tools/virtiofsd/helper.c

   1 /*
   2  * FUSE: Filesystem in Userspace
   3  * Copyright (C) 2001-2007  Miklos Szeredi <miklos@szeredi.hu>
   4  *
   5  * Helper functions to create (simple) standalone programs. With the
   6  * aid of these functions it should be possible to create full FUSE
   7  * file system by implementing nothing but the request handlers.
   8
   9  * This program can be distributed under the terms of the GNU LGPLv2.
  10  * See the file COPYING.LIB.
  11  */
  12
  13 #include "qemu/osdep.h"
  14 #include "fuse_i.h"
  15 #include "fuse_lowlevel.h"
  16 #include "fuse_misc.h"
  17 #include "fuse_opt.h"
  18
  19 #include <errno.h>
  20 #include <limits.h>
  21 #include <stddef.h>
  22 #include <stdio.h>
  23 #include <stdlib.h>
  24 #include <string.h>
  25 #include <sys/param.h>
  26 #include <sys/time.h>
  27 #include <sys/resource.h>
  28 #include <unistd.h>
  29
  30 #define FUSE_HELPER_OPT(t, p)                       \
  31     {                                               \
  32         t, offsetof(struct fuse_cmdline_opts, p), 1 \
  33     }
  34 #define FUSE_HELPER_OPT_VALUE(t, p, v)              \
  35     {                                               \
  36         t, offsetof(struct fuse_cmdline_opts, p), v \
  37     }
  38
  39 static const struct fuse_opt fuse_helper_opts[] = {
  40     FUSE_HELPER_OPT("-h", show_help),
  41     FUSE_HELPER_OPT("--help", show_help),
  42     FUSE_HELPER_OPT("-V", show_version),
  43     FUSE_HELPER_OPT("--version", show_version),
  44     FUSE_HELPER_OPT("--print-capabilities", print_capabilities),
  45     FUSE_HELPER_OPT("-d", debug),
  46     FUSE_HELPER_OPT("debug", debug),
  47     FUSE_HELPER_OPT("-d", foreground),
  48     FUSE_HELPER_OPT("debug", foreground),
  49     FUSE_OPT_KEY("-d", FUSE_OPT_KEY_KEEP),
  50     FUSE_OPT_KEY("debug", FUSE_OPT_KEY_KEEP),
  51     FUSE_HELPER_OPT("-f", foreground),
  52     FUSE_HELPER_OPT_VALUE("--daemonize", foreground, 0),
  53     FUSE_HELPER_OPT("fsname=", nodefault_subtype),
  54     FUSE_OPT_KEY("fsname=", FUSE_OPT_KEY_KEEP),
  55     FUSE_HELPER_OPT("subtype=", nodefault_subtype),
  56     FUSE_OPT_KEY("subtype=", FUSE_OPT_KEY_KEEP),
  57     FUSE_HELPER_OPT("max_idle_threads=%u", max_idle_threads),
  58     FUSE_HELPER_OPT("--rlimit-nofile=%lu", rlimit_nofile),
  59     FUSE_HELPER_OPT("--syslog", syslog),
  60     FUSE_HELPER_OPT_VALUE("log_level=debug", log_level, FUSE_LOG_DEBUG),
  61     FUSE_HELPER_OPT_VALUE("log_level=info", log_level, FUSE_LOG_INFO),
  62     FUSE_HELPER_OPT_VALUE("log_level=warn", log_level, FUSE_LOG_WARNING),
  63     FUSE_HELPER_OPT_VALUE("log_level=err", log_level, FUSE_LOG_ERR),
  64     FUSE_OPT_END
  65 };
  66
  67 struct fuse_conn_info_opts {
  68     int atomic_o_trunc;
  69     int no_remote_posix_lock;
  70     int no_remote_flock;
  71     int splice_write;
  72     int splice_move;
  73     int splice_read;
  74     int no_splice_write;
  75     int no_splice_move;
  76     int no_splice_read;
  77     int auto_inval_data;
  78     int no_auto_inval_data;
  79     int no_readdirplus;
  80     int no_readdirplus_auto;
  81     int async_dio;
  82     int no_async_dio;
  83     int writeback_cache;
  84     int no_writeback_cache;
  85     int async_read;
  86     int sync_read;
  87     unsigned max_write;
  88     unsigned max_readahead;
  89     unsigned max_background;
  90     unsigned congestion_threshold;
  91     unsigned time_gran;
  92     int set_max_write;
  93     int set_max_readahead;
  94     int set_max_background;
  95     int set_congestion_threshold;
  96     int set_time_gran;
  97 };
  98
  99 #define CONN_OPTION(t, p, v)                          \
 100     {                                                 \
 101         t, offsetof(struct fuse_conn_info_opts, p), v \
 102     }
 103 static const struct fuse_opt conn_info_opt_spec[] = {
 104     CONN_OPTION("max_write=%u", max_write, 0),
 105     CONN_OPTION("max_write=", set_max_write, 1),
 106     CONN_OPTION("max_readahead=%u", max_readahead, 0),
 107     CONN_OPTION("max_readahead=", set_max_readahead, 1),
 108     CONN_OPTION("max_background=%u", max_background, 0),
 109     CONN_OPTION("max_background=", set_max_background, 1),
 110     CONN_OPTION("congestion_threshold=%u", congestion_threshold, 0),
 111     CONN_OPTION("congestion_threshold=", set_congestion_threshold, 1),
 112     CONN_OPTION("sync_read", sync_read, 1),
 113     CONN_OPTION("async_read", async_read, 1),
 114     CONN_OPTION("atomic_o_trunc", atomic_o_trunc, 1),
 115     CONN_OPTION("no_remote_lock", no_remote_posix_lock, 1),
 116     CONN_OPTION("no_remote_lock", no_remote_flock, 1),
 117     CONN_OPTION("no_remote_flock", no_remote_flock, 1),
 118     CONN_OPTION("no_remote_posix_lock", no_remote_posix_lock, 1),
 119     CONN_OPTION("splice_write", splice_write, 1),
 120     CONN_OPTION("no_splice_write", no_splice_write, 1),
 121     CONN_OPTION("splice_move", splice_move, 1),
 122     CONN_OPTION("no_splice_move", no_splice_move, 1),
 123     CONN_OPTION("splice_read", splice_read, 1),
 124     CONN_OPTION("no_splice_read", no_splice_read, 1),
 125     CONN_OPTION("auto_inval_data", auto_inval_data, 1),
 126     CONN_OPTION("no_auto_inval_data", no_auto_inval_data, 1),
 127     CONN_OPTION("readdirplus=no", no_readdirplus, 1),
 128     CONN_OPTION("readdirplus=yes", no_readdirplus, 0),
 129     CONN_OPTION("readdirplus=yes", no_readdirplus_auto, 1),
 130     CONN_OPTION("readdirplus=auto", no_readdirplus, 0),
 131     CONN_OPTION("readdirplus=auto", no_readdirplus_auto, 0),
 132     CONN_OPTION("async_dio", async_dio, 1),
 133     CONN_OPTION("no_async_dio", no_async_dio, 1),
 134     CONN_OPTION("writeback_cache", writeback_cache, 1),
 135     CONN_OPTION("no_writeback_cache", no_writeback_cache, 1),
 136     CONN_OPTION("time_gran=%u", time_gran, 0),
 137     CONN_OPTION("time_gran=", set_time_gran, 1),
 138     FUSE_OPT_END
 139 };
 140
 141
 142 void fuse_cmdline_help(void)
 143 {
 144     printf("    -h   --help                print help\n"
 145            "    -V   --version             print version\n"
 146            "    --print-capabilities       print vhost-user.json\n"
 147            "    -d   -o debug              enable debug output (implies -f)\n"
 148            "    --syslog                   log to syslog (default stderr)\n"
 149            "    -f                         foreground operation\n"
 150            "    --daemonize                run in background\n"
 151            "    -o cache=<mode>            cache mode. could be one of \"auto, "
 152            "always, none\"\n"
 153            "                               default: auto\n"
 154            "    -o flock|no_flock          enable/disable flock\n"
 155            "                               default: no_flock\n"
 156            "    -o log_level=<level>       log level, default to \"info\"\n"
 157            "                               level could be one of \"debug, "
 158            "info, warn, err\"\n"
 159            "    -o max_idle_threads        the maximum number of idle worker "
 160            "threads\n"
 161            "                               allowed (default: 10)\n"
 162            "    -o posix_lock|no_posix_lock\n"
 163            "                               enable/disable remote posix lock\n"
 164            "                               default: posix_lock\n"
 165            "    -o readdirplus|no_readdirplus\n"
 166            "                               enable/disable readirplus\n"
 167            "                               default: readdirplus except with "
 168            "cache=none\n"
 169            "    -o timeout=<number>        I/O timeout (seconds)\n"
 170            "                               default: depends on cache= option.\n"
 171            "    -o writeback|no_writeback  enable/disable writeback cache\n"
 172            "                               default: no_writeback\n"
 173            "    -o xattr|no_xattr          enable/disable xattr\n"
 174            "                               default: no_xattr\n"
 175            "    -o modcaps=CAPLIST         Modify the list of capabilities\n"
 176            "                               e.g. -o modcaps=+sys_admin:-chown\n"
 177            "    --rlimit-nofile=<num>      set maximum number of file descriptors\n"
 178            "                               (0 leaves rlimit unchanged)\n"
 179            "                               default: min(1000000, fs.file-max - 16384)\n"
 180            "                                        if the current rlimit is lower\n"
 181            "    -o allow_direct_io|no_allow_direct_io\n"
 182            "                               retain/discard O_DIRECT flags passed down\n"
 183            "                               to virtiofsd from guest applications.\n"
 184            "                               default: no_allow_direct_io\n"
 185            );
 186 }
 187
 188 static int fuse_helper_opt_proc(void *data, const char *arg, int key,
 189                                 struct fuse_args *outargs)
 190 {
 191     (void)data;
 192     (void)outargs;
 193
 194     switch (key) {
 195     case FUSE_OPT_KEY_NONOPT:
 196         fuse_log(FUSE_LOG_ERR, "fuse: invalid argument `%s'\n", arg);
 197         return -1;
 198
 199     default:
 200         /* Pass through unknown options */
 201         return 1;
 202     }
 203 }
 204
 205 static unsigned long get_default_rlimit_nofile(void)
 206 {
 207     g_autofree gchar *file_max_str = NULL;
 208     const rlim_t reserved_fds = 16384; /* leave at least this many fds free */
 209     rlim_t max_fds = 1000000; /* our default RLIMIT_NOFILE target */
 210     rlim_t file_max;
 211     struct rlimit rlim;
 212
 213     /*
 214      * Reduce max_fds below the system-wide maximum, if necessary.  This
 215      * ensures there are fds available for other processes so we don't
 216      * cause resource exhaustion.
 217      */
 218     if (!g_file_get_contents("/proc/sys/fs/file-max", &file_max_str,
 219                              NULL, NULL)) {
 220         fuse_log(FUSE_LOG_ERR, "can't read /proc/sys/fs/file-max\n");
 221         exit(1);
 222     }
 223     file_max = g_ascii_strtoull(file_max_str, NULL, 10);
 224     if (file_max < 2 * reserved_fds) {
 225         fuse_log(FUSE_LOG_ERR,
 226                  "The fs.file-max sysctl is too low (%lu) to allow a "
 227                  "reasonable number of open files.\n",
 228                  (unsigned long)file_max);
 229         exit(1);
 230     }
 231     max_fds = MIN(file_max - reserved_fds, max_fds);
 232
 233     if (getrlimit(RLIMIT_NOFILE, &rlim) < 0) {
 234         fuse_log(FUSE_LOG_ERR, "getrlimit(RLIMIT_NOFILE): %m\n");
 235         exit(1);
 236     }
 237
 238     if (rlim.rlim_cur >= max_fds) {
 239         return 0; /* we have more fds available than required! */
 240     }
 241     return max_fds;
 242 }
 243
 244 int fuse_parse_cmdline(struct fuse_args *args, struct fuse_cmdline_opts *opts)
 245 {
 246     memset(opts, 0, sizeof(struct fuse_cmdline_opts));
 247
 248     opts->max_idle_threads = 10;
 249     opts->rlimit_nofile = get_default_rlimit_nofile();
 250     opts->foreground = 1;
 251
 252     if (fuse_opt_parse(args, opts, fuse_helper_opts, fuse_helper_opt_proc) ==
 253         -1) {
 254         return -1;
 255     }
 256
 257     return 0;
 258 }
 259
 260
 261 int fuse_daemonize(int foreground)
 262 {
 263     int ret = 0, rett;
 264     if (!foreground) {
 265         int nullfd;
 266         int waiter[2];
 267         char completed;
 268
 269         if (pipe(waiter)) {
 270             fuse_log(FUSE_LOG_ERR, "fuse_daemonize: pipe: %s\n",
 271                      strerror(errno));
 272             return -1;
 273         }
 274
 275         /*
 276          * demonize current process by forking it and killing the
 277          * parent.  This makes current process as a child of 'init'.
 278          */
 279         switch (fork()) {
 280         case -1:
 281             fuse_log(FUSE_LOG_ERR, "fuse_daemonize: fork: %s\n",
 282                      strerror(errno));
 283             return -1;
 284         case 0:
 285             break;
 286         default:
 287             _exit(read(waiter[0], &completed,
 288                        sizeof(completed) != sizeof(completed)));
 289         }
 290
 291         if (setsid() == -1) {
 292             fuse_log(FUSE_LOG_ERR, "fuse_daemonize: setsid: %s\n",
 293                      strerror(errno));
 294             return -1;
 295         }
 296
 297         ret = chdir("/");
 298
 299         nullfd = open("/dev/null", O_RDWR, 0);
 300         if (nullfd != -1) {
 301             rett = dup2(nullfd, 0);
 302             if (!ret) {
 303                 ret = rett;
 304             }
 305             rett = dup2(nullfd, 1);
 306             if (!ret) {
 307                 ret = rett;
 308             }
 309             rett = dup2(nullfd, 2);
 310             if (!ret) {
 311                 ret = rett;
 312             }
 313             if (nullfd > 2) {
 314                 close(nullfd);
 315             }
 316         }
 317
 318         /* Propagate completion of daemon initialization */
 319         completed = 1;
 320         rett = write(waiter[1], &completed, sizeof(completed));
 321         if (!ret) {
 322             ret = rett;
 323         }
 324         close(waiter[0]);
 325         close(waiter[1]);
 326     } else {
 327         ret = chdir("/");
 328     }
 329     return ret;
 330 }
 331
 332 void fuse_apply_conn_info_opts(struct fuse_conn_info_opts *opts,
 333                                struct fuse_conn_info *conn)
 334 {
 335     if (opts->set_max_write) {
 336         conn->max_write = opts->max_write;
 337     }
 338     if (opts->set_max_background) {
 339         conn->max_background = opts->max_background;
 340     }
 341     if (opts->set_congestion_threshold) {
 342         conn->congestion_threshold = opts->congestion_threshold;
 343     }
 344     if (opts->set_time_gran) {
 345         conn->time_gran = opts->time_gran;
 346     }
 347     if (opts->set_max_readahead) {
 348         conn->max_readahead = opts->max_readahead;
 349     }
 350
 351 #define LL_ENABLE(cond, cap) \
 352     if (cond)                \
 353         conn->want |= (cap)
 354 #define LL_DISABLE(cond, cap) \
 355     if (cond)                 \
 356         conn->want &= ~(cap)
 357
 358     LL_ENABLE(opts->splice_read, FUSE_CAP_SPLICE_READ);
 359     LL_DISABLE(opts->no_splice_read, FUSE_CAP_SPLICE_READ);
 360
 361     LL_ENABLE(opts->splice_write, FUSE_CAP_SPLICE_WRITE);
 362     LL_DISABLE(opts->no_splice_write, FUSE_CAP_SPLICE_WRITE);
 363
 364     LL_ENABLE(opts->splice_move, FUSE_CAP_SPLICE_MOVE);
 365     LL_DISABLE(opts->no_splice_move, FUSE_CAP_SPLICE_MOVE);
 366
 367     LL_ENABLE(opts->auto_inval_data, FUSE_CAP_AUTO_INVAL_DATA);
 368     LL_DISABLE(opts->no_auto_inval_data, FUSE_CAP_AUTO_INVAL_DATA);
 369
 370     LL_DISABLE(opts->no_readdirplus, FUSE_CAP_READDIRPLUS);
 371     LL_DISABLE(opts->no_readdirplus_auto, FUSE_CAP_READDIRPLUS_AUTO);
 372
 373     LL_ENABLE(opts->async_dio, FUSE_CAP_ASYNC_DIO);
 374     LL_DISABLE(opts->no_async_dio, FUSE_CAP_ASYNC_DIO);
 375
 376     LL_ENABLE(opts->writeback_cache, FUSE_CAP_WRITEBACK_CACHE);
 377     LL_DISABLE(opts->no_writeback_cache, FUSE_CAP_WRITEBACK_CACHE);
 378
 379     LL_ENABLE(opts->async_read, FUSE_CAP_ASYNC_READ);
 380     LL_DISABLE(opts->sync_read, FUSE_CAP_ASYNC_READ);
 381
 382     LL_DISABLE(opts->no_remote_posix_lock, FUSE_CAP_POSIX_LOCKS);
 383     LL_DISABLE(opts->no_remote_flock, FUSE_CAP_FLOCK_LOCKS);
 384 }
 385
 386 struct fuse_conn_info_opts *fuse_parse_conn_info_opts(struct fuse_args *args)
 387 {
 388     struct fuse_conn_info_opts *opts;
 389
 390     opts = calloc(1, sizeof(struct fuse_conn_info_opts));
 391     if (opts == NULL) {
 392         fuse_log(FUSE_LOG_ERR, "calloc failed\n");
 393         return NULL;
 394     }
 395     if (fuse_opt_parse(args, opts, conn_info_opt_spec, NULL) == -1) {
 396         free(opts);
 397         return NULL;
 398     }
 399     return opts;
 400 }