/*
* Requests larger than 1/2 the cache size will be bypassed and go
* directly to the disk. XXX tune this.
*/
int
bcache_strategy(void *devdata, int unit, int rw, daddr_t blk, size_t size,
char *buf, size_t *rsize)
{
static int bcache_unit = -1;
struct bcache_devdata *dd = (struct bcache_devdata *)devdata;
bcache_ops++;
if(bcache_unit != unit) {
bcache_flush();
bcache_unit = unit;
}
/* bypass large requests, or when the cache is inactive */
if ((bcache_data == NULL) || ((size * 2 / bcache_blksize) > bcache_nblks)) {
DEBUG("bypass %d from %d", size / bcache_blksize, blk);
bcache_bypasses++;
return(dd->dv_strategy(dd->dv_devdata, rw, blk, size, buf, rsize));
}
switch (rw) {
case F_READ:
return read_strategy(devdata, unit, rw, blk, size, buf, rsize);
case F_WRITE:
return write_strategy(devdata, unit, rw, blk, size, buf, rsize);
}
return -1;
}
ssize_t res_counter_write(struct res_counter *counter, int member,
const char __user *userbuf, size_t nbytes, loff_t *pos,
int (*write_strategy)(char *st_buf, unsigned long long *val))
{
int ret;
char *buf, *end;
unsigned long flags;
unsigned long long tmp, *val;
buf = kmalloc(nbytes + 1, GFP_KERNEL);
ret = -ENOMEM;
if (buf == NULL)
goto out;
buf[nbytes] = '\0';
ret = -EFAULT;
if (copy_from_user(buf, userbuf, nbytes))
goto out_free;
ret = -EINVAL;
strstrip(buf);
if (write_strategy) {
if (write_strategy(buf, &tmp)) {
goto out_free;
}
} else {
tmp = simple_strtoull(buf, &end, 10);
if (*end != '\0')
goto out_free;
}
spin_lock_irqsave(&counter->lock, flags);
val = res_counter_member(counter, member);
*val = tmp;
spin_unlock_irqrestore(&counter->lock, flags);
ret = nbytes;
out_free:
kfree(buf);
out:
return ret;
}