lib/fuse_loop_mt.c

   1 /*
   2   FUSE: Filesystem in Userspace
   3   Copyright (C) 2001-2007  Miklos Szeredi <miklos@szeredi.hu>
   4
   5   This program can be distributed under the terms of the GNU LGPLv2.
   6   See the file COPYING.LIB.
   7 */
   8
   9 #include "fuse_lowlevel.h"
  10 #include "fuse_misc.h"
  11 #include "fuse_kernel.h"
  12
  13 #include <stdio.h>
  14 #include <stdlib.h>
  15 #include <string.h>
  16 #include <unistd.h>
  17 #include <signal.h>
  18 #include <semaphore.h>
  19 #include <errno.h>
  20 #include <sys/time.h>
  21
  22 /* Environment var controlling the thread stack size */
  23 #define ENVNAME_THREAD_STACK "FUSE_THREAD_STACK"
  24
  25 struct fuse_worker {
  26         struct fuse_worker *prev;
  27         struct fuse_worker *next;
  28         pthread_t thread_id;
  29         size_t bufsize;
  30         char *buf;
  31         struct fuse_mt *mt;
  32 };
  33
  34 struct fuse_mt {
  35         pthread_mutex_t lock;
  36         int numworker;
  37         int numavail;
  38         struct fuse_session *se;
  39         struct fuse_chan *prevch;
  40         struct fuse_worker main;
  41         sem_t finish;
  42         int exit;
  43         int error;
  44 };
  45
  46 static void list_add_worker(struct fuse_worker *w, struct fuse_worker *next)
  47 {
  48         struct fuse_worker *prev = next->prev;
  49         w->next = next;
  50         w->prev = prev;
  51         prev->next = w;
  52         next->prev = w;
  53 }
  54
  55 static void list_del_worker(struct fuse_worker *w)
  56 {
  57         struct fuse_worker *prev = w->prev;
  58         struct fuse_worker *next = w->next;
  59         prev->next = next;
  60         next->prev = prev;
  61 }
  62
  63 static int fuse_start_thread(struct fuse_mt *mt);
  64
  65 static void *fuse_do_work(void *data)
  66 {
  67         struct fuse_worker *w = (struct fuse_worker *) data;
  68         struct fuse_mt *mt = w->mt;
  69
  70         while (!fuse_session_exited(mt->se)) {
  71                 int isforget = 0;
  72                 struct fuse_chan *ch = mt->prevch;
  73                 struct fuse_buf fbuf = {
  74                         .mem = w->buf,
  75                         .size = w->bufsize,
  76                 };
  77                 int res;
  78
  79                 pthread_setcancelstate(PTHREAD_CANCEL_ENABLE, NULL);
  80                 res = fuse_session_receive_buf(mt->se, &fbuf, &ch);
  81                 pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, NULL);
  82                 if (res == -EINTR)
  83                         continue;
  84                 if (res <= 0) {
  85                         if (res < 0) {
  86                                 fuse_session_exit(mt->se);
  87                                 mt->error = -1;
  88                         }
  89                         break;
  90                 }
  91
  92                 pthread_mutex_lock(&mt->lock);
  93                 if (mt->exit) {
  94                         pthread_mutex_unlock(&mt->lock);
  95                         return NULL;
  96                 }
  97
  98                 /*
  99                  * This disgusting hack is needed so that zillions of threads
 100                  * are not created on a burst of FORGET messages
 101                  */
 102                 if (!(fbuf.flags & FUSE_BUF_IS_FD) &&
 103                     ((struct fuse_in_header *) fbuf.mem)->opcode == FUSE_FORGET)
 104                         isforget = 1;
 105
 106                 if (!isforget)
 107                         mt->numavail--;
 108                 if (mt->numavail == 0)
 109                         fuse_start_thread(mt);
 110                 pthread_mutex_unlock(&mt->lock);
 111
 112                 fuse_session_process_buf(mt->se, &fbuf, ch);
 113
 114                 pthread_mutex_lock(&mt->lock);
 115                 if (!isforget)
 116                         mt->numavail++;
 117                 if (mt->numavail > 10) {
 118                         if (mt->exit) {
 119                                 pthread_mutex_unlock(&mt->lock);
 120                                 return NULL;
 121                         }
 122                         list_del_worker(w);
 123                         mt->numavail--;
 124                         mt->numworker--;
 125                         pthread_mutex_unlock(&mt->lock);
 126
 127                         pthread_detach(w->thread_id);
 128                         free(w->buf);
 129                         free(w);
 130                         return NULL;
 131                 }
 132                 pthread_mutex_unlock(&mt->lock);
 133         }
 134
 135         sem_post(&mt->finish);
 136
 137         return NULL;
 138 }
 139
 140 static int fuse_start_thread(struct fuse_mt *mt)
 141 {
 142         sigset_t oldset;
 143         sigset_t newset;
 144         int res;
 145         pthread_attr_t attr;
 146         char *stack_size;
 147         struct fuse_worker *w = malloc(sizeof(struct fuse_worker));
 148         if (!w) {
 149                 fprintf(stderr, "fuse: failed to allocate worker structure\n");
 150                 return -1;
 151         }
 152         memset(w, 0, sizeof(struct fuse_worker));
 153         w->bufsize = fuse_chan_bufsize(mt->prevch);
 154         w->buf = malloc(w->bufsize);
 155         w->mt = mt;
 156         if (!w->buf) {
 157                 fprintf(stderr, "fuse: failed to allocate read buffer\n");
 158                 free(w);
 159                 return -1;
 160         }
 161
 162         /* Override default stack size */
 163         pthread_attr_init(&attr);
 164         stack_size = getenv(ENVNAME_THREAD_STACK);
 165         if (stack_size && pthread_attr_setstacksize(&attr, atoi(stack_size)))
 166                 fprintf(stderr, "fuse: invalid stack size: %s\n", stack_size);
 167
 168         /* Disallow signal reception in worker threads */
 169         sigemptyset(&newset);
 170         sigaddset(&newset, SIGTERM);
 171         sigaddset(&newset, SIGINT);
 172         sigaddset(&newset, SIGHUP);
 173         sigaddset(&newset, SIGQUIT);
 174         pthread_sigmask(SIG_BLOCK, &newset, &oldset);
 175         res = pthread_create(&w->thread_id, &attr, fuse_do_work, w);
 176         pthread_sigmask(SIG_SETMASK, &oldset, NULL);
 177         pthread_attr_destroy(&attr);
 178         if (res != 0) {
 179                 fprintf(stderr, "fuse: error creating thread: %s\n",
 180                         strerror(res));
 181                 free(w->buf);
 182                 free(w);
 183                 return -1;
 184         }
 185         list_add_worker(w, &mt->main);
 186         mt->numavail ++;
 187         mt->numworker ++;
 188
 189         return 0;
 190 }
 191
 192 static void fuse_join_worker(struct fuse_mt *mt, struct fuse_worker *w)
 193 {
 194         pthread_join(w->thread_id, NULL);
 195         pthread_mutex_lock(&mt->lock);
 196         list_del_worker(w);
 197         pthread_mutex_unlock(&mt->lock);
 198         free(w->buf);
 199         free(w);
 200 }
 201
 202 int fuse_session_loop_mt(struct fuse_session *se)
 203 {
 204         int err;
 205         struct fuse_mt mt;
 206         struct fuse_worker *w;
 207
 208         memset(&mt, 0, sizeof(struct fuse_mt));
 209         mt.se = se;
 210         mt.prevch = fuse_session_next_chan(se, NULL);
 211         mt.error = 0;
 212         mt.numworker = 0;
 213         mt.numavail = 0;
 214         mt.main.thread_id = pthread_self();
 215         mt.main.prev = mt.main.next = &mt.main;
 216         sem_init(&mt.finish, 0, 0);
 217         fuse_mutex_init(&mt.lock);
 218
 219         pthread_mutex_lock(&mt.lock);
 220         err = fuse_start_thread(&mt);
 221         pthread_mutex_unlock(&mt.lock);
 222         if (!err) {
 223                 /* sem_wait() is interruptible */
 224                 while (!fuse_session_exited(se))
 225                         sem_wait(&mt.finish);
 226
 227                 for (w = mt.main.next; w != &mt.main; w = w->next)
 228                         pthread_cancel(w->thread_id);
 229                 mt.exit = 1;
 230                 pthread_mutex_unlock(&mt.lock);
 231
 232                 while (mt.main.next != &mt.main)
 233                         fuse_join_worker(&mt, mt.main.next);
 234
 235                 err = mt.error;
 236         }
 237
 238         pthread_mutex_destroy(&mt.lock);
 239         sem_destroy(&mt.finish);
 240         fuse_session_reset(se);
 241         return err;
 242 }