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 "internal.h"
11
12 static void netfs_free_request(struct work_struct *work);
13
14 /*
15 * Allocate an I/O request and initialise it.
16 */
netfs_alloc_request(struct address_space * mapping,struct file * file,loff_t start,size_t len,enum netfs_io_origin origin)17 struct netfs_io_request *netfs_alloc_request(struct address_space *mapping,
18 struct file *file,
19 loff_t start, size_t len,
20 enum netfs_io_origin origin)
21 {
22 static atomic_t debug_ids;
23 struct inode *inode = file ? file_inode(file) : mapping->host;
24 struct netfs_inode *ctx = netfs_inode(inode);
25 struct netfs_io_request *rreq;
26 mempool_t *mempool = ctx->ops->request_pool ?: &netfs_request_pool;
27 struct kmem_cache *cache = mempool->pool_data;
28 gfp_t gfp = GFP_KERNEL;
29 int ret;
30
31 /* Writeback is part of memory reclaim and must not fail due to ENOMEM. */
32 if (origin == NETFS_WRITEBACK || origin == NETFS_WRITEBACK_SINGLE) {
33 gfp = GFP_NOFS; /* Allows use of mempools. */
34
35 rreq = mempool_alloc(mempool, gfp);
36 } else {
37 rreq = mempool->alloc(gfp, mempool->pool_data);
38 if (!rreq)
39 return ERR_PTR(-ENOMEM);
40 }
41
42 memset(rreq, 0, kmem_cache_size(cache));
43 INIT_WORK(&rreq->cleanup_work, netfs_free_request);
44 rreq->gfp = gfp;
45 rreq->start = start;
46 rreq->collected_to = start;
47 rreq->cleaned_to = start;
48 rreq->len = len;
49 rreq->progress_at = 0;
50 rreq->origin = origin;
51 rreq->netfs_ops = ctx->ops;
52 rreq->mapping = mapping;
53 rreq->inode = inode;
54 rreq->i_size = i_size_read(inode);
55 rreq->debug_id = atomic_inc_return(&debug_ids);
56 rreq->wsize = INT_MAX;
57 rreq->io_streams[0].sreq_max_len = ULONG_MAX;
58 rreq->io_streams[0].sreq_max_segs = 0;
59 spin_lock_init(&rreq->lock);
60 init_waitqueue_head(&rreq->waitq);
61 refcount_set(&rreq->ref, 2);
62
63 for (int s = 0; s < NR_IO_STREAMS; s++) {
64 struct netfs_io_stream *stream = &rreq->io_streams[s];
65
66 INIT_LIST_HEAD(&stream->subrequests);
67 stream->collected_to = rreq->start;
68 }
69
70 if (origin == NETFS_READAHEAD ||
71 origin == NETFS_READPAGE ||
72 origin == NETFS_READ_GAPS ||
73 origin == NETFS_READ_SINGLE ||
74 origin == NETFS_READ_FOR_WRITE ||
75 origin == NETFS_UNBUFFERED_READ ||
76 origin == NETFS_DIO_READ) {
77 INIT_WORK(&rreq->work, netfs_read_collection_worker);
78 rreq->io_streams[0].avail = true;
79 } else {
80 INIT_WORK(&rreq->work, netfs_write_collection_worker);
81 }
82
83 __set_bit(NETFS_RREQ_IN_PROGRESS, &rreq->flags);
84 if (rreq->netfs_ops->init_request) {
85 ret = rreq->netfs_ops->init_request(rreq, file);
86 if (ret < 0) {
87 mempool_free(rreq, rreq->netfs_ops->request_pool ?: &netfs_request_pool);
88 return ERR_PTR(ret);
89 }
90 }
91
92 atomic_inc(&ctx->io_count);
93 trace_netfs_rreq_ref(rreq->debug_id, refcount_read(&rreq->ref), netfs_rreq_trace_new);
94 netfs_proc_add_rreq(rreq);
95 netfs_stat(&netfs_n_rh_rreq);
96 return rreq;
97 }
98
netfs_get_request(struct netfs_io_request * rreq,enum netfs_rreq_ref_trace what)99 void netfs_get_request(struct netfs_io_request *rreq, enum netfs_rreq_ref_trace what)
100 {
101 int r;
102
103 __refcount_inc(&rreq->ref, &r);
104 trace_netfs_rreq_ref(rreq->debug_id, r + 1, what);
105 }
106
netfs_clear_subrequests(struct netfs_io_request * rreq)107 void netfs_clear_subrequests(struct netfs_io_request *rreq)
108 {
109 struct netfs_io_subrequest *subreq;
110 struct netfs_io_stream *stream;
111 int s;
112
113 for (s = 0; s < ARRAY_SIZE(rreq->io_streams); s++) {
114 stream = &rreq->io_streams[s];
115 while (!list_empty(&stream->subrequests)) {
116 subreq = list_first_entry(&stream->subrequests,
117 struct netfs_io_subrequest, rreq_link);
118 list_del(&subreq->rreq_link);
119 netfs_put_subrequest(subreq, netfs_sreq_trace_put_clear);
120 }
121 }
122 }
123
netfs_free_request_rcu(struct rcu_head * rcu)124 static void netfs_free_request_rcu(struct rcu_head *rcu)
125 {
126 struct netfs_io_request *rreq = container_of(rcu, struct netfs_io_request, rcu);
127
128 mempool_free(rreq, rreq->netfs_ops->request_pool ?: &netfs_request_pool);
129 netfs_stat_d(&netfs_n_rh_rreq);
130 }
131
netfs_deinit_request(struct netfs_io_request * rreq)132 static void netfs_deinit_request(struct netfs_io_request *rreq)
133 {
134 struct netfs_inode *ictx = netfs_inode(rreq->inode);
135 unsigned int i;
136
137 trace_netfs_rreq(rreq, netfs_rreq_trace_free);
138
139 /* Cancel/flush the result collection worker. That does not carry a
140 * ref of its own, so we must wait for it somewhere.
141 */
142 cancel_work_sync(&rreq->work);
143
144 netfs_proc_del_rreq(rreq);
145 netfs_clear_subrequests(rreq);
146 if (rreq->netfs_ops->free_request)
147 rreq->netfs_ops->free_request(rreq);
148 if (rreq->cache_resources.ops)
149 rreq->cache_resources.ops->end_operation(&rreq->cache_resources);
150 if (rreq->direct_bv) {
151 for (i = 0; i < rreq->direct_bv_count; i++) {
152 if (rreq->direct_bv[i].bv_page) {
153 if (rreq->direct_bv_unpin)
154 unpin_user_page(rreq->direct_bv[i].bv_page);
155 }
156 }
157 kvfree(rreq->direct_bv);
158 }
159 rolling_buffer_clear(&rreq->buffer);
160
161 if (atomic_dec_and_test(&ictx->io_count))
162 wake_up_var(&ictx->io_count);
163 }
164
netfs_free_request(struct work_struct * work)165 static void netfs_free_request(struct work_struct *work)
166 {
167 struct netfs_io_request *rreq =
168 container_of(work, struct netfs_io_request, cleanup_work);
169
170 netfs_deinit_request(rreq);
171 call_rcu(&rreq->rcu, netfs_free_request_rcu);
172 }
173
netfs_put_request(struct netfs_io_request * rreq,enum netfs_rreq_ref_trace what)174 void netfs_put_request(struct netfs_io_request *rreq, enum netfs_rreq_ref_trace what)
175 {
176 unsigned int debug_id;
177 bool dead;
178 int r;
179
180 if (rreq) {
181 debug_id = rreq->debug_id;
182 dead = __refcount_dec_and_test(&rreq->ref, &r);
183 trace_netfs_rreq_ref(debug_id, r - 1, what);
184 if (dead)
185 WARN_ON(!queue_work(system_dfl_wq, &rreq->cleanup_work));
186 }
187 }
188
189 /*
190 * Free a request (synchronously) that was just allocated but has
191 * failed before it could be submitted.
192 */
netfs_put_failed_request(struct netfs_io_request * rreq)193 void netfs_put_failed_request(struct netfs_io_request *rreq)
194 {
195 int r = refcount_read(&rreq->ref);
196
197 /* new requests have two references (see
198 * netfs_alloc_request(), and this function is only allowed on
199 * new request objects
200 */
201 WARN_ON_ONCE(r != 2);
202
203 trace_netfs_rreq_ref(rreq->debug_id, r, netfs_rreq_trace_put_failed);
204 netfs_free_request(&rreq->cleanup_work);
205 }
206
207 /*
208 * Allocate and partially initialise an I/O request structure.
209 */
netfs_alloc_subrequest(struct netfs_io_request * rreq)210 struct netfs_io_subrequest *netfs_alloc_subrequest(struct netfs_io_request *rreq)
211 {
212 struct netfs_io_subrequest *subreq;
213 mempool_t *mempool = rreq->netfs_ops->subrequest_pool ?: &netfs_subrequest_pool;
214 struct kmem_cache *cache = mempool->pool_data;
215
216 if (rreq->gfp == GFP_KERNEL)
217 subreq = mempool->alloc(rreq->gfp, mempool->pool_data);
218 else
219 subreq = mempool_alloc(mempool, rreq->gfp);
220 if (!subreq)
221 return NULL;
222
223 memset(subreq, 0, kmem_cache_size(cache));
224 INIT_WORK(&subreq->work, NULL);
225 INIT_LIST_HEAD(&subreq->rreq_link);
226 refcount_set(&subreq->ref, 2);
227 subreq->rreq = rreq;
228 subreq->debug_index = atomic_inc_return(&rreq->subreq_counter);
229 netfs_get_request(rreq, netfs_rreq_trace_get_subreq);
230 netfs_stat(&netfs_n_rh_sreq);
231 return subreq;
232 }
233
netfs_get_subrequest(struct netfs_io_subrequest * subreq,enum netfs_sreq_ref_trace what)234 void netfs_get_subrequest(struct netfs_io_subrequest *subreq,
235 enum netfs_sreq_ref_trace what)
236 {
237 int r;
238
239 __refcount_inc(&subreq->ref, &r);
240 trace_netfs_sreq_ref(subreq->rreq->debug_id, subreq->debug_index, r + 1,
241 what);
242 }
243
netfs_free_subrequest(struct netfs_io_subrequest * subreq)244 static void netfs_free_subrequest(struct netfs_io_subrequest *subreq)
245 {
246 struct netfs_io_request *rreq = subreq->rreq;
247
248 trace_netfs_sreq(subreq, netfs_sreq_trace_free);
249 if (rreq->netfs_ops->free_subrequest)
250 rreq->netfs_ops->free_subrequest(subreq);
251 mempool_free(subreq, rreq->netfs_ops->subrequest_pool ?: &netfs_subrequest_pool);
252 netfs_stat_d(&netfs_n_rh_sreq);
253 netfs_put_request(rreq, netfs_rreq_trace_put_subreq);
254 }
255
netfs_put_subrequest(struct netfs_io_subrequest * subreq,enum netfs_sreq_ref_trace what)256 void netfs_put_subrequest(struct netfs_io_subrequest *subreq,
257 enum netfs_sreq_ref_trace what)
258 {
259 unsigned int debug_index = subreq->debug_index;
260 unsigned int debug_id = subreq->rreq->debug_id;
261 bool dead;
262 int r;
263
264 dead = __refcount_dec_and_test(&subreq->ref, &r);
265 trace_netfs_sreq_ref(debug_id, debug_index, r - 1, what);
266 if (dead)
267 netfs_free_subrequest(subreq);
268 }
269