| 1 | /* vfs_bio.c 3.1 %H% */ |
| 2 | |
| 3 | #include "../h/param.h" |
| 4 | #include "../h/systm.h" |
| 5 | #include "../h/dir.h" |
| 6 | #include "../h/user.h" |
| 7 | #include "../h/buf.h" |
| 8 | #include "../h/conf.h" |
| 9 | #include "../h/proc.h" |
| 10 | #include "../h/seg.h" |
| 11 | #include "../h/pte.h" |
| 12 | #include "../h/vm.h" |
| 13 | |
| 14 | /* #define DISKMON 1 */ |
| 15 | |
| 16 | #ifdef DISKMON |
| 17 | struct { |
| 18 | int nbuf; |
| 19 | long nread; |
| 20 | long nreada; |
| 21 | long ncache; |
| 22 | long nwrite; |
| 23 | long bufcount[NBUF]; |
| 24 | } io_info; |
| 25 | #endif |
| 26 | |
| 27 | /* |
| 28 | * Swap IO headers - |
| 29 | * They contain the necessary information for the swap I/O. |
| 30 | * At any given time, a swap header can be in three |
| 31 | * different lists. When free it is in the free list, |
| 32 | * when allocated and the I/O queued, it is on the swap |
| 33 | * device list, and finally, if the operation was a dirty |
| 34 | * page push, when the I/O completes, it is inserted |
| 35 | * in a list of cleaned pages to be processed by the pageout daemon. |
| 36 | */ |
| 37 | struct buf swbuf[NSWBUF]; |
| 38 | short swsize[NSWBUF]; /* CAN WE JUST USE B_BCOUNT? */ |
| 39 | int swpf[NSWBUF]; |
| 40 | |
| 41 | /* |
| 42 | * The following several routines allocate and free |
| 43 | * buffers with various side effects. In general the |
| 44 | * arguments to an allocate routine are a device and |
| 45 | * a block number, and the value is a pointer to |
| 46 | * to the buffer header; the buffer is marked "busy" |
| 47 | * so that no one else can touch it. If the block was |
| 48 | * already in core, no I/O need be done; if it is |
| 49 | * already busy, the process waits until it becomes free. |
| 50 | * The following routines allocate a buffer: |
| 51 | * getblk |
| 52 | * bread |
| 53 | * breada |
| 54 | * baddr (if it is incore) |
| 55 | * Eventually the buffer must be released, possibly with the |
| 56 | * side effect of writing it out, by using one of |
| 57 | * bwrite |
| 58 | * bdwrite |
| 59 | * bawrite |
| 60 | * brelse |
| 61 | */ |
| 62 | |
| 63 | #ifdef FASTVAX |
| 64 | #define notavail(bp) \ |
| 65 | { \ |
| 66 | int s = spl6(); \ |
| 67 | (bp)->av_back->av_forw = (bp)->av_forw; \ |
| 68 | (bp)->av_forw->av_back = (bp)->av_back; \ |
| 69 | (bp)->b_flags |= B_BUSY; \ |
| 70 | splx(s); \ |
| 71 | } |
| 72 | #endif |
| 73 | |
| 74 | /* |
| 75 | * Read in (if necessary) the block and return a buffer pointer. |
| 76 | */ |
| 77 | struct buf * |
| 78 | bread(dev, blkno) |
| 79 | dev_t dev; |
| 80 | daddr_t blkno; |
| 81 | { |
| 82 | register struct buf *bp; |
| 83 | |
| 84 | bp = getblk(dev, blkno); |
| 85 | if (bp->b_flags&B_DONE) { |
| 86 | #ifdef DISKMON |
| 87 | io_info.ncache++; |
| 88 | #endif |
| 89 | return(bp); |
| 90 | } |
| 91 | bp->b_flags |= B_READ; |
| 92 | bp->b_bcount = BSIZE; |
| 93 | (*bdevsw[major(dev)].d_strategy)(bp); |
| 94 | #ifdef DISKMON |
| 95 | io_info.nread++; |
| 96 | #endif |
| 97 | u.u_vm.vm_inblk++; /* pay for read */ |
| 98 | iowait(bp); |
| 99 | return(bp); |
| 100 | } |
| 101 | |
| 102 | /* |
| 103 | * Read in the block, like bread, but also start I/O on the |
| 104 | * read-ahead block (which is not allocated to the caller) |
| 105 | */ |
| 106 | struct buf * |
| 107 | breada(dev, blkno, rablkno) |
| 108 | dev_t dev; |
| 109 | daddr_t blkno, rablkno; |
| 110 | { |
| 111 | register struct buf *bp, *rabp; |
| 112 | |
| 113 | bp = NULL; |
| 114 | if (!incore(dev, blkno)) { |
| 115 | bp = getblk(dev, blkno); |
| 116 | if ((bp->b_flags&B_DONE) == 0) { |
| 117 | bp->b_flags |= B_READ; |
| 118 | bp->b_bcount = BSIZE; |
| 119 | (*bdevsw[major(dev)].d_strategy)(bp); |
| 120 | #ifdef DISKMON |
| 121 | io_info.nread++; |
| 122 | #endif |
| 123 | u.u_vm.vm_inblk++; /* pay for read */ |
| 124 | } |
| 125 | } |
| 126 | if (rablkno && !incore(dev, rablkno)) { |
| 127 | rabp = getblk(dev, rablkno); |
| 128 | if (rabp->b_flags & B_DONE) |
| 129 | brelse(rabp); |
| 130 | else { |
| 131 | rabp->b_flags |= B_READ|B_ASYNC; |
| 132 | rabp->b_bcount = BSIZE; |
| 133 | (*bdevsw[major(dev)].d_strategy)(rabp); |
| 134 | #ifdef DISKMON |
| 135 | io_info.nreada++; |
| 136 | #endif |
| 137 | u.u_vm.vm_inblk++; /* pay in advance */ |
| 138 | } |
| 139 | } |
| 140 | if(bp == NULL) |
| 141 | return(bread(dev, blkno)); |
| 142 | iowait(bp); |
| 143 | return(bp); |
| 144 | } |
| 145 | |
| 146 | /* |
| 147 | * Write the buffer, waiting for completion. |
| 148 | * Then release the buffer. |
| 149 | */ |
| 150 | bwrite(bp) |
| 151 | register struct buf *bp; |
| 152 | { |
| 153 | register flag; |
| 154 | |
| 155 | flag = bp->b_flags; |
| 156 | bp->b_flags &= ~(B_READ | B_DONE | B_ERROR | B_DELWRI | B_AGE); |
| 157 | bp->b_bcount = BSIZE; |
| 158 | #ifdef DISKMON |
| 159 | io_info.nwrite++; |
| 160 | #endif |
| 161 | if ((flag&B_DELWRI) == 0) |
| 162 | u.u_vm.vm_oublk++; /* noone paid yet */ |
| 163 | (*bdevsw[major(bp->b_dev)].d_strategy)(bp); |
| 164 | if ((flag&B_ASYNC) == 0) { |
| 165 | iowait(bp); |
| 166 | brelse(bp); |
| 167 | } else if (flag & B_DELWRI) |
| 168 | bp->b_flags |= B_AGE; |
| 169 | else |
| 170 | geterror(bp); |
| 171 | } |
| 172 | |
| 173 | /* |
| 174 | * Release the buffer, marking it so that if it is grabbed |
| 175 | * for another purpose it will be written out before being |
| 176 | * given up (e.g. when writing a partial block where it is |
| 177 | * assumed that another write for the same block will soon follow). |
| 178 | * This can't be done for magtape, since writes must be done |
| 179 | * in the same order as requested. |
| 180 | */ |
| 181 | bdwrite(bp) |
| 182 | register struct buf *bp; |
| 183 | { |
| 184 | register struct buf *dp; |
| 185 | |
| 186 | if ((bp->b_flags&B_DELWRI) == 0) |
| 187 | u.u_vm.vm_oublk++; /* noone paid yet */ |
| 188 | dp = bdevsw[major(bp->b_dev)].d_tab; |
| 189 | if(dp->b_flags & B_TAPE) |
| 190 | bawrite(bp); |
| 191 | else { |
| 192 | bp->b_flags |= B_DELWRI | B_DONE; |
| 193 | brelse(bp); |
| 194 | } |
| 195 | } |
| 196 | |
| 197 | /* |
| 198 | * Release the buffer, start I/O on it, but don't wait for completion. |
| 199 | */ |
| 200 | bawrite(bp) |
| 201 | register struct buf *bp; |
| 202 | { |
| 203 | |
| 204 | bp->b_flags |= B_ASYNC; |
| 205 | bwrite(bp); |
| 206 | } |
| 207 | |
| 208 | /* |
| 209 | * release the buffer, with no I/O implied. |
| 210 | */ |
| 211 | brelse(bp) |
| 212 | register struct buf *bp; |
| 213 | { |
| 214 | register struct buf **backp; |
| 215 | register s; |
| 216 | |
| 217 | if (bp->b_flags&B_WANTED) |
| 218 | wakeup((caddr_t)bp); |
| 219 | if (bfreelist.b_flags&B_WANTED) { |
| 220 | bfreelist.b_flags &= ~B_WANTED; |
| 221 | wakeup((caddr_t)&bfreelist); |
| 222 | } |
| 223 | if (bp->b_flags&B_ERROR) |
| 224 | bp->b_dev = NODEV; /* no assoc. on error */ |
| 225 | s = spl6(); |
| 226 | if(bp->b_flags & (B_AGE|B_ERROR)) { |
| 227 | backp = &bfreelist.av_forw; |
| 228 | (*backp)->av_back = bp; |
| 229 | bp->av_forw = *backp; |
| 230 | *backp = bp; |
| 231 | bp->av_back = &bfreelist; |
| 232 | } else { |
| 233 | backp = &bfreelist.av_back; |
| 234 | (*backp)->av_forw = bp; |
| 235 | bp->av_back = *backp; |
| 236 | *backp = bp; |
| 237 | bp->av_forw = &bfreelist; |
| 238 | } |
| 239 | bp->b_flags &= ~(B_WANTED|B_BUSY|B_ASYNC|B_AGE); |
| 240 | splx(s); |
| 241 | } |
| 242 | |
| 243 | /* |
| 244 | * See if the block is associated with some buffer |
| 245 | * (mainly to avoid getting hung up on a wait in breada) |
| 246 | */ |
| 247 | incore(dev, blkno) |
| 248 | dev_t dev; |
| 249 | daddr_t blkno; |
| 250 | { |
| 251 | register struct buf *bp; |
| 252 | register struct buf *dp; |
| 253 | register int dblkno = fsbtodb(blkno); |
| 254 | |
| 255 | dp = bdevsw[major(dev)].d_tab; |
| 256 | for (bp=dp->b_forw; bp != dp; bp = bp->b_forw) |
| 257 | if (bp->b_blkno==dblkno && bp->b_dev==dev) |
| 258 | return(1); |
| 259 | return(0); |
| 260 | } |
| 261 | |
| 262 | struct buf * |
| 263 | baddr(dev, blkno) |
| 264 | dev_t dev; |
| 265 | daddr_t blkno; |
| 266 | { |
| 267 | |
| 268 | if (incore(dev, blkno)) |
| 269 | return (bread(dev, blkno)); |
| 270 | return (0); |
| 271 | } |
| 272 | |
| 273 | /* |
| 274 | * Assign a buffer for the given block. If the appropriate |
| 275 | * block is already associated, return it; otherwise search |
| 276 | * for the oldest non-busy buffer and reassign it. |
| 277 | */ |
| 278 | struct buf * |
| 279 | getblk(dev, blkno) |
| 280 | dev_t dev; |
| 281 | daddr_t blkno; |
| 282 | { |
| 283 | register struct buf *bp; |
| 284 | register struct buf *dp; |
| 285 | #ifdef DISKMON |
| 286 | register i; |
| 287 | #endif |
| 288 | register int dblkno = fsbtodb(blkno); |
| 289 | |
| 290 | if(major(dev) >= nblkdev) |
| 291 | panic("blkdev"); |
| 292 | |
| 293 | loop: |
| 294 | VOID spl0(); |
| 295 | dp = bdevsw[major(dev)].d_tab; |
| 296 | if(dp == NULL) |
| 297 | panic("devtab"); |
| 298 | for (bp=dp->b_forw; bp != dp; bp = bp->b_forw) { |
| 299 | if (bp->b_blkno!=dblkno || bp->b_dev!=dev) |
| 300 | continue; |
| 301 | VOID spl6(); |
| 302 | if (bp->b_flags&B_BUSY) { |
| 303 | bp->b_flags |= B_WANTED; |
| 304 | sleep((caddr_t)bp, PRIBIO+1); |
| 305 | goto loop; |
| 306 | } |
| 307 | VOID spl0(); |
| 308 | #ifdef DISKMON |
| 309 | i = 0; |
| 310 | dp = bp->av_forw; |
| 311 | while (dp != &bfreelist) { |
| 312 | i++; |
| 313 | dp = dp->av_forw; |
| 314 | } |
| 315 | if (i<NBUF) |
| 316 | io_info.bufcount[i]++; |
| 317 | #endif |
| 318 | notavail(bp); |
| 319 | bp->b_flags |= B_CACHE; |
| 320 | return(bp); |
| 321 | } |
| 322 | VOID spl6(); |
| 323 | if (bfreelist.av_forw == &bfreelist) { |
| 324 | bfreelist.b_flags |= B_WANTED; |
| 325 | sleep((caddr_t)&bfreelist, PRIBIO+1); |
| 326 | goto loop; |
| 327 | } |
| 328 | spl0(); |
| 329 | bp = bfreelist.av_forw; |
| 330 | notavail(bp); |
| 331 | if (bp->b_flags & B_DELWRI) { |
| 332 | bp->b_flags |= B_ASYNC; |
| 333 | bwrite(bp); |
| 334 | goto loop; |
| 335 | } |
| 336 | bp->b_flags = B_BUSY; |
| 337 | bp->b_back->b_forw = bp->b_forw; |
| 338 | bp->b_forw->b_back = bp->b_back; |
| 339 | bp->b_forw = dp->b_forw; |
| 340 | bp->b_back = dp; |
| 341 | dp->b_forw->b_back = bp; |
| 342 | dp->b_forw = bp; |
| 343 | bp->b_dev = dev; |
| 344 | bp->b_blkno = dblkno; |
| 345 | return(bp); |
| 346 | } |
| 347 | |
| 348 | /* |
| 349 | * get an empty block, |
| 350 | * not assigned to any particular device |
| 351 | */ |
| 352 | struct buf * |
| 353 | geteblk() |
| 354 | { |
| 355 | register struct buf *bp; |
| 356 | register struct buf *dp; |
| 357 | |
| 358 | loop: |
| 359 | VOID spl6(); |
| 360 | while (bfreelist.av_forw == &bfreelist) { |
| 361 | bfreelist.b_flags |= B_WANTED; |
| 362 | sleep((caddr_t)&bfreelist, PRIBIO+1); |
| 363 | } |
| 364 | VOID spl0(); |
| 365 | dp = &bfreelist; |
| 366 | bp = bfreelist.av_forw; |
| 367 | notavail(bp); |
| 368 | if (bp->b_flags & B_DELWRI) { |
| 369 | bp->b_flags |= B_ASYNC; |
| 370 | bwrite(bp); |
| 371 | goto loop; |
| 372 | } |
| 373 | bp->b_flags = B_BUSY; |
| 374 | bp->b_back->b_forw = bp->b_forw; |
| 375 | bp->b_forw->b_back = bp->b_back; |
| 376 | bp->b_forw = dp->b_forw; |
| 377 | bp->b_back = dp; |
| 378 | dp->b_forw->b_back = bp; |
| 379 | dp->b_forw = bp; |
| 380 | bp->b_dev = (dev_t)NODEV; |
| 381 | return(bp); |
| 382 | } |
| 383 | |
| 384 | /* |
| 385 | * Wait for I/O completion on the buffer; return errors |
| 386 | * to the user. |
| 387 | */ |
| 388 | iowait(bp) |
| 389 | register struct buf *bp; |
| 390 | { |
| 391 | |
| 392 | VOID spl6(); |
| 393 | while ((bp->b_flags&B_DONE)==0) |
| 394 | sleep((caddr_t)bp, PRIBIO); |
| 395 | VOID spl0(); |
| 396 | geterror(bp); |
| 397 | } |
| 398 | |
| 399 | #ifndef FASTVAX |
| 400 | /* |
| 401 | * Unlink a buffer from the available list and mark it busy. |
| 402 | * (internal interface) |
| 403 | */ |
| 404 | notavail(bp) |
| 405 | register struct buf *bp; |
| 406 | { |
| 407 | register s; |
| 408 | |
| 409 | s = spl6(); |
| 410 | bp->av_back->av_forw = bp->av_forw; |
| 411 | bp->av_forw->av_back = bp->av_back; |
| 412 | bp->b_flags |= B_BUSY; |
| 413 | splx(s); |
| 414 | } |
| 415 | #endif |
| 416 | |
| 417 | /* |
| 418 | * Mark I/O complete on a buffer. If the header |
| 419 | * indicates a dirty page push completion, the |
| 420 | * header is inserted into the ``cleaned'' list |
| 421 | * to be processed by the pageout daemon. Otherwise |
| 422 | * release it if I/O is asynchronous, and wake |
| 423 | * up anyone waiting for it. |
| 424 | */ |
| 425 | iodone(bp) |
| 426 | register struct buf *bp; |
| 427 | { |
| 428 | register int s; |
| 429 | |
| 430 | bp->b_flags |= B_DONE; |
| 431 | if (bp->b_flags & B_DIRTY) { |
| 432 | if (bp->b_flags & B_ERROR) |
| 433 | panic("IO err in push"); |
| 434 | s = spl6(); |
| 435 | cnt.v_pgout++; |
| 436 | bp->av_forw = bclnlist; |
| 437 | bp->b_bcount = swsize[bp - swbuf]; |
| 438 | bp->b_pfcent = swpf[bp - swbuf]; |
| 439 | bclnlist = bp; |
| 440 | if (bswlist.b_flags & B_WANTED) |
| 441 | wakeup((caddr_t)&proc[2]); |
| 442 | splx(s); |
| 443 | } |
| 444 | if (bp->b_flags&B_ASYNC) |
| 445 | brelse(bp); |
| 446 | else { |
| 447 | bp->b_flags &= ~B_WANTED; |
| 448 | wakeup((caddr_t)bp); |
| 449 | } |
| 450 | } |
| 451 | |
| 452 | /* |
| 453 | * Zero the core associated with a buffer. |
| 454 | */ |
| 455 | clrbuf(bp) |
| 456 | struct buf *bp; |
| 457 | { |
| 458 | register *p; |
| 459 | register c; |
| 460 | |
| 461 | p = bp->b_un.b_words; |
| 462 | c = BSIZE/sizeof(int); |
| 463 | do |
| 464 | *p++ = 0; |
| 465 | while (--c); |
| 466 | bp->b_resid = 0; |
| 467 | } |
| 468 | |
| 469 | /* |
| 470 | * swap I/O - |
| 471 | * |
| 472 | * If the flag indicates a dirty page push initiated |
| 473 | * by the pageout daemon, we map the page into the i th |
| 474 | * virtual page of process 2 (the daemon itself) where i is |
| 475 | * the index of the swap header that has been allocated. |
| 476 | * We simply initialize the header and queue the I/O but |
| 477 | * do not wait for completion. When the I/O completes, |
| 478 | * iodone() will link the header to a list of cleaned |
| 479 | * pages to be processed by the pageout daemon. |
| 480 | */ |
| 481 | swap(p, dblkno, addr, nbytes, rdflg, flag, dev, pfcent) |
| 482 | struct proc *p; |
| 483 | swblk_t dblkno; |
| 484 | caddr_t addr; |
| 485 | int flag, nbytes; |
| 486 | dev_t dev; |
| 487 | unsigned pfcent; |
| 488 | { |
| 489 | register struct buf *bp; |
| 490 | register int c; |
| 491 | int p2dp; |
| 492 | register struct pte *dpte, *vpte; |
| 493 | |
| 494 | VOID spl6(); |
| 495 | while (bswlist.av_forw == NULL) { |
| 496 | bswlist.b_flags |= B_WANTED; |
| 497 | sleep((caddr_t)&bswlist, PSWP+1); |
| 498 | } |
| 499 | bp = bswlist.av_forw; |
| 500 | bswlist.av_forw = bp->av_forw; |
| 501 | VOID spl0(); |
| 502 | |
| 503 | bp->b_flags = B_BUSY | B_PHYS | rdflg | flag; |
| 504 | if ((bp->b_flags & (B_DIRTY|B_PGIN)) == 0) |
| 505 | if (rdflg == B_READ) |
| 506 | sum.v_pswpin += btoc(nbytes); |
| 507 | else |
| 508 | sum.v_pswpout += btoc(nbytes); |
| 509 | bp->b_proc = p; |
| 510 | if (flag & B_DIRTY) { |
| 511 | p2dp = ((bp - swbuf) * CLSIZE) * KLMAX; |
| 512 | dpte = dptopte(&proc[2], p2dp); |
| 513 | vpte = vtopte(p, btop(addr)); |
| 514 | for (c = 0; c < nbytes; c += NBPG) { |
| 515 | if (vpte->pg_pfnum == 0 || vpte->pg_fod) |
| 516 | panic("swap bad pte"); |
| 517 | *dpte++ = *vpte++; |
| 518 | } |
| 519 | bp->b_un.b_addr = (caddr_t)ctob(p2dp); |
| 520 | } else |
| 521 | bp->b_un.b_addr = addr; |
| 522 | while (nbytes > 0) { |
| 523 | c = imin(ctob(120), nbytes); |
| 524 | bp->b_bcount = c; |
| 525 | bp->b_blkno = dblkno; |
| 526 | bp->b_dev = dev; |
| 527 | if (dev == swapdev) |
| 528 | bp->b_blkno += swplo; |
| 529 | (*bdevsw[major(dev)].d_strategy)(bp); |
| 530 | if (flag & B_DIRTY) { |
| 531 | if (c < nbytes) |
| 532 | panic("big push"); |
| 533 | swsize[bp - swbuf] = nbytes; |
| 534 | swpf[bp - swbuf] = pfcent; |
| 535 | return; |
| 536 | } |
| 537 | VOID spl6(); |
| 538 | while((bp->b_flags&B_DONE)==0) |
| 539 | sleep((caddr_t)bp, PSWP); |
| 540 | VOID spl0(); |
| 541 | bp->b_un.b_addr += c; |
| 542 | bp->b_flags &= ~B_DONE; |
| 543 | if (bp->b_flags & B_ERROR) { |
| 544 | if ((flag & (B_UAREA|B_PAGET)) || rdflg == B_WRITE) |
| 545 | panic("hard IO err in swap"); |
| 546 | swkill(p, (char *)0); |
| 547 | } |
| 548 | nbytes -= c; |
| 549 | dblkno += btoc(c); |
| 550 | } |
| 551 | VOID spl6(); |
| 552 | bp->b_flags &= ~(B_BUSY|B_WANTED|B_PHYS|B_PAGET|B_UAREA|B_DIRTY); |
| 553 | bp->av_forw = bswlist.av_forw; |
| 554 | bswlist.av_forw = bp; |
| 555 | if (bswlist.b_flags & B_WANTED) { |
| 556 | bswlist.b_flags &= ~B_WANTED; |
| 557 | wakeup((caddr_t)&bswlist); |
| 558 | wakeup((caddr_t)&proc[2]); |
| 559 | } |
| 560 | VOID spl0(); |
| 561 | } |
| 562 | |
| 563 | /* |
| 564 | * If rout == 0 then killed on swap error, else |
| 565 | * rout is the name of the routine where we ran out of |
| 566 | * swap space. |
| 567 | */ |
| 568 | swkill(p, rout) |
| 569 | struct proc *p; |
| 570 | char *rout; |
| 571 | { |
| 572 | |
| 573 | printf("%d: ", p->p_pid); |
| 574 | if (rout) |
| 575 | printf("out of swap space in %s\n", rout); |
| 576 | else |
| 577 | printf("killed on swap error\n"); |
| 578 | /* |
| 579 | * To be sure no looping (e.g. in vmsched trying to |
| 580 | * swap out) mark process locked in core (as though |
| 581 | * done by user) after killing it so noone will try |
| 582 | * to swap it out. |
| 583 | */ |
| 584 | psignal(p, SIGKIL); |
| 585 | p->p_flag |= SULOCK; |
| 586 | } |
| 587 | |
| 588 | /* |
| 589 | * make sure all write-behind blocks |
| 590 | * on dev (or NODEV for all) |
| 591 | * are flushed out. |
| 592 | * (from umount and update) |
| 593 | */ |
| 594 | bflush(dev) |
| 595 | dev_t dev; |
| 596 | { |
| 597 | register struct buf *bp; |
| 598 | |
| 599 | loop: |
| 600 | VOID spl6(); |
| 601 | for (bp = bfreelist.av_forw; bp != &bfreelist; bp = bp->av_forw) { |
| 602 | if (bp->b_flags&B_DELWRI && (dev == NODEV||dev==bp->b_dev)) { |
| 603 | bp->b_flags |= B_ASYNC; |
| 604 | notavail(bp); |
| 605 | bwrite(bp); |
| 606 | goto loop; |
| 607 | } |
| 608 | } |
| 609 | VOID spl0(); |
| 610 | } |
| 611 | |
| 612 | /* |
| 613 | * Raw I/O. The arguments are |
| 614 | * The strategy routine for the device |
| 615 | * A buffer, which will always be a special buffer |
| 616 | * header owned exclusively by the device for this purpose |
| 617 | * The device number |
| 618 | * Read/write flag |
| 619 | * Essentially all the work is computing physical addresses and |
| 620 | * validating them. |
| 621 | * If the user has the proper access privilidges, the process is |
| 622 | * marked 'delayed unlock' and the pages involved in the I/O are |
| 623 | * faulted and locked. After the completion of the I/O, the above pages |
| 624 | * are unlocked. |
| 625 | */ |
| 626 | physio(strat, bp, dev, rw, mincnt) |
| 627 | int (*strat)(); |
| 628 | register struct buf *bp; |
| 629 | unsigned (*mincnt)(); |
| 630 | { |
| 631 | register int c; |
| 632 | char *a; |
| 633 | |
| 634 | if (useracc(u.u_base,u.u_count,rw==B_READ?B_WRITE:B_READ) == NULL) { |
| 635 | u.u_error = EFAULT; |
| 636 | return; |
| 637 | } |
| 638 | VOID spl6(); |
| 639 | while (bp->b_flags&B_BUSY) { |
| 640 | bp->b_flags |= B_WANTED; |
| 641 | sleep((caddr_t)bp, PRIBIO+1); |
| 642 | } |
| 643 | bp->b_error = 0; |
| 644 | bp->b_proc = u.u_procp; |
| 645 | bp->b_un.b_addr = u.u_base; |
| 646 | while (u.u_count != 0 && bp->b_error==0) { |
| 647 | bp->b_flags = B_BUSY | B_PHYS | rw; |
| 648 | bp->b_dev = dev; |
| 649 | bp->b_blkno = u.u_offset >> PGSHIFT; |
| 650 | bp->b_bcount = u.u_count; |
| 651 | (*mincnt)(bp); |
| 652 | c = bp->b_bcount; |
| 653 | u.u_procp->p_flag |= SPHYSIO; |
| 654 | vslock(a = bp->b_un.b_addr, c); |
| 655 | (*strat)(bp); |
| 656 | VOID spl6(); |
| 657 | while ((bp->b_flags&B_DONE) == 0) |
| 658 | sleep((caddr_t)bp, PRIBIO); |
| 659 | vsunlock(a, c, rw); |
| 660 | u.u_procp->p_flag &= ~SPHYSIO; |
| 661 | if (bp->b_flags&B_WANTED) |
| 662 | wakeup((caddr_t)bp); |
| 663 | VOID spl0(); |
| 664 | bp->b_un.b_addr += c; |
| 665 | u.u_count -= c; |
| 666 | u.u_offset += c; |
| 667 | } |
| 668 | bp->b_flags &= ~(B_BUSY|B_WANTED|B_PHYS); |
| 669 | u.u_count = bp->b_resid; |
| 670 | geterror(bp); |
| 671 | } |
| 672 | |
| 673 | /*ARGSUSED*/ |
| 674 | unsigned |
| 675 | minphys(bp) |
| 676 | struct buf *bp; |
| 677 | { |
| 678 | |
| 679 | if (bp->b_bcount > 60 * 1024) |
| 680 | bp->b_bcount = 60 * 1024; |
| 681 | } |
| 682 | |
| 683 | /* |
| 684 | * Pick up the device's error number and pass it to the user; |
| 685 | * if there is an error but the number is 0 set a generalized |
| 686 | * code. Actually the latter is always true because devices |
| 687 | * don't yet return specific errors. |
| 688 | */ |
| 689 | geterror(bp) |
| 690 | register struct buf *bp; |
| 691 | { |
| 692 | |
| 693 | if (bp->b_flags&B_ERROR) |
| 694 | if ((u.u_error = bp->b_error)==0) |
| 695 | u.u_error = EIO; |
| 696 | } |