source3/modules/vfs_preopen.c

   1 /*
   2  * Force a readahead of files by opening them and reading the first bytes
   3  *
   4  * Copyright (C) Volker Lendecke 2008
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, write to the Free Software
  18  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  19  */
  20
  21 #include "includes.h"
  22 #include "system/filesys.h"
  23
  24 struct preopen_state;
  25
  26 struct preopen_helper {
  27         struct preopen_state *state;
  28         struct fd_event *fde;
  29         pid_t pid;
  30         int fd;
  31         bool busy;
  32 };
  33
  34 struct preopen_state {
  35         int num_helpers;
  36         struct preopen_helper *helpers;
  37
  38         size_t to_read;         /* How many bytes to read in children? */
  39         int queue_max;
  40
  41         char *template_fname;   /* Filename to be sent to children */
  42         size_t number_start;    /* start offset into "template_fname" */
  43         int num_digits;         /* How many digits is the number long? */
  44
  45         int fnum_sent;          /* last fname sent to children */
  46
  47         int fnum_queue_end;     /* last fname to be sent, based on
  48                                  * last open call + preopen:queuelen
  49                                  */
  50
  51         name_compare_entry *preopen_names;
  52 };
  53
  54 static void preopen_helper_destroy(struct preopen_helper *c)
  55 {
  56         int status;
  57         close(c->fd);
  58         c->fd = -1;
  59         kill(c->pid, SIGKILL);
  60         waitpid(c->pid, &status, 0);
  61         c->busy = true;
  62 }
  63
  64 static void preopen_queue_run(struct preopen_state *state)
  65 {
  66         char *pdelimiter;
  67         char delimiter;
  68
  69         pdelimiter = state->template_fname + state->number_start
  70                 + state->num_digits;
  71         delimiter = *pdelimiter;
  72
  73         while (state->fnum_sent < state->fnum_queue_end) {
  74
  75                 ssize_t written;
  76                 size_t to_write;
  77                 int helper;
  78
  79                 for (helper=0; helper<state->num_helpers; helper++) {
  80                         if (state->helpers[helper].busy) {
  81                                 continue;
  82                         }
  83                         break;
  84                 }
  85                 if (helper == state->num_helpers) {
  86                         /* everyone is busy */
  87                         return;
  88                 }
  89
  90                 snprintf(state->template_fname + state->number_start,
  91                          state->num_digits + 1,
  92                          "%.*lu", state->num_digits,
  93                          (long unsigned int)(state->fnum_sent + 1));
  94                 *pdelimiter = delimiter;
  95
  96                 to_write = talloc_get_size(state->template_fname);
  97                 written = write_data(state->helpers[helper].fd,
  98                                      state->template_fname, to_write);
  99                 state->helpers[helper].busy = true;
 100
 101                 if (written != to_write) {
 102                         preopen_helper_destroy(&state->helpers[helper]);
 103                 }
 104                 state->fnum_sent += 1;
 105         }
 106 }
 107
 108 static void preopen_helper_readable(struct event_context *ev,
 109                                     struct fd_event *fde, uint16_t flags,
 110                                     void *priv)
 111 {
 112         struct preopen_helper *helper = (struct preopen_helper *)priv;
 113         struct preopen_state *state = helper->state;
 114         ssize_t nread;
 115         char c;
 116
 117         if ((flags & EVENT_FD_READ) == 0) {
 118                 return;
 119         }
 120
 121         nread = read(helper->fd, &c, 1);
 122         if (nread <= 0) {
 123                 preopen_helper_destroy(helper);
 124                 return;
 125         }
 126
 127         helper->busy = false;
 128
 129         preopen_queue_run(state);
 130 }
 131
 132 static int preopen_helpers_destructor(struct preopen_state *c)
 133 {
 134         int i;
 135
 136         for (i=0; i<c->num_helpers; i++) {
 137                 if (c->helpers[i].fd == -1) {
 138                         continue;
 139                 }
 140                 preopen_helper_destroy(&c->helpers[i]);
 141         }
 142
 143         return 0;
 144 }
 145
 146 static bool preopen_helper_open_one(int sock_fd, char **pnamebuf,
 147                                     size_t to_read, void *filebuf)
 148 {
 149         char *namebuf = *pnamebuf;
 150         ssize_t nwritten, nread;
 151         char c = 0;
 152         int fd;
 153
 154         nread = 0;
 155
 156         while ((nread == 0) || (namebuf[nread-1] != '\0')) {
 157                 ssize_t thistime;
 158
 159                 thistime = read(sock_fd, namebuf + nread,
 160                                 talloc_get_size(namebuf) - nread);
 161                 if (thistime <= 0) {
 162                         return false;
 163                 }
 164
 165                 nread += thistime;
 166
 167                 if (nread == talloc_get_size(namebuf)) {
 168                         namebuf = TALLOC_REALLOC_ARRAY(
 169                                 NULL, namebuf, char,
 170                                 talloc_get_size(namebuf) * 2);
 171                         if (namebuf == NULL) {
 172                                 return false;
 173                         }
 174                         *pnamebuf = namebuf;
 175                 }
 176         }
 177
 178         fd = open(namebuf, O_RDONLY);
 179         if (fd == -1) {
 180                 goto done;
 181         }
 182         nread = read(fd, filebuf, to_read);
 183         close(fd);
 184
 185  done:
 186         nwritten = write(sock_fd, &c, 1);
 187         return true;
 188 }
 189
 190 static bool preopen_helper(int fd, size_t to_read)
 191 {
 192         char *namebuf;
 193         void *readbuf;
 194
 195         namebuf = TALLOC_ARRAY(NULL, char, 1024);
 196         if (namebuf == NULL) {
 197                 return false;
 198         }
 199
 200         readbuf = talloc_size(NULL, to_read);
 201         if (readbuf == NULL) {
 202                 TALLOC_FREE(namebuf);
 203                 return false;
 204         }
 205
 206         while (preopen_helper_open_one(fd, &namebuf, to_read, readbuf)) {
 207                 ;
 208         }
 209
 210         TALLOC_FREE(readbuf);
 211         TALLOC_FREE(namebuf);
 212         return false;
 213 }
 214
 215 static NTSTATUS preopen_init_helper(struct preopen_helper *h)
 216 {
 217         int fdpair[2];
 218         NTSTATUS status;
 219
 220         if (socketpair(AF_UNIX, SOCK_STREAM, 0, fdpair) == -1) {
 221                 status = map_nt_error_from_unix(errno);
 222                 DEBUG(10, ("socketpair() failed: %s\n", strerror(errno)));
 223                 return status;
 224         }
 225
 226         h->pid = sys_fork();
 227
 228         if (h->pid == -1) {
 229                 return map_nt_error_from_unix(errno);
 230         }
 231
 232         if (h->pid == 0) {
 233                 close(fdpair[0]);
 234                 preopen_helper(fdpair[1], h->state->to_read);
 235                 exit(0);
 236         }
 237         close(fdpair[1]);
 238         h->fd = fdpair[0];
 239         h->fde = event_add_fd(smbd_event_context(), h->state, h->fd,
 240                               EVENT_FD_READ, preopen_helper_readable, h);
 241         if (h->fde == NULL) {
 242                 close(h->fd);
 243                 h->fd = -1;
 244                 return NT_STATUS_NO_MEMORY;
 245         }
 246         h->busy = false;
 247         return NT_STATUS_OK;
 248 }
 249
 250 static NTSTATUS preopen_init_helpers(TALLOC_CTX *mem_ctx, size_t to_read,
 251                                      int num_helpers, int queue_max,
 252                                      struct preopen_state **presult)
 253 {
 254         struct preopen_state *result;
 255         int i;
 256
 257         result = talloc(mem_ctx, struct preopen_state);
 258         if (result == NULL) {
 259                 return NT_STATUS_NO_MEMORY;
 260         }
 261
 262         result->num_helpers = num_helpers;
 263         result->helpers = TALLOC_ARRAY(result, struct preopen_helper,
 264                                        num_helpers);
 265         if (result->helpers == NULL) {
 266                 TALLOC_FREE(result);
 267                 return NT_STATUS_NO_MEMORY;
 268         }
 269
 270         result->to_read = to_read;
 271         result->queue_max = queue_max;
 272         result->template_fname = NULL;
 273         result->fnum_sent = 0;
 274
 275         for (i=0; i<num_helpers; i++) {
 276                 result->helpers[i].state = result;
 277                 result->helpers[i].fd = -1;
 278         }
 279
 280         talloc_set_destructor(result, preopen_helpers_destructor);
 281
 282         for (i=0; i<num_helpers; i++) {
 283                 preopen_init_helper(&result->helpers[i]);
 284         }
 285
 286         *presult = result;
 287         return NT_STATUS_OK;
 288 }
 289
 290 static void preopen_free_helpers(void **ptr)
 291 {
 292         TALLOC_FREE(*ptr);
 293 }
 294
 295 static struct preopen_state *preopen_state_get(vfs_handle_struct *handle)
 296 {
 297         struct preopen_state *state;
 298         NTSTATUS status;
 299         const char *namelist;
 300
 301         if (SMB_VFS_HANDLE_TEST_DATA(handle)) {
 302                 SMB_VFS_HANDLE_GET_DATA(handle, state, struct preopen_state,
 303                                         return NULL);
 304                 return state;
 305         }
 306
 307         namelist = lp_parm_const_string(SNUM(handle->conn), "preopen", "names",
 308                                         NULL);
 309
 310         if (namelist == NULL) {
 311                 return NULL;
 312         }
 313
 314         status = preopen_init_helpers(
 315                 NULL,
 316                 lp_parm_int(SNUM(handle->conn), "preopen", "num_bytes", 1),
 317                 lp_parm_int(SNUM(handle->conn), "preopen", "helpers", 1),
 318                 lp_parm_int(SNUM(handle->conn), "preopen", "queuelen", 10),
 319                 &state);
 320         if (!NT_STATUS_IS_OK(status)) {
 321                 return NULL;
 322         }
 323
 324         set_namearray(&state->preopen_names, (char *)namelist);
 325
 326         if (state->preopen_names == NULL) {
 327                 TALLOC_FREE(state);
 328                 return NULL;
 329         }
 330
 331         if (!SMB_VFS_HANDLE_TEST_DATA(handle)) {
 332                 SMB_VFS_HANDLE_SET_DATA(handle, state, preopen_free_helpers,
 333                                         struct preopen_state, return NULL);
 334         }
 335
 336         return state;
 337 }
 338
 339 static bool preopen_parse_fname(const char *fname, unsigned long *pnum,
 340                                 size_t *pstart_idx, int *pnum_digits)
 341 {
 342         const char *p, *q;
 343         unsigned long num;
 344
 345         p = strrchr_m(fname, '/');
 346         if (p == NULL) {
 347                 p = fname;
 348         }
 349
 350         p += 1;
 351         while (p[0] != '\0') {
 352                 if (isdigit(p[0]) && isdigit(p[1]) && isdigit(p[2])) {
 353                         break;
 354                 }
 355                 p += 1;
 356         }
 357         if (*p == '\0') {
 358                 /* no digits around */
 359                 return false;
 360         }
 361
 362         num = strtoul(p, (char **)&q, 10);
 363
 364         if (num+1 < num) {
 365                 /* overflow */
 366                 return false;
 367         }
 368
 369         *pnum = num;
 370         *pstart_idx = (p - fname);
 371         *pnum_digits = (q - p);
 372         return true;
 373 }
 374
 375 static int preopen_open(vfs_handle_struct *handle,
 376                         struct smb_filename *smb_fname, files_struct *fsp,
 377                         int flags, mode_t mode)
 378 {
 379         struct preopen_state *state;
 380         int res;
 381         unsigned long num;
 382
 383         DEBUG(10, ("preopen_open called on %s\n", smb_fname_str_dbg(smb_fname)));
 384
 385         state = preopen_state_get(handle);
 386         if (state == NULL) {
 387                 return SMB_VFS_NEXT_OPEN(handle, smb_fname, fsp, flags, mode);
 388         }
 389
 390         res = SMB_VFS_NEXT_OPEN(handle, smb_fname, fsp, flags, mode);
 391         if (res == -1) {
 392                 return -1;
 393         }
 394
 395         if (flags != O_RDONLY) {
 396                 return res;
 397         }
 398
 399         if (!is_in_path(smb_fname->base_name, state->preopen_names, true)) {
 400                 DEBUG(10, ("%s does not match the preopen:names list\n",
 401                            smb_fname_str_dbg(smb_fname)));
 402                 return res;
 403         }
 404
 405         TALLOC_FREE(state->template_fname);
 406         state->template_fname = talloc_asprintf(
 407                 state, "%s/%s", fsp->conn->connectpath, smb_fname->base_name);
 408
 409         if (state->template_fname == NULL) {
 410                 return res;
 411         }
 412
 413         if (!preopen_parse_fname(state->template_fname, &num,
 414                                  &state->number_start, &state->num_digits)) {
 415                 TALLOC_FREE(state->template_fname);
 416                 return res;
 417         }
 418
 419         if (num > state->fnum_sent) {
 420                 /*
 421                  * Helpers were too slow, there's no point in reading
 422                  * files in helpers that we already read in the
 423                  * parent.
 424                  */
 425                 state->fnum_sent = num;
 426         }
 427
 428         if ((state->fnum_queue_end != 0) /* Something was started earlier */
 429             && (num < (state->fnum_queue_end - state->queue_max))) {
 430                 /*
 431                  * "num" is before the queue we announced. This means
 432                  * a new run is started.
 433                  */
 434                 state->fnum_sent = num;
 435         }
 436
 437         state->fnum_queue_end = num + state->queue_max;
 438
 439         preopen_queue_run(state);
 440
 441         return res;
 442 }
 443
 444 static struct vfs_fn_pointers vfs_preopen_fns = {
 445         .open = preopen_open
 446 };
 447
 448 NTSTATUS vfs_preopen_init(void);
 449 NTSTATUS vfs_preopen_init(void)
 450 {
 451         return smb_register_vfs(SMB_VFS_INTERFACE_VERSION,
 452                                 "preopen", &vfs_preopen_fns);
 453 }