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venti: avoid race in mirrorarenas (Michael Kaminsky)

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This commit is contained in:
Russ Cox 2007-08-23 11:10:58 -04:00
parent 92baf59b69
commit 6610dac99c
1 changed files with 3 additions and 6 deletions
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9
src/cmd/venti/srv/mirrorarenas.c
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@ -93,6 +93,7 @@ ewritepart(Part *p, u64int offset, u8int *buf, u32int count)
* src with writing dst during copy. This is an easy factor of two
* (almost) in performance.
*/
static Write wsync;
static void
writeproc(void *v)
{
@ -100,7 +101,7 @@ writeproc(void *v)
USED(v);
while((w = recvp(writechan)) != nil){
if(w->n == 0)
if(w == &wsync)
continue;
if(ewritepart(dst, w->o, w->p, w->n) < 0)
w->error = 1;
@ -147,11 +148,7 @@ copy(uvlong start, uvlong end, char *what, DigestState *ds)
/*
* wait for queued write to finish
*/
w[i].p = nil;
w[i].o = 0;
w[i].n = 0;
w[i].error = 0;
sendp(writechan, &w[i]);
sendp(writechan, &wsync);
i = 1-i;
if(w[i].error)
return -1;