ref: 15d1425b276495a82621a8d075176a59a512cdf3
dir: /sys/src/cmd/dossrv/iotrack.c/
#include <u.h> #include <libc.h> #include "iotrack.h" #include "dat.h" #include "fns.h" static MLock freelock; static Iosect * freelist; #define HIOB 31 /* a prime */ #define NIOBUF 80 static Iotrack hiob[HIOB+1]; /* hash buckets + lru list */ static Iotrack iobuf[NIOBUF]; /* the real ones */ #define UNLINK(p, nx, pr) ((p)->pr->nx = (p)->nx, (p)->nx->pr = (p)->pr) #define LINK(h, p, nx, pr) ((p)->nx = (h)->nx, (p)->pr = (h), \ (h)->nx->pr = (p), (h)->nx = (p)) #define HTOFRONT(h, p) ((h)->hnext != (p) && (UNLINK(p,hnext,hprev), LINK(h,p,hnext,hprev))) #define TOFRONT(h, p) ((h)->next != (p) && (UNLINK(p, next, prev), LINK(h,p, next, prev))) static Iotrack *getiotrack(Xfs*, vlong); static Iosect *getiosect(Xfs*, vlong, int); static void purgetrack(Iotrack*); Iosect * getsect(Xfs *xf, vlong addr) { return getiosect(xf, addr, 1); } Iosect * getosect(Xfs *xf, vlong addr) { return getiosect(xf, addr, 0); } static Iosect * getiosect(Xfs *xf, vlong addr, int rflag) { vlong taddr; int toff; Iotrack *t; Iosect *p; if(addr < 0) return nil; toff = addr % xf->sect2trk; taddr = addr - toff; t = getiotrack(xf, taddr); if(t == nil) return nil; if(rflag && (t->flags&BSTALE)){ if(tread(t) < 0){ unmlock(&t->lock); return nil; } t->flags &= ~BSTALE; } p = t->tp[toff]; if(p == nil){ mlock(&freelock); p = freelist; if(p != nil) freelist = p->next; else { p = malloc(sizeof(Iosect)); if(p == nil) { unmlock(&freelock); unmlock(&t->lock); return nil; } } p->next = nil; unmlock(&freelock); p->flags = t->flags&BSTALE; p->lock.key = 0; p->iobuf = ((uchar*)&t->tp[xf->sect2trk]) + toff*xf->sectsize; p->t = t; t->tp[toff] = p; } t->ref++; unmlock(&t->lock); mlock(&p->lock); return p; } void putsect(Iosect *p) { Iotrack *t; if(canmlock(&p->lock)) panic("putsect"); t = p->t; mlock(&t->lock); t->flags |= p->flags; p->flags = 0; t->ref--; if(t->flags & BIMM){ if(t->flags & BMOD) twrite(t); t->flags &= ~(BMOD|BIMM); } unmlock(&t->lock); unmlock(&p->lock); } static Iotrack * getiotrack(Xfs *xf, vlong addr) { Iotrack *hp, *p; Iotrack *mp = &hiob[HIOB]; long h; /* * chat("iotrack %d,%d...", dev, addr); */ h = (xf->dev<<24) ^ (long)addr; if(h < 0) h = ~h; h %= HIOB; hp = &hiob[h]; loop: /* * look for it in the active list */ mlock(&hp->lock); for(p=hp->hnext; p != hp; p=p->hnext){ if(p->addr != addr || p->xf != xf) continue; unmlock(&hp->lock); mlock(&p->lock); if(p->addr == addr && p->xf == xf) goto out; unmlock(&p->lock); goto loop; } unmlock(&hp->lock); /* * not found * take oldest unref'd entry */ mlock(&mp->lock); for(p=mp->prev; p != mp; p=p->prev) if(p->ref == 0 && canmlock(&p->lock)){ if(p->ref == 0) break; unmlock(&p->lock); } unmlock(&mp->lock); if(p == mp){ fprint(2, "iotrack all ref'd\n"); goto loop; } if(p->flags & BMOD){ twrite(p); p->flags &= ~(BMOD|BIMM); unmlock(&p->lock); goto loop; } purgetrack(p); p->tp = malloc(xf->sect2trk*sizeof(Iosect*) + xf->sect2trk*xf->sectsize); if(p->tp == nil){ unmlock(&p->lock); return nil; } memset(p->tp, 0, xf->sect2trk*sizeof(Iosect*)); p->xf = xf; p->addr = addr; p->flags = BSTALE; out: mlock(&hp->lock); HTOFRONT(hp, p); unmlock(&hp->lock); mlock(&mp->lock); TOFRONT(mp, p); unmlock(&mp->lock); return p; } static void purgetrack(Iotrack *t) { if(t->tp != nil){ Xfs *xf = t->xf; int i, ref = xf->sect2trk; for(i=0; i<xf->sect2trk; i++){ Iosect *p = t->tp[i]; if(p == nil){ --ref; continue; } if(canmlock(&p->lock)){ t->tp[i] = nil; mlock(&freelock); p->next = freelist; freelist = p; unmlock(&freelock); --ref; } } if(t->ref != ref) panic("purgetrack"); if(ref != 0) return; free(t->tp); } assert(t->ref == 0); t->tp = nil; t->xf = nil; t->addr = -1; t->flags = 0; } int twrite(Iotrack *t) { Xfs *xf = t->xf; chat("[twrite %lld+%lld...", t->addr, xf->offset); if(t->flags & BSTALE){ int i, ref = 0; for(i=0; i<xf->sect2trk; i++) if(t->tp[i] != nil) ++ref; if(ref < xf->sect2trk){ if(tread(t) < 0){ chat("error]"); return -1; } }else t->flags &= ~BSTALE; } if(devwrite(xf, t->addr, (uchar*)&t->tp[xf->sect2trk], xf->sect2trk*xf->sectsize) < 0){ chat("error]"); return -1; } chat(" done]"); return 0; } int tread(Iotrack *t) { Xfs *xf = t->xf; int i, ref = 0; chat("[tread %lld+%lld...", t->addr, xf->offset); for(i=0; i<xf->sect2trk; i++) if(t->tp[i] != nil) ++ref; if(ref == 0){ if(devread(xf, t->addr, (uchar*)&t->tp[xf->sect2trk], xf->sect2trk*xf->sectsize) < 0){ chat("error]"); return -1; } } else { for(i=0; i<xf->sect2trk; i++){ if(t->tp[i] != nil) continue; if(devread(xf, t->addr + i, ((uchar*)&t->tp[xf->sect2trk]) + i*xf->sectsize, xf->sectsize) < 0){ chat("error]"); return -1; } chat("%d ", i); } } t->flags &= ~BSTALE; chat("done]"); return 0; } void purgebuf(Xfs *xf) { Iotrack *p; for(p=&iobuf[0]; p<&iobuf[NIOBUF]; p++){ if(p->xf != xf) continue; mlock(&p->lock); if(p->xf == xf){ if(p->flags & BMOD) twrite(p); p->flags = BSTALE; purgetrack(p); } unmlock(&p->lock); } } void sync(void) { Iotrack *p; for(p=&iobuf[0]; p<&iobuf[NIOBUF]; p++){ if(!(p->flags & BMOD)) continue; mlock(&p->lock); if(p->flags & BMOD){ twrite(p); p->flags &= ~(BMOD|BIMM); } unmlock(&p->lock); } } void iotrack_init(void) { Iotrack *mp, *p; for (mp=&hiob[0]; mp<&hiob[HIOB]; mp++) mp->hprev = mp->hnext = mp; mp->prev = mp->next = mp; for (p=&iobuf[0]; p<&iobuf[NIOBUF]; p++) { p->hprev = p->hnext = p; p->prev = p->next = p; TOFRONT(mp, p); purgetrack(p); } }