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dm bio prison v1: add dm_cell_key_has_valid_range 

Don't have bio_detain() BUG_ON if a dm_cell_key is beyond
BIO_PRISON_MAX_RANGE or spans a boundary.

Update dm-thin.c:build_key() to use dm_cell_key_has_valid_range() which
will do this checking without using BUG_ON. Also update
process_discard_bio() to check the discard bio that DM core passes in
(having first imposed max_discard_granularity based splitting).

dm_cell_key_has_valid_range() will merely WARN_ON_ONCE if it returns
false because if it does: it is programmer error that should be caught
with proper testing. So relax the BUG_ONs to be WARN_ON_ONCE.

Signed-off-by: Mike Snitzer <snitzer@kernel.org>
This commit is contained in:
Mike Snitzer 2023-03-25 17:52:01 -04:00
parent e2dd8aca2d
commit 3f8d3f5432
3 changed files with 29 additions and 11 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

14
drivers/md/dm-bio-prison-v1.c
View File

@ -120,12 +120,17 @@ static unsigned lock_nr(struct dm_cell_key *key)
return (key->block_begin >> BIO_PRISON_MAX_RANGE_SHIFT) & LOCK_MASK;
}
static void check_range(struct dm_cell_key *key)
bool dm_cell_key_has_valid_range(struct dm_cell_key *key)
{
BUG_ON(key->block_end - key->block_begin > BIO_PRISON_MAX_RANGE);
BUG_ON((key->block_begin >> BIO_PRISON_MAX_RANGE_SHIFT) !=
((key->block_end - 1) >> BIO_PRISON_MAX_RANGE_SHIFT));
if (WARN_ON_ONCE(key->block_end - key->block_begin > BIO_PRISON_MAX_RANGE))
return false;
if (WARN_ON_ONCE((key->block_begin >> BIO_PRISON_MAX_RANGE_SHIFT) !=
(key->block_end - 1) >> BIO_PRISON_MAX_RANGE_SHIFT))
return false;
return true;
}
EXPORT_SYMBOL(dm_cell_key_has_valid_range);
static int __bio_detain(struct rb_root *root,
struct dm_cell_key *key,
@ -172,7 +177,6 @@ static int bio_detain(struct dm_bio_prison *prison,
{
int r;
unsigned l = lock_nr(key);
check_range(key);
spin_lock_irq(&prison->regions[l].lock);
r = __bio_detain(&prison->regions[l].cell, key, inmate, cell_prealloc, cell_result);

5
drivers/md/dm-bio-prison-v1.h
View File

@ -83,6 +83,11 @@ int dm_get_cell(struct dm_bio_prison *prison,
struct dm_bio_prison_cell *cell_prealloc,
struct dm_bio_prison_cell **cell_result);
/*
* Returns false if key is beyond BIO_PRISON_MAX_RANGE or spans a boundary.
*/
bool dm_cell_key_has_valid_range(struct dm_cell_key *key);
/*
* An atomic op that combines retrieving or creating a cell, and adding a
* bio to it.

21
drivers/md/dm-thin.c
View File

@ -118,25 +118,27 @@ enum lock_space {
PHYSICAL
};
static void build_key(struct dm_thin_device *td, enum lock_space ls,
static bool build_key(struct dm_thin_device *td, enum lock_space ls,
dm_block_t b, dm_block_t e, struct dm_cell_key *key)
{
key->virtual = (ls == VIRTUAL);
key->dev = dm_thin_dev_id(td);
key->block_begin = b;
key->block_end = e;
return dm_cell_key_has_valid_range(key);
}
static void build_data_key(struct dm_thin_device *td, dm_block_t b,
struct dm_cell_key *key)
{
build_key(td, PHYSICAL, b, b + 1llu, key);
(void) build_key(td, PHYSICAL, b, b + 1llu, key);
}
static void build_virtual_key(struct dm_thin_device *td, dm_block_t b,
struct dm_cell_key *key)
{
build_key(td, VIRTUAL, b, b + 1llu, key);
(void) build_key(td, VIRTUAL, b, b + 1llu, key);
}
/*----------------------------------------------------------------*/
@ -1702,7 +1704,8 @@ static void break_up_discard_bio(struct thin_c *tc, dm_block_t begin, dm_block_t
<< BIO_PRISON_MAX_RANGE_SHIFT;
len = min_t(sector_t, data_end - data_begin, next_boundary - data_begin);
build_key(tc->td, PHYSICAL, data_begin, data_begin + len, &data_key);
/* This key is certainly within range given the above splitting */
(void) build_key(tc->td, PHYSICAL, data_begin, data_begin + len, &data_key);
if (bio_detain(tc->pool, &data_key, NULL, &data_cell)) {
/* contention, we'll give up with this range */
data_begin += len;
@ -1778,8 +1781,13 @@ static void process_discard_bio(struct thin_c *tc, struct bio *bio)
return;
}
build_key(tc->td, VIRTUAL, begin, end, &virt_key);
if (bio_detain(tc->pool, &virt_key, bio, &virt_cell))
if (unlikely(!build_key(tc->td, VIRTUAL, begin, end, &virt_key))) {
DMERR_LIMIT("Discard doesn't respect bio prison limits");
bio_endio(bio);
return;
}
if (bio_detain(tc->pool, &virt_key, bio, &virt_cell)) {
/*
* Potential starvation issue: We're relying on the
* fs/application being well behaved, and not trying to
@ -1788,6 +1796,7 @@ static void process_discard_bio(struct thin_c *tc, struct bio *bio)
* cell will never be granted.
*/
return;
}
tc->pool->process_discard_cell(tc, virt_cell);
}