libfuse: fuse-3.11.0/lib/fuse_loop_mt.c Source File

libfuse

fuse_loop_mt.c
1 /*
2 FUSE: Filesystem in Userspace
3 Copyright (C) 2001-2007 Miklos Szeredi <miklos@szeredi.hu>
4
5 Implementation of the multi-threaded FUSE session loop.
6
7 This program can be distributed under the terms of the GNU LGPLv2.
8 See the file COPYING.LIB.
9 */
10
11 #include "config.h"
12 #include "fuse_lowlevel.h"
13 #include "fuse_misc.h"
14 #include "fuse_kernel.h"
15 #include "fuse_i.h"
16
17 #include <stdio.h>
18 #include <stdlib.h>
19 #include <string.h>
20 #include <unistd.h>
21 #include <signal.h>
22 #include <semaphore.h>
23 #include <errno.h>
24 #include <sys/time.h>
25 #include <sys/ioctl.h>
26 #include <assert.h>
27
28 /* Environment var controlling the thread stack size */
29 #define ENVNAME_THREAD_STACK "FUSE_THREAD_STACK"
30
31 struct fuse_worker {
32 struct fuse_worker *prev;
33 struct fuse_worker *next;
34 pthread_t thread_id;
35
36 // We need to include fuse_buf so that we can properly free
37 // it when a thread is terminated by pthread_cancel().
38 struct fuse_buf fbuf;
39 struct fuse_chan *ch;
40 struct fuse_mt *mt;
41 };
42
43 struct fuse_mt {
44 pthread_mutex_t lock;
45 int numworker;
46 int numavail;
47 struct fuse_session *se;
48 struct fuse_worker main;
49 sem_t finish;
50 int exit;
51 int error;
52 int clone_fd;
53 int max_idle;
54 };
55
56 static struct fuse_chan *fuse_chan_new(int fd)
57 {
58 struct fuse_chan *ch = (struct fuse_chan *) malloc(sizeof(*ch));
59 if (ch == NULL) {
60 fuse_log(FUSE_LOG_ERR, "fuse: failed to allocate channel\n");
61 return NULL;
62 }
63
64 memset(ch, 0, sizeof(*ch));
65 ch->fd = fd;
66 ch->ctr = 1;
67 pthread_mutex_init(&ch->lock, NULL);
68
69 return ch;
70 }
71
72 struct fuse_chan *fuse_chan_get(struct fuse_chan *ch)
73 {
74 assert(ch->ctr > 0);
75 pthread_mutex_lock(&ch->lock);
76 ch->ctr++;
77 pthread_mutex_unlock(&ch->lock);
78
79 return ch;
80 }
81
82 void fuse_chan_put(struct fuse_chan *ch)
83 {
84 if (ch == NULL)
85 return;
86 pthread_mutex_lock(&ch->lock);
87 ch->ctr--;
88 if (!ch->ctr) {
89 pthread_mutex_unlock(&ch->lock);
90 close(ch->fd);
91 pthread_mutex_destroy(&ch->lock);
92 free(ch);
93 } else
94 pthread_mutex_unlock(&ch->lock);
95 }
96
97 static void list_add_worker(struct fuse_worker *w, struct fuse_worker *next)
98 {
99 struct fuse_worker *prev = next->prev;
100 w->next = next;
101 w->prev = prev;
102 prev->next = w;
103 next->prev = w;
104 }
105
106 static void list_del_worker(struct fuse_worker *w)
107 {
108 struct fuse_worker *prev = w->prev;
109 struct fuse_worker *next = w->next;
110 prev->next = next;
111 next->prev = prev;
112 }
113
114 static int fuse_loop_start_thread(struct fuse_mt *mt);
115
116 static void *fuse_do_work(void *data)
117 {
118 struct fuse_worker *w = (struct fuse_worker *) data;
119 struct fuse_mt *mt = w->mt;
120
121 while (!fuse_session_exited(mt->se)) {
122 int isforget = 0;
123 int res;
124
125 pthread_setcancelstate(PTHREAD_CANCEL_ENABLE, NULL);
126 res = fuse_session_receive_buf_int(mt->se, &w->fbuf, w->ch);
127 pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, NULL);
128 if (res == -EINTR)
129 continue;
130 if (res <= 0) {
131 if (res < 0) {
132 fuse_session_exit(mt->se);
133 mt->error = res;
134 }
135 break;
136 }
137
138 pthread_mutex_lock(&mt->lock);
139 if (mt->exit) {
140 pthread_mutex_unlock(&mt->lock);
141 return NULL;
142 }
143
144 /*
145 * This disgusting hack is needed so that zillions of threads
146 * are not created on a burst of FORGET messages
147 */
148 if (!(w->fbuf.flags & FUSE_BUF_IS_FD)) {
149 struct fuse_in_header *in = w->fbuf.mem;
150
151 if (in->opcode == FUSE_FORGET ||
152 in->opcode == FUSE_BATCH_FORGET)
153 isforget = 1;
154 }
155
156 if (!isforget)
157 mt->numavail--;
158 if (mt->numavail == 0)
159 fuse_loop_start_thread(mt);
160 pthread_mutex_unlock(&mt->lock);
161
162 fuse_session_process_buf_int(mt->se, &w->fbuf, w->ch);
163
164 pthread_mutex_lock(&mt->lock);
165 if (!isforget)
166 mt->numavail++;
167 if (mt->numavail > mt->max_idle) {
168 if (mt->exit) {
169 pthread_mutex_unlock(&mt->lock);
170 return NULL;
171 }
172 list_del_worker(w);
173 mt->numavail--;
174 mt->numworker--;
175 pthread_mutex_unlock(&mt->lock);
176
177 pthread_detach(w->thread_id);
178 free(w->fbuf.mem);
179 fuse_chan_put(w->ch);
180 free(w);
181 return NULL;
182 }
183 pthread_mutex_unlock(&mt->lock);
184 }
185
186 sem_post(&mt->finish);
187
188 return NULL;
189 }
190
191 int fuse_start_thread(pthread_t *thread_id, void *(*func)(void *), void *arg)
192 {
193 sigset_t oldset;
194 sigset_t newset;
195 int res;
196 pthread_attr_t attr;
197 char *stack_size;
198
199 /* Override default stack size */
200 pthread_attr_init(&attr);
201 stack_size = getenv(ENVNAME_THREAD_STACK);
202 if (stack_size && pthread_attr_setstacksize(&attr, atoi(stack_size)))
203 fuse_log(FUSE_LOG_ERR, "fuse: invalid stack size: %s\n", stack_size);
204
205 /* Disallow signal reception in worker threads */
206 sigemptyset(&newset);
207 sigaddset(&newset, SIGTERM);
208 sigaddset(&newset, SIGINT);
209 sigaddset(&newset, SIGHUP);
210 sigaddset(&newset, SIGQUIT);
211 pthread_sigmask(SIG_BLOCK, &newset, &oldset);
212 res = pthread_create(thread_id, &attr, func, arg);
213 pthread_sigmask(SIG_SETMASK, &oldset, NULL);
214 pthread_attr_destroy(&attr);
215 if (res != 0) {
216 fuse_log(FUSE_LOG_ERR, "fuse: error creating thread: %s\n",
217 strerror(res));
218 return -1;
219 }
220
221 return 0;
222 }
223
224 static struct fuse_chan *fuse_clone_chan(struct fuse_mt *mt)
225 {
226 int res;
227 int clonefd;
228 uint32_t masterfd;
229 struct fuse_chan *newch;
230 const char *devname = "/dev/fuse";
231
232 #ifndef O_CLOEXEC
233 #define O_CLOEXEC 0
234 #endif
235 clonefd = open(devname, O_RDWR | O_CLOEXEC);
236 if (clonefd == -1) {
237 fuse_log(FUSE_LOG_ERR, "fuse: failed to open %s: %s\n", devname,
238 strerror(errno));
239 return NULL;
240 }
241 fcntl(clonefd, F_SETFD, FD_CLOEXEC);
242
243 masterfd = mt->se->fd;
244 res = ioctl(clonefd, FUSE_DEV_IOC_CLONE, &masterfd);
245 if (res == -1) {
246 fuse_log(FUSE_LOG_ERR, "fuse: failed to clone device fd: %s\n",
247 strerror(errno));
248 close(clonefd);
249 return NULL;
250 }
251 newch = fuse_chan_new(clonefd);
252 if (newch == NULL)
253 close(clonefd);
254
255 return newch;
256 }
257
258 static int fuse_loop_start_thread(struct fuse_mt *mt)
259 {
260 int res;
261
262 struct fuse_worker *w = malloc(sizeof(struct fuse_worker));
263 if (!w) {
264 fuse_log(FUSE_LOG_ERR, "fuse: failed to allocate worker structure\n");
265 return -1;
266 }
267 memset(w, 0, sizeof(struct fuse_worker));
268 w->fbuf.mem = NULL;
269 w->mt = mt;
270
271 w->ch = NULL;
272 if (mt->clone_fd) {
273 w->ch = fuse_clone_chan(mt);
274 if(!w->ch) {
275 /* Don't attempt this again */
276 fuse_log(FUSE_LOG_ERR, "fuse: trying to continue "
277 "without -o clone_fd.\n");
278 mt->clone_fd = 0;
279 }
280 }
281
282 res = fuse_start_thread(&w->thread_id, fuse_do_work, w);
283 if (res == -1) {
284 fuse_chan_put(w->ch);
285 free(w);
286 return -1;
287 }
288 list_add_worker(w, &mt->main);
289 mt->numavail ++;
290 mt->numworker ++;
291
292 return 0;
293 }
294
295 static void fuse_join_worker(struct fuse_mt *mt, struct fuse_worker *w)
296 {
297 pthread_join(w->thread_id, NULL);
298 pthread_mutex_lock(&mt->lock);
299 list_del_worker(w);
300 pthread_mutex_unlock(&mt->lock);
301 free(w->fbuf.mem);
302 fuse_chan_put(w->ch);
303 free(w);
304 }
305
306 FUSE_SYMVER("fuse_session_loop_mt_32", "fuse_session_loop_mt@@FUSE_3.2")
307 int fuse_session_loop_mt_32(struct fuse_session *se, struct fuse_loop_config *config)
308 {
309 int err;
310 struct fuse_mt mt;
311 struct fuse_worker *w;
312
313 memset(&mt, 0, sizeof(struct fuse_mt));
314 mt.se = se;
315 mt.clone_fd = config->clone_fd;
316 mt.error = 0;
317 mt.numworker = 0;
318 mt.numavail = 0;
319 mt.max_idle = config->max_idle_threads;
320 mt.main.thread_id = pthread_self();
321 mt.main.prev = mt.main.next = &mt.main;
322 sem_init(&mt.finish, 0, 0);
323 pthread_mutex_init(&mt.lock, NULL);
324
325 pthread_mutex_lock(&mt.lock);
326 err = fuse_loop_start_thread(&mt);
327 pthread_mutex_unlock(&mt.lock);
328 if (!err) {
329 /* sem_wait() is interruptible */
330 while (!fuse_session_exited(se))
331 sem_wait(&mt.finish);
332
333 pthread_mutex_lock(&mt.lock);
334 for (w = mt.main.next; w != &mt.main; w = w->next)
335 pthread_cancel(w->thread_id);
336 mt.exit = 1;
337 pthread_mutex_unlock(&mt.lock);
338
339 while (mt.main.next != &mt.main)
340 fuse_join_worker(&mt, mt.main.next);
341
342 err = mt.error;
343 }
344
345 pthread_mutex_destroy(&mt.lock);
346 sem_destroy(&mt.finish);
347 if(se->error != 0)
348 err = se->error;
349 fuse_session_reset(se);
350 return err;
351 }
352
353 int fuse_session_loop_mt_31(struct fuse_session *se, int clone_fd);
354 FUSE_SYMVER("fuse_session_loop_mt_31", "fuse_session_loop_mt@FUSE_3.0")
355 int fuse_session_loop_mt_31(struct fuse_session *se, int clone_fd)
356 {
357 struct fuse_loop_config config;
358 config.clone_fd = clone_fd;
359 config.max_idle_threads = 10;
360 return fuse_session_loop_mt_32(se, &config);
361 }
FUSE_BUF_IS_FD
@ FUSE_BUF_IS_FD
Definition: fuse_common.h:633
fuse_log
void fuse_log(enum fuse_log_level level, const char *fmt,...)
Definition: fuse_log.c:33
fuse_session_exit
void fuse_session_exit(struct fuse_session *se)
fuse_session_exited
int fuse_session_exited(struct fuse_session *se)
fuse_session_reset
void fuse_session_reset(struct fuse_session *se)
fuse_buf
Definition: fuse_common.h:702
fuse_loop_config
Definition: fuse_common.h:107
fuse_loop_config::clone_fd
int clone_fd
Definition: fuse_common.h:112