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// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (c) 2018 Red Hat, Inc.
*
* This is a test "dust" device, which fails reads on specified
* sectors, emulating the behavior of a hard disk drive sending
* a "Read Medium Error" sense.
*
*/
#include <linux/device-mapper.h>
#include <linux/module.h>
#include <linux/rbtree.h>
#define DM_MSG_PREFIX "dust"
struct badblock {
struct rb_node node;
sector_t bb;
unsigned char wr_fail_cnt;
};
struct dust_device {
struct dm_dev *dev;
struct rb_root badblocklist;
unsigned long long badblock_count;
spinlock_t dust_lock;
unsigned int blksz;
int sect_per_block_shift;
unsigned int sect_per_block;
sector_t start;
bool fail_read_on_bb:1;
bool quiet_mode:1;
};
static struct badblock *dust_rb_search(struct rb_root *root, sector_t blk)
{
struct rb_node *node = root->rb_node;
while (node) {
struct badblock *bblk = rb_entry(node, struct badblock, node);
if (bblk->bb > blk)
node = node->rb_left;
else if (bblk->bb < blk)
node = node->rb_right;
else
return bblk;
}
return NULL;
}
static bool dust_rb_insert(struct rb_root *root, struct badblock *new)
{
struct badblock *bblk;
struct rb_node **link = &root->rb_node, *parent = NULL;
sector_t value = new->bb;
while (*link) {
parent = *link;
bblk = rb_entry(parent, struct badblock, node);
if (bblk->bb > value)
link = &(*link)->rb_left;
else if (bblk->bb < value)
link = &(*link)->rb_right;
else
return false;
}
rb_link_node(&new->node, parent, link);
rb_insert_color(&new->node, root);
return true;
}
static int dust_remove_block(struct dust_device *dd, unsigned long long block)
{
struct badblock *bblock;
unsigned long flags;
spin_lock_irqsave(&dd->dust_lock, flags);
bblock = dust_rb_search(&dd->badblocklist, block);
if (bblock == NULL) {
if (!dd->quiet_mode) {
DMERR("%s: block %llu not found in badblocklist",
__func__, block);
}
spin_unlock_irqrestore(&dd->dust_lock, flags);
return -EINVAL;
}
rb_erase(&bblock->node, &dd->badblocklist);
dd->badblock_count--;
if (!dd->quiet_mode)
DMINFO("%s: badblock removed at block %llu", __func__, block);
kfree(bblock);
spin_unlock_irqrestore(&dd->dust_lock, flags);
return 0;
}
static int dust_add_block(struct dust_device *dd, unsigned long long block,
unsigned char wr_fail_cnt)
{
struct badblock *bblock;
unsigned long flags;
bblock = kmalloc(sizeof(*bblock), GFP_KERNEL);
if (bblock == NULL) {
if (!dd->quiet_mode)
DMERR("%s: badblock allocation failed", __func__);
return -ENOMEM;
}
spin_lock_irqsave(&dd->dust_lock, flags);
bblock->bb = block;
bblock->wr_fail_cnt = wr_fail_cnt;
if (!dust_rb_insert(&dd->badblocklist, bblock)) {
if (!dd->quiet_mode) {
DMERR("%s: block %llu already in badblocklist",
__func__, block);
}
spin_unlock_irqrestore(&dd->dust_lock, flags);
kfree(bblock);
return -EINVAL;
}
dd->badblock_count++;
if (!dd->quiet_mode) {
DMINFO("%s: badblock added at block %llu with write fail count %hhu",
__func__, block, wr_fail_cnt);
}
spin_unlock_irqrestore(&dd->dust_lock, flags);
return 0;
}
static int dust_query_block(struct dust_device *dd, unsigned long long block)
{
struct badblock *bblock;
unsigned long flags;
spin_lock_irqsave(&dd->dust_lock, flags);
bblock = dust_rb_search(&dd->badblocklist, block);
if (bblock != NULL)
DMINFO("%s: block %llu found in badblocklist", __func__, block);
else
DMINFO("%s: block %llu not found in badblocklist", __func__, block);
spin_unlock_irqrestore(&dd->dust_lock, flags);
return 0;
}
static int __dust_map_read(struct dust_device *dd, sector_t thisblock)
{
struct badblock *bblk = dust_rb_search(&dd->badblocklist, thisblock);
if (bblk)
return DM_MAPIO_KILL;
return DM_MAPIO_REMAPPED;
}
static int dust_map_read(struct dust_device *dd, sector_t thisblock,
bool fail_read_on_bb)
{
unsigned long flags;
int r = DM_MAPIO_REMAPPED;
if (fail_read_on_bb) {
thisblock >>= dd->sect_per_block_shift;
spin_lock_irqsave(&dd->dust_lock, flags);
r = __dust_map_read(dd, thisblock);
spin_unlock_irqrestore(&dd->dust_lock, flags);
}
return r;
}
static int __dust_map_write(struct dust_device *dd, sector_t thisblock)
{
struct badblock *bblk = dust_rb_search(&dd->badblocklist, thisblock);
if (bblk && bblk->wr_fail_cnt > 0) {
bblk->wr_fail_cnt--;
return DM_MAPIO_KILL;
}
if (bblk) {
rb_erase(&bblk->node, &dd->badblocklist);
dd->badblock_count--;
kfree(bblk);
if (!dd->quiet_mode) {
sector_div(thisblock, dd->sect_per_block);
DMINFO("block %llu removed from badblocklist by write",
(unsigned long long)thisblock);
}
}
return DM_MAPIO_REMAPPED;
}
static int dust_map_write(struct dust_device *dd, sector_t thisblock,
bool fail_read_on_bb)
{
unsigned long flags;
int r = DM_MAPIO_REMAPPED;
if (fail_read_on_bb) {
thisblock >>= dd->sect_per_block_shift;
spin_lock_irqsave(&dd->dust_lock, flags);
r = __dust_map_write(dd, thisblock);
spin_unlock_irqrestore(&dd->dust_lock, flags);
}
return r;
}
static int dust_map(struct dm_target *ti, struct bio *bio)
{
struct dust_device *dd = ti->private;
int r;
bio_set_dev(bio, dd->dev->bdev);
bio->bi_iter.bi_sector = dd->start + dm_target_offset(ti, bio->bi_iter.bi_sector);
if (bio_data_dir(bio) == READ)
r = dust_map_read(dd, bio->bi_iter.bi_sector, dd->fail_read_on_bb);
else
r = dust_map_write(dd, bio->bi_iter.bi_sector, dd->fail_read_on_bb);
return r;
}
static bool __dust_clear_badblocks(struct rb_root *tree,
unsigned long long count)
{
struct rb_node *node = NULL, *nnode = NULL;
nnode = rb_first(tree);
if (nnode == NULL) {
BUG_ON(count != 0);
return false;
}
while (nnode) {
node = nnode;
nnode = rb_next(node);
rb_erase(node, tree);
count--;
kfree(node);
}
BUG_ON(count != 0);
BUG_ON(tree->rb_node != NULL);
return true;
}
static int dust_clear_badblocks(struct dust_device *dd)
{
unsigned long flags;
struct rb_root badblocklist;
unsigned long long badblock_count;
spin_lock_irqsave(&dd->dust_lock, flags);
badblocklist = dd->badblocklist;
badblock_count = dd->badblock_count;
dd->badblocklist = RB_ROOT;
dd->badblock_count = 0;
spin_unlock_irqrestore(&dd->dust_lock, flags);
if (!__dust_clear_badblocks(&badblocklist, badblock_count))
DMINFO("%s: no badblocks found", __func__);
else
DMINFO("%s: badblocks cleared", __func__);
return 0;
}
/*
* Target parameters:
*
* <device_path> <offset> <blksz>
*
* device_path: path to the block device
* offset: offset to data area from start of device_path
* blksz: block size (minimum 512, maximum 1073741824, must be a power of 2)
*/
static int dust_ctr(struct dm_target *ti, unsigned int argc, char **argv)
{
struct dust_device *dd;
unsigned long long tmp;
char dummy;
unsigned int blksz;
unsigned int sect_per_block;
sector_t DUST_MAX_BLKSZ_SECTORS = 2097152;
sector_t max_block_sectors = min(ti->len, DUST_MAX_BLKSZ_SECTORS);
if (argc != 3) {
ti->error = "Invalid argument count";
return -EINVAL;
}
if (kstrtouint(argv[2], 10, &blksz) || !blksz) {
ti->error = "Invalid block size parameter";
return -EINVAL;
}
if (blksz < 512) {
ti->error = "Block size must be at least 512";
return -EINVAL;
}
if (!is_power_of_2(blksz)) {
ti->error = "Block size must be a power of 2";
return -EINVAL;
}
if (to_sector(blksz) > max_block_sectors) {
ti->error = "Block size is too large";
return -EINVAL;
}
sect_per_block = (blksz >> SECTOR_SHIFT);
if (sscanf(argv[1], "%llu%c", &tmp, &dummy) != 1 || tmp != (sector_t)tmp) {
ti->error = "Invalid device offset sector";
return -EINVAL;
}
dd = kzalloc(sizeof(struct dust_device), GFP_KERNEL);
if (dd == NULL) {
ti->error = "Cannot allocate context";
return -ENOMEM;
}
if (dm_get_device(ti, argv[0], dm_table_get_mode(ti->table), &dd->dev)) {
ti->error = "Device lookup failed";
kfree(dd);
return -EINVAL;
}
dd->sect_per_block = sect_per_block;
dd->blksz = blksz;
dd->start = tmp;
dd->sect_per_block_shift = __ffs(sect_per_block);
/*
* Whether to fail a read on a "bad" block.
* Defaults to false; enabled later by message.
*/
dd->fail_read_on_bb = false;
/*
* Initialize bad block list rbtree.
*/
dd->badblocklist = RB_ROOT;
dd->badblock_count = 0;
spin_lock_init(&dd->dust_lock);
dd->quiet_mode = false;
BUG_ON(dm_set_target_max_io_len(ti, dd->sect_per_block) != 0);
ti->num_discard_bios = 1;
ti->num_flush_bios = 1;
ti->private = dd;
return 0;
}
static void dust_dtr(struct dm_target *ti)
{
struct dust_device *dd = ti->private;
__dust_clear_badblocks(&dd->badblocklist, dd->badblock_count);
dm_put_device(ti, dd->dev);
kfree(dd);
}
static int dust_message(struct dm_target *ti, unsigned int argc, char **argv,
char *result_buf, unsigned int maxlen)
{
struct dust_device *dd = ti->private;
sector_t size = i_size_read(dd->dev->bdev->bd_inode) >> SECTOR_SHIFT;
bool invalid_msg = false;
int r = -EINVAL;
unsigned long long tmp, block;
unsigned char wr_fail_cnt;
unsigned int tmp_ui;
unsigned long flags;
char dummy;
if (argc == 1) {
if (!strcasecmp(argv[0], "addbadblock") ||
!strcasecmp(argv[0], "removebadblock") ||
!strcasecmp(argv[0], "queryblock")) {
DMERR("%s requires an additional argument", argv[0]);
} else if (!strcasecmp(argv[0], "disable")) {
DMINFO("disabling read failures on bad sectors");
dd->fail_read_on_bb = false;
r = 0;
} else if (!strcasecmp(argv[0], "enable")) {
DMINFO("enabling read failures on bad sectors");
dd->fail_read_on_bb = true;
r = 0;
} else if (!strcasecmp(argv[0], "countbadblocks")) {
spin_lock_irqsave(&dd->dust_lock, flags);
DMINFO("countbadblocks: %llu badblock(s) found",
dd->badblock_count);
spin_unlock_irqrestore(&dd->dust_lock, flags);
r = 0;
} else if (!strcasecmp(argv[0], "clearbadblocks")) {
r = dust_clear_badblocks(dd);
} else if (!strcasecmp(argv[0], "quiet")) {
if (!dd->quiet_mode)
dd->quiet_mode = true;
else
dd->quiet_mode = false;
r = 0;
} else {
invalid_msg = true;
}
} else if (argc == 2) {
if (sscanf(argv[1], "%llu%c", &tmp, &dummy) != 1)
return r;
block = tmp;
sector_div(size, dd->sect_per_block);
if (block > size) {
DMERR("selected block value out of range");
return r;
}
if (!strcasecmp(argv[0], "addbadblock"))
r = dust_add_block(dd, block, 0);
else if (!strcasecmp(argv[0], "removebadblock"))
r = dust_remove_block(dd, block);
else if (!strcasecmp(argv[0], "queryblock"))
r = dust_query_block(dd, block);
else
invalid_msg = true;
} else if (argc == 3) {
if (sscanf(argv[1], "%llu%c", &tmp, &dummy) != 1)
return r;
if (sscanf(argv[2], "%u%c", &tmp_ui, &dummy) != 1)
return r;
block = tmp;
if (tmp_ui > 255) {
DMERR("selected write fail count out of range");
return r;
}
wr_fail_cnt = tmp_ui;
sector_div(size, dd->sect_per_block);
if (block > size) {
DMERR("selected block value out of range");
return r;
}
if (!strcasecmp(argv[0], "addbadblock"))
r = dust_add_block(dd, block, wr_fail_cnt);
else
invalid_msg = true;
} else
DMERR("invalid number of arguments '%d'", argc);
if (invalid_msg)
DMERR("unrecognized message '%s' received", argv[0]);
return r;
}
static void dust_status(struct dm_target *ti, status_type_t type,
unsigned int status_flags, char *result, unsigned int maxlen)
{
struct dust_device *dd = ti->private;
unsigned int sz = 0;
switch (type) {
case STATUSTYPE_INFO:
DMEMIT("%s %s %s", dd->dev->name,
dd->fail_read_on_bb ? "fail_read_on_bad_block" : "bypass",
dd->quiet_mode ? "quiet" : "verbose");
break;
case STATUSTYPE_TABLE:
DMEMIT("%s %llu %u", dd->dev->name,
(unsigned long long)dd->start, dd->blksz);
break;
}
}
static int dust_prepare_ioctl(struct dm_target *ti, struct block_device **bdev)
{
struct dust_device *dd = ti->private;
struct dm_dev *dev = dd->dev;
*bdev = dev->bdev;
/*
* Only pass ioctls through if the device sizes match exactly.
*/
if (dd->start ||
ti->len != i_size_read(dev->bdev->bd_inode) >> SECTOR_SHIFT)
return 1;
return 0;
}
static int dust_iterate_devices(struct dm_target *ti, iterate_devices_callout_fn fn,
void *data)
{
struct dust_device *dd = ti->private;
return fn(ti, dd->dev, dd->start, ti->len, data);
}
static struct target_type dust_target = {
.name = "dust",
.version = {1, 0, 0},
.module = THIS_MODULE,
.ctr = dust_ctr,
.dtr = dust_dtr,
.iterate_devices = dust_iterate_devices,
.map = dust_map,
.message = dust_message,
.status = dust_status,
.prepare_ioctl = dust_prepare_ioctl,
};
static int __init dm_dust_init(void)
{
int r = dm_register_target(&dust_target);
if (r < 0)
DMERR("dm_register_target failed %d", r);
return r;
}
static void __exit dm_dust_exit(void)
{
dm_unregister_target(&dust_target);
}
module_init(dm_dust_init);
module_exit(dm_dust_exit);
MODULE_DESCRIPTION(DM_NAME " dust test target");
MODULE_AUTHOR("Bryan Gurney <dm-devel@redhat.com>");
MODULE_LICENSE("GPL");