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 #include "smbd/smbd.h"
  24 #include "lib/util/sys_rw.h"
  25 #include "lib/util/sys_rw_data.h"
  26 #include "lib/util/smb_strtox.h"
  27
  28 struct preopen_state;
  29
  30 struct preopen_helper {
  31         struct preopen_state *state;
  32         struct tevent_fd *fde;
  33         pid_t pid;
  34         int fd;
  35         bool busy;
  36 };
  37
  38 struct preopen_state {
  39         int num_helpers;
  40         struct preopen_helper *helpers;
  41
  42         size_t to_read;         /* How many bytes to read in children? */
  43         int queue_max;
  44
  45         char *template_fname;   /* Filename to be sent to children */
  46         size_t number_start;    /* start offset into "template_fname" */
  47         int num_digits;         /* How many digits is the number long? */
  48
  49         int fnum_sent;          /* last fname sent to children */
  50
  51         int fnum_queue_end;     /* last fname to be sent, based on
  52                                  * last open call + preopen:queuelen
  53                                  */
  54
  55         name_compare_entry *preopen_names;
  56 };
  57
  58 static void preopen_helper_destroy(struct preopen_helper *c)
  59 {
  60         int status;
  61         TALLOC_FREE(c->fde);
  62         close(c->fd);
  63         c->fd = -1;
  64         kill(c->pid, SIGKILL);
  65         waitpid(c->pid, &status, 0);
  66         c->busy = true;
  67 }
  68
  69 static void preopen_queue_run(struct preopen_state *state)
  70 {
  71         char *pdelimiter;
  72         char delimiter;
  73
  74         pdelimiter = state->template_fname + state->number_start
  75                 + state->num_digits;
  76         delimiter = *pdelimiter;
  77
  78         while (state->fnum_sent < state->fnum_queue_end) {
  79
  80                 ssize_t written;
  81                 size_t to_write;
  82                 int helper;
  83
  84                 for (helper=0; helper<state->num_helpers; helper++) {
  85                         if (state->helpers[helper].busy) {
  86                                 continue;
  87                         }
  88                         break;
  89                 }
  90                 if (helper == state->num_helpers) {
  91                         /* everyone is busy */
  92                         return;
  93                 }
  94
  95                 snprintf(state->template_fname + state->number_start,
  96                          state->num_digits + 1,
  97                          "%.*lu", state->num_digits,
  98                          (long unsigned int)(state->fnum_sent + 1));
  99                 *pdelimiter = delimiter;
 100
 101                 to_write = talloc_get_size(state->template_fname);
 102                 written = write_data(state->helpers[helper].fd,
 103                                      state->template_fname, to_write);
 104                 state->helpers[helper].busy = true;
 105
 106                 if (written != to_write) {
 107                         preopen_helper_destroy(&state->helpers[helper]);
 108                 }
 109                 state->fnum_sent += 1;
 110         }
 111 }
 112
 113 static void preopen_helper_readable(struct tevent_context *ev,
 114                                     struct tevent_fd *fde, uint16_t flags,
 115                                     void *priv)
 116 {
 117         struct preopen_helper *helper = (struct preopen_helper *)priv;
 118         struct preopen_state *state = helper->state;
 119         ssize_t nread;
 120         char c;
 121
 122         if ((flags & TEVENT_FD_READ) == 0) {
 123                 return;
 124         }
 125
 126         nread = read(helper->fd, &c, 1);
 127         if (nread <= 0) {
 128                 preopen_helper_destroy(helper);
 129                 return;
 130         }
 131
 132         helper->busy = false;
 133
 134         preopen_queue_run(state);
 135 }
 136
 137 static int preopen_helpers_destructor(struct preopen_state *c)
 138 {
 139         int i;
 140
 141         for (i=0; i<c->num_helpers; i++) {
 142                 if (c->helpers[i].fd == -1) {
 143                         continue;
 144                 }
 145                 preopen_helper_destroy(&c->helpers[i]);
 146         }
 147
 148         return 0;
 149 }
 150
 151 static bool preopen_helper_open_one(int sock_fd, char **pnamebuf,
 152                                     size_t to_read, void *filebuf)
 153 {
 154         char *namebuf = *pnamebuf;
 155         ssize_t nread;
 156         char c = 0;
 157         int fd;
 158
 159         nread = 0;
 160
 161         do {
 162                 ssize_t thistime;
 163
 164                 thistime = read(sock_fd, namebuf + nread,
 165                                 talloc_get_size(namebuf) - nread);
 166                 if (thistime <= 0) {
 167                         return false;
 168                 }
 169
 170                 nread += thistime;
 171
 172                 if (nread == talloc_get_size(namebuf)) {
 173                         namebuf = talloc_realloc(
 174                                 NULL, namebuf, char,
 175                                 talloc_get_size(namebuf) * 2);
 176                         if (namebuf == NULL) {
 177                                 return false;
 178                         }
 179                         *pnamebuf = namebuf;
 180                 }
 181         } while (namebuf[nread - 1] != '\0');
 182
 183         fd = open(namebuf, O_RDONLY);
 184         if (fd == -1) {
 185                 goto done;
 186         }
 187         nread = read(fd, filebuf, to_read);
 188         close(fd);
 189
 190  done:
 191         sys_write_v(sock_fd, &c, 1);
 192         return true;
 193 }
 194
 195 static bool preopen_helper(int fd, size_t to_read)
 196 {
 197         char *namebuf;
 198         void *readbuf;
 199
 200         namebuf = talloc_array(NULL, char, 1024);
 201         if (namebuf == NULL) {
 202                 return false;
 203         }
 204
 205         readbuf = talloc_size(NULL, to_read);
 206         if (readbuf == NULL) {
 207                 TALLOC_FREE(namebuf);
 208                 return false;
 209         }
 210
 211         while (preopen_helper_open_one(fd, &namebuf, to_read, readbuf)) {
 212                 ;
 213         }
 214
 215         TALLOC_FREE(readbuf);
 216         TALLOC_FREE(namebuf);
 217         return false;
 218 }
 219
 220 static NTSTATUS preopen_init_helper(struct preopen_helper *h)
 221 {
 222         int fdpair[2];
 223         NTSTATUS status;
 224
 225         if (socketpair(AF_UNIX, SOCK_STREAM, 0, fdpair) == -1) {
 226                 status = map_nt_error_from_unix(errno);
 227                 DEBUG(10, ("socketpair() failed: %s\n", strerror(errno)));
 228                 return status;
 229         }
 230
 231         h->pid = fork();
 232
 233         if (h->pid == -1) {
 234                 return map_nt_error_from_unix(errno);
 235         }
 236
 237         if (h->pid == 0) {
 238                 close(fdpair[0]);
 239                 preopen_helper(fdpair[1], h->state->to_read);
 240                 exit(0);
 241         }
 242         close(fdpair[1]);
 243         h->fd = fdpair[0];
 244         h->fde = tevent_add_fd(global_event_context(), h->state, h->fd,
 245                               TEVENT_FD_READ, preopen_helper_readable, h);
 246         if (h->fde == NULL) {
 247                 close(h->fd);
 248                 h->fd = -1;
 249                 return NT_STATUS_NO_MEMORY;
 250         }
 251         h->busy = false;
 252         return NT_STATUS_OK;
 253 }
 254
 255 static NTSTATUS preopen_init_helpers(TALLOC_CTX *mem_ctx, size_t to_read,
 256                                      int num_helpers, int queue_max,
 257                                      struct preopen_state **presult)
 258 {
 259         struct preopen_state *result;
 260         int i;
 261
 262         result = talloc(mem_ctx, struct preopen_state);
 263         if (result == NULL) {
 264                 return NT_STATUS_NO_MEMORY;
 265         }
 266
 267         result->num_helpers = num_helpers;
 268         result->helpers = talloc_array(result, struct preopen_helper,
 269                                        num_helpers);
 270         if (result->helpers == NULL) {
 271                 TALLOC_FREE(result);
 272                 return NT_STATUS_NO_MEMORY;
 273         }
 274
 275         result->to_read = to_read;
 276         result->queue_max = queue_max;
 277         result->template_fname = NULL;
 278         result->fnum_sent = 0;
 279         result->fnum_queue_end = 0;
 280
 281         for (i=0; i<num_helpers; i++) {
 282                 result->helpers[i].state = result;
 283                 result->helpers[i].fd = -1;
 284         }
 285
 286         talloc_set_destructor(result, preopen_helpers_destructor);
 287
 288         for (i=0; i<num_helpers; i++) {
 289                 preopen_init_helper(&result->helpers[i]);
 290         }
 291
 292         *presult = result;
 293         return NT_STATUS_OK;
 294 }
 295
 296 static void preopen_free_helpers(void **ptr)
 297 {
 298         TALLOC_FREE(*ptr);
 299 }
 300
 301 static struct preopen_state *preopen_state_get(vfs_handle_struct *handle)
 302 {
 303         struct preopen_state *state;
 304         NTSTATUS status;
 305         const char *namelist;
 306
 307         if (SMB_VFS_HANDLE_TEST_DATA(handle)) {
 308                 SMB_VFS_HANDLE_GET_DATA(handle, state, struct preopen_state,
 309                                         return NULL);
 310                 return state;
 311         }
 312
 313         namelist = lp_parm_const_string(SNUM(handle->conn), "preopen", "names",
 314                                         NULL);
 315
 316         if (namelist == NULL) {
 317                 return NULL;
 318         }
 319
 320         status = preopen_init_helpers(
 321                 NULL,
 322                 lp_parm_int(SNUM(handle->conn), "preopen", "num_bytes", 1),
 323                 lp_parm_int(SNUM(handle->conn), "preopen", "helpers", 1),
 324                 lp_parm_int(SNUM(handle->conn), "preopen", "queuelen", 10),
 325                 &state);
 326         if (!NT_STATUS_IS_OK(status)) {
 327                 return NULL;
 328         }
 329
 330         set_namearray(&state->preopen_names, namelist);
 331
 332         if (state->preopen_names == NULL) {
 333                 TALLOC_FREE(state);
 334                 return NULL;
 335         }
 336
 337         if (!SMB_VFS_HANDLE_TEST_DATA(handle)) {
 338                 SMB_VFS_HANDLE_SET_DATA(handle, state, preopen_free_helpers,
 339                                         struct preopen_state, return NULL);
 340         }
 341
 342         return state;
 343 }
 344
 345 static bool preopen_parse_fname(const char *fname, unsigned long *pnum,
 346                                 size_t *pstart_idx, int *pnum_digits)
 347 {
 348         const char *p;
 349         char *q = NULL;
 350         unsigned long num;
 351         int error = 0;
 352
 353         p = strrchr_m(fname, '/');
 354         if (p == NULL) {
 355                 p = fname;
 356         }
 357
 358         p += 1;
 359         while (p[0] != '\0') {
 360                 if (isdigit(p[0]) && isdigit(p[1]) && isdigit(p[2])) {
 361                         break;
 362                 }
 363                 p += 1;
 364         }
 365         if (*p == '\0') {
 366                 /* no digits around */
 367                 return false;
 368         }
 369
 370         num = smb_strtoul(p, (char **)&q, 10, &error, SMB_STR_STANDARD);
 371         if (error != 0) {
 372                 return false;
 373         }
 374
 375         if (num+1 < num) {
 376                 /* overflow */
 377                 return false;
 378         }
 379
 380         *pnum = num;
 381         *pstart_idx = (p - fname);
 382         *pnum_digits = (q - p);
 383         return true;
 384 }
 385
 386 static int preopen_openat(struct vfs_handle_struct *handle,
 387                           const struct files_struct *dirfsp,
 388                           const struct smb_filename *smb_fname,
 389                           struct files_struct *fsp,
 390                           int flags,
 391                           mode_t mode)
 392 {
 393         struct preopen_state *state;
 394         int res;
 395         unsigned long num;
 396
 397         DEBUG(10, ("preopen_open called on %s\n", smb_fname_str_dbg(smb_fname)));
 398
 399         state = preopen_state_get(handle);
 400         if (state == NULL) {
 401                 return SMB_VFS_NEXT_OPENAT(handle,
 402                                            dirfsp,
 403                                            smb_fname,
 404                                            fsp,
 405                                            flags,
 406                                            mode);
 407         }
 408
 409         res = SMB_VFS_NEXT_OPENAT(handle, dirfsp, smb_fname, fsp, flags, mode);
 410         if (res == -1) {
 411                 return -1;
 412         }
 413
 414         if ((flags & O_ACCMODE) != O_RDONLY) {
 415                 return res;
 416         }
 417
 418         if (!is_in_path(smb_fname->base_name, state->preopen_names, true)) {
 419                 DEBUG(10, ("%s does not match the preopen:names list\n",
 420                            smb_fname_str_dbg(smb_fname)));
 421                 return res;
 422         }
 423
 424         TALLOC_FREE(state->template_fname);
 425         state->template_fname = talloc_asprintf(
 426                 state, "%s/%s",
 427                 dirfsp->fsp_name->base_name, smb_fname->base_name);
 428
 429         if (state->template_fname == NULL) {
 430                 return res;
 431         }
 432
 433         if (!preopen_parse_fname(state->template_fname, &num,
 434                                  &state->number_start, &state->num_digits)) {
 435                 TALLOC_FREE(state->template_fname);
 436                 return res;
 437         }
 438
 439         if (num > state->fnum_sent) {
 440                 /*
 441                  * Helpers were too slow, there's no point in reading
 442                  * files in helpers that we already read in the
 443                  * parent.
 444                  */
 445                 state->fnum_sent = num;
 446         }
 447
 448         if ((state->fnum_queue_end != 0) /* Something was started earlier */
 449             && (num < (state->fnum_queue_end - state->queue_max))) {
 450                 /*
 451                  * "num" is before the queue we announced. This means
 452                  * a new run is started.
 453                  */
 454                 state->fnum_sent = num;
 455         }
 456
 457         state->fnum_queue_end = num + state->queue_max;
 458
 459         preopen_queue_run(state);
 460
 461         return res;
 462 }
 463
 464 static struct vfs_fn_pointers vfs_preopen_fns = {
 465         .openat_fn = preopen_openat,
 466 };
 467
 468 static_decl_vfs;
 469 NTSTATUS vfs_preopen_init(TALLOC_CTX *ctx)
 470 {
 471         return smb_register_vfs(SMB_VFS_INTERFACE_VERSION,
 472                                 "preopen", &vfs_preopen_fns);
 473 }