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