objects.c

  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 <linux/mempool.h>
 10#include <linux/delay.h>
 11#include "internal.h"
 12
 13static void netfs_free_request(struct work_struct *work);
 14
 15/*
 16 * Allocate an I/O request and initialise it.
 17 */
 18struct netfs_io_request *netfs_alloc_request(struct address_space *mapping,
 19					     struct file *file,
 20					     loff_t start, size_t len,
 21					     enum netfs_io_origin origin)
 22{
 23	static atomic_t debug_ids;
 24	struct inode *inode = file ? file_inode(file) : mapping->host;
 25	struct netfs_inode *ctx = netfs_inode(inode);
 26	struct netfs_io_request *rreq;
 27	mempool_t *mempool = ctx->ops->request_pool ?: &netfs_request_pool;
 28	struct kmem_cache *cache = mempool->pool_data;
 29	int ret;
 30
 31	for (;;) {
 32		rreq = mempool_alloc(mempool, GFP_KERNEL);
 33		if (rreq)
 34			break;
 35		msleep(10);
 36	}
 37
 38	memset(rreq, 0, kmem_cache_size(cache));
 39	INIT_WORK(&rreq->cleanup_work, netfs_free_request);
 40	rreq->start	= start;
 41	rreq->len	= len;
 42	rreq->origin	= origin;
 43	rreq->netfs_ops	= ctx->ops;
 44	rreq->mapping	= mapping;
 45	rreq->inode	= inode;
 46	rreq->i_size	= i_size_read(inode);
 47	rreq->debug_id	= atomic_inc_return(&debug_ids);
 48	rreq->wsize	= INT_MAX;
 49	rreq->io_streams[0].sreq_max_len = ULONG_MAX;
 50	rreq->io_streams[0].sreq_max_segs = 0;
 51	spin_lock_init(&rreq->lock);
 52	INIT_LIST_HEAD(&rreq->io_streams[0].subrequests);
 53	INIT_LIST_HEAD(&rreq->io_streams[1].subrequests);
 54	init_waitqueue_head(&rreq->waitq);
 55	refcount_set(&rreq->ref, 2);
 56
 57	if (origin == NETFS_READAHEAD ||
 58	    origin == NETFS_READPAGE ||
 59	    origin == NETFS_READ_GAPS ||
 60	    origin == NETFS_READ_SINGLE ||
 61	    origin == NETFS_READ_FOR_WRITE ||
 62	    origin == NETFS_UNBUFFERED_READ ||
 63	    origin == NETFS_DIO_READ) {
 64		INIT_WORK(&rreq->work, netfs_read_collection_worker);
 65		rreq->io_streams[0].avail = true;
 66	} else {
 67		INIT_WORK(&rreq->work, netfs_write_collection_worker);
 68	}
 69
 70	__set_bit(NETFS_RREQ_IN_PROGRESS, &rreq->flags);
 71	if (rreq->netfs_ops->init_request) {
 72		ret = rreq->netfs_ops->init_request(rreq, file);
 73		if (ret < 0) {
 74			mempool_free(rreq, rreq->netfs_ops->request_pool ?: &netfs_request_pool);
 75			return ERR_PTR(ret);
 76		}
 77	}
 78
 79	atomic_inc(&ctx->io_count);
 80	trace_netfs_rreq_ref(rreq->debug_id, refcount_read(&rreq->ref), netfs_rreq_trace_new);
 81	netfs_proc_add_rreq(rreq);
 82	netfs_stat(&netfs_n_rh_rreq);
 83	return rreq;
 84}
 85
 86void netfs_get_request(struct netfs_io_request *rreq, enum netfs_rreq_ref_trace what)
 87{
 88	int r;
 89
 90	__refcount_inc(&rreq->ref, &r);
 91	trace_netfs_rreq_ref(rreq->debug_id, r + 1, what);
 92}
 93
 94void netfs_clear_subrequests(struct netfs_io_request *rreq)
 95{
 96	struct netfs_io_subrequest *subreq;
 97	struct netfs_io_stream *stream;
 98	int s;
 99
100	for (s = 0; s < ARRAY_SIZE(rreq->io_streams); s++) {
101		stream = &rreq->io_streams[s];
102		while (!list_empty(&stream->subrequests)) {
103			subreq = list_first_entry(&stream->subrequests,
104						  struct netfs_io_subrequest, rreq_link);
105			list_del(&subreq->rreq_link);
106			netfs_put_subrequest(subreq, netfs_sreq_trace_put_clear);
107		}
108	}
109}
110
111static void netfs_free_request_rcu(struct rcu_head *rcu)
112{
113	struct netfs_io_request *rreq = container_of(rcu, struct netfs_io_request, rcu);
114
115	mempool_free(rreq, rreq->netfs_ops->request_pool ?: &netfs_request_pool);
116	netfs_stat_d(&netfs_n_rh_rreq);
117}
118
119static void netfs_deinit_request(struct netfs_io_request *rreq)
120{
121	struct netfs_inode *ictx = netfs_inode(rreq->inode);
122	unsigned int i;
123
124	trace_netfs_rreq(rreq, netfs_rreq_trace_free);
125
126	/* Cancel/flush the result collection worker.  That does not carry a
127	 * ref of its own, so we must wait for it somewhere.
128	 */
129	cancel_work_sync(&rreq->work);
130
131	netfs_proc_del_rreq(rreq);
132	netfs_clear_subrequests(rreq);
133	if (rreq->netfs_ops->free_request)
134		rreq->netfs_ops->free_request(rreq);
135	if (rreq->cache_resources.ops)
136		rreq->cache_resources.ops->end_operation(&rreq->cache_resources);
137	if (rreq->direct_bv) {
138		for (i = 0; i < rreq->direct_bv_count; i++) {
139			if (rreq->direct_bv[i].bv_page) {
140				if (rreq->direct_bv_unpin)
141					unpin_user_page(rreq->direct_bv[i].bv_page);
142			}
143		}
144		kvfree(rreq->direct_bv);
145	}
146	rolling_buffer_clear(&rreq->buffer);
147
148	if (atomic_dec_and_test(&ictx->io_count))
149		wake_up_var(&ictx->io_count);
150}
151
152static void netfs_free_request(struct work_struct *work)
153{
154	struct netfs_io_request *rreq =
155		container_of(work, struct netfs_io_request, cleanup_work);
156
157	netfs_deinit_request(rreq);
158	call_rcu(&rreq->rcu, netfs_free_request_rcu);
159}
160
161void netfs_put_request(struct netfs_io_request *rreq, enum netfs_rreq_ref_trace what)
162{
163	unsigned int debug_id;
164	bool dead;
165	int r;
166
167	if (rreq) {
168		debug_id = rreq->debug_id;
169		dead = __refcount_dec_and_test(&rreq->ref, &r);
170		trace_netfs_rreq_ref(debug_id, r - 1, what);
171		if (dead)
172			WARN_ON(!queue_work(system_dfl_wq, &rreq->cleanup_work));
173	}
174}
175
176/*
177 * Free a request (synchronously) that was just allocated but has
178 * failed before it could be submitted.
179 */
180void netfs_put_failed_request(struct netfs_io_request *rreq)
181{
182	int r = refcount_read(&rreq->ref);
183
184	/* new requests have two references (see
185	 * netfs_alloc_request(), and this function is only allowed on
186	 * new request objects
187	 */
188	WARN_ON_ONCE(r != 2);
189
190	trace_netfs_rreq_ref(rreq->debug_id, r, netfs_rreq_trace_put_failed);
191	netfs_free_request(&rreq->cleanup_work);
192}
193
194/*
195 * Allocate and partially initialise an I/O request structure.
196 */
197struct netfs_io_subrequest *netfs_alloc_subrequest(struct netfs_io_request *rreq)
198{
199	struct netfs_io_subrequest *subreq;
200	mempool_t *mempool = rreq->netfs_ops->subrequest_pool ?: &netfs_subrequest_pool;
201	struct kmem_cache *cache = mempool->pool_data;
202
203	for (;;) {
204		subreq = mempool_alloc(rreq->netfs_ops->subrequest_pool ?: &netfs_subrequest_pool,
205				       GFP_KERNEL);
206		if (subreq)
207			break;
208		msleep(10);
209	}
210
211	memset(subreq, 0, kmem_cache_size(cache));
212	INIT_WORK(&subreq->work, NULL);
213	INIT_LIST_HEAD(&subreq->rreq_link);
214	refcount_set(&subreq->ref, 2);
215	subreq->rreq = rreq;
216	subreq->debug_index = atomic_inc_return(&rreq->subreq_counter);
217	netfs_get_request(rreq, netfs_rreq_trace_get_subreq);
218	netfs_stat(&netfs_n_rh_sreq);
219	return subreq;
220}
221
222void netfs_get_subrequest(struct netfs_io_subrequest *subreq,
223			  enum netfs_sreq_ref_trace what)
224{
225	int r;
226
227	__refcount_inc(&subreq->ref, &r);
228	trace_netfs_sreq_ref(subreq->rreq->debug_id, subreq->debug_index, r + 1,
229			     what);
230}
231
232static void netfs_free_subrequest(struct netfs_io_subrequest *subreq)
233{
234	struct netfs_io_request *rreq = subreq->rreq;
235
236	trace_netfs_sreq(subreq, netfs_sreq_trace_free);
237	if (rreq->netfs_ops->free_subrequest)
238		rreq->netfs_ops->free_subrequest(subreq);
239	mempool_free(subreq, rreq->netfs_ops->subrequest_pool ?: &netfs_subrequest_pool);
240	netfs_stat_d(&netfs_n_rh_sreq);
241	netfs_put_request(rreq, netfs_rreq_trace_put_subreq);
242}
243
244void netfs_put_subrequest(struct netfs_io_subrequest *subreq,
245			  enum netfs_sreq_ref_trace what)
246{
247	unsigned int debug_index = subreq->debug_index;
248	unsigned int debug_id = subreq->rreq->debug_id;
249	bool dead;
250	int r;
251
252	dead = __refcount_dec_and_test(&subreq->ref, &r);
253	trace_netfs_sreq_ref(debug_id, debug_index, r - 1, what);
254	if (dead)
255		netfs_free_subrequest(subreq);
256}