ref: 3f869a689403c385ca761be5535a5de2db054db4
dir: /sys/src/cmd/disk/kfs/iobuf.c/
#include "all.h" #define DEBUG 0 long niob; long nhiob; Hiob *hiob; Iobuf* getbuf(Device dev, long addr, int flag) { Iobuf *p, *s; Hiob *hp; long h; if(DEBUG) print("getbuf %D(%ld) f=%x\n", dev, addr, flag); h = addr + dev.type*1009L + dev.ctrl*10007L + dev.unit*100003L + dev.part*1000003L; if(h < 0) h = ~h; h %= nhiob; hp = &hiob[h]; loop: lock(hp); /* * look for it in the active list */ s = hp->link; for(p=s;;) { if(p->addr == addr && !devcmp(p->dev, dev)) { if(p != s) { p->back->fore = p->fore; p->fore->back = p->back; p->fore = s; p->back = s->back; s->back = p; p->back->fore = p; hp->link = p; } unlock(hp); qlock(p); if(p->addr != addr || devcmp(p->dev, dev)) { qunlock(p); goto loop; } p->flags |= flag; cons.bhit.count++; p->iobuf = p->xiobuf; return p; } p = p->fore; if(p == s) break; } if(flag & Bprobe) { unlock(hp); return 0; } /* * not found * take oldest unlocked entry in this queue */ xloop: p = s->back; if(!canqlock(p)) { if(p == hp->link) { unlock(hp); print("iobuf all locked\n"); goto loop; } s = p; goto xloop; } /* * its dangerous to flush the pseudo * devices since they recursively call * getbuf/putbuf. deadlock! */ if(p->flags & Bres) { qunlock(p); if(p == hp->link) { unlock(hp); print("iobuf all resed\n"); goto loop; } s = p; goto xloop; } if(p->flags & Bmod) { unlock(hp); if(!devwrite(p->dev, p->addr, p->xiobuf)) p->flags &= ~(Bimm|Bmod); qunlock(p); goto loop; } hp->link = p; p->addr = addr; p->dev = dev; p->flags = flag; unlock(hp); p->iobuf = p->xiobuf; if(flag & Bread) { if(devread(p->dev, p->addr, p->iobuf)) { p->flags = 0; p->dev = devnone; p->addr = -1; p->iobuf = (char*)-1; qunlock(p); return 0; } cons.bread.count++; return p; } cons.binit.count++; return p; } /* * syncblock tries to put out a block per hashline * returns 0 all done, * returns 1 if it missed something */ int syncblock(void) { Iobuf *p, *s, *q; Hiob *hp; long h; int flag; flag = 0; for(h=0; h<nhiob; h++) { q = 0; hp = &hiob[h]; lock(hp); s = hp->link; for(p=s;;) { if(p->flags & Bmod) { if(q) flag = 1; /* more than 1 mod/line */ q = p; } p = p->fore; if(p == s) break; } unlock(hp); if(q) { if(!canqlock(q)) { flag = 1; /* missed -- was locked */ continue; } if(!(q->flags & Bmod)) { qunlock(q); continue; } if(!devwrite(q->dev, q->addr, q->xiobuf)) q->flags &= ~(Bmod|Bimm); qunlock(q); } } return flag; } void sync(char *reason) { long i; print("sync: %s\n", reason); for(i=10*nhiob; i>0; i--) if(!syncblock()) return; print("sync shorted\n"); } void putbuf(Iobuf *p) { if(canqlock(p)) print("buffer not locked %D(%ld)\n", p->dev, p->addr); if(p->flags & Bimm) { if(!(p->flags & Bmod)) print("imm and no mod %D(%ld)\n", p->dev, p->addr); if(!devwrite(p->dev, p->addr, p->iobuf)) p->flags &= ~(Bmod|Bimm); } p->iobuf = (char*)-1; qunlock(p); } int checktag(Iobuf *p, int tag, long qpath) { Tag *t; t = (Tag*)(p->iobuf+BUFSIZE); if(t->tag != tag) { if(1 || CHAT(0)) print(" tag = %G; expected %G; addr = %lud\n", t->tag, tag, p->addr); return 2; } if(qpath != QPNONE) { qpath &= ~QPDIR; if(qpath != t->path) { if(qpath == (t->path&~QPDIR)) /* old bug */ return 0; if(1 || CHAT(0)) print(" tag/path = %lux; expected %G/%lux\n", t->path, tag, qpath); return 1; } } return 0; } void settag(Iobuf *p, int tag, long qpath) { Tag *t; t = (Tag*)(p->iobuf+BUFSIZE); t->tag = tag; if(qpath != QPNONE) t->path = qpath & ~QPDIR; p->flags |= Bmod; }