1 /*- 2 * Copyright (c) 1980, 1991, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 3. All advertising materials mentioning features or use of this software 14 * must display the following acknowledgement: 15 * This product includes software developed by the University of 16 * California, Berkeley and its contributors. 17 * 4. Neither the name of the University nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 */ 33 34 #ifndef lint 35 #if 0 36 static char sccsid[] = "@(#)tape.c 8.4 (Berkeley) 5/1/95"; 37 #endif 38 static const char rcsid[] = 39 "$FreeBSD$"; 40 #endif /* not lint */ 41 42 #include <sys/param.h> 43 #include <sys/socket.h> 44 #include <sys/time.h> 45 #include <sys/wait.h> 46 #ifdef sunos 47 #include <sys/vnode.h> 48 49 #include <ufs/fs.h> 50 #include <ufs/inode.h> 51 #else 52 #include <ufs/ufs/dinode.h> 53 #include <ufs/ffs/fs.h> 54 #endif 55 56 #include <protocols/dumprestore.h> 57 58 #include <errno.h> 59 #include <fcntl.h> 60 #include <setjmp.h> 61 #include <signal.h> 62 #include <stdio.h> 63 #ifdef __STDC__ 64 #include <stdlib.h> 65 #include <string.h> 66 #include <unistd.h> 67 #else 68 int write(), read(); 69 #endif 70 71 #include "dump.h" 72 73 int writesize; /* size of malloc()ed buffer for tape */ 74 long lastspclrec = -1; /* tape block number of last written header */ 75 int trecno = 0; /* next record to write in current block */ 76 extern long blocksperfile; /* number of blocks per output file */ 77 long blocksthisvol; /* number of blocks on current output file */ 78 extern int ntrec; /* blocking factor on tape */ 79 extern int cartridge; 80 extern char *host; 81 char *nexttape; 82 83 static int atomic __P((ssize_t (*)(), int, char *, int)); 84 static void doslave __P((int, int)); 85 static void enslave __P((void)); 86 static void flushtape __P((void)); 87 static void killall __P((void)); 88 static void rollforward __P((void)); 89 90 /* 91 * Concurrent dump mods (Caltech) - disk block reading and tape writing 92 * are exported to several slave processes. While one slave writes the 93 * tape, the others read disk blocks; they pass control of the tape in 94 * a ring via signals. The parent process traverses the filesystem and 95 * sends writeheader()'s and lists of daddr's to the slaves via pipes. 96 * The following structure defines the instruction packets sent to slaves. 97 */ 98 struct req { 99 daddr_t dblk; 100 int count; 101 }; 102 int reqsiz; 103 104 #define SLAVES 3 /* 1 slave writing, 1 reading, 1 for slack */ 105 struct slave { 106 int tapea; /* header number at start of this chunk */ 107 int count; /* count to next header (used for TS_TAPE */ 108 /* after EOT) */ 109 int inode; /* inode that we are currently dealing with */ 110 int fd; /* FD for this slave */ 111 int pid; /* PID for this slave */ 112 int sent; /* 1 == we've sent this slave requests */ 113 int firstrec; /* record number of this block */ 114 char (*tblock)[TP_BSIZE]; /* buffer for data blocks */ 115 struct req *req; /* buffer for requests */ 116 } slaves[SLAVES+1]; 117 struct slave *slp; 118 119 char (*nextblock)[TP_BSIZE]; 120 121 int master; /* pid of master, for sending error signals */ 122 int tenths; /* length of tape used per block written */ 123 static int caught; /* have we caught the signal to proceed? */ 124 static int ready; /* have we reached the lock point without having */ 125 /* received the SIGUSR2 signal from the prev slave? */ 126 static jmp_buf jmpbuf; /* where to jump to if we are ready when the */ 127 /* SIGUSR2 arrives from the previous slave */ 128 129 int 130 alloctape() 131 { 132 int pgoff = getpagesize() - 1; 133 char *buf; 134 int i; 135 136 writesize = ntrec * TP_BSIZE; 137 reqsiz = (ntrec + 1) * sizeof(struct req); 138 /* 139 * CDC 92181's and 92185's make 0.8" gaps in 1600-bpi start/stop mode 140 * (see DEC TU80 User's Guide). The shorter gaps of 6250-bpi require 141 * repositioning after stopping, i.e, streaming mode, where the gap is 142 * variable, 0.30" to 0.45". The gap is maximal when the tape stops. 143 */ 144 if (blocksperfile == 0 && !unlimited) 145 tenths = writesize / density + 146 (cartridge ? 16 : density == 625 ? 5 : 8); 147 /* 148 * Allocate tape buffer contiguous with the array of instruction 149 * packets, so flushtape() can write them together with one write(). 150 * Align tape buffer on page boundary to speed up tape write(). 151 */ 152 for (i = 0; i <= SLAVES; i++) { 153 buf = (char *) 154 malloc((unsigned)(reqsiz + writesize + pgoff + TP_BSIZE)); 155 if (buf == NULL) 156 return(0); 157 slaves[i].tblock = (char (*)[TP_BSIZE]) 158 (((long)&buf[ntrec + 1] + pgoff) &~ pgoff); 159 slaves[i].req = (struct req *)slaves[i].tblock - ntrec - 1; 160 } 161 slp = &slaves[0]; 162 slp->count = 1; 163 slp->tapea = 0; 164 slp->firstrec = 0; 165 nextblock = slp->tblock; 166 return(1); 167 } 168 169 void 170 writerec(dp, isspcl) 171 char *dp; 172 int isspcl; 173 { 174 175 slp->req[trecno].dblk = (daddr_t)0; 176 slp->req[trecno].count = 1; 177 #ifndef __alpha__ 178 *(union u_spcl *)(*(nextblock)++) = *(union u_spcl *)dp; 179 #else 180 bcopy(dp, *(nextblock)++, sizeof (union u_spcl)); 181 #endif 182 if (isspcl) 183 lastspclrec = spcl.c_tapea; 184 trecno++; 185 spcl.c_tapea++; 186 if (trecno >= ntrec) 187 flushtape(); 188 } 189 190 void 191 dumpblock(blkno, size) 192 daddr_t blkno; 193 int size; 194 { 195 int avail, tpblks, dblkno; 196 197 dblkno = fsbtodb(sblock, blkno); 198 tpblks = size >> tp_bshift; 199 while ((avail = MIN(tpblks, ntrec - trecno)) > 0) { 200 slp->req[trecno].dblk = dblkno; 201 slp->req[trecno].count = avail; 202 trecno += avail; 203 spcl.c_tapea += avail; 204 if (trecno >= ntrec) 205 flushtape(); 206 dblkno += avail << (tp_bshift - dev_bshift); 207 tpblks -= avail; 208 } 209 } 210 211 int nogripe = 0; 212 213 void 214 tperror(signo) 215 int signo; 216 { 217 218 if (pipeout) { 219 msg("write error on %s\n", tape); 220 quit("Cannot recover\n"); 221 /* NOTREACHED */ 222 } 223 msg("write error %d blocks into volume %d\n", blocksthisvol, tapeno); 224 broadcast("DUMP WRITE ERROR!\n"); 225 if (!query("Do you want to restart?")) 226 dumpabort(0); 227 msg("Closing this volume. Prepare to restart with new media;\n"); 228 msg("this dump volume will be rewritten.\n"); 229 killall(); 230 nogripe = 1; 231 close_rewind(); 232 Exit(X_REWRITE); 233 } 234 235 void 236 sigpipe(signo) 237 int signo; 238 { 239 240 quit("Broken pipe\n"); 241 } 242 243 static void 244 flushtape() 245 { 246 int i, blks, got; 247 long lastfirstrec; 248 249 int siz = (char *)nextblock - (char *)slp->req; 250 251 slp->req[trecno].count = 0; /* Sentinel */ 252 253 if (atomic(write, slp->fd, (char *)slp->req, siz) != siz) 254 quit("error writing command pipe: %s\n", strerror(errno)); 255 slp->sent = 1; /* we sent a request, read the response later */ 256 257 lastfirstrec = slp->firstrec; 258 259 if (++slp >= &slaves[SLAVES]) 260 slp = &slaves[0]; 261 262 /* Read results back from next slave */ 263 if (slp->sent) { 264 if (atomic(read, slp->fd, (char *)&got, sizeof got) 265 != sizeof got) { 266 perror(" DUMP: error reading command pipe in master"); 267 dumpabort(0); 268 } 269 slp->sent = 0; 270 271 /* Check for end of tape */ 272 if (got < writesize) { 273 msg("End of tape detected\n"); 274 275 /* 276 * Drain the results, don't care what the values were. 277 * If we read them here then trewind won't... 278 */ 279 for (i = 0; i < SLAVES; i++) { 280 if (slaves[i].sent) { 281 if (atomic(read, slaves[i].fd, 282 (char *)&got, sizeof got) 283 != sizeof got) { 284 perror(" DUMP: error reading command pipe in master"); 285 dumpabort(0); 286 } 287 slaves[i].sent = 0; 288 } 289 } 290 291 close_rewind(); 292 rollforward(); 293 return; 294 } 295 } 296 297 blks = 0; 298 if (spcl.c_type != TS_END) { 299 for (i = 0; i < spcl.c_count; i++) 300 if (spcl.c_addr[i] != 0) 301 blks++; 302 } 303 slp->count = lastspclrec + blks + 1 - spcl.c_tapea; 304 slp->tapea = spcl.c_tapea; 305 slp->firstrec = lastfirstrec + ntrec; 306 slp->inode = curino; 307 nextblock = slp->tblock; 308 trecno = 0; 309 asize += tenths; 310 blockswritten += ntrec; 311 blocksthisvol += ntrec; 312 if (!pipeout && !unlimited && (blocksperfile ? 313 (blocksthisvol >= blocksperfile) : (asize > tsize))) { 314 close_rewind(); 315 startnewtape(0); 316 } 317 timeest(); 318 } 319 320 void 321 trewind() 322 { 323 int f; 324 int got; 325 326 for (f = 0; f < SLAVES; f++) { 327 /* 328 * Drain the results, but unlike EOT we DO (or should) care 329 * what the return values were, since if we detect EOT after 330 * we think we've written the last blocks to the tape anyway, 331 * we have to replay those blocks with rollforward. 332 * 333 * fixme: punt for now. 334 */ 335 if (slaves[f].sent) { 336 if (atomic(read, slaves[f].fd, (char *)&got, sizeof got) 337 != sizeof got) { 338 perror(" DUMP: error reading command pipe in master"); 339 dumpabort(0); 340 } 341 slaves[f].sent = 0; 342 if (got != writesize) { 343 msg("EOT detected in last 2 tape records!\n"); 344 msg("Use a longer tape, decrease the size estimate\n"); 345 quit("or use no size estimate at all.\n"); 346 } 347 } 348 (void) close(slaves[f].fd); 349 } 350 while (wait((int *)NULL) >= 0) /* wait for any signals from slaves */ 351 /* void */; 352 353 if (pipeout) 354 return; 355 356 msg("Closing %s\n", tape); 357 358 #ifdef RDUMP 359 if (host) { 360 rmtclose(); 361 while (rmtopen(tape, 0) < 0) 362 sleep(10); 363 rmtclose(); 364 return; 365 } 366 #endif 367 (void) close(tapefd); 368 while ((f = open(tape, 0)) < 0) 369 sleep (10); 370 (void) close(f); 371 } 372 373 void 374 close_rewind() 375 { 376 time_t tstart_changevol, tend_changevol; 377 378 trewind(); 379 if (nexttape) 380 return; 381 (void)time((time_t *)&(tstart_changevol)); 382 if (!nogripe) { 383 msg("Change Volumes: Mount volume #%d\n", tapeno+1); 384 broadcast("CHANGE DUMP VOLUMES!\a\a\n"); 385 } 386 while (!query("Is the new volume mounted and ready to go?")) 387 if (query("Do you want to abort?")) { 388 dumpabort(0); 389 /*NOTREACHED*/ 390 } 391 (void)time((time_t *)&(tend_changevol)); 392 if ((tstart_changevol != (time_t)-1) && (tend_changevol != (time_t)-1)) 393 tstart_writing += (tend_changevol - tstart_changevol); 394 } 395 396 void 397 rollforward() 398 { 399 register struct req *p, *q, *prev; 400 register struct slave *tslp; 401 int i, size, savedtapea, got; 402 union u_spcl *ntb, *otb; 403 tslp = &slaves[SLAVES]; 404 ntb = (union u_spcl *)tslp->tblock[1]; 405 406 /* 407 * Each of the N slaves should have requests that need to 408 * be replayed on the next tape. Use the extra slave buffers 409 * (slaves[SLAVES]) to construct request lists to be sent to 410 * each slave in turn. 411 */ 412 for (i = 0; i < SLAVES; i++) { 413 q = &tslp->req[1]; 414 otb = (union u_spcl *)slp->tblock; 415 416 /* 417 * For each request in the current slave, copy it to tslp. 418 */ 419 420 prev = NULL; 421 for (p = slp->req; p->count > 0; p += p->count) { 422 *q = *p; 423 if (p->dblk == 0) 424 *ntb++ = *otb++; /* copy the datablock also */ 425 prev = q; 426 q += q->count; 427 } 428 if (prev == NULL) 429 quit("rollforward: protocol botch"); 430 if (prev->dblk != 0) 431 prev->count -= 1; 432 else 433 ntb--; 434 q -= 1; 435 q->count = 0; 436 q = &tslp->req[0]; 437 if (i == 0) { 438 q->dblk = 0; 439 q->count = 1; 440 trecno = 0; 441 nextblock = tslp->tblock; 442 savedtapea = spcl.c_tapea; 443 spcl.c_tapea = slp->tapea; 444 startnewtape(0); 445 spcl.c_tapea = savedtapea; 446 lastspclrec = savedtapea - 1; 447 } 448 size = (char *)ntb - (char *)q; 449 if (atomic(write, slp->fd, (char *)q, size) != size) { 450 perror(" DUMP: error writing command pipe"); 451 dumpabort(0); 452 } 453 slp->sent = 1; 454 if (++slp >= &slaves[SLAVES]) 455 slp = &slaves[0]; 456 457 q->count = 1; 458 459 if (prev->dblk != 0) { 460 /* 461 * If the last one was a disk block, make the 462 * first of this one be the last bit of that disk 463 * block... 464 */ 465 q->dblk = prev->dblk + 466 prev->count * (TP_BSIZE / DEV_BSIZE); 467 ntb = (union u_spcl *)tslp->tblock; 468 } else { 469 /* 470 * It wasn't a disk block. Copy the data to its 471 * new location in the buffer. 472 */ 473 q->dblk = 0; 474 *((union u_spcl *)tslp->tblock) = *ntb; 475 ntb = (union u_spcl *)tslp->tblock[1]; 476 } 477 } 478 slp->req[0] = *q; 479 nextblock = slp->tblock; 480 if (q->dblk == 0) 481 nextblock++; 482 trecno = 1; 483 484 /* 485 * Clear the first slaves' response. One hopes that it 486 * worked ok, otherwise the tape is much too short! 487 */ 488 if (slp->sent) { 489 if (atomic(read, slp->fd, (char *)&got, sizeof got) 490 != sizeof got) { 491 perror(" DUMP: error reading command pipe in master"); 492 dumpabort(0); 493 } 494 slp->sent = 0; 495 496 if (got != writesize) { 497 quit("EOT detected at start of the tape!\n"); 498 } 499 } 500 } 501 502 /* 503 * We implement taking and restoring checkpoints on the tape level. 504 * When each tape is opened, a new process is created by forking; this 505 * saves all of the necessary context in the parent. The child 506 * continues the dump; the parent waits around, saving the context. 507 * If the child returns X_REWRITE, then it had problems writing that tape; 508 * this causes the parent to fork again, duplicating the context, and 509 * everything continues as if nothing had happened. 510 */ 511 void 512 startnewtape(top) 513 int top; 514 { 515 int parentpid; 516 int childpid; 517 int status; 518 int waitpid; 519 char *p; 520 #ifdef sunos 521 void (*interrupt_save)(); 522 #else 523 sig_t interrupt_save; 524 #endif 525 526 interrupt_save = signal(SIGINT, SIG_IGN); 527 parentpid = getpid(); 528 529 restore_check_point: 530 (void)signal(SIGINT, interrupt_save); 531 /* 532 * All signals are inherited... 533 */ 534 childpid = fork(); 535 if (childpid < 0) { 536 msg("Context save fork fails in parent %d\n", parentpid); 537 Exit(X_ABORT); 538 } 539 if (childpid != 0) { 540 /* 541 * PARENT: 542 * save the context by waiting 543 * until the child doing all of the work returns. 544 * don't catch the interrupt 545 */ 546 signal(SIGINT, SIG_IGN); 547 #ifdef TDEBUG 548 msg("Tape: %d; parent process: %d child process %d\n", 549 tapeno+1, parentpid, childpid); 550 #endif /* TDEBUG */ 551 while ((waitpid = wait(&status)) != childpid) 552 msg("Parent %d waiting for child %d has another child %d return\n", 553 parentpid, childpid, waitpid); 554 if (status & 0xFF) { 555 msg("Child %d returns LOB status %o\n", 556 childpid, status&0xFF); 557 } 558 status = (status >> 8) & 0xFF; 559 #ifdef TDEBUG 560 switch(status) { 561 case X_FINOK: 562 msg("Child %d finishes X_FINOK\n", childpid); 563 break; 564 case X_ABORT: 565 msg("Child %d finishes X_ABORT\n", childpid); 566 break; 567 case X_REWRITE: 568 msg("Child %d finishes X_REWRITE\n", childpid); 569 break; 570 default: 571 msg("Child %d finishes unknown %d\n", 572 childpid, status); 573 break; 574 } 575 #endif /* TDEBUG */ 576 switch(status) { 577 case X_FINOK: 578 Exit(X_FINOK); 579 case X_ABORT: 580 Exit(X_ABORT); 581 case X_REWRITE: 582 goto restore_check_point; 583 default: 584 msg("Bad return code from dump: %d\n", status); 585 Exit(X_ABORT); 586 } 587 /*NOTREACHED*/ 588 } else { /* we are the child; just continue */ 589 #ifdef TDEBUG 590 sleep(4); /* allow time for parent's message to get out */ 591 msg("Child on Tape %d has parent %d, my pid = %d\n", 592 tapeno+1, parentpid, getpid()); 593 #endif /* TDEBUG */ 594 /* 595 * If we have a name like "/dev/rmt0,/dev/rmt1", 596 * use the name before the comma first, and save 597 * the remaining names for subsequent volumes. 598 */ 599 tapeno++; /* current tape sequence */ 600 if (nexttape || strchr(tape, ',')) { 601 if (nexttape && *nexttape) 602 tape = nexttape; 603 if ((p = strchr(tape, ',')) != NULL) { 604 *p = '\0'; 605 nexttape = p + 1; 606 } else 607 nexttape = NULL; 608 msg("Dumping volume %d on %s\n", tapeno, tape); 609 } 610 #ifdef RDUMP 611 while ((tapefd = (host ? rmtopen(tape, 2) : 612 pipeout ? 1 : open(tape, O_WRONLY|O_CREAT, 0666))) < 0) 613 #else 614 while ((tapefd = (pipeout ? 1 : 615 open(tape, O_WRONLY|O_CREAT, 0666))) < 0) 616 #endif 617 { 618 msg("Cannot open output \"%s\".\n", tape); 619 if (!query("Do you want to retry the open?")) 620 dumpabort(0); 621 } 622 623 enslave(); /* Share open tape file descriptor with slaves */ 624 625 asize = 0; 626 blocksthisvol = 0; 627 if (top) 628 newtape++; /* new tape signal */ 629 spcl.c_count = slp->count; 630 /* 631 * measure firstrec in TP_BSIZE units since restore doesn't 632 * know the correct ntrec value... 633 */ 634 spcl.c_firstrec = slp->firstrec; 635 spcl.c_volume++; 636 spcl.c_type = TS_TAPE; 637 spcl.c_flags |= DR_NEWHEADER; 638 writeheader((ino_t)slp->inode); 639 spcl.c_flags &=~ DR_NEWHEADER; 640 if (tapeno > 1) 641 msg("Volume %d begins with blocks from inode %d\n", 642 tapeno, slp->inode); 643 } 644 } 645 646 void 647 dumpabort(signo) 648 int signo; 649 { 650 651 if (master != 0 && master != getpid()) 652 /* Signals master to call dumpabort */ 653 (void) kill(master, SIGTERM); 654 else { 655 killall(); 656 msg("The ENTIRE dump is aborted.\n"); 657 } 658 #ifdef RDUMP 659 rmtclose(); 660 #endif 661 Exit(X_ABORT); 662 } 663 664 void 665 Exit(status) 666 int status; 667 { 668 669 #ifdef TDEBUG 670 msg("pid = %d exits with status %d\n", getpid(), status); 671 #endif /* TDEBUG */ 672 exit(status); 673 } 674 675 /* 676 * proceed - handler for SIGUSR2, used to synchronize IO between the slaves. 677 */ 678 void 679 proceed(signo) 680 int signo; 681 { 682 683 if (ready) 684 longjmp(jmpbuf, 1); 685 caught++; 686 } 687 688 void 689 enslave() 690 { 691 int cmd[2]; 692 register int i, j; 693 694 master = getpid(); 695 696 signal(SIGTERM, dumpabort); /* Slave sends SIGTERM on dumpabort() */ 697 signal(SIGPIPE, sigpipe); 698 signal(SIGUSR1, tperror); /* Slave sends SIGUSR1 on tape errors */ 699 signal(SIGUSR2, proceed); /* Slave sends SIGUSR2 to next slave */ 700 701 for (i = 0; i < SLAVES; i++) { 702 if (i == slp - &slaves[0]) { 703 caught = 1; 704 } else { 705 caught = 0; 706 } 707 708 if (socketpair(AF_UNIX, SOCK_STREAM, 0, cmd) < 0 || 709 (slaves[i].pid = fork()) < 0) 710 quit("too many slaves, %d (recompile smaller): %s\n", 711 i, strerror(errno)); 712 713 slaves[i].fd = cmd[1]; 714 slaves[i].sent = 0; 715 if (slaves[i].pid == 0) { /* Slave starts up here */ 716 for (j = 0; j <= i; j++) 717 (void) close(slaves[j].fd); 718 signal(SIGINT, SIG_IGN); /* Master handles this */ 719 doslave(cmd[0], i); 720 Exit(X_FINOK); 721 } 722 } 723 724 for (i = 0; i < SLAVES; i++) 725 (void) atomic(write, slaves[i].fd, 726 (char *) &slaves[(i + 1) % SLAVES].pid, 727 sizeof slaves[0].pid); 728 729 master = 0; 730 } 731 732 void 733 killall() 734 { 735 register int i; 736 737 for (i = 0; i < SLAVES; i++) 738 if (slaves[i].pid > 0) { 739 (void) kill(slaves[i].pid, SIGKILL); 740 slaves[i].sent = 0; 741 } 742 } 743 744 /* 745 * Synchronization - each process has a lockfile, and shares file 746 * descriptors to the following process's lockfile. When our write 747 * completes, we release our lock on the following process's lock- 748 * file, allowing the following process to lock it and proceed. We 749 * get the lock back for the next cycle by swapping descriptors. 750 */ 751 static void 752 doslave(cmd, slave_number) 753 register int cmd; 754 int slave_number; 755 { 756 register int nread; 757 int nextslave, size, wrote, eot_count; 758 759 /* 760 * Need our own seek pointer. 761 */ 762 (void) close(diskfd); 763 if ((diskfd = open(disk, O_RDONLY)) < 0) 764 quit("slave couldn't reopen disk: %s\n", strerror(errno)); 765 766 /* 767 * Need the pid of the next slave in the loop... 768 */ 769 if ((nread = atomic(read, cmd, (char *)&nextslave, sizeof nextslave)) 770 != sizeof nextslave) { 771 quit("master/slave protocol botched - didn't get pid of next slave.\n"); 772 } 773 774 /* 775 * Get list of blocks to dump, read the blocks into tape buffer 776 */ 777 while ((nread = atomic(read, cmd, (char *)slp->req, reqsiz)) == reqsiz) { 778 register struct req *p = slp->req; 779 780 for (trecno = 0; trecno < ntrec; 781 trecno += p->count, p += p->count) { 782 if (p->dblk) { 783 bread(p->dblk, slp->tblock[trecno], 784 p->count * TP_BSIZE); 785 } else { 786 if (p->count != 1 || atomic(read, cmd, 787 (char *)slp->tblock[trecno], 788 TP_BSIZE) != TP_BSIZE) 789 quit("master/slave protocol botched.\n"); 790 } 791 } 792 if (setjmp(jmpbuf) == 0) { 793 ready = 1; 794 if (!caught) 795 (void) pause(); 796 } 797 ready = 0; 798 caught = 0; 799 800 /* Try to write the data... */ 801 eot_count = 0; 802 size = 0; 803 804 while (eot_count < 10 && size < writesize) { 805 #ifdef RDUMP 806 if (host) 807 wrote = rmtwrite(slp->tblock[0]+size, 808 writesize-size); 809 else 810 #endif 811 wrote = write(tapefd, slp->tblock[0]+size, 812 writesize-size); 813 #ifdef WRITEDEBUG 814 printf("slave %d wrote %d\n", slave_number, wrote); 815 #endif 816 if (wrote < 0) 817 break; 818 if (wrote == 0) 819 eot_count++; 820 size += wrote; 821 } 822 823 #ifdef WRITEDEBUG 824 if (size != writesize) 825 printf("slave %d only wrote %d out of %d bytes and gave up.\n", 826 slave_number, size, writesize); 827 #endif 828 829 /* 830 * Handle ENOSPC as an EOT condition. 831 */ 832 if (wrote < 0 && errno == ENOSPC) { 833 wrote = 0; 834 eot_count++; 835 } 836 837 if (eot_count > 0) 838 size = 0; 839 840 if (wrote < 0) { 841 (void) kill(master, SIGUSR1); 842 for (;;) 843 (void) sigpause(0); 844 } else { 845 /* 846 * pass size of write back to master 847 * (for EOT handling) 848 */ 849 (void) atomic(write, cmd, (char *)&size, sizeof size); 850 } 851 852 /* 853 * If partial write, don't want next slave to go. 854 * Also jolts him awake. 855 */ 856 (void) kill(nextslave, SIGUSR2); 857 } 858 if (nread != 0) 859 quit("error reading command pipe: %s\n", strerror(errno)); 860 } 861 862 /* 863 * Since a read from a pipe may not return all we asked for, 864 * or a write may not write all we ask if we get a signal, 865 * loop until the count is satisfied (or error). 866 */ 867 static int 868 atomic(func, fd, buf, count) 869 ssize_t (*func)(); 870 int fd; 871 char *buf; 872 int count; 873 { 874 int got, need = count; 875 876 while ((got = (*func)(fd, buf, need)) > 0 && (need -= got) > 0) 877 buf += got; 878 return (got < 0 ? got : count - need); 879 } 880