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1.1 root 1: /* bio.c 4.23 81/07/25 */
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: #include "../h/trace.h"
14:
15: /*
16: * The following several routines allocate and free
17: * buffers with various side effects. In general the
18: * arguments to an allocate routine are a device and
19: * a block number, and the value is a pointer to
20: * to the buffer header; the buffer is marked "busy"
21: * so that no one else can touch it. If the block was
22: * already in core, no I/O need be done; if it is
23: * already busy, the process waits until it becomes free.
24: * The following routines allocate a buffer:
25: * getblk
26: * bread
27: * breada
28: * baddr (if it is incore)
29: * Eventually the buffer must be released, possibly with the
30: * side effect of writing it out, by using one of
31: * bwrite
32: * bdwrite
33: * bawrite
34: * brelse
35: */
36:
37: struct buf bfreelist[BQUEUES];
38: struct buf bswlist, *bclnlist;
39:
40: #define BUFHSZ 63
41: struct bufhd bufhash[BUFHSZ];
42: #define BUFHASH(dev, dblkno) \
43: ((struct buf *)&bufhash[((int)(dev)+(int)(dblkno)) % BUFHSZ])
44:
45: /*
46: * Initialize hash links for buffers.
47: */
48: bhinit()
49: {
50: register int i;
51: register struct bufhd *bp;
52:
53: for (bp = bufhash, i = 0; i < BUFHSZ; i++, bp++)
54: bp->b_forw = bp->b_back = (struct buf *)bp;
55: }
56:
57: /* #define DISKMON 1 */
58:
59: #ifdef DISKMON
60: struct {
61: int nbuf;
62: long nread;
63: long nreada;
64: long ncache;
65: long nwrite;
66: long bufcount[64];
67: } io_info;
68: #endif
69:
70: /*
71: * Swap IO headers -
72: * They contain the necessary information for the swap I/O.
73: * At any given time, a swap header can be in three
74: * different lists. When free it is in the free list,
75: * when allocated and the I/O queued, it is on the swap
76: * device list, and finally, if the operation was a dirty
77: * page push, when the I/O completes, it is inserted
78: * in a list of cleaned pages to be processed by the pageout daemon.
79: */
80: struct buf *swbuf;
81: short *swsize; /* CAN WE JUST USE B_BCOUNT? */
82: int *swpf;
83:
84:
85: #ifndef UNFAST
86: #define notavail(bp) \
87: { \
88: int s = spl6(); \
89: (bp)->av_back->av_forw = (bp)->av_forw; \
90: (bp)->av_forw->av_back = (bp)->av_back; \
91: (bp)->b_flags |= B_BUSY; \
92: splx(s); \
93: }
94: #endif
95:
96: /*
97: * Read in (if necessary) the block and return a buffer pointer.
98: */
99: struct buf *
100: bread(dev, blkno)
101: dev_t dev;
102: daddr_t blkno;
103: {
104: register struct buf *bp;
105:
106: bp = getblk(dev, blkno);
107: if (bp->b_flags&B_DONE) {
108: #ifdef TRACE
109: trace(TR_BREADHIT, dev, blkno);
110: #endif
111: #ifdef DISKMON
112: io_info.ncache++;
113: #endif
114: return(bp);
115: }
116: bp->b_flags |= B_READ;
117: bp->b_bcount = BSIZE;
118: (*bdevsw[major(dev)].d_strategy)(bp);
119: #ifdef TRACE
120: trace(TR_BREADMISS, dev, blkno);
121: #endif
122: #ifdef DISKMON
123: io_info.nread++;
124: #endif
125: u.u_vm.vm_inblk++; /* pay for read */
126: iowait(bp);
127: return(bp);
128: }
129:
130: /*
131: * Read in the block, like bread, but also start I/O on the
132: * read-ahead block (which is not allocated to the caller)
133: */
134: struct buf *
135: breada(dev, blkno, rablkno)
136: dev_t dev;
137: daddr_t blkno, rablkno;
138: {
139: register struct buf *bp, *rabp;
140:
141: bp = NULL;
142: if (!incore(dev, blkno)) {
143: bp = getblk(dev, blkno);
144: if ((bp->b_flags&B_DONE) == 0) {
145: bp->b_flags |= B_READ;
146: bp->b_bcount = BSIZE;
147: (*bdevsw[major(dev)].d_strategy)(bp);
148: #ifdef TRACE
149: trace(TR_BREADMISS, dev, blkno);
150: #endif
151: #ifdef DISKMON
152: io_info.nread++;
153: #endif
154: u.u_vm.vm_inblk++; /* pay for read */
155: }
156: #ifdef TRACE
157: else
158: trace(TR_BREADHIT, dev, blkno);
159: #endif
160: }
161: if (rablkno && !incore(dev, rablkno)) {
162: rabp = getblk(dev, rablkno);
163: if (rabp->b_flags & B_DONE) {
164: brelse(rabp);
165: #ifdef TRACE
166: trace(TR_BREADHITRA, dev, blkno);
167: #endif
168: } else {
169: rabp->b_flags |= B_READ|B_ASYNC;
170: rabp->b_bcount = BSIZE;
171: (*bdevsw[major(dev)].d_strategy)(rabp);
172: #ifdef TRACE
173: trace(TR_BREADMISSRA, dev, rablock);
174: #endif
175: #ifdef DISKMON
176: io_info.nreada++;
177: #endif
178: u.u_vm.vm_inblk++; /* pay in advance */
179: }
180: }
181: if(bp == NULL)
182: return(bread(dev, blkno));
183: iowait(bp);
184: return(bp);
185: }
186:
187: /*
188: * Write the buffer, waiting for completion.
189: * Then release the buffer.
190: */
191: bwrite(bp)
192: register struct buf *bp;
193: {
194: register flag;
195:
196: flag = bp->b_flags;
197: bp->b_flags &= ~(B_READ | B_DONE | B_ERROR | B_DELWRI | B_AGE);
198: bp->b_bcount = BSIZE;
199: #ifdef DISKMON
200: io_info.nwrite++;
201: #endif
202: if ((flag&B_DELWRI) == 0)
203: u.u_vm.vm_oublk++; /* noone paid yet */
204: #ifdef TRACE
205: trace(TR_BWRITE, bp->b_dev, bp->b_blkno);
206: #endif
207: (*bdevsw[major(bp->b_dev)].d_strategy)(bp);
208: if ((flag&B_ASYNC) == 0) {
209: iowait(bp);
210: brelse(bp);
211: } else if (flag & B_DELWRI)
212: bp->b_flags |= B_AGE;
213: else
214: geterror(bp);
215: }
216:
217: /*
218: * Release the buffer, marking it so that if it is grabbed
219: * for another purpose it will be written out before being
220: * given up (e.g. when writing a partial block where it is
221: * assumed that another write for the same block will soon follow).
222: * This can't be done for magtape, since writes must be done
223: * in the same order as requested.
224: */
225: bdwrite(bp)
226: register struct buf *bp;
227: {
228: register int flags;
229:
230: if ((bp->b_flags&B_DELWRI) == 0)
231: u.u_vm.vm_oublk++; /* noone paid yet */
232: flags = bdevsw[major(bp->b_dev)].d_flags;
233: if(flags & B_TAPE)
234: bawrite(bp);
235: else {
236: bp->b_flags |= B_DELWRI | B_DONE;
237: brelse(bp);
238: }
239: }
240:
241: /*
242: * Release the buffer, start I/O on it, but don't wait for completion.
243: */
244: bawrite(bp)
245: register struct buf *bp;
246: {
247:
248: bp->b_flags |= B_ASYNC;
249: bwrite(bp);
250: }
251:
252: /*
253: * release the buffer, with no I/O implied.
254: */
255: brelse(bp)
256: register struct buf *bp;
257: {
258: register struct buf *flist;
259: register s;
260:
261: if (bp->b_flags&B_WANTED)
262: wakeup((caddr_t)bp);
263: if (bfreelist[0].b_flags&B_WANTED) {
264: bfreelist[0].b_flags &= ~B_WANTED;
265: wakeup((caddr_t)bfreelist);
266: }
267: if (bp->b_flags&B_ERROR)
268: if (bp->b_flags & B_LOCKED)
269: bp->b_flags &= ~B_ERROR; /* try again later */
270: else
271: bp->b_dev = NODEV; /* no assoc */
272: s = spl6();
273: if (bp->b_flags & (B_ERROR|B_INVAL)) {
274: /* block has no info ... put at front of most free list */
275: flist = &bfreelist[BQUEUES-1];
276: flist->av_forw->av_back = bp;
277: bp->av_forw = flist->av_forw;
278: flist->av_forw = bp;
279: bp->av_back = flist;
280: } else {
281: if (bp->b_flags & B_LOCKED)
282: flist = &bfreelist[BQ_LOCKED];
283: else if (bp->b_flags & B_AGE)
284: flist = &bfreelist[BQ_AGE];
285: else
286: flist = &bfreelist[BQ_LRU];
287: flist->av_back->av_forw = bp;
288: bp->av_back = flist->av_back;
289: flist->av_back = bp;
290: bp->av_forw = flist;
291: }
292: bp->b_flags &= ~(B_WANTED|B_BUSY|B_ASYNC|B_AGE);
293: splx(s);
294: }
295:
296: /*
297: * See if the block is associated with some buffer
298: * (mainly to avoid getting hung up on a wait in breada)
299: */
300: incore(dev, blkno)
301: dev_t dev;
302: daddr_t blkno;
303: {
304: register struct buf *bp;
305: register struct buf *dp;
306: register int dblkno = fsbtodb(blkno);
307:
308: dp = BUFHASH(dev, dblkno);
309: for (bp = dp->b_forw; bp != dp; bp = bp->b_forw)
310: if (bp->b_blkno == dblkno && bp->b_dev == dev &&
311: !(bp->b_flags & B_INVAL))
312: return (1);
313: return (0);
314: }
315:
316: struct buf *
317: baddr(dev, blkno)
318: dev_t dev;
319: daddr_t blkno;
320: {
321:
322: if (incore(dev, blkno))
323: return (bread(dev, blkno));
324: return (0);
325: }
326:
327: /*
328: * Assign a buffer for the given block. If the appropriate
329: * block is already associated, return it; otherwise search
330: * for the oldest non-busy buffer and reassign it.
331: */
332: struct buf *
333: getblk(dev, blkno)
334: dev_t dev;
335: daddr_t blkno;
336: {
337: register struct buf *bp, *dp, *ep;
338: register int dblkno = fsbtodb(blkno);
339: #ifdef DISKMON
340: register int i;
341: #endif
342:
343: if ((unsigned)blkno >= 1 << (sizeof(int)*NBBY-PGSHIFT))
344: blkno = 1 << ((sizeof(int)*NBBY-PGSHIFT) + 1);
345: dblkno = fsbtodb(blkno);
346: dp = BUFHASH(dev, dblkno);
347: loop:
348: (void) spl0();
349: for (bp = dp->b_forw; bp != dp; bp = bp->b_forw) {
350: if (bp->b_blkno != dblkno || bp->b_dev != dev ||
351: bp->b_flags&B_INVAL)
352: continue;
353: (void) spl6();
354: if (bp->b_flags&B_BUSY) {
355: bp->b_flags |= B_WANTED;
356: sleep((caddr_t)bp, PRIBIO+1);
357: goto loop;
358: }
359: (void) spl0();
360: #ifdef DISKMON
361: i = 0;
362: dp = bp->av_forw;
363: while ((dp->b_flags & B_HEAD) == 0) {
364: i++;
365: dp = dp->av_forw;
366: }
367: if (i<64)
368: io_info.bufcount[i]++;
369: #endif
370: notavail(bp);
371: bp->b_flags |= B_CACHE;
372: return(bp);
373: }
374: if (major(dev) >= nblkdev)
375: panic("blkdev");
376: (void) spl6();
377: for (ep = &bfreelist[BQUEUES-1]; ep > bfreelist; ep--)
378: if (ep->av_forw != ep)
379: break;
380: if (ep == bfreelist) { /* no free blocks at all */
381: ep->b_flags |= B_WANTED;
382: sleep((caddr_t)ep, PRIBIO+1);
383: goto loop;
384: }
385: (void) spl0();
386: bp = ep->av_forw;
387: notavail(bp);
388: if (bp->b_flags & B_DELWRI) {
389: bp->b_flags |= B_ASYNC;
390: bwrite(bp);
391: goto loop;
392: }
393: #ifdef TRACE
394: trace(TR_BRELSE, bp->b_dev, bp->b_blkno);
395: #endif
396: bp->b_flags = B_BUSY;
397: bp->b_back->b_forw = bp->b_forw;
398: bp->b_forw->b_back = bp->b_back;
399: bp->b_forw = dp->b_forw;
400: bp->b_back = dp;
401: dp->b_forw->b_back = bp;
402: dp->b_forw = bp;
403: bp->b_dev = dev;
404: bp->b_blkno = dblkno;
405: return(bp);
406: }
407:
408: /*
409: * get an empty block,
410: * not assigned to any particular device
411: */
412: struct buf *
413: geteblk()
414: {
415: register struct buf *bp, *dp;
416:
417: loop:
418: (void) spl6();
419: for (dp = &bfreelist[BQUEUES-1]; dp > bfreelist; dp--)
420: if (dp->av_forw != dp)
421: break;
422: if (dp == bfreelist) { /* no free blocks */
423: dp->b_flags |= B_WANTED;
424: sleep((caddr_t)dp, PRIBIO+1);
425: goto loop;
426: }
427: (void) spl0();
428: bp = dp->av_forw;
429: notavail(bp);
430: if (bp->b_flags & B_DELWRI) {
431: bp->b_flags |= B_ASYNC;
432: bwrite(bp);
433: goto loop;
434: }
435: #ifdef TRACE
436: trace(TR_BRELSE, bp->b_dev, bp->b_blkno);
437: #endif
438: bp->b_flags = B_BUSY|B_INVAL;
439: bp->b_back->b_forw = bp->b_forw;
440: bp->b_forw->b_back = bp->b_back;
441: bp->b_forw = dp->b_forw;
442: bp->b_back = dp;
443: dp->b_forw->b_back = bp;
444: dp->b_forw = bp;
445: bp->b_dev = (dev_t)NODEV;
446: return(bp);
447: }
448:
449: /*
450: * Wait for I/O completion on the buffer; return errors
451: * to the user.
452: */
453: iowait(bp)
454: register struct buf *bp;
455: {
456:
457: (void) spl6();
458: while ((bp->b_flags&B_DONE)==0)
459: sleep((caddr_t)bp, PRIBIO);
460: (void) spl0();
461: geterror(bp);
462: }
463:
464: #ifdef UNFAST
465: /*
466: * Unlink a buffer from the available list and mark it busy.
467: * (internal interface)
468: */
469: notavail(bp)
470: register struct buf *bp;
471: {
472: register s;
473:
474: s = spl6();
475: bp->av_back->av_forw = bp->av_forw;
476: bp->av_forw->av_back = bp->av_back;
477: bp->b_flags |= B_BUSY;
478: splx(s);
479: }
480: #endif
481:
482: /*
483: * Mark I/O complete on a buffer. If the header
484: * indicates a dirty page push completion, the
485: * header is inserted into the ``cleaned'' list
486: * to be processed by the pageout daemon. Otherwise
487: * release it if I/O is asynchronous, and wake
488: * up anyone waiting for it.
489: */
490: iodone(bp)
491: register struct buf *bp;
492: {
493: register int s;
494:
495: if (bp->b_flags & B_DONE)
496: panic("dup iodone");
497: bp->b_flags |= B_DONE;
498: if (bp->b_flags & B_DIRTY) {
499: if (bp->b_flags & B_ERROR)
500: panic("IO err in push");
501: s = spl6();
502: bp->av_forw = bclnlist;
503: bp->b_bcount = swsize[bp - swbuf];
504: bp->b_pfcent = swpf[bp - swbuf];
505: cnt.v_pgout++;
506: cnt.v_pgpgout += bp->b_bcount / NBPG;
507: bclnlist = bp;
508: if (bswlist.b_flags & B_WANTED)
509: wakeup((caddr_t)&proc[2]);
510: splx(s);
511: return;
512: }
513: if (bp->b_flags&B_ASYNC)
514: brelse(bp);
515: else {
516: bp->b_flags &= ~B_WANTED;
517: wakeup((caddr_t)bp);
518: }
519: }
520:
521: /*
522: * Zero the core associated with a buffer.
523: */
524: clrbuf(bp)
525: struct buf *bp;
526: {
527: register *p;
528: register c;
529:
530: p = bp->b_un.b_words;
531: c = BSIZE/sizeof(int);
532: do
533: *p++ = 0;
534: while (--c);
535: bp->b_resid = 0;
536: }
537:
538: /*
539: * swap I/O -
540: *
541: * If the flag indicates a dirty page push initiated
542: * by the pageout daemon, we map the page into the i th
543: * virtual page of process 2 (the daemon itself) where i is
544: * the index of the swap header that has been allocated.
545: * We simply initialize the header and queue the I/O but
546: * do not wait for completion. When the I/O completes,
547: * iodone() will link the header to a list of cleaned
548: * pages to be processed by the pageout daemon.
549: */
550: swap(p, dblkno, addr, nbytes, rdflg, flag, dev, pfcent)
551: struct proc *p;
552: swblk_t dblkno;
553: caddr_t addr;
554: int flag, nbytes;
555: dev_t dev;
556: unsigned pfcent;
557: {
558: register struct buf *bp;
559: register int c;
560: int p2dp;
561: register struct pte *dpte, *vpte;
562:
563: (void) spl6();
564: while (bswlist.av_forw == NULL) {
565: bswlist.b_flags |= B_WANTED;
566: sleep((caddr_t)&bswlist, PSWP+1);
567: }
568: bp = bswlist.av_forw;
569: bswlist.av_forw = bp->av_forw;
570: (void) spl0();
571:
572: bp->b_flags = B_BUSY | B_PHYS | rdflg | flag;
573: if ((bp->b_flags & (B_DIRTY|B_PGIN)) == 0)
574: if (rdflg == B_READ)
575: sum.v_pswpin += btoc(nbytes);
576: else
577: sum.v_pswpout += btoc(nbytes);
578: bp->b_proc = p;
579: if (flag & B_DIRTY) {
580: p2dp = ((bp - swbuf) * CLSIZE) * KLMAX;
581: dpte = dptopte(&proc[2], p2dp);
582: vpte = vtopte(p, btop(addr));
583: for (c = 0; c < nbytes; c += NBPG) {
584: if (vpte->pg_pfnum == 0 || vpte->pg_fod)
585: panic("swap bad pte");
586: *dpte++ = *vpte++;
587: }
588: bp->b_un.b_addr = (caddr_t)ctob(p2dp);
589: } else
590: bp->b_un.b_addr = addr;
591: while (nbytes > 0) {
592: c = imin(ctob(120), nbytes);
593: bp->b_bcount = c;
594: bp->b_blkno = dblkno;
595: bp->b_dev = dev;
596: if (flag & B_DIRTY) {
597: swpf[bp - swbuf] = pfcent;
598: swsize[bp - swbuf] = nbytes;
599: }
600: #ifdef TRACE
601: trace(TR_SWAPIO, dev, bp->b_blkno);
602: #endif
603: (*bdevsw[major(dev)].d_strategy)(bp);
604: if (flag & B_DIRTY) {
605: if (c < nbytes)
606: panic("big push");
607: return;
608: }
609: (void) spl6();
610: while((bp->b_flags&B_DONE)==0)
611: sleep((caddr_t)bp, PSWP);
612: (void) spl0();
613: bp->b_un.b_addr += c;
614: bp->b_flags &= ~B_DONE;
615: if (bp->b_flags & B_ERROR) {
616: if ((flag & (B_UAREA|B_PAGET)) || rdflg == B_WRITE)
617: panic("hard IO err in swap");
618: swkill(p, (char *)0);
619: }
620: nbytes -= c;
621: dblkno += btoc(c);
622: }
623: (void) spl6();
624: bp->b_flags &= ~(B_BUSY|B_WANTED|B_PHYS|B_PAGET|B_UAREA|B_DIRTY);
625: bp->av_forw = bswlist.av_forw;
626: bswlist.av_forw = bp;
627: if (bswlist.b_flags & B_WANTED) {
628: bswlist.b_flags &= ~B_WANTED;
629: wakeup((caddr_t)&bswlist);
630: wakeup((caddr_t)&proc[2]);
631: }
632: (void) spl0();
633: }
634:
635: /*
636: * If rout == 0 then killed on swap error, else
637: * rout is the name of the routine where we ran out of
638: * swap space.
639: */
640: swkill(p, rout)
641: struct proc *p;
642: char *rout;
643: {
644: char *mesg;
645:
646: printf("pid %d: ", p->p_pid);
647: if (rout)
648: printf(mesg = "killed due to no swap space\n");
649: else
650: printf(mesg = "killed on swap error\n");
651: uprintf("sorry, pid %d was %s", p->p_pid, mesg);
652: /*
653: * To be sure no looping (e.g. in vmsched trying to
654: * swap out) mark process locked in core (as though
655: * done by user) after killing it so noone will try
656: * to swap it out.
657: */
658: psignal(p, SIGKILL);
659: p->p_flag |= SULOCK;
660: }
661:
662: /*
663: * make sure all write-behind blocks
664: * on dev (or NODEV for all)
665: * are flushed out.
666: * (from umount and update)
667: */
668: bflush(dev)
669: dev_t dev;
670: {
671: register struct buf *bp;
672: register struct buf *flist;
673:
674: loop:
675: (void) spl6();
676: for (flist = bfreelist; flist < &bfreelist[BQUEUES]; flist++)
677: for (bp = flist->av_forw; bp != flist; bp = bp->av_forw) {
678: if (bp->b_flags&B_DELWRI && (dev == NODEV||dev==bp->b_dev)) {
679: bp->b_flags |= B_ASYNC;
680: notavail(bp);
681: bwrite(bp);
682: goto loop;
683: }
684: }
685: (void) spl0();
686: }
687:
688: /*
689: * Raw I/O. The arguments are
690: * The strategy routine for the device
691: * A buffer, which will always be a special buffer
692: * header owned exclusively by the device for this purpose
693: * The device number
694: * Read/write flag
695: * Essentially all the work is computing physical addresses and
696: * validating them.
697: * If the user has the proper access privilidges, the process is
698: * marked 'delayed unlock' and the pages involved in the I/O are
699: * faulted and locked. After the completion of the I/O, the above pages
700: * are unlocked.
701: */
702: physio(strat, bp, dev, rw, mincnt)
703: int (*strat)();
704: register struct buf *bp;
705: unsigned (*mincnt)();
706: {
707: register int c;
708: char *a;
709:
710: if (useracc(u.u_base,u.u_count,rw==B_READ?B_WRITE:B_READ) == NULL) {
711: u.u_error = EFAULT;
712: return;
713: }
714: (void) spl6();
715: while (bp->b_flags&B_BUSY) {
716: bp->b_flags |= B_WANTED;
717: sleep((caddr_t)bp, PRIBIO+1);
718: }
719: bp->b_error = 0;
720: bp->b_proc = u.u_procp;
721: bp->b_un.b_addr = u.u_base;
722: while (u.u_count != 0) {
723: bp->b_flags = B_BUSY | B_PHYS | rw;
724: bp->b_dev = dev;
725: bp->b_blkno = u.u_offset >> PGSHIFT;
726: bp->b_bcount = u.u_count;
727: (*mincnt)(bp);
728: c = bp->b_bcount;
729: u.u_procp->p_flag |= SPHYSIO;
730: vslock(a = bp->b_un.b_addr, c);
731: (*strat)(bp);
732: (void) spl6();
733: while ((bp->b_flags&B_DONE) == 0)
734: sleep((caddr_t)bp, PRIBIO);
735: vsunlock(a, c, rw);
736: u.u_procp->p_flag &= ~SPHYSIO;
737: if (bp->b_flags&B_WANTED)
738: wakeup((caddr_t)bp);
739: (void) spl0();
740: bp->b_un.b_addr += c;
741: u.u_count -= c;
742: u.u_offset += c;
743: if (bp->b_flags&B_ERROR)
744: break;
745: }
746: bp->b_flags &= ~(B_BUSY|B_WANTED|B_PHYS);
747: u.u_count = bp->b_resid;
748: geterror(bp);
749: }
750:
751: /*ARGSUSED*/
752: unsigned
753: minphys(bp)
754: struct buf *bp;
755: {
756:
757: if (bp->b_bcount > 60 * 1024)
758: bp->b_bcount = 60 * 1024;
759: }
760:
761: /*
762: * Pick up the device's error number and pass it to the user;
763: * if there is an error but the number is 0 set a generalized
764: * code. Actually the latter is always true because devices
765: * don't yet return specific errors.
766: */
767: geterror(bp)
768: register struct buf *bp;
769: {
770:
771: if (bp->b_flags&B_ERROR)
772: if ((u.u_error = bp->b_error)==0)
773: u.u_error = EIO;
774: }
775:
776: /*
777: * Invalidate in core blocks belonging to closed or umounted filesystem
778: *
779: * This is not nicely done at all - the buffer ought to be removed from the
780: * hash chains & have its dev/blkno fields clobbered, but unfortunately we
781: * can't do that here, as it is quite possible that the block is still
782: * being used for i/o. Eventually, all disc drivers should be forced to
783: * have a close routine, which ought ensure that the queue is empty, then
784: * properly flush the queues. Until that happy day, this suffices for
785: * correctness. ... kre
786: */
787: binval(dev)
788: dev_t dev;
789: {
790: register struct buf *bp;
791: register struct bufhd *hp;
792: #define dp ((struct buf *)hp)
793:
794: for (hp = bufhash; hp < &bufhash[BUFHSZ]; hp++)
795: for (bp = dp->b_forw; bp != dp; bp = bp->b_forw)
796: if (bp->b_dev == dev)
797: bp->b_flags |= B_INVAL;
798: }
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