ref: a090f5f5efa78bb496bd9f033903f842250dc7f3
dir: /kern/exportfs.c/
#include "u.h" #include "lib.h" #include "dat.h" #include "fns.h" #include "error.h" typedef struct Fid Fid; typedef struct Export Export; typedef struct Exq Exq; #define nil ((void*)0) enum { Nfidhash = 1, MAXRPC = MAXMSG+MAXFDATA, MAXDIRREAD = (MAXFDATA/DIRLEN)*DIRLEN }; struct Export { Ref r; Exq* work; Lock fidlock; Fid* fid[Nfidhash]; Chan* root; Chan* io; Pgrp* pgrp; int npart; char part[MAXRPC]; }; struct Fid { Fid* next; Fid** last; Chan* chan; long offset; int fid; int ref; /* fcalls using the fid; locked by Export.Lock */ int attached; /* fid attached or cloned but not clunked */ }; struct Exq { Lock lk; int nointr; int noresponse; /* don't respond to this one */ Exq* next; int shut; /* has been noted for shutdown */ Export* export; void* slave; Fcall rpc; char buf[MAXRPC]; }; struct { Lock l; Qlock qwait; Rendez rwait; Exq *head; /* work waiting for a slave */ Exq *tail; }exq; static void exshutdown(Export*); static void exflush(Export*, int, int); static void exslave(void*); static void exfree(Export*); static void exportproc(Export*); static char* Exauth(Export*, Fcall*); static char* Exattach(Export*, Fcall*); static char* Exclunk(Export*, Fcall*); static char* Excreate(Export*, Fcall*); static char* Exopen(Export*, Fcall*); static char* Exread(Export*, Fcall*); static char* Exremove(Export*, Fcall*); static char* Exstat(Export*, Fcall*); static char* Exwalk(Export*, Fcall*); static char* Exwrite(Export*, Fcall*); static char* Exwstat(Export*, Fcall*); static char* Exversion(Export*, Fcall*); static char *(*fcalls[Tmax])(Export*, Fcall*); static char Enofid[] = "no such fid"; static char Eseekdir[] = "can't seek on a directory"; static char Ereaddir[] = "unaligned read of a directory"; static int exdebug = 0; int sysexport(int fd) { Chan *c; Export *fs; if(waserror()) return -1; c = fdtochan(fd, ORDWR, 1, 1); poperror(); c->flag |= CMSG; fs = mallocz(sizeof(Export)); fs->r.ref = 1; fs->pgrp = up->pgrp; refinc(&fs->pgrp->r); refinc(&up->slash->r); fs->root = up->slash; refinc(&fs->root->r); fs->root = domount(fs->root); fs->io = c; exportproc(fs); return 0; } static void exportinit(void) { lock(&exq.l); if(fcalls[Tversion] != nil) { unlock(&exq.l); return; } fmtinstall('F', fcallfmt); fmtinstall('D', dirfmt); fmtinstall('M', dirmodefmt); fcalls[Tversion] = Exversion; fcalls[Tauth] = Exauth; fcalls[Tattach] = Exattach; fcalls[Twalk] = Exwalk; fcalls[Topen] = Exopen; fcalls[Tcreate] = Excreate; fcalls[Tread] = Exread; fcalls[Twrite] = Exwrite; fcalls[Tclunk] = Exclunk; fcalls[Tremove] = Exremove; fcalls[Tstat] = Exstat; fcalls[Twstat] = Exwstat; unlock(&exq.l); } void exportproc(Export *fs) { Exq *q; char *buf; int n, cn, len; exportinit(); for(;;){ q = mallocz(sizeof(Exq)); if(q == 0) panic("no memory"); q->rpc.data = q->buf + MAXMSG; buf = q->buf; len = MAXRPC; if(fs->npart) { memmove(buf, fs->part, fs->npart); buf += fs->npart; len -= fs->npart; goto chk; } for(;;) { if(waserror()) goto bad; n = (*devtab[fs->io->type].read)(fs->io, buf, len, 0); poperror(); if(n <= 0) goto bad; buf += n; len -= n; chk: n = buf - q->buf; /* convM2S returns size of correctly decoded message */ cn = convM2S(q->buf, &q->rpc, n); if(cn < 0){ iprint("bad message type in devmnt\n"); goto bad; } if(cn > 0) { n -= cn; if(n < 0){ iprint("negative size in devmnt"); goto bad; } fs->npart = n; if(n != 0) memmove(fs->part, q->buf+cn, n); break; } } if(exdebug) iprint("export %d <- %F\n", getpid(), &q->rpc); if(q->rpc.type == Tflush){ exflush(fs, q->rpc.tag, q->rpc.oldtag); free(q); continue; } q->export = fs; refinc(&fs->r); lock(&exq.l); if(exq.head == nil) exq.head = q; else exq.tail->next = q; q->next = nil; exq.tail = q; unlock(&exq.l); if(exq.qwait.first == nil) { n = thread("exportfs", exslave, nil); /* iprint("launch export (pid=%ux)\n", n); */ } rendwakeup(&exq.rwait); } bad: free(q); exshutdown(fs); exfree(fs); } void exflush(Export *fs, int flushtag, int tag) { Exq *q, **last; int n; Fcall fc; char buf[MAXMSG]; /* hasn't been started? */ lock(&exq.l); last = &exq.head; for(q = exq.head; q != nil; q = q->next){ if(q->export == fs && q->rpc.tag == tag){ *last = q->next; unlock(&exq.l); exfree(fs); free(q); goto Respond; } last = &q->next; } unlock(&exq.l); /* in progress? */ lock(&fs->r.l); for(q = fs->work; q != nil; q = q->next){ if(q->rpc.tag == tag && !q->noresponse){ lock(&q->lk); q->noresponse = 1; if(!q->nointr) intr(q->slave); unlock(&q->lk); unlock(&fs->r.l); goto Respond; return; } } unlock(&fs->r.l); if(exdebug) iprint("exflush: did not find rpc: %d\n", tag); Respond: fc.type = Rflush; fc.tag = flushtag; n = convS2M(&fc, buf); if(exdebug) iprint("exflush -> %F\n", &fc); if(!waserror()){ (*devtab[fs->io->type].write)(fs->io, buf, n, 0); poperror(); } } void exshutdown(Export *fs) { Exq *q, **last; lock(&exq.l); last = &exq.head; for(q = exq.head; q != nil; q = *last){ if(q->export == fs){ *last = q->next; exfree(fs); free(q); continue; } last = &q->next; } unlock(&exq.l); lock(&fs->r.l); q = fs->work; while(q != nil){ if(q->shut){ q = q->next; continue; } q->shut = 1; unlock(&fs->r.l); /* postnote(q->slave, 1, "interrupted", NUser); */ iprint("postnote 2!\n"); lock(&fs->r.l); q = fs->work; } unlock(&fs->r.l); } void exfree(Export *fs) { Fid *f, *n; int i; if(refdec(&fs->r) != 0) return; closepgrp(fs->pgrp); cclose(fs->root); cclose(fs->io); for(i = 0; i < Nfidhash; i++){ for(f = fs->fid[i]; f != nil; f = n){ if(f->chan != nil) cclose(f->chan); n = f->next; free(f); } } free(fs); } int exwork(void *a) { return exq.head != nil; } void exslave(void *a) { Export *fs; Exq *q, *t, **last; char *err; int n; /* closepgrp(up->pgrp); up->pgrp = nil; */ for(;;){ qlock(&exq.qwait); rendsleep(&exq.rwait, exwork, nil); lock(&exq.l); q = exq.head; if(q == nil) { unlock(&exq.l); qunlock(&exq.qwait); continue; } exq.head = q->next; q->slave = curthread(); unlock(&exq.l); qunlock(&exq.qwait); q->noresponse = 0; q->nointr = 0; fs = q->export; lock(&fs->r.l); q->next = fs->work; fs->work = q; unlock(&fs->r.l); up->pgrp = q->export->pgrp; if(exdebug > 1) iprint("exslave dispatch %d %F\n", getpid(), &q->rpc); if(waserror()){ iprint("exslave err %r\n"); err = up->errstr; goto Err; } if(q->rpc.type >= Tmax || !fcalls[q->rpc.type]) err = "bad fcall type"; else err = (*fcalls[q->rpc.type])(fs, &q->rpc); poperror(); Err:; q->rpc.type++; if(err){ q->rpc.type = Rerror; strncpy(q->rpc.ename, err, ERRLEN); } n = convS2M(&q->rpc, q->buf); if(exdebug) iprint("exslve %d -> %F\n", getpid(), &q->rpc); lock(&q->lk); if(q->noresponse == 0){ q->nointr = 1; clearintr(); if(!waserror()){ (*devtab[fs->io->type].write)(fs->io, q->buf, n, 0); poperror(); } } unlock(&q->lk); /* * exflush might set noresponse at this point, but * setting noresponse means don't send a response now; * it's okay that we sent a response already. */ if(exdebug > 1) iprint("exslave %d written %d\n", getpid(), q->rpc.tag); lock(&fs->r.l); last = &fs->work; for(t = fs->work; t != nil; t = t->next){ if(t == q){ *last = q->next; break; } last = &t->next; } unlock(&fs->r.l); exfree(q->export); free(q); } iprint("exslave shut down"); threadexit(); } Fid* Exmkfid(Export *fs, int fid) { ulong h; Fid *f, *nf; nf = mallocz(sizeof(Fid)); if(nf == nil) return nil; lock(&fs->fidlock); h = fid % Nfidhash; for(f = fs->fid[h]; f != nil; f = f->next){ if(f->fid == fid){ unlock(&fs->fidlock); free(nf); return nil; } } nf->next = fs->fid[h]; if(nf->next != nil) nf->next->last = &nf->next; nf->last = &fs->fid[h]; fs->fid[h] = nf; nf->fid = fid; nf->ref = 1; nf->attached = 1; nf->offset = 0; nf->chan = nil; unlock(&fs->fidlock); return nf; } Fid* Exgetfid(Export *fs, int fid) { Fid *f; ulong h; lock(&fs->fidlock); h = fid % Nfidhash; for(f = fs->fid[h]; f; f = f->next) { if(f->fid == fid){ if(f->attached == 0) break; f->ref++; unlock(&fs->fidlock); return f; } } unlock(&fs->fidlock); return nil; } void Exputfid(Export *fs, Fid *f) { lock(&fs->fidlock); f->ref--; if(f->ref == 0 && f->attached == 0){ if(f->chan != nil) cclose(f->chan); f->chan = nil; *f->last = f->next; if(f->next != nil) f->next->last = f->last; unlock(&fs->fidlock); free(f); return; } unlock(&fs->fidlock); } char* Exsession(Export *e, Fcall *rpc) { memset(rpc->authid, 0, sizeof(rpc->authid)); memset(rpc->authdom, 0, sizeof(rpc->authdom)); memset(rpc->chal, 0, sizeof(rpc->chal)); return nil; } char* Exauth(Export *e, Fcall *f) { return "authentication not required"; } char* Exattach(Export *fs, Fcall *rpc) { Fid *f; f = Exmkfid(fs, rpc->fid); if(f == nil) return Einuse; if(waserror()){ f->attached = 0; Exputfid(fs, f); return up->errstr; } f->chan = clone(fs->root, nil); poperror(); rpc->qid = f->chan->qid; Exputfid(fs, f); return nil; } char* Exclone(Export *fs, Fcall *rpc) { Fid *f, *nf; if(rpc->fid == rpc->newfid) return Einuse; f = Exgetfid(fs, rpc->fid); if(f == nil) return Enofid; nf = Exmkfid(fs, rpc->newfid); if(nf == nil){ Exputfid(fs, f); return Einuse; } if(waserror()){ Exputfid(fs, f); Exputfid(fs, nf); return up->errstr; } nf->chan = clone(f->chan, nil); poperror(); Exputfid(fs, f); Exputfid(fs, nf); return nil; } char* Exclunk(Export *fs, Fcall *rpc) { Fid *f; f = Exgetfid(fs, rpc->fid); if(f != nil){ f->attached = 0; Exputfid(fs, f); } return nil; } char* Exwalk(Export *fs, Fcall *rpc) { Fid *f; Chan *c; f = Exgetfid(fs, rpc->fid); if(f == nil) return Enofid; if(waserror()){ Exputfid(fs, f); return up->errstr; } c = walk(f->chan, rpc->name, 1); if(c == nil) error(Enonexist); poperror(); f->chan = c; rpc->qid = c->qid; Exputfid(fs, f); return nil; } char* Exopen(Export *fs, Fcall *rpc) { Fid *f; Chan *c; f = Exgetfid(fs, rpc->fid); if(f == nil) return Enofid; if(waserror()){ Exputfid(fs, f); return up->errstr; } c = f->chan; c = (*devtab[c->type].open)(c, rpc->mode); poperror(); f->chan = c; f->offset = 0; rpc->qid = f->chan->qid; Exputfid(fs, f); return nil; } char* Excreate(Export *fs, Fcall *rpc) { Fid *f; Chan *c; f = Exgetfid(fs, rpc->fid); if(f == nil) return Enofid; if(waserror()){ Exputfid(fs, f); return up->errstr; } c = f->chan; if(c->mnt && !(c->flag&CCREATE)) c = createdir(c); (*devtab[c->type].create)(c, rpc->name, rpc->mode, rpc->perm); poperror(); f->chan = c; rpc->qid = f->chan->qid; Exputfid(fs, f); return nil; } char* Exread(Export *fs, Fcall *rpc) { Fid *f; Chan *c; long off; int dir, n, seek; f = Exgetfid(fs, rpc->fid); if(f == nil) return Enofid; c = f->chan; dir = c->qid.path & CHDIR; if(dir){ rpc->count -= rpc->count%DIRLEN; if(rpc->offset%DIRLEN || rpc->count==0){ Exputfid(fs, f); return Ereaddir; } if(f->offset > rpc->offset){ Exputfid(fs, f); return Eseekdir; } } if(waserror()) { Exputfid(fs, f); return up->errstr; } for(;;){ n = rpc->count; seek = 0; off = rpc->offset; if(dir && f->offset != off){ off = f->offset; n = rpc->offset - off; if(n > MAXDIRREAD) n = MAXDIRREAD; seek = 1; } if(dir && c->mnt != nil) n = unionread(c, rpc->data, n); else{ c->offset = off; n = (*devtab[c->type].read)(c, rpc->data, n, off); } if(n == 0 || !seek) break; f->offset = off + n; c->offset += n; } rpc->count = n; poperror(); Exputfid(fs, f); return nil; } char* Exwrite(Export *fs, Fcall *rpc) { Fid *f; Chan *c; f = Exgetfid(fs, rpc->fid); if(f == nil) return Enofid; if(waserror()){ Exputfid(fs, f); return up->errstr; } c = f->chan; if(c->qid.path & CHDIR) error(Eisdir); rpc->count = (*devtab[c->type].write)(c, rpc->data, rpc->count, rpc->offset); poperror(); Exputfid(fs, f); return nil; } char* Exstat(Export *fs, Fcall *rpc) { Fid *f; Chan *c; f = Exgetfid(fs, rpc->fid); if(f == nil) return Enofid; if(waserror()){ Exputfid(fs, f); return up->errstr; } c = f->chan; (*devtab[c->type].stat)(c, rpc->stat); poperror(); Exputfid(fs, f); return nil; } char* Exwstat(Export *fs, Fcall *rpc) { Fid *f; Chan *c; f = Exgetfid(fs, rpc->fid); if(f == nil) return Enofid; if(waserror()){ Exputfid(fs, f); return up->errstr; } c = f->chan; (*devtab[c->type].wstat)(c, rpc->stat); poperror(); Exputfid(fs, f); return nil; } char* Exremove(Export *fs, Fcall *rpc) { Fid *f; Chan *c; f = Exgetfid(fs, rpc->fid); if(f == nil) return Enofid; if(waserror()){ Exputfid(fs, f); return up->errstr; } c = f->chan; (*devtab[c->type].remove)(c); poperror(); /* * chan is already clunked by remove. * however, we need to recover the chan, * and follow sysremove's lead in making to point to root. */ c->type = 0; f->attached = 0; Exputfid(fs, f); return nil; }