[PATCH v6 4/5] dm-thin: Add REQ_OP_PROVISION support

Sarthak Kukreti
2023-05-06T06:29:47Z

dm-thinpool uses the provision request to provision
blocks for a dm-thin device. dm-thinpool currently does not
pass through REQ_OP_PROVISION to underlying devices.

For shared blocks, provision requests will break sharing and copy the
contents of the entire block. Additionally, if 'skip_block_zeroing'
is not set, dm-thin will opt to zero out the entire range as a part
of provisioning.

Signed-off-by: Sarthak Kukreti <sarthakkukreti@chromium.org>
---
drivers/md/dm-thin.c | 70 +++++++++++++++++++++++++++++++++++++++++---
1 file changed, 66 insertions(+), 4 deletions(-)

diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c
index 2b13c949bd72..3f94f53ac956 100644
--- a/drivers/md/dm-thin.c
+++ b/drivers/md/dm-thin.c
@@ -274,6 +274,7 @@ struct pool {

process_bio_fn process_bio;
process_bio_fn process_discard;
+ process_bio_fn process_provision;

process_cell_fn process_cell;
process_cell_fn process_discard_cell;
@@ -913,7 +914,8 @@ static void __inc_remap_and_issue_cell(void *context,
struct bio *bio;

while ((bio = bio_list_pop(&cell->bios))) {
- if (op_is_flush(bio->bi_opf) || bio_op(bio) == REQ_OP_DISCARD)
+ if (op_is_flush(bio->bi_opf) || bio_op(bio) == REQ_OP_DISCARD ||
+ bio_op(bio) == REQ_OP_PROVISION)
bio_list_add(&info->defer_bios, bio);
else {
inc_all_io_entry(info->tc->pool, bio);
@@ -1245,8 +1247,8 @@ static int io_overlaps_block(struct pool *pool, struct bio *bio)

static int io_overwrites_block(struct pool *pool, struct bio *bio)
{
- return (bio_data_dir(bio) == WRITE) &&
- io_overlaps_block(pool, bio);
+ return (bio_data_dir(bio) == WRITE) && io_overlaps_block(pool, bio) &&
+ bio_op(bio) != REQ_OP_PROVISION;
}

static void save_and_set_endio(struct bio *bio, bio_end_io_t **save,
@@ -1953,6 +1955,51 @@ static void provision_block(struct thin_c *tc, struct bio *bio, dm_block_t block
}
}

+static void process_provision_bio(struct thin_c *tc, struct bio *bio)
+{
+ int r;
+ struct pool *pool = tc->pool;
+ dm_block_t block = get_bio_block(tc, bio);
+ struct dm_bio_prison_cell *cell;
+ struct dm_cell_key key;
+ struct dm_thin_lookup_result lookup_result;
+
+ /*
+ * If cell is already occupied, then the block is already
+ * being provisioned so we have nothing further to do here.
+ */
+ build_virtual_key(tc->td, block, &key);
+ if (bio_detain(pool, &key, bio, &cell))
+ return;
+
+ if (tc->requeue_mode) {
+ cell_requeue(pool, cell);
+ return;
+ }
+
+ r = dm_thin_find_block(tc->td, block, 1, &lookup_result);
+ switch (r) {
+ case 0:
+ if (lookup_result.shared) {
+ process_shared_bio(tc, bio, block, &lookup_result, cell);
+ } else {
+ bio_endio(bio);
+ cell_defer_no_holder(tc, cell);
+ }
+ break;
+ case -ENODATA:
+ provision_block(tc, bio, block, cell);
+ break;
+
+ default:
+ DMERR_LIMIT("%s: dm_thin_find_block() failed: error = %d",
+ __func__, r);
+ cell_defer_no_holder(tc, cell);
+ bio_io_error(bio);
+ break;
+ }
+}
+
static void process_cell(struct thin_c *tc, struct dm_bio_prison_cell *cell)
{
int r;
@@ -2228,6 +2275,8 @@ static void process_thin_deferred_bios(struct thin_c *tc)

if (bio_op(bio) == REQ_OP_DISCARD)
pool->process_discard(tc, bio);
+ else if (bio_op(bio) == REQ_OP_PROVISION)
+ pool->process_provision(tc, bio);
else
pool->process_bio(tc, bio);

@@ -2579,6 +2628,7 @@ static void set_pool_mode(struct pool *pool, enum pool_mode new_mode)
dm_pool_metadata_read_only(pool->pmd);
pool->process_bio = process_bio_fail;
pool->process_discard = process_bio_fail;
+ pool->process_provision = process_bio_fail;
pool->process_cell = process_cell_fail;
pool->process_discard_cell = process_cell_fail;
pool->process_prepared_mapping = process_prepared_mapping_fail;
@@ -2592,6 +2642,7 @@ static void set_pool_mode(struct pool *pool, enum pool_mode new_mode)
dm_pool_metadata_read_only(pool->pmd);
pool->process_bio = process_bio_read_only;
pool->process_discard = process_bio_success;
+ pool->process_provision = process_bio_fail;
pool->process_cell = process_cell_read_only;
pool->process_discard_cell = process_cell_success;
pool->process_prepared_mapping = process_prepared_mapping_fail;
@@ -2612,6 +2663,7 @@ static void set_pool_mode(struct pool *pool, enum pool_mode new_mode)
pool->out_of_data_space = true;
pool->process_bio = process_bio_read_only;
pool->process_discard = process_discard_bio;
+ pool->process_provision = process_bio_fail;
pool->process_cell = process_cell_read_only;
pool->process_prepared_mapping = process_prepared_mapping;
set_discard_callbacks(pool);
@@ -2628,6 +2680,7 @@ static void set_pool_mode(struct pool *pool, enum pool_mode new_mode)
dm_pool_metadata_read_write(pool->pmd);
pool->process_bio = process_bio;
pool->process_discard = process_discard_bio;
+ pool->process_provision = process_provision_bio;
pool->process_cell = process_cell;
pool->process_prepared_mapping = process_prepared_mapping;
set_discard_callbacks(pool);
@@ -2749,7 +2802,8 @@ static int thin_bio_map(struct dm_target *ti, struct bio *bio)
return DM_MAPIO_SUBMITTED;
}

- if (op_is_flush(bio->bi_opf) || bio_op(bio) == REQ_OP_DISCARD) {
+ if (op_is_flush(bio->bi_opf) || bio_op(bio) == REQ_OP_DISCARD ||
+ bio_op(bio) == REQ_OP_PROVISION) {
thin_defer_bio_with_throttle(tc, bio);
return DM_MAPIO_SUBMITTED;
}
@@ -3396,6 +3450,9 @@ static int pool_ctr(struct dm_target *ti, unsigned int argc, char **argv)
pt->adjusted_pf = pt->requested_pf = pf;
ti->num_flush_bios = 1;
ti->limit_swap_bios = true;
+ ti->num_provision_bios = 1;
+ ti->provision_supported = true;
+ ti->max_provision_granularity = true;

/*
* Only need to enable discards if the pool should pass
@@ -4114,6 +4171,8 @@ static void pool_io_hints(struct dm_target *ti, struct queue_limits *limits)
* The pool uses the same discard limits as the underlying data
* device. DM core has already set this up.
*/
+
+ limits->max_provision_sectors = pool->sectors_per_block;
}

static struct target_type pool_target = {
@@ -4288,6 +4347,9 @@ static int thin_ctr(struct dm_target *ti, unsigned int argc, char **argv)
ti->max_discard_granularity = true;
}

+ ti->num_provision_bios = 1;
+ ti->provision_supported = true;
+
mutex_unlock(&dm_thin_pool_table.mutex);

spin_lock_irq(&tc->pool->lock);
--
2.40.1.521.gf1e218fcd8-goog