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 "$Id: tape.c,v 1.9 1998/06/15 06:58:11 charnier Exp $"; 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 *(union u_spcl *)(*(nextblock)++) = *(union u_spcl *)dp; 178 if (isspcl) 179 lastspclrec = spcl.c_tapea; 180 trecno++; 181 spcl.c_tapea++; 182 if (trecno >= ntrec) 183 flushtape(); 184 } 185 186 void 187 dumpblock(blkno, size) 188 daddr_t blkno; 189 int size; 190 { 191 int avail, tpblks, dblkno; 192 193 dblkno = fsbtodb(sblock, blkno); 194 tpblks = size >> tp_bshift; 195 while ((avail = MIN(tpblks, ntrec - trecno)) > 0) { 196 slp->req[trecno].dblk = dblkno; 197 slp->req[trecno].count = avail; 198 trecno += avail; 199 spcl.c_tapea += avail; 200 if (trecno >= ntrec) 201 flushtape(); 202 dblkno += avail << (tp_bshift - dev_bshift); 203 tpblks -= avail; 204 } 205 } 206 207 int nogripe = 0; 208 209 void 210 tperror(signo) 211 int signo; 212 { 213 214 if (pipeout) { 215 msg("write error on %s\n", tape); 216 quit("Cannot recover\n"); 217 /* NOTREACHED */ 218 } 219 msg("write error %d blocks into volume %d\n", blocksthisvol, tapeno); 220 broadcast("DUMP WRITE ERROR!\n"); 221 if (!query("Do you want to restart?")) 222 dumpabort(0); 223 msg("Closing this volume. Prepare to restart with new media;\n"); 224 msg("this dump volume will be rewritten.\n"); 225 killall(); 226 nogripe = 1; 227 close_rewind(); 228 Exit(X_REWRITE); 229 } 230 231 void 232 sigpipe(signo) 233 int signo; 234 { 235 236 quit("Broken pipe\n"); 237 } 238 239 static void 240 flushtape() 241 { 242 int i, blks, got; 243 long lastfirstrec; 244 245 int siz = (char *)nextblock - (char *)slp->req; 246 247 slp->req[trecno].count = 0; /* Sentinel */ 248 249 if (atomic(write, slp->fd, (char *)slp->req, siz) != siz) 250 quit("error writing command pipe: %s\n", strerror(errno)); 251 slp->sent = 1; /* we sent a request, read the response later */ 252 253 lastfirstrec = slp->firstrec; 254 255 if (++slp >= &slaves[SLAVES]) 256 slp = &slaves[0]; 257 258 /* Read results back from next slave */ 259 if (slp->sent) { 260 if (atomic(read, slp->fd, (char *)&got, sizeof got) 261 != sizeof got) { 262 perror(" DUMP: error reading command pipe in master"); 263 dumpabort(0); 264 } 265 slp->sent = 0; 266 267 /* Check for end of tape */ 268 if (got < writesize) { 269 msg("End of tape detected\n"); 270 271 /* 272 * Drain the results, don't care what the values were. 273 * If we read them here then trewind won't... 274 */ 275 for (i = 0; i < SLAVES; i++) { 276 if (slaves[i].sent) { 277 if (atomic(read, slaves[i].fd, 278 (char *)&got, sizeof got) 279 != sizeof got) { 280 perror(" DUMP: error reading command pipe in master"); 281 dumpabort(0); 282 } 283 slaves[i].sent = 0; 284 } 285 } 286 287 close_rewind(); 288 rollforward(); 289 return; 290 } 291 } 292 293 blks = 0; 294 if (spcl.c_type != TS_END) { 295 for (i = 0; i < spcl.c_count; i++) 296 if (spcl.c_addr[i] != 0) 297 blks++; 298 } 299 slp->count = lastspclrec + blks + 1 - spcl.c_tapea; 300 slp->tapea = spcl.c_tapea; 301 slp->firstrec = lastfirstrec + ntrec; 302 slp->inode = curino; 303 nextblock = slp->tblock; 304 trecno = 0; 305 asize += tenths; 306 blockswritten += ntrec; 307 blocksthisvol += ntrec; 308 if (!pipeout && !unlimited && (blocksperfile ? 309 (blocksthisvol >= blocksperfile) : (asize > tsize))) { 310 close_rewind(); 311 startnewtape(0); 312 } 313 timeest(); 314 } 315 316 void 317 trewind() 318 { 319 int f; 320 int got; 321 322 for (f = 0; f < SLAVES; f++) { 323 /* 324 * Drain the results, but unlike EOT we DO (or should) care 325 * what the return values were, since if we detect EOT after 326 * we think we've written the last blocks to the tape anyway, 327 * we have to replay those blocks with rollforward. 328 * 329 * fixme: punt for now. 330 */ 331 if (slaves[f].sent) { 332 if (atomic(read, slaves[f].fd, (char *)&got, sizeof got) 333 != sizeof got) { 334 perror(" DUMP: error reading command pipe in master"); 335 dumpabort(0); 336 } 337 slaves[f].sent = 0; 338 if (got != writesize) { 339 msg("EOT detected in last 2 tape records!\n"); 340 msg("Use a longer tape, decrease the size estimate\n"); 341 quit("or use no size estimate at all.\n"); 342 } 343 } 344 (void) close(slaves[f].fd); 345 } 346 while (wait((int *)NULL) >= 0) /* wait for any signals from slaves */ 347 /* void */; 348 349 if (pipeout) 350 return; 351 352 msg("Closing %s\n", tape); 353 354 #ifdef RDUMP 355 if (host) { 356 rmtclose(); 357 while (rmtopen(tape, 0) < 0) 358 sleep(10); 359 rmtclose(); 360 return; 361 } 362 #endif 363 (void) close(tapefd); 364 while ((f = open(tape, 0)) < 0) 365 sleep (10); 366 (void) close(f); 367 } 368 369 void 370 close_rewind() 371 { 372 time_t tstart_changevol, tend_changevol; 373 374 trewind(); 375 if (nexttape) 376 return; 377 (void)time((time_t *)&(tstart_changevol)); 378 if (!nogripe) { 379 msg("Change Volumes: Mount volume #%d\n", tapeno+1); 380 broadcast("CHANGE DUMP VOLUMES!\7\7\n"); 381 } 382 while (!query("Is the new volume mounted and ready to go?")) 383 if (query("Do you want to abort?")) { 384 dumpabort(0); 385 /*NOTREACHED*/ 386 } 387 (void)time((time_t *)&(tend_changevol)); 388 if ((tstart_changevol != (time_t)-1) && (tend_changevol != (time_t)-1)) 389 tstart_writing += (tend_changevol - tstart_changevol); 390 } 391 392 void 393 rollforward() 394 { 395 register struct req *p, *q, *prev; 396 register struct slave *tslp; 397 int i, size, savedtapea, got; 398 union u_spcl *ntb, *otb; 399 tslp = &slaves[SLAVES]; 400 ntb = (union u_spcl *)tslp->tblock[1]; 401 402 /* 403 * Each of the N slaves should have requests that need to 404 * be replayed on the next tape. Use the extra slave buffers 405 * (slaves[SLAVES]) to construct request lists to be sent to 406 * each slave in turn. 407 */ 408 for (i = 0; i < SLAVES; i++) { 409 q = &tslp->req[1]; 410 otb = (union u_spcl *)slp->tblock; 411 412 /* 413 * For each request in the current slave, copy it to tslp. 414 */ 415 416 prev = NULL; 417 for (p = slp->req; p->count > 0; p += p->count) { 418 *q = *p; 419 if (p->dblk == 0) 420 *ntb++ = *otb++; /* copy the datablock also */ 421 prev = q; 422 q += q->count; 423 } 424 if (prev == NULL) 425 quit("rollforward: protocol botch"); 426 if (prev->dblk != 0) 427 prev->count -= 1; 428 else 429 ntb--; 430 q -= 1; 431 q->count = 0; 432 q = &tslp->req[0]; 433 if (i == 0) { 434 q->dblk = 0; 435 q->count = 1; 436 trecno = 0; 437 nextblock = tslp->tblock; 438 savedtapea = spcl.c_tapea; 439 spcl.c_tapea = slp->tapea; 440 startnewtape(0); 441 spcl.c_tapea = savedtapea; 442 lastspclrec = savedtapea - 1; 443 } 444 size = (char *)ntb - (char *)q; 445 if (atomic(write, slp->fd, (char *)q, size) != size) { 446 perror(" DUMP: error writing command pipe"); 447 dumpabort(0); 448 } 449 slp->sent = 1; 450 if (++slp >= &slaves[SLAVES]) 451 slp = &slaves[0]; 452 453 q->count = 1; 454 455 if (prev->dblk != 0) { 456 /* 457 * If the last one was a disk block, make the 458 * first of this one be the last bit of that disk 459 * block... 460 */ 461 q->dblk = prev->dblk + 462 prev->count * (TP_BSIZE / DEV_BSIZE); 463 ntb = (union u_spcl *)tslp->tblock; 464 } else { 465 /* 466 * It wasn't a disk block. Copy the data to its 467 * new location in the buffer. 468 */ 469 q->dblk = 0; 470 *((union u_spcl *)tslp->tblock) = *ntb; 471 ntb = (union u_spcl *)tslp->tblock[1]; 472 } 473 } 474 slp->req[0] = *q; 475 nextblock = slp->tblock; 476 if (q->dblk == 0) 477 nextblock++; 478 trecno = 1; 479 480 /* 481 * Clear the first slaves' response. One hopes that it 482 * worked ok, otherwise the tape is much too short! 483 */ 484 if (slp->sent) { 485 if (atomic(read, slp->fd, (char *)&got, sizeof got) 486 != sizeof got) { 487 perror(" DUMP: error reading command pipe in master"); 488 dumpabort(0); 489 } 490 slp->sent = 0; 491 492 if (got != writesize) { 493 quit("EOT detected at start of the tape!\n"); 494 } 495 } 496 } 497 498 /* 499 * We implement taking and restoring checkpoints on the tape level. 500 * When each tape is opened, a new process is created by forking; this 501 * saves all of the necessary context in the parent. The child 502 * continues the dump; the parent waits around, saving the context. 503 * If the child returns X_REWRITE, then it had problems writing that tape; 504 * this causes the parent to fork again, duplicating the context, and 505 * everything continues as if nothing had happened. 506 */ 507 void 508 startnewtape(top) 509 int top; 510 { 511 int parentpid; 512 int childpid; 513 int status; 514 int waitpid; 515 char *p; 516 #ifdef sunos 517 void (*interrupt_save)(); 518 #else 519 sig_t interrupt_save; 520 #endif 521 522 interrupt_save = signal(SIGINT, SIG_IGN); 523 parentpid = getpid(); 524 525 restore_check_point: 526 (void)signal(SIGINT, interrupt_save); 527 /* 528 * All signals are inherited... 529 */ 530 childpid = fork(); 531 if (childpid < 0) { 532 msg("Context save fork fails in parent %d\n", parentpid); 533 Exit(X_ABORT); 534 } 535 if (childpid != 0) { 536 /* 537 * PARENT: 538 * save the context by waiting 539 * until the child doing all of the work returns. 540 * don't catch the interrupt 541 */ 542 signal(SIGINT, SIG_IGN); 543 #ifdef TDEBUG 544 msg("Tape: %d; parent process: %d child process %d\n", 545 tapeno+1, parentpid, childpid); 546 #endif /* TDEBUG */ 547 while ((waitpid = wait(&status)) != childpid) 548 msg("Parent %d waiting for child %d has another child %d return\n", 549 parentpid, childpid, waitpid); 550 if (status & 0xFF) { 551 msg("Child %d returns LOB status %o\n", 552 childpid, status&0xFF); 553 } 554 status = (status >> 8) & 0xFF; 555 #ifdef TDEBUG 556 switch(status) { 557 case X_FINOK: 558 msg("Child %d finishes X_FINOK\n", childpid); 559 break; 560 case X_ABORT: 561 msg("Child %d finishes X_ABORT\n", childpid); 562 break; 563 case X_REWRITE: 564 msg("Child %d finishes X_REWRITE\n", childpid); 565 break; 566 default: 567 msg("Child %d finishes unknown %d\n", 568 childpid, status); 569 break; 570 } 571 #endif /* TDEBUG */ 572 switch(status) { 573 case X_FINOK: 574 Exit(X_FINOK); 575 case X_ABORT: 576 Exit(X_ABORT); 577 case X_REWRITE: 578 goto restore_check_point; 579 default: 580 msg("Bad return code from dump: %d\n", status); 581 Exit(X_ABORT); 582 } 583 /*NOTREACHED*/ 584 } else { /* we are the child; just continue */ 585 #ifdef TDEBUG 586 sleep(4); /* allow time for parent's message to get out */ 587 msg("Child on Tape %d has parent %d, my pid = %d\n", 588 tapeno+1, parentpid, getpid()); 589 #endif /* TDEBUG */ 590 /* 591 * If we have a name like "/dev/rmt0,/dev/rmt1", 592 * use the name before the comma first, and save 593 * the remaining names for subsequent volumes. 594 */ 595 tapeno++; /* current tape sequence */ 596 if (nexttape || strchr(tape, ',')) { 597 if (nexttape && *nexttape) 598 tape = nexttape; 599 if ((p = strchr(tape, ',')) != NULL) { 600 *p = '\0'; 601 nexttape = p + 1; 602 } else 603 nexttape = NULL; 604 msg("Dumping volume %d on %s\n", tapeno, tape); 605 } 606 #ifdef RDUMP 607 while ((tapefd = (host ? rmtopen(tape, 2) : 608 pipeout ? 1 : open(tape, O_WRONLY|O_CREAT, 0666))) < 0) 609 #else 610 while ((tapefd = (pipeout ? 1 : 611 open(tape, O_WRONLY|O_CREAT, 0666))) < 0) 612 #endif 613 { 614 msg("Cannot open output \"%s\".\n", tape); 615 if (!query("Do you want to retry the open?")) 616 dumpabort(0); 617 } 618 619 enslave(); /* Share open tape file descriptor with slaves */ 620 621 asize = 0; 622 blocksthisvol = 0; 623 if (top) 624 newtape++; /* new tape signal */ 625 spcl.c_count = slp->count; 626 /* 627 * measure firstrec in TP_BSIZE units since restore doesn't 628 * know the correct ntrec value... 629 */ 630 spcl.c_firstrec = slp->firstrec; 631 spcl.c_volume++; 632 spcl.c_type = TS_TAPE; 633 spcl.c_flags |= DR_NEWHEADER; 634 writeheader((ino_t)slp->inode); 635 spcl.c_flags &=~ DR_NEWHEADER; 636 if (tapeno > 1) 637 msg("Volume %d begins with blocks from inode %d\n", 638 tapeno, slp->inode); 639 } 640 } 641 642 void 643 dumpabort(signo) 644 int signo; 645 { 646 647 if (master != 0 && master != getpid()) 648 /* Signals master to call dumpabort */ 649 (void) kill(master, SIGTERM); 650 else { 651 killall(); 652 msg("The ENTIRE dump is aborted.\n"); 653 } 654 #ifdef RDUMP 655 rmtclose(); 656 #endif 657 Exit(X_ABORT); 658 } 659 660 void 661 Exit(status) 662 int status; 663 { 664 665 #ifdef TDEBUG 666 msg("pid = %d exits with status %d\n", getpid(), status); 667 #endif /* TDEBUG */ 668 exit(status); 669 } 670 671 /* 672 * proceed - handler for SIGUSR2, used to synchronize IO between the slaves. 673 */ 674 void 675 proceed(signo) 676 int signo; 677 { 678 679 if (ready) 680 longjmp(jmpbuf, 1); 681 caught++; 682 } 683 684 void 685 enslave() 686 { 687 int cmd[2]; 688 register int i, j; 689 690 master = getpid(); 691 692 signal(SIGTERM, dumpabort); /* Slave sends SIGTERM on dumpabort() */ 693 signal(SIGPIPE, sigpipe); 694 signal(SIGUSR1, tperror); /* Slave sends SIGUSR1 on tape errors */ 695 signal(SIGUSR2, proceed); /* Slave sends SIGUSR2 to next slave */ 696 697 for (i = 0; i < SLAVES; i++) { 698 if (i == slp - &slaves[0]) { 699 caught = 1; 700 } else { 701 caught = 0; 702 } 703 704 if (socketpair(AF_UNIX, SOCK_STREAM, 0, cmd) < 0 || 705 (slaves[i].pid = fork()) < 0) 706 quit("too many slaves, %d (recompile smaller): %s\n", 707 i, strerror(errno)); 708 709 slaves[i].fd = cmd[1]; 710 slaves[i].sent = 0; 711 if (slaves[i].pid == 0) { /* Slave starts up here */ 712 for (j = 0; j <= i; j++) 713 (void) close(slaves[j].fd); 714 signal(SIGINT, SIG_IGN); /* Master handles this */ 715 doslave(cmd[0], i); 716 Exit(X_FINOK); 717 } 718 } 719 720 for (i = 0; i < SLAVES; i++) 721 (void) atomic(write, slaves[i].fd, 722 (char *) &slaves[(i + 1) % SLAVES].pid, 723 sizeof slaves[0].pid); 724 725 master = 0; 726 } 727 728 void 729 killall() 730 { 731 register int i; 732 733 for (i = 0; i < SLAVES; i++) 734 if (slaves[i].pid > 0) { 735 (void) kill(slaves[i].pid, SIGKILL); 736 slaves[i].sent = 0; 737 } 738 } 739 740 /* 741 * Synchronization - each process has a lockfile, and shares file 742 * descriptors to the following process's lockfile. When our write 743 * completes, we release our lock on the following process's lock- 744 * file, allowing the following process to lock it and proceed. We 745 * get the lock back for the next cycle by swapping descriptors. 746 */ 747 static void 748 doslave(cmd, slave_number) 749 register int cmd; 750 int slave_number; 751 { 752 register int nread; 753 int nextslave, size, wrote, eot_count; 754 755 /* 756 * Need our own seek pointer. 757 */ 758 (void) close(diskfd); 759 if ((diskfd = open(disk, O_RDONLY)) < 0) 760 quit("slave couldn't reopen disk: %s\n", strerror(errno)); 761 762 /* 763 * Need the pid of the next slave in the loop... 764 */ 765 if ((nread = atomic(read, cmd, (char *)&nextslave, sizeof nextslave)) 766 != sizeof nextslave) { 767 quit("master/slave protocol botched - didn't get pid of next slave.\n"); 768 } 769 770 /* 771 * Get list of blocks to dump, read the blocks into tape buffer 772 */ 773 while ((nread = atomic(read, cmd, (char *)slp->req, reqsiz)) == reqsiz) { 774 register struct req *p = slp->req; 775 776 for (trecno = 0; trecno < ntrec; 777 trecno += p->count, p += p->count) { 778 if (p->dblk) { 779 bread(p->dblk, slp->tblock[trecno], 780 p->count * TP_BSIZE); 781 } else { 782 if (p->count != 1 || atomic(read, cmd, 783 (char *)slp->tblock[trecno], 784 TP_BSIZE) != TP_BSIZE) 785 quit("master/slave protocol botched.\n"); 786 } 787 } 788 if (setjmp(jmpbuf) == 0) { 789 ready = 1; 790 if (!caught) 791 (void) pause(); 792 } 793 ready = 0; 794 caught = 0; 795 796 /* Try to write the data... */ 797 eot_count = 0; 798 size = 0; 799 800 while (eot_count < 10 && size < writesize) { 801 #ifdef RDUMP 802 if (host) 803 wrote = rmtwrite(slp->tblock[0]+size, 804 writesize-size); 805 else 806 #endif 807 wrote = write(tapefd, slp->tblock[0]+size, 808 writesize-size); 809 #ifdef WRITEDEBUG 810 printf("slave %d wrote %d\n", slave_number, wrote); 811 #endif 812 if (wrote < 0) 813 break; 814 if (wrote == 0) 815 eot_count++; 816 size += wrote; 817 } 818 819 #ifdef WRITEDEBUG 820 if (size != writesize) 821 printf("slave %d only wrote %d out of %d bytes and gave up.\n", 822 slave_number, size, writesize); 823 #endif 824 825 /* 826 * Handle ENOSPC as an EOT condition. 827 */ 828 if (wrote < 0 && errno == ENOSPC) { 829 wrote = 0; 830 eot_count++; 831 } 832 833 if (eot_count > 0) 834 size = 0; 835 836 if (wrote < 0) { 837 (void) kill(master, SIGUSR1); 838 for (;;) 839 (void) sigpause(0); 840 } else { 841 /* 842 * pass size of write back to master 843 * (for EOT handling) 844 */ 845 (void) atomic(write, cmd, (char *)&size, sizeof size); 846 } 847 848 /* 849 * If partial write, don't want next slave to go. 850 * Also jolts him awake. 851 */ 852 (void) kill(nextslave, SIGUSR2); 853 } 854 if (nread != 0) 855 quit("error reading command pipe: %s\n", strerror(errno)); 856 } 857 858 /* 859 * Since a read from a pipe may not return all we asked for, 860 * or a write may not write all we ask if we get a signal, 861 * loop until the count is satisfied (or error). 862 */ 863 static int 864 atomic(func, fd, buf, count) 865 ssize_t (*func)(); 866 int fd; 867 char *buf; 868 int count; 869 { 870 int got, need = count; 871 872 while ((got = (*func)(fd, buf, need)) > 0 && (need -= got) > 0) 873 buf += got; 874 return (got < 0 ? got : count - need); 875 } 876