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hjfs: eleminate seek syscalls

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reduce syscalls by using pread/pwrite instead
of seek/read/write.
This commit is contained in:
cinap_lenrek 2012-11-18 12:53:31 +01:00
parent 68639edbad
commit f188f2f073
1 changed files with 12 additions and 5 deletions
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17
sys/src/cmd/hjfs/dev.c
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@ -30,20 +30,27 @@ devwork(void *v)
b->error = Einval;
goto reply;
}
seek(d->fd, b->off * BLOCK, 0);
b->error = nil;
if(b->op & BWRITE){
memset(buf, 0, sizeof(buf));
pack(b, buf);
if(write(d->fd, buf, BLOCK) < BLOCK){
if(pwrite(d->fd, buf, BLOCK, b->off*BLOCK) < BLOCK){
dprint("hjfs: write: %r\n");
b->error = Eio;
}
}else{
if(readn(d->fd, buf, BLOCK) < 0){
dprint("hjfs: read: %r\n");
int n, m;
for(n = 0; n < BLOCK; n += m){
m = pread(d->fd, buf+n, BLOCK-n, b->off*BLOCK+n);
if(m < 0)
dprint("hjfs: read: %r\n");
if(m <= 0)
break;
}
if(n < BLOCK)
b->error = Eio;
}else
else
unpack(b, buf);
}
reply: