minix/drivers/fbd/action.c

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#include <minix/drivers.h>
#include <sys/ioc_fbd.h>
#include <assert.h>
#include "rule.h"
/*===========================================================================*
* get_rand *
*===========================================================================*/
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static u32_t get_rand(u32_t max)
{
/* Las Vegas algorithm for getting a random number in the range from
* 0 to max, inclusive.
*/
u32_t val, top;
/* Get an initial random number. */
val = lrand48() ^ (lrand48() << 1);
/* Make 'max' exclusive. If it wraps, we can use the full width. */
if (++max == 0) return val;
/* Find the largest multiple of the given range, and return a random
* number from the range, throwing away any random numbers not below
* this largest multiple.
*/
top = (((u32_t) -1) / max) * max;
while (val >= top)
val = lrand48() ^ (lrand48() << 1);
return val % max;
}
/*===========================================================================*
* get_range *
*===========================================================================*/
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static size_t get_range(struct fbd_rule *rule, u64_t pos, size_t *size,
u64_t *skip)
{
/* Compute the range within the given request range that is affected
* by the given rule, and optionally the number of bytes preceding
* the range that are also affected by the rule.
*/
u64_t delta;
size_t off;
int to_eof;
to_eof = cmp64(rule->start, rule->end) >= 0;
if (cmp64(pos, rule->start) > 0) {
if (skip != NULL) *skip = sub64(pos, rule->start);
off = 0;
}
else {
if (skip != NULL) *skip = ((u64_t)(0));
delta = sub64(rule->start, pos);
assert(ex64hi(delta) == 0);
off = ex64lo(delta);
}
if (!to_eof) {
assert(cmp64(pos, rule->end) < 0);
delta = sub64(rule->end, pos);
if (cmp64u(delta, *size) < 0)
*size = ex64lo(delta);
}
assert(*size > off);
*size -= off;
return off;
}
/*===========================================================================*
* limit_range *
*===========================================================================*/
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static void limit_range(iovec_t *iov, unsigned *count, size_t size)
{
/* Limit the given vector to the given size.
*/
size_t chunk;
int i;
for (i = 0; i < *count && size > 0; i++) {
chunk = MIN(iov[i].iov_size, size);
if (chunk == size)
iov[i].iov_size = size;
size -= chunk;
}
*count = i;
}
/*===========================================================================*
* action_io_corrupt *
*===========================================================================*/
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static void action_io_corrupt(struct fbd_rule *rule, char *buf, size_t size,
u64_t pos, int UNUSED(flag))
{
u64_t skip;
u32_t val;
buf += get_range(rule, pos, &size, &skip);
switch (rule->params.corrupt.type) {
case FBD_CORRUPT_ZERO:
memset(buf, 0, size);
break;
case FBD_CORRUPT_PERSIST:
/* Non-dword-aligned positions and sizes are not supported;
* not by us, and not by the driver.
*/
if (ex64lo(pos) & (sizeof(val) - 1)) break;
if (size & (sizeof(val) - 1)) break;
/* Consistently produce the same pattern for the same range. */
val = ex64lo(skip);
for ( ; size >= sizeof(val); size -= sizeof(val)) {
*((u32_t *) buf) = val ^ 0xdeadbeefUL;
val += sizeof(val);
buf += sizeof(val);
}
break;
case FBD_CORRUPT_RANDOM:
while (size--)
*buf++ = get_rand(255);
break;
default:
printf("FBD: unknown corruption type %d\n",
rule->params.corrupt.type);
}
}
/*===========================================================================*
* action_pre_error *
*===========================================================================*/
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static void action_pre_error(struct fbd_rule *rule, iovec_t *iov,
unsigned *count, size_t *size, u64_t *pos)
{
/* Limit the request to the part that precedes the matched range. */
*size = get_range(rule, *pos, size, NULL);
limit_range(iov, count, *size);
}
/*===========================================================================*
* action_post_error *
*===========================================================================*/
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static void action_post_error(struct fbd_rule *rule, size_t UNUSED(osize),
int *result)
{
/* Upon success of the first part, return the specified error code. */
if (*result >= 0 && rule->params.error.code != OK)
*result = rule->params.error.code;
}
/*===========================================================================*
* action_pre_misdir *
*===========================================================================*/
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static void action_pre_misdir(struct fbd_rule *rule, iovec_t *UNUSED(iov),
unsigned *UNUSED(count), size_t *UNUSED(size), u64_t *pos)
{
/* Randomize the request position to fall within the range (and have
* the alignment) given by the rule.
*/
u32_t range, choice;
/* Unfortunately, we cannot interpret 0 as end as "up to end of disk"
* here, because we have no idea about the actual disk size, and the
* resulting address must of course be valid..
*/
range = div64u(add64u(sub64(rule->params.misdir.end,
rule->params.misdir.start), 1), rule->params.misdir.align);
if (range > 0)
choice = get_rand(range - 1);
else
choice = 0;
*pos = add64(rule->params.misdir.start,
mul64u(choice, rule->params.misdir.align));
}
/*===========================================================================*
* action_pre_losttorn *
*===========================================================================*/
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static void action_pre_losttorn(struct fbd_rule *rule, iovec_t *iov,
unsigned *count, size_t *size, u64_t *UNUSED(pos))
{
if (*size > rule->params.losttorn.lead)
*size = rule->params.losttorn.lead;
limit_range(iov, count, *size);
}
/*===========================================================================*
* action_post_losttorn *
*===========================================================================*/
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static void action_post_losttorn(struct fbd_rule *UNUSED(rule), size_t osize,
int *result)
{
/* On success, pretend full completion. */
if (*result < 0) return;
*result = osize;
}
/*===========================================================================*
* action_mask *
*===========================================================================*/
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int action_mask(struct fbd_rule *rule)
{
/* Return the hook mask for the given rule's action type. */
switch (rule->action) {
case FBD_ACTION_CORRUPT: return IO_HOOK;
case FBD_ACTION_ERROR: return PRE_HOOK | POST_HOOK;
case FBD_ACTION_MISDIR: return PRE_HOOK;
case FBD_ACTION_LOSTTORN: return PRE_HOOK | POST_HOOK;
default:
printf("FBD: unknown action type %d\n", rule->action);
return 0;
}
}
/*===========================================================================*
* action_pre_hook *
*===========================================================================*/
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void action_pre_hook(struct fbd_rule *rule, iovec_t *iov,
unsigned *count, size_t *size, u64_t *pos)
{
switch (rule->action) {
case FBD_ACTION_ERROR:
action_pre_error(rule, iov, count, size, pos);
break;
case FBD_ACTION_MISDIR:
action_pre_misdir(rule, iov, count, size, pos);
break;
case FBD_ACTION_LOSTTORN:
action_pre_losttorn(rule, iov, count, size, pos);
break;
default:
printf("FBD: bad action type %d for PRE hook\n", rule->action);
}
}
/*===========================================================================*
* action_io_hook *
*===========================================================================*/
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void action_io_hook(struct fbd_rule *rule, char *buf, size_t size,
u64_t pos, int flag)
{
switch (rule->action) {
case FBD_ACTION_CORRUPT:
action_io_corrupt(rule, buf, size, pos, flag);
break;
default:
printf("FBD: bad action type %d for IO hook\n", rule->action);
}
}
/*===========================================================================*
* action_post_hook *
*===========================================================================*/
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void action_post_hook(struct fbd_rule *rule, size_t osize, int *result)
{
switch (rule->action) {
case FBD_ACTION_ERROR:
action_post_error(rule, osize, result);
return;
case FBD_ACTION_LOSTTORN:
action_post_losttorn(rule, osize, result);
return;
default:
printf("FBD: bad action type %d for POST hook\n",
rule->action);
}
}