a ref on an operation
|
|
|
+ */
|
|
|
+static int fscache_op_get_ref(struct slow_work *work)
|
|
|
+{
|
|
|
+ struct fscache_operation *op =
|
|
|
+ container_of(work, struct fscache_operation, slow_work);
|
|
|
+
|
|
|
+ atomic_inc(&op->usage);
|
|
|
+ return 0;
|
|
|
+}
|
|
|
+
|
|
|
+/*
|
|
|
+ * allow the slow work item processor to discard a ref on an operation
|
|
|
+ */
|
|
|
+static void fscache_op_put_ref(struct slow_work *work)
|
|
|
+{
|
|
|
+ struct fscache_operation *op =
|
|
|
+ container_of(work, struct fscache_operation, slow_work);
|
|
|
+
|
|
|
+ fscache_put_operation(op);
|
|
|
+}
|
|
|
+
|
|
|
+/*
|
|
|
+ * execute an operation using the slow thread pool to provide processing context
|
|
|
+ * - the caller holds a ref to this object, so we don't need to hold one
|
|
|
+ */
|
|
|
+static void fscache_op_execute(struct slow_work *work)
|
|
|
+{
|
|
|
+ struct fscache_operation *op =
|
|
|
+ container_of(work, struct fscache_operation, slow_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);
|
|
|
+
|
|
|
+ _leave("");
|
|
|
+}
|
|
|
+
|
|
|
+const struct slow_work_ops fscache_op_slow_work_ops = {
|
|
|
+ .get_ref = fscache_op_get_ref,
|
|
|
+ .put_ref = fscache_op_put_ref,
|
|
|
+ .execute = fscache_op_execute,
|
|
|
+};
|
David Howells