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