1// SPDX-License-Identifier: GPL-2.0-only
  2/* Object lifetime handling and tracing.
  3 *
  4 * Copyright (C) 2022 Red Hat, Inc. All Rights Reserved.
  5 * Written by David Howells (dhowells@redhat.com)
  6 */
  7
  8#include <linux/slab.h>
  9#include "internal.h"
 10
 11/*
 12 * Allocate an I/O request and initialise it.
 13 */
 14struct netfs_io_request *netfs_alloc_request(struct address_space *mapping,
 15					     struct file *file,
 16					     loff_t start, size_t len,
 17					     enum netfs_io_origin origin)
 18{
 19	static atomic_t debug_ids;
 20	struct inode *inode = file ? file_inode(file) : mapping->host;
 21	struct netfs_inode *ctx = netfs_inode(inode);
 22	struct netfs_io_request *rreq;
 23	int ret;
 24
 25	rreq = kzalloc(sizeof(struct netfs_io_request), GFP_KERNEL);
 26	if (!rreq)
 27		return ERR_PTR(-ENOMEM);
 28
 29	rreq->start	= start;
 30	rreq->len	= len;
 31	rreq->origin	= origin;
 32	rreq->netfs_ops	= ctx->ops;
 33	rreq->mapping	= mapping;
 34	rreq->inode	= inode;
 35	rreq->i_size	= i_size_read(inode);
 36	rreq->debug_id	= atomic_inc_return(&debug_ids);
 37	INIT_LIST_HEAD(&rreq->subrequests);
 38	refcount_set(&rreq->ref, 1);
 39	__set_bit(NETFS_RREQ_IN_PROGRESS, &rreq->flags);
 40	if (rreq->netfs_ops->init_request) {
 41		ret = rreq->netfs_ops->init_request(rreq, file);
 42		if (ret < 0) {
 43			kfree(rreq);
 44			return ERR_PTR(ret);
 45		}
 46	}
 47
 48	netfs_stat(&netfs_n_rh_rreq);
 49	return rreq;
 50}
 51
 52void netfs_get_request(struct netfs_io_request *rreq, enum netfs_rreq_ref_trace what)
 53{
 54	int r;
 55
 56	__refcount_inc(&rreq->ref, &r);
 57	trace_netfs_rreq_ref(rreq->debug_id, r + 1, what);
 58}
 59
 60void netfs_clear_subrequests(struct netfs_io_request *rreq, bool was_async)
 61{
 62	struct netfs_io_subrequest *subreq;
 63
 64	while (!list_empty(&rreq->subrequests)) {
 65		subreq = list_first_entry(&rreq->subrequests,
 66					  struct netfs_io_subrequest, rreq_link);
 67		list_del(&subreq->rreq_link);
 68		netfs_put_subrequest(subreq, was_async,
 69				     netfs_sreq_trace_put_clear);
 70	}
 71}
 72
 73static void netfs_free_request(struct work_struct *work)
 74{
 75	struct netfs_io_request *rreq =
 76		container_of(work, struct netfs_io_request, work);
 77
 78	trace_netfs_rreq(rreq, netfs_rreq_trace_free);
 79	netfs_clear_subrequests(rreq, false);
 80	if (rreq->netfs_ops->free_request)
 81		rreq->netfs_ops->free_request(rreq);
 82	if (rreq->cache_resources.ops)
 83		rreq->cache_resources.ops->end_operation(&rreq->cache_resources);
 84	kfree(rreq);
 85	netfs_stat_d(&netfs_n_rh_rreq);
 86}
 87
 88void netfs_put_request(struct netfs_io_request *rreq, bool was_async,
 89		       enum netfs_rreq_ref_trace what)
 90{
 91	unsigned int debug_id = rreq->debug_id;
 92	bool dead;
 93	int r;
 94
 95	dead = __refcount_dec_and_test(&rreq->ref, &r);
 96	trace_netfs_rreq_ref(debug_id, r - 1, what);
 97	if (dead) {
 98		if (was_async) {
 99			rreq->work.func = netfs_free_request;
100			if (!queue_work(system_unbound_wq, &rreq->work))
101				BUG();
102		} else {
103			netfs_free_request(&rreq->work);
104		}
105	}
106}
107
108/*
109 * Allocate and partially initialise an I/O request structure.
110 */
111struct netfs_io_subrequest *netfs_alloc_subrequest(struct netfs_io_request *rreq)
112{
113	struct netfs_io_subrequest *subreq;
114
115	subreq = kzalloc(sizeof(struct netfs_io_subrequest), GFP_KERNEL);
116	if (subreq) {
117		INIT_LIST_HEAD(&subreq->rreq_link);
118		refcount_set(&subreq->ref, 2);
119		subreq->rreq = rreq;
120		netfs_get_request(rreq, netfs_rreq_trace_get_subreq);
121		netfs_stat(&netfs_n_rh_sreq);
122	}
123
124	return subreq;
125}
126
127void netfs_get_subrequest(struct netfs_io_subrequest *subreq,
128			  enum netfs_sreq_ref_trace what)
129{
130	int r;
131
132	__refcount_inc(&subreq->ref, &r);
133	trace_netfs_sreq_ref(subreq->rreq->debug_id, subreq->debug_index, r + 1,
134			     what);
135}
136
137static void netfs_free_subrequest(struct netfs_io_subrequest *subreq,
138				  bool was_async)
139{
140	struct netfs_io_request *rreq = subreq->rreq;
141
142	trace_netfs_sreq(subreq, netfs_sreq_trace_free);
143	kfree(subreq);
144	netfs_stat_d(&netfs_n_rh_sreq);
145	netfs_put_request(rreq, was_async, netfs_rreq_trace_put_subreq);
146}
147
148void netfs_put_subrequest(struct netfs_io_subrequest *subreq, bool was_async,
149			  enum netfs_sreq_ref_trace what)
150{
151	unsigned int debug_index = subreq->debug_index;
152	unsigned int debug_id = subreq->rreq->debug_id;
153	bool dead;
154	int r;
155
156	dead = __refcount_dec_and_test(&subreq->ref, &r);
157	trace_netfs_sreq_ref(debug_id, debug_index, r - 1, what);
158	if (dead)
159		netfs_free_subrequest(subreq, was_async);
160}