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