path: root/fs/netfs/read_helper.c

// SPDX-License-Identifier: GPL-2.0-or-later
/* Network filesystem high-level read support.
 *
 * Copyright (C) 2021 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 */

#include <linux/module.h>
#include <linux/export.h>
#include <linux/fs.h>
#include <linux/mm.h>
#include <linux/pagemap.h>
#include <linux/slab.h>
#include <linux/uio.h>
#include <linux/sched/mm.h>
#include <linux/task_io_accounting_ops.h>
#include <linux/netfs.h>
#include "internal.h"
#define CREATE_TRACE_POINTS
#include <trace/events/netfs.h>

MODULE_DESCRIPTION("Network fs support");
MODULE_AUTHOR("Red Hat, Inc.");
MODULE_LICENSE("GPL");

unsigned netfs_debug;
module_param_named(debug, netfs_debug, uint, S_IWUSR | S_IRUGO);
MODULE_PARM_DESC(netfs_debug, "Netfs support debugging mask");

static void netfs_rreq_work(struct work_struct *);
static void __netfs_put_subrequest(struct netfs_read_subrequest *, bool);

static void netfs_put_subrequest(struct netfs_read_subrequest *subreq,
				 bool was_async)
{
	if (refcount_dec_and_test(&subreq->usage))
		__netfs_put_subrequest(subreq, was_async);
}

static struct netfs_read_request *netfs_alloc_read_request(
	const struct netfs_read_request_ops *ops, void *netfs_priv,
	struct file *file)
{
	static atomic_t debug_ids;
	struct netfs_read_request *rreq;

	rreq = kzalloc(sizeof(struct netfs_read_request), GFP_KERNEL);
	if (rreq) {
		rreq->netfs_ops	= ops;
		rreq->netfs_priv = netfs_priv;
		rreq->inode	= file_inode(file);
		rreq->i_size	= i_size_read(rreq->inode);
		rreq->debug_id	= atomic_inc_return(&debug_ids);
		INIT_LIST_HEAD(&rreq->subrequests);
		INIT_WORK(&rreq->work, netfs_rreq_work);
		refcount_set(&rreq->usage, 1);
		__set_bit(NETFS_RREQ_IN_PROGRESS, &rreq->flags);
		ops->init_rreq(rreq, file);
		netfs_stat(&netfs_n_rh_rreq);
	}

	return rreq;
}

static void netfs_get_read_request(struct netfs_read_request *rreq)
{
	refcount_inc(&rreq->usage);
}

static void netfs_rreq_clear_subreqs(struct netfs_read_request *rreq,
				     bool was_async)
{
	struct netfs_read_subrequest *subreq;

	while (!list_empty(&rreq->subrequests)) {
		subreq = list_first_entry(&rreq->subrequests,
					  struct netfs_read_subrequest, rreq_link);
		list_del(&subreq->rreq_link);
		netfs_put_subrequest(subreq, was_async);
	}
}

static void netfs_free_read_request(struct work_struct *work)
{
	struct netfs_read_request *rreq =
		container_of(work, struct netfs_read_request, work);
	netfs_rreq_clear_subreqs(rreq, false);
	if (rreq->netfs_priv)
		rreq->netfs_ops->cleanup(rreq->mapping, rreq->netfs_priv);
	trace_netfs_rreq(rreq, netfs_rreq_trace_free);
	if (rreq->cache_resources.ops)
		rreq->cache_resources.ops->end_operation(&rreq->cache_resources);
	kfree(rreq);
	netfs_stat_d(&netfs_n_rh_rreq);
}

static void netfs_put_read_request(struct netfs_read_request *rreq, bool was_async)
{
	if (refcount_dec_and_test(&rreq->usage)) {
		if (was_async) {
			rreq->work.func = netfs_free_read_request;
			if (!queue_work(system_unbound_wq, &rreq->work))
				BUG();
		} else {
			netfs_free_read_request(&rreq->work);
		}
	}
}

/*
 * Allocate and partially initialise an I/O request structure.
 */
static struct netfs_read_subrequest *net