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dm dust: make badblock messages target-relative

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dm-dust currently treats addbadblock, removebadblock and queryblock
arguments as block numbers on the underlying device. That is surprising
for a device-mapper target: a dm-dust table with a non-zero backing
offset can add bad blocks that are outside the mapped target, and a
badblock added for logical block 0 is missed because the I/O path checks
the remapped backing-device block instead.

Interpret badblock message arguments as blocks relative to the start of
the dm-dust target instead. Bound the arguments by the target length and
perform badblock lookup using target-relative sectors before remapping
the bio to the underlying device.

This intentionally changes the non-zero backing-offset behavior to make
the badblock control interface match the mapped dm-dust device, rather
than the underlying device.

Assisted-by: Codex:gpt-5.5-cyber-preview
Signed-off-by: Samuel Moelius <sam.moelius@trailofbits.com>
Tested-by: Bryan Gurney <bgurney@redhat.com>
Reviewed-by: Benjamin Marzinski <bmarzins@redhat.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
This commit is contained in:
Samuel Moelius
2026-08-03 14:09:13 +00:00
committed by Mikulas Patocka
parent cc87e26d9c
commit 066976b7db
1 changed files with 7 additions and 9 deletions
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16
drivers/md/dm-dust.c
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@@ -196,7 +196,6 @@ static int __dust_map_write(struct dust_device *dd, sector_t thisblock)
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);
}
@@ -224,15 +223,16 @@ static int dust_map_write(struct dust_device *dd, sector_t thisblock,
static int dust_map(struct dm_target *ti, struct bio *bio)
{
struct dust_device *dd = ti->private;
sector_t dust_sector = dm_target_offset(ti, bio->bi_iter.bi_sector);
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);
bio->bi_iter.bi_sector = dd->start + dust_sector;
if (bio_data_dir(bio) == READ)
r = dust_map_read(dd, bio->bi_iter.bi_sector, dd->fail_read_on_bb);
r = dust_map_read(dd, dust_sector, dd->fail_read_on_bb);
else
r = dust_map_write(dd, bio->bi_iter.bi_sector, dd->fail_read_on_bb);
r = dust_map_write(dd, dust_sector, dd->fail_read_on_bb);
return r;
}
@@ -415,7 +415,7 @@ static int dust_message(struct dm_target *ti, unsigned int argc, char **argv,
char *result, unsigned int maxlen)
{
struct dust_device *dd = ti->private;
sector_t size = bdev_nr_sectors(dd->dev->bdev);
sector_t size = dm_sector_div_up(ti->len, dd->sect_per_block);
bool invalid_msg = false;
int r = -EINVAL;
unsigned long long tmp, block;
@@ -462,8 +462,7 @@ static int dust_message(struct dm_target *ti, unsigned int argc, char **argv,
return r;
block = tmp;
sector_div(size, dd->sect_per_block);
if (block > size) {
if (block >= size) {
DMERR("selected block value out of range");
return r;
}
@@ -490,8 +489,7 @@ static int dust_message(struct dm_target *ti, unsigned int argc, char **argv,
return r;
}
wr_fail_cnt = tmp_ui;
sector_div(size, dd->sect_per_block);
if (block > size) {
if (block >= size) {
DMERR("selected block value out of range");
return r;
}