exportfs: bring back the changes, bug was due to rendezvous group being shared by listen
exportfs used pid of slave proc as rendezvous tag. when we changed it to use Proc* memory address, there where tag collisions because listen didnt fork the rendezvous group (bug!). for now, just do rfork(RFREND) in main just in case. will fix aux/listen in a follow up changeset. -- cinap
This commit is contained in:
cinap_lenrek
parent
d7378c10d8
commit
40d71baf7f
3 changed files with 67 additions and 79 deletions
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@ -230,7 +230,7 @@ main(int argc, char **argv)
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DEBUG(DFD, "exportfs: started\n");
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rfork(RFNOTEG);
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rfork(RFNOTEG|RFREND);
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if(messagesize == 0){
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messagesize = iounit(netfd);
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@ -460,8 +460,8 @@ reply(Fcall *r, Fcall *t, char *err)
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fatal(Enomem);
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n = convS2M(t, data, messagesize);
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if(write(netfd, data, n)!=n){
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syslog(0, "exportfs", "short write: %r");
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fatal("mount write");
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/* not fatal, might have got a note due to flush */
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fprint(2, "exportfs: short write in reply: %r\n");
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}
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free(data);
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}
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@ -570,8 +570,6 @@ getsbuf(void)
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unlock(&sbufalloc);
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w = emallocz(sizeof(*w) + messagesize);
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}
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w->pid = 0;
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w->canint = 0;
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w->flushtag = NOTAG;
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return w;
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}
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@ -579,8 +577,6 @@ getsbuf(void)
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void
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putsbuf(Fsrpc *w)
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{
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w->pid = 0;
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w->canint = 0;
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w->flushtag = NOTAG;
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lock(&sbufalloc);
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w->next = sbufalloc.free;
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@ -15,8 +15,6 @@ typedef struct Qidtab Qidtab;
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struct Fsrpc
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{
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Fsrpc *next; /* freelist */
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uintptr pid; /* Pid of slave process executing the rpc */
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int canint; /* Interrupt gate */
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int flushtag; /* Tag on which to reply to flush */
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Fcall work; /* Plan 9 incoming Fcall */
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uchar buf[]; /* Data buffer */
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@ -53,9 +51,10 @@ struct File
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struct Proc
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{
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uintptr pid;
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Lock;
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Fsrpc *busy;
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Proc *next;
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int pid;
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};
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struct Qidtab
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@ -70,7 +69,6 @@ struct Qidtab
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enum
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{
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MAXPROC = 50,
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FHASHSIZE = 64,
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Fidchunk = 1000,
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Npsmpt = 32,
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@ -128,7 +126,7 @@ void freefile(File*);
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void slaveopen(Fsrpc*);
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void slaveread(Fsrpc*);
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void slavewrite(Fsrpc*);
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void blockingslave(void);
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void blockingslave(Proc*);
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void reopen(Fid *f);
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void noteproc(int, char*);
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void flushaction(void*, char*);
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@ -64,14 +64,20 @@ Xflush(Fsrpc *t)
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for(m = Proclist; m; m = m->next){
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w = m->busy;
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if(w != 0 && w->pid == m->pid && w->work.tag == t->work.oldtag) {
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if(w == nil || w->work.tag != t->work.oldtag)
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continue;
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lock(m);
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w = m->busy;
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if(w != nil && w->work.tag == t->work.oldtag) {
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w->flushtag = t->work.tag;
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DEBUG(DFD, "\tset flushtag %d\n", t->work.tag);
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if(w->canint)
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postnote(PNPROC, w->pid, "flush");
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postnote(PNPROC, m->pid, "flush");
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unlock(m);
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putsbuf(t);
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return;
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}
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unlock(m);
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}
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reply(&t->work, &rhdr, 0);
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@ -459,10 +465,10 @@ procsetname(char *fmt, ...)
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void
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slave(Fsrpc *f)
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{
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Proc *p;
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uintptr pid;
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Fcall rhdr;
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static int nproc;
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Proc *m, **l;
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Fcall rhdr;
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int pid;
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if(readonly){
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switch(f->work.type){
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@ -479,30 +485,41 @@ slave(Fsrpc *f)
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}
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}
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for(;;) {
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for(p = Proclist; p; p = p->next) {
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if(p->busy == 0) {
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f->pid = p->pid;
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p->busy = f;
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do {
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pid = (uintptr)rendezvous((void*)p->pid, f);
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}
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while(pid == ~0); /* Interrupted */
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if(pid != p->pid)
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fatal("rendezvous sync fail");
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return;
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}
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}
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for(l = &Proclist; (m = *l) != nil; l = &m->next) {
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if(m->busy != nil)
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continue;
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if(nproc >= MAXPROC){
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reply(&f->work, &rhdr, Enoprocs);
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putsbuf(f);
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return;
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m->busy = f;
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while(rendezvous(m, f) == (void*)~0)
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;
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/* swept a slave proc */
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if(f == nil){
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*l = m->next;
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free(m);
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nproc--;
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break;
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}
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f = nil;
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/*
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* as long as the number of slave procs
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* is small, dont bother sweeping.
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*/
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if(nproc < 16)
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break;
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}
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nproc++;
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pid = rfork(RFPROC|RFMEM);
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if(f == nil)
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return;
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m = emallocz(sizeof(Proc));
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pid = rfork(RFPROC|RFMEM|RFNOWAIT);
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switch(pid) {
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case -1:
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fatal("rfork");
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reply(&f->work, &rhdr, Enoprocs);
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putsbuf(f);
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free(m);
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return;
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case 0:
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if (local[0] != '\0')
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@ -511,44 +528,34 @@ slave(Fsrpc *f)
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local, remote);
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else
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procsetname("%s -> %s", local, remote);
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blockingslave();
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fatal("slave");
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blockingslave(m);
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_exits(0);
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default:
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p = emallocz(sizeof(Proc));
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p->busy = 0;
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p->pid = pid;
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p->next = Proclist;
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Proclist = p;
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while(rendezvous((void*)pid, p) == (void*)~0)
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;
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m->pid = pid;
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m->next = Proclist;
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Proclist = m;
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nproc++;
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}
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}
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}
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void
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blockingslave(void)
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blockingslave(Proc *m)
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{
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Fsrpc *p;
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Fcall rhdr;
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Proc *m;
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uintptr pid;
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notify(flushaction);
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pid = getpid();
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do {
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m = rendezvous((void*)pid, 0);
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}
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while(m == (void*)~0); /* Interrupted */
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for(;;) {
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p = rendezvous((void*)pid, (void*)pid);
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if(p == (void*)~0) /* Interrupted */
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p = rendezvous(m, nil);
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if(p == (void*)~0) /* Interrupted */
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continue;
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if(p == nil) /* Swept */
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break;
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DEBUG(DFD, "\tslave: %p %F p %p\n", pid, &p->work, p->pid);
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DEBUG(DFD, "\tslave: %d %F\n", m->pid, &p->work);
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if(p->flushtag != NOTAG)
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goto flushme;
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@ -568,13 +575,17 @@ blockingslave(void)
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default:
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reply(&p->work, &rhdr, "exportfs: slave type error");
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}
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if(p->flushtag != NOTAG) {
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flushme:
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lock(m);
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m->busy = nil;
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unlock(m);
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/* no more flushes can come in now */
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if(p->flushtag != NOTAG) {
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p->work.type = Tflush;
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p->work.tag = p->flushtag;
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reply(&p->work, &rhdr, 0);
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}
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m->busy = 0;
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putsbuf(p);
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}
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}
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@ -654,16 +665,8 @@ slaveopen(Fsrpc *p)
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path = makepath(f->f, "");
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DEBUG(DFD, "\topen: %s %d\n", path, work->mode);
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p->canint = 1;
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if(p->flushtag != NOTAG){
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free(path);
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return;
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}
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/* There is a race here I ignore because there are no locks */
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f->fid = open(path, work->mode);
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free(path);
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p->canint = 0;
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if(f->fid < 0 || (d = dirfstat(f->fid)) == nil) {
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Error:
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errstr(err, sizeof err);
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@ -703,9 +706,6 @@ slaveread(Fsrpc *p)
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}
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n = (work->count > messagesize-IOHDRSZ) ? messagesize-IOHDRSZ : work->count;
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p->canint = 1;
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if(p->flushtag != NOTAG)
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return;
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data = malloc(n);
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if(data == 0) {
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reply(work, &rhdr, Enomem);
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@ -717,14 +717,12 @@ slaveread(Fsrpc *p)
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r = preaddir(f, (uchar*)data, n, work->offset);
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else
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r = pread(f->fid, data, n, work->offset);
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p->canint = 0;
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if(r < 0) {
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free(data);
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errstr(err, sizeof err);
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reply(work, &rhdr, err);
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return;
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}
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DEBUG(DFD, "\tread: fd=%d %d bytes\n", f->fid, r);
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rhdr.data = data;
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@ -750,11 +748,7 @@ slavewrite(Fsrpc *p)
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}
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n = (work->count > messagesize-IOHDRSZ) ? messagesize-IOHDRSZ : work->count;
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p->canint = 1;
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if(p->flushtag != NOTAG)
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return;
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n = pwrite(f->fid, work->data, n, work->offset);
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p->canint = 0;
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if(n < 0) {
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errstr(err, sizeof err);
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reply(work, &rhdr, err);
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