#include <linux/device-mapper.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/blkdev.h>
#include <linux/bio.h>
#include <linux/slab.h>
#define DM_MSG_PREFIX "flakey"
#define PROBABILITY_BASE 1000000000
#define all_corrupt_bio_flags_match(bio, fc) \
(((bio)->bi_opf & (fc)->corrupt_bio_flags) == (fc)->corrupt_bio_flags)
struct flakey_c {
struct dm_dev *dev;
unsigned long start_time;
sector_t start;
unsigned int up_interval;
unsigned int down_interval;
unsigned long flags;
unsigned int corrupt_bio_byte;
unsigned int corrupt_bio_rw;
unsigned int corrupt_bio_value;
blk_opf_t corrupt_bio_flags;
unsigned int random_read_corrupt;
unsigned int random_write_corrupt;
};
enum feature_flag_bits {
ERROR_READS,
DROP_WRITES,
ERROR_WRITES
};
struct per_bio_data {
bool bio_can_corrupt;
struct bvec_iter saved_iter;
};
static int parse_features(struct dm_arg_set *as, struct flakey_c *fc,
struct dm_target *ti)
{
int r = 0;
unsigned int argc = 0;
const char *arg_name;
static const struct dm_arg _args[] = {
{0, 11, "Invalid number of feature args"},
{1, UINT_MAX, "Invalid corrupt bio byte"},
{0, 255, "Invalid corrupt value to write into bio byte (0-255)"},
{0, UINT_MAX, "Invalid corrupt bio flags mask"},
{0, PROBABILITY_BASE, "Invalid random corrupt argument"},
};
if (as->argc && (r = dm_read_arg_group(_args, as, &argc, &ti->error)))
return r;
if (!argc)
goto error_all_io;
while (argc) {
arg_name = dm_shift_arg(as);
argc--;
if (!arg_name) {
ti->error = "Insufficient feature arguments";
return -EINVAL;
}
if (!strcasecmp(arg_name, "error_reads")) {
if (test_and_set_bit(ERROR_READS, &fc->flags)) {
ti->error = "Feature error_reads duplicated";
return -EINVAL;
}
continue;
}
if (!strcasecmp(arg_name, "drop_writes")) {
if (test_and_set_bit(DROP_WRITES, &fc->flags)) {
ti->error = "Feature drop_writes duplicated";
return -EINVAL;
} else if (test_bit(ERROR_WRITES, &fc->flags)) {
ti->error = "Feature drop_writes conflicts with feature error_writes";
return -EINVAL;
}
continue;
}
if (!strcasecmp(arg_name, "error_writes")) {
if (test_and_set_bit(ERROR_WRITES, &fc->flags)) {
ti->error = "Feature error_writes duplicated";
return -EINVAL;
} else if (test_bit(DROP_WRITES, &fc->flags)) {
ti->error = "Feature error_writes conflicts with feature drop_writes";
return -EINVAL;
}
continue;
}
if (!strcasecmp(arg_name, "corrupt_bio_byte")) {
if (fc->corrupt_bio_byte) {
ti->error = "Feature corrupt_bio_byte duplicated";
return -EINVAL;
} else if (argc < 4) {
ti->error = "Feature corrupt_bio_byte requires 4 parameters";
return -EINVAL;
}
r = dm_read_arg(_args + 1, as, &fc->corrupt_bio_byte, &ti->error);
if (r)
return r;
argc--;
arg_name = dm_shift_arg(as);
if (arg_name && !strcasecmp(arg_name, "w"))
fc->corrupt_bio_rw = WRITE;
else if (arg_name && !strcasecmp(arg_name, "r"))
fc->corrupt_bio_rw = READ;
else {
ti->error = "Invalid corrupt bio direction (r or w)";
return -EINVAL;
}
argc--;
r = dm_read_arg(_args + 2, as, &fc->corrupt_bio_value, &ti->error);
if (r)
return r;
argc--;
BUILD_BUG_ON(sizeof(fc->corrupt_bio_flags) !=
sizeof(unsigned int));
r = dm_read_arg(_args + 3, as,
(__force unsigned int *)&fc->corrupt_bio_flags,
&ti->error);
if (r)
return r;
argc--;
continue;
}
if (!strcasecmp(arg_name, "random_read_corrupt")) {
if (fc->random_read_corrupt) {
ti->error = "Feature random_read_corrupt duplicated";
return -EINVAL;
} else if (!argc) {
ti->error = "Feature random_read_corrupt requires a parameter";
return -EINVAL;
}
r = dm_read_arg(_args + 4, as, &fc->random_read_corrupt, &ti->error);
if (r)
return r;
argc--;
continue;
}
if (!strcasecmp(arg_name, "random_write_corrupt")) {
if (fc->random_write_corrupt) {
ti->error = "Feature random_write_corrupt duplicated";
return -EINVAL;
} else if (!argc) {
ti->error = "Feature random_write_corrupt requires a parameter";
return -EINVAL;
}
r = dm_read_arg(_args + 4, as, &fc->random_write_corrupt, &ti->error);
if (r)
return r;
argc--;
continue;
}
ti->error = "Unrecognised flakey feature requested";
return -EINVAL;
}
if (test_bit(DROP_WRITES, &fc->flags) &&
((fc->corrupt_bio_byte && fc->corrupt_bio_rw == WRITE) ||
fc->random_write_corrupt)) {
ti->error = "drop_writes is incompatible with random_write_corrupt or corrupt_bio_byte with the WRITE flag set";
return -EINVAL;
} else if (test_bit(ERROR_WRITES, &fc->flags) &&
((fc->corrupt_bio_byte && fc->corrupt_bio_rw == WRITE) ||
fc->random_write_corrupt)) {
ti->error = "error_writes is incompatible with random_write_corrupt or corrupt_bio_byte with the WRITE flag set";
return -EINVAL;
} else if (test_bit(ERROR_READS, &fc->flags) &&
((fc->corrupt_bio_byte && fc->corrupt_bio_rw == READ) ||
fc->random_read_corrupt)) {
ti->error = "error_reads is incompatible with random_read_corrupt or corrupt_bio_byte with the READ flag set";
return -EINVAL;
}
if (!fc->corrupt_bio_byte && !test_bit(ERROR_READS, &fc->flags) &&
!test_bit(DROP_WRITES, &fc->flags) && !test_bit(ERROR_WRITES, &fc->flags) &&
!fc->random_read_corrupt && !fc->random_write_corrupt) {
error_all_io:
set_bit(ERROR_WRITES, &fc->flags);
set_bit(ERROR_READS, &fc->flags);
}
return 0;
}
static int flakey_ctr(struct dm_target *ti, unsigned int argc, char **argv)
{
static const struct dm_arg _args[] = {
{0, UINT_MAX, "Invalid up interval"},
{0, UINT_MAX, "Invalid down interval"},
};
int r;
struct flakey_c *fc;
unsigned long long tmpll;
struct dm_arg_set as;
const char *devname;
char dummy;
as.argc = argc;
as.argv = argv;
if (argc < 4) {
ti->error = "Invalid argument count";
return -EINVAL;
}
fc = kzalloc_obj(*fc);
if (!fc) {
ti->error = "Cannot allocate context";
return -ENOMEM;
}
fc->start_time = jiffies;
devname = dm_shift_arg(&as);
r = -EINVAL;
if (sscanf(dm_shift_arg(&as), "%llu%c", &tmpll, &dummy) != 1 || tmpll != (sector_t)tmpll) {
ti->error = "Invalid device sector";
goto bad;
}
fc->start = tmpll;
r = dm_read_arg(_args, &as, &fc->up_interval, &ti->error);
if (r)
goto bad;
r = dm_read_arg(_args + 1, &as, &fc->down_interval, &ti->error);
if (r)
goto bad;
if (!(fc->up_interval + fc->down_interval)) {
ti->error = "Total (up + down) interval is zero";
r = -EINVAL;
goto bad;
}
if (fc->up_interval + fc->down_interval < fc->up_interval) {
ti->error = "Interval overflow";
r = -EINVAL;
goto bad;
}
r = parse_features(&as, fc, ti);
if (r)
goto bad;
r = dm_get_device(ti, devname, dm_table_get_mode(ti->table), &fc->dev);
if (r) {
ti->error = "Device lookup failed";
goto bad;
}
ti->num_flush_bios = 1;
ti->num_discard_bios = 1;
ti->per_io_data_size = sizeof(struct per_bio_data);
ti->private = fc;
return 0;
bad:
kfree(fc);
return r;
}
static void flakey_dtr(struct dm_target *ti)
{
struct flakey_c *fc = ti->private;
dm_put_device(ti, fc->dev);
kfree(fc);
}
static sector_t flakey_map_sector(struct dm_target *ti, sector_t bi_sector)
{
struct flakey_c *fc = ti->private;
return fc->start + dm_target_offset(ti, bi_sector);
}
static void flakey_map_bio(struct dm_target *ti, struct bio *bio)
{
struct flakey_c *fc = ti->private;
bio_set_dev(bio, fc->dev->bdev);
bio->bi_iter.bi_sector = flakey_map_sector(ti, bio->bi_iter.bi_sector);
}
static void corrupt_bio_common(struct bio *bio, unsigned int corrupt_bio_byte,
unsigned char corrupt_bio_value,
struct bvec_iter start)
{
struct bvec_iter iter;
struct bio_vec bvec;
__bio_for_each_segment(bvec, bio, iter, start) {
if (bio_iter_len(bio, iter) > corrupt_bio_byte) {
unsigned char *segment = bvec_kmap_local(&bvec);
segment[corrupt_bio_byte] = corrupt_bio_value;
kunmap_local(segment);
DMDEBUG("Corrupting data bio=%p by writing %u to byte %u "
"(rw=%c bi_opf=%u bi_sector=%llu size=%u)\n",
bio, corrupt_bio_value, corrupt_bio_byte,
(bio_data_dir(bio) == WRITE) ? 'w' : 'r', bio->bi_opf,
(unsigned long long)start.bi_sector,
start.bi_size);
break;
}
corrupt_bio_byte -= bio_iter_len(bio, iter);
}
}
static void corrupt_bio_data(struct bio *bio, struct flakey_c *fc,
struct bvec_iter start)
{
unsigned int corrupt_bio_byte = fc->corrupt_bio_byte - 1;
corrupt_bio_common(bio, corrupt_bio_byte, fc->corrupt_bio_value, start);
}
static void corrupt_bio_random(struct bio *bio, struct bvec_iter start)
{
unsigned int corrupt_byte;
unsigned char corrupt_value;
corrupt_byte = get_random_u32() % start.bi_size;
corrupt_value = get_random_u8();
corrupt_bio_common(bio, corrupt_byte, corrupt_value, start);
}
static void clone_free(struct bio *clone)
{
struct folio_iter fi;
if (clone->bi_vcnt > 0) {
bio_for_each_folio_all(fi, clone)
folio_put(fi.folio);
}
bio_uninit(clone);
kfree(clone);
}
static void clone_endio(struct bio *clone)
{
struct bio *bio = clone->bi_private;
bio->bi_status = clone->bi_status;
clone_free(clone);
bio_endio(bio);
}
static struct bio *clone_bio(struct dm_target *ti, struct flakey_c *fc, struct bio *bio)
{
struct bio *clone;
unsigned size, remaining_size, nr_iovecs, order;
struct bvec_iter iter = bio->bi_iter;
if (unlikely(bio->bi_iter.bi_size > UIO_MAXIOV << PAGE_SHIFT))
dm_accept_partial_bio(bio, UIO_MAXIOV << PAGE_SHIFT >> SECTOR_SHIFT);
size = bio->bi_iter.bi_size;
nr_iovecs = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
clone = bio_kmalloc(nr_iovecs, GFP_NOIO | __GFP_NORETRY | __GFP_NOWARN);
if (!clone)
return NULL;
bio_init_inline(clone, fc->dev->bdev, nr_iovecs, bio->bi_opf);
clone->bi_iter.bi_sector = flakey_map_sector(ti, bio->bi_iter.bi_sector);
clone->bi_private = bio;
clone->bi_end_io = clone_endio;
remaining_size = size;
order = MAX_PAGE_ORDER;
while (remaining_size) {
struct page *pages;
unsigned size_to_add, to_copy;
unsigned char *virt;
unsigned remaining_order = __fls((remaining_size + PAGE_SIZE - 1) >> PAGE_SHIFT);
order = min(order, remaining_order);
retry_alloc_pages:
pages = alloc_pages(GFP_NOIO | __GFP_NORETRY | __GFP_NOWARN | __GFP_COMP, order);
if (unlikely(!pages)) {
if (order) {
order--;
goto retry_alloc_pages;
}
clone_free(clone);
return NULL;
}
size_to_add = min((unsigned)PAGE_SIZE << order, remaining_size);
virt = page_to_virt(pages);
to_copy = size_to_add;
do {
struct bio_vec bvec = bvec_iter_bvec(bio->bi_io_vec, iter);
unsigned this_step = min(bvec.bv_len, to_copy);
void *map = bvec_kmap_local(&bvec);
memcpy(virt, map, this_step);
kunmap_local(map);
bvec_iter_advance(bio->bi_io_vec, &iter, this_step);
to_copy -= this_step;
virt += this_step;
} while (to_copy);
__bio_add_page(clone, pages, size_to_add, 0);
remaining_size -= size_to_add;
}
return clone;
}
static int flakey_map(struct dm_target *ti, struct bio *bio)
{
struct flakey_c *fc = ti->private;
unsigned int elapsed;
struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data));
pb->bio_can_corrupt = false;
if (op_is_zone_mgmt(bio_op(bio)))
goto map_bio;
elapsed = (jiffies - fc->start_time) / HZ;
if (elapsed % (fc->up_interval + fc->down_interval) >= fc->up_interval) {
bool corrupt_fixed, corrupt_random;
if (bio_has_data(bio)) {
pb->bio_can_corrupt = true;
pb->saved_iter = bio->bi_iter;
}
if (bio_data_dir(bio) == READ) {
if (test_bit(ERROR_READS, &fc->flags))
return DM_MAPIO_KILL;
goto map_bio;
}
if (test_bit(DROP_WRITES, &fc->flags)) {
bio_endio(bio);
return DM_MAPIO_SUBMITTED;
} else if (test_bit(ERROR_WRITES, &fc->flags)) {
bio_io_error(bio);
return DM_MAPIO_SUBMITTED;
}
if (!pb->bio_can_corrupt)
goto map_bio;
corrupt_fixed = false;
corrupt_random = false;
if (fc->corrupt_bio_byte && fc->corrupt_bio_rw == WRITE) {
if (all_corrupt_bio_flags_match(bio, fc))
corrupt_fixed = true;
}
if (fc->random_write_corrupt) {
u64 rnd = get_random_u64();
u32 rem = do_div(rnd, PROBABILITY_BASE);
if (rem < fc->random_write_corrupt)
corrupt_random = true;
}
if (corrupt_fixed || corrupt_random) {
struct bio *clone = clone_bio(ti, fc, bio);
if (clone) {
if (corrupt_fixed)
corrupt_bio_data(clone, fc,
clone->bi_iter);
if (corrupt_random)
corrupt_bio_random(clone,
clone->bi_iter);
submit_bio(clone);
return DM_MAPIO_SUBMITTED;
}
}
}
map_bio:
flakey_map_bio(ti, bio);
return DM_MAPIO_REMAPPED;
}
static int flakey_end_io(struct dm_target *ti, struct bio *bio,
blk_status_t *error)
{
struct flakey_c *fc = ti->private;
struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data));
if (op_is_zone_mgmt(bio_op(bio)))
return DM_ENDIO_DONE;
if (!*error && pb->bio_can_corrupt && (bio_data_dir(bio) == READ)) {
if (fc->corrupt_bio_byte) {
if ((fc->corrupt_bio_rw == READ) &&
all_corrupt_bio_flags_match(bio, fc)) {
corrupt_bio_data(bio, fc, pb->saved_iter);
}
}
if (fc->random_read_corrupt) {
u64 rnd = get_random_u64();
u32 rem = do_div(rnd, PROBABILITY_BASE);
if (rem < fc->random_read_corrupt)
corrupt_bio_random(bio, pb->saved_iter);
}
}
return DM_ENDIO_DONE;
}
static void flakey_status(struct dm_target *ti, status_type_t type,
unsigned int status_flags, char *result, unsigned int maxlen)
{
unsigned int sz = 0;
struct flakey_c *fc = ti->private;
unsigned int error_reads, drop_writes, error_writes;
switch (type) {
case STATUSTYPE_INFO:
result[0] = '\0';
break;
case STATUSTYPE_TABLE:
DMEMIT("%s %llu %u %u", fc->dev->name,
(unsigned long long)fc->start, fc->up_interval,
fc->down_interval);
error_reads = test_bit(ERROR_READS, &fc->flags);
drop_writes = test_bit(DROP_WRITES, &fc->flags);
error_writes = test_bit(ERROR_WRITES, &fc->flags);
DMEMIT(" %u", error_reads + drop_writes + error_writes +
(fc->corrupt_bio_byte > 0) * 5 +
(fc->random_read_corrupt > 0) * 2 +
(fc->random_write_corrupt > 0) * 2);
if (error_reads)
DMEMIT(" error_reads");
if (drop_writes)
DMEMIT(" drop_writes");
else if (error_writes)
DMEMIT(" error_writes");
if (fc->corrupt_bio_byte)
DMEMIT(" corrupt_bio_byte %u %c %u %u",
fc->corrupt_bio_byte,
(fc->corrupt_bio_rw == WRITE) ? 'w' : 'r',
fc->corrupt_bio_value, fc->corrupt_bio_flags);
if (fc->random_read_corrupt > 0)
DMEMIT(" random_read_corrupt %u", fc->random_read_corrupt);
if (fc->random_write_corrupt > 0)
DMEMIT(" random_write_corrupt %u", fc->random_write_corrupt);
break;
case STATUSTYPE_IMA:
result[0] = '\0';
break;
}
}
static int flakey_prepare_ioctl(struct dm_target *ti, struct block_device **bdev,
unsigned int cmd, unsigned long arg,
bool *forward)
{
struct flakey_c *fc = ti->private;
*bdev = fc->dev->bdev;
if (fc->start || ti->len != bdev_nr_sectors((*bdev)))
return 1;
return 0;
}
#ifdef CONFIG_BLK_DEV_ZONED
static int flakey_report_zones(struct dm_target *ti,
struct dm_report_zones_args *args, unsigned int nr_zones)
{
struct flakey_c *fc = ti->private;
return dm_report_zones(fc->dev->bdev, fc->start,
flakey_map_sector(ti, args->next_sector),
args, nr_zones);
}
#else
#define flakey_report_zones NULL
#endif
static int flakey_iterate_devices(struct dm_target *ti, iterate_devices_callout_fn fn, void *data)
{
struct flakey_c *fc = ti->private;
return fn(ti, fc->dev, fc->start, ti->len, data);
}
static struct target_type flakey_target = {
.name = "flakey",
.version = {1, 5, 0},
.features = DM_TARGET_ZONED_HM | DM_TARGET_PASSES_CRYPTO,
.report_zones = flakey_report_zones,
.module = THIS_MODULE,
.ctr = flakey_ctr,
.dtr = flakey_dtr,
.map = flakey_map,
.end_io = flakey_end_io,
.status = flakey_status,
.prepare_ioctl = flakey_prepare_ioctl,
.iterate_devices = flakey_iterate_devices,
};
module_dm(flakey);
MODULE_DESCRIPTION(DM_NAME " flakey target");
MODULE_AUTHOR("Joe Thornber <dm-devel@lists.linux.dev>");
MODULE_LICENSE("GPL");
