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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>
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parent
e2dd8aca2d
commit
3f8d3f5432
3 changed files with 29 additions and 11 deletions
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@ -120,12 +120,17 @@ static unsigned lock_nr(struct dm_cell_key *key)
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return (key->block_begin >> BIO_PRISON_MAX_RANGE_SHIFT) & LOCK_MASK;
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return (key->block_begin >> BIO_PRISON_MAX_RANGE_SHIFT) & LOCK_MASK;
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}
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}
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static void check_range(struct dm_cell_key *key)
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bool dm_cell_key_has_valid_range(struct dm_cell_key *key)
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{
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{
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BUG_ON(key->block_end - key->block_begin > BIO_PRISON_MAX_RANGE);
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if (WARN_ON_ONCE(key->block_end - key->block_begin > BIO_PRISON_MAX_RANGE))
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BUG_ON((key->block_begin >> BIO_PRISON_MAX_RANGE_SHIFT) !=
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return false;
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((key->block_end - 1) >> BIO_PRISON_MAX_RANGE_SHIFT));
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if (WARN_ON_ONCE((key->block_begin >> BIO_PRISON_MAX_RANGE_SHIFT) !=
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(key->block_end - 1) >> BIO_PRISON_MAX_RANGE_SHIFT))
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return false;
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return true;
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}
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}
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EXPORT_SYMBOL(dm_cell_key_has_valid_range);
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static int __bio_detain(struct rb_root *root,
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static int __bio_detain(struct rb_root *root,
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struct dm_cell_key *key,
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struct dm_cell_key *key,
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@ -172,7 +177,6 @@ static int bio_detain(struct dm_bio_prison *prison,
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{
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{
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int r;
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int r;
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unsigned l = lock_nr(key);
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unsigned l = lock_nr(key);
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check_range(key);
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spin_lock_irq(&prison->regions[l].lock);
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spin_lock_irq(&prison->regions[l].lock);
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r = __bio_detain(&prison->regions[l].cell, key, inmate, cell_prealloc, cell_result);
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r = __bio_detain(&prison->regions[l].cell, key, inmate, cell_prealloc, cell_result);
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@ -83,6 +83,11 @@ int dm_get_cell(struct dm_bio_prison *prison,
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struct dm_bio_prison_cell *cell_prealloc,
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struct dm_bio_prison_cell *cell_prealloc,
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struct dm_bio_prison_cell **cell_result);
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struct dm_bio_prison_cell **cell_result);
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/*
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* Returns false if key is beyond BIO_PRISON_MAX_RANGE or spans a boundary.
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*/
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bool dm_cell_key_has_valid_range(struct dm_cell_key *key);
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/*
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/*
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* An atomic op that combines retrieving or creating a cell, and adding a
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* An atomic op that combines retrieving or creating a cell, and adding a
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* bio to it.
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* bio to it.
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@ -118,25 +118,27 @@ enum lock_space {
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PHYSICAL
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PHYSICAL
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};
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};
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static void build_key(struct dm_thin_device *td, enum lock_space ls,
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static bool build_key(struct dm_thin_device *td, enum lock_space ls,
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dm_block_t b, dm_block_t e, struct dm_cell_key *key)
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dm_block_t b, dm_block_t e, struct dm_cell_key *key)
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{
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{
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key->virtual = (ls == VIRTUAL);
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key->virtual = (ls == VIRTUAL);
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key->dev = dm_thin_dev_id(td);
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key->dev = dm_thin_dev_id(td);
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key->block_begin = b;
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key->block_begin = b;
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key->block_end = e;
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key->block_end = e;
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return dm_cell_key_has_valid_range(key);
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}
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}
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static void build_data_key(struct dm_thin_device *td, dm_block_t b,
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static void build_data_key(struct dm_thin_device *td, dm_block_t b,
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struct dm_cell_key *key)
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struct dm_cell_key *key)
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{
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{
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build_key(td, PHYSICAL, b, b + 1llu, key);
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(void) build_key(td, PHYSICAL, b, b + 1llu, key);
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}
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}
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static void build_virtual_key(struct dm_thin_device *td, dm_block_t b,
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static void build_virtual_key(struct dm_thin_device *td, dm_block_t b,
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struct dm_cell_key *key)
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struct dm_cell_key *key)
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{
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{
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build_key(td, VIRTUAL, b, b + 1llu, key);
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(void) build_key(td, VIRTUAL, b, b + 1llu, key);
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}
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}
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/*----------------------------------------------------------------*/
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/*----------------------------------------------------------------*/
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@ -1702,7 +1704,8 @@ static void break_up_discard_bio(struct thin_c *tc, dm_block_t begin, dm_block_t
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<< BIO_PRISON_MAX_RANGE_SHIFT;
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<< BIO_PRISON_MAX_RANGE_SHIFT;
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len = min_t(sector_t, data_end - data_begin, next_boundary - data_begin);
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len = min_t(sector_t, data_end - data_begin, next_boundary - data_begin);
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build_key(tc->td, PHYSICAL, data_begin, data_begin + len, &data_key);
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/* This key is certainly within range given the above splitting */
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(void) build_key(tc->td, PHYSICAL, data_begin, data_begin + len, &data_key);
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if (bio_detain(tc->pool, &data_key, NULL, &data_cell)) {
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if (bio_detain(tc->pool, &data_key, NULL, &data_cell)) {
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/* contention, we'll give up with this range */
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/* contention, we'll give up with this range */
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data_begin += len;
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data_begin += len;
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@ -1778,8 +1781,13 @@ static void process_discard_bio(struct thin_c *tc, struct bio *bio)
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return;
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return;
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}
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}
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build_key(tc->td, VIRTUAL, begin, end, &virt_key);
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if (unlikely(!build_key(tc->td, VIRTUAL, begin, end, &virt_key))) {
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if (bio_detain(tc->pool, &virt_key, bio, &virt_cell))
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DMERR_LIMIT("Discard doesn't respect bio prison limits");
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bio_endio(bio);
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return;
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}
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if (bio_detain(tc->pool, &virt_key, bio, &virt_cell)) {
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/*
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/*
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* Potential starvation issue: We're relying on the
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* Potential starvation issue: We're relying on the
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* fs/application being well behaved, and not trying to
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* fs/application being well behaved, and not trying to
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@ -1788,6 +1796,7 @@ static void process_discard_bio(struct thin_c *tc, struct bio *bio)
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* cell will never be granted.
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* cell will never be granted.
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*/
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*/
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return;
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return;
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}
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tc->pool->process_discard_cell(tc, virt_cell);
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tc->pool->process_discard_cell(tc, virt_cell);
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}
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}
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