[PATCH RFC 2/8] dm: Add support for block provisioning

Sarthak Kukreti
2022-09-15T16:49:03Z

From: Sarthak Kukreti <sarthakkukreti@chromium.org>

Add support to dm devices for REQ_OP_PROVISION. The default mode
is to pass through the request and dm-thin will utilize it to provision
blocks.

Signed-off-by: Sarthak Kukreti <sarthakkukreti@chromium.org>
---
drivers/md/dm-crypt.c | 4 +-
drivers/md/dm-linear.c | 1 +
drivers/md/dm-table.c | 17 +++++++
drivers/md/dm-thin.c | 86 +++++++++++++++++++++++++++++++++--
drivers/md/dm.c | 4 ++
include/linux/device-mapper.h | 6 +++
6 files changed, 113 insertions(+), 5 deletions(-)

diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
index 159c6806c19b..357f0899cfb6 100644
--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -3081,6 +3081,8 @@ static int crypt_ctr_optional(struct dm_target *ti, unsigned int argc, char **ar
if (ret)
return ret;

+ ti->num_provision_bios = 1;
+
while (opt_params--) {
opt_string = dm_shift_arg(&as);
if (!opt_string) {
@@ -3384,7 +3386,7 @@ static int crypt_map(struct dm_target *ti, struct bio *bio)
* - for REQ_OP_DISCARD caller must use flush if IO ordering matters
*/
if (unlikely(bio->bi_opf & REQ_PREFLUSH ||
- bio_op(bio) == REQ_OP_DISCARD)) {
+ bio_op(bio) == REQ_OP_DISCARD || bio_op(bio) == REQ_OP_PROVISION)) {
bio_set_dev(bio, cc->dev->bdev);
if (bio_sectors(bio))
bio->bi_iter.bi_sector = cc->start +
diff --git a/drivers/md/dm-linear.c b/drivers/md/dm-linear.c
index 3212ef6aa81b..1aa782149428 100644
--- a/drivers/md/dm-linear.c
+++ b/drivers/md/dm-linear.c
@@ -61,6 +61,7 @@ static int linear_ctr(struct dm_target *ti, unsigned int argc, char **argv)
ti->num_discard_bios = 1;
ti->num_secure_erase_bios = 1;
ti->num_write_zeroes_bios = 1;
+ ti->num_provision_bios = 1;
ti->private = lc;
return 0;

diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index 332f96b58252..b7f9cb66b7ba 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -1853,6 +1853,18 @@ static bool dm_table_supports_write_zeroes(struct dm_table *t)
return true;
}

+static bool dm_table_supports_provision(struct dm_table *t)
+{
+ for (unsigned int i = 0; i < t->num_targets; i++) {
+ struct dm_target *ti = dm_table_get_target(t, i);
+
+ if (ti->num_provision_bios)
+ return true;
+ }
+
+ return false;
+}
+
static int device_not_nowait_capable(struct dm_target *ti, struct dm_dev *dev,
sector_t start, sector_t len, void *data)
{
@@ -1989,6 +2001,11 @@ int dm_table_set_restrictions(struct dm_table *t, struct request_queue *q,
if (!dm_table_supports_write_zeroes(t))
q->limits.max_write_zeroes_sectors = 0;

+ if (dm_table_supports_provision(t))
+ blk_queue_max_provision_sectors(q, UINT_MAX >> 9);
+ else
+ q->limits.max_provision_sectors = 0;
+
dm_table_verify_integrity(t);

/*
diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c
index e76c96c760a9..fd3eb306c823 100644
--- a/drivers/md/dm-thin.c
+++ b/drivers/md/dm-thin.c
@@ -908,7 +908,8 @@ 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);
@@ -1012,6 +1013,9 @@ static void process_prepared_mapping(struct dm_thin_new_mapping *m)
goto out;
}

+ if (bio && bio_op(bio) == REQ_OP_PROVISION)
+ return;
+
/*
* Release any bios held while the block was being provisioned.
* If we are processing a write bio that completely covers the block,
@@ -1388,6 +1392,9 @@ static void schedule_zero(struct thin_c *tc, dm_block_t virt_block,
m->data_block = data_block;
m->cell = cell;

+ if (bio && bio_op(bio) == REQ_OP_PROVISION)
+ m->bio = bio;
+
/*
* If the whole block of data is being overwritten or we are not
* zeroing pre-existing data, we can issue the bio immediately.
@@ -1897,7 +1904,7 @@ static void provision_block(struct thin_c *tc, struct bio *bio, dm_block_t block
/*
* Fill read bios with zeroes and complete them immediately.
*/
- if (bio_data_dir(bio) == READ) {
+ if (bio_data_dir(bio) == READ && bio_op(bio) != REQ_OP_PROVISION) {
zero_fill_bio(bio);
cell_defer_no_holder(tc, cell);
bio_endio(bio);
@@ -1980,6 +1987,69 @@ static void process_cell(struct thin_c *tc, struct dm_bio_prison_cell *cell)
}
}

+static void process_provision_cell(struct thin_c *tc, struct dm_bio_prison_cell *cell)
+{
+ int r;
+ struct pool *pool = tc->pool;
+ struct bio *bio = cell->holder;
+ dm_block_t begin, end;
+ struct dm_thin_lookup_result lookup_result;
+
+ if (tc->requeue_mode) {
+ cell_requeue(pool, cell);
+ return;
+ }
+
+ get_bio_block_range(tc, bio, &begin, &end);
+
+ while (begin != end) {
+ r = ensure_next_mapping(pool);
+ if (r)
+ /* we did our best */
+ return;
+
+ r = dm_thin_find_block(tc->td, begin, 1, &lookup_result);
+ switch (r) {
+ case 0:
+ begin++;
+ break;
+ case -ENODATA:
+ provision_block(tc, bio, begin, cell);
+ begin++;
+ break;
+ default:
+ DMERR_LIMIT(
+ "%s: dm_thin_find_block() failed: error = %d",
+ __func__, r);
+ cell_defer_no_holder(tc, cell);
+ bio_io_error(bio);
+ begin++;
+ break;
+ }
+ }
+ bio_endio(bio);
+ cell_defer_no_holder(tc, cell);
+}
+
+static void process_provision_bio(struct thin_c *tc, struct bio *bio)
+{
+ dm_block_t begin, end;
+ struct dm_cell_key virt_key;
+ struct dm_bio_prison_cell *virt_cell;
+
+ get_bio_block_range(tc, bio, &begin, &end);
+ if (begin == end) {
+ bio_endio(bio);
+ return;
+ }
+
+ build_key(tc->td, VIRTUAL, begin, end, &virt_key);
+ if (bio_detain(tc->pool, &virt_key, bio, &virt_cell))
+ return;
+
+ process_provision_cell(tc, virt_cell);
+}
+
static void process_bio(struct thin_c *tc, struct bio *bio)
{
struct pool *pool = tc->pool;
@@ -2024,7 +2094,7 @@ static void __process_bio_read_only(struct thin_c *tc, struct bio *bio,
case -ENODATA:
if (cell)
cell_defer_no_holder(tc, cell);
- if (rw != READ) {
+ if (rw != READ || bio_op(bio) == REQ_OP_PROVISION) {
handle_unserviceable_bio(tc->pool, bio);
break;
}
@@ -2200,6 +2270,8 @@ 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)
+ process_provision_bio(tc, bio);
else
pool->process_bio(tc, bio);

@@ -2716,7 +2788,8 @@ 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;
}
@@ -3353,6 +3426,7 @@ static int pool_ctr(struct dm_target *ti, unsigned argc, char **argv)
pt->low_water_blocks = low_water_blocks;
pt->adjusted_pf = pt->requested_pf = pf;
ti->num_flush_bios = 1;
+ ti->num_provision_bios = 1;

/*
* Only need to enable discards if the pool should pass
@@ -4043,6 +4117,7 @@ static void pool_io_hints(struct dm_target *ti, struct queue_limits *limits)
blk_limits_io_opt(limits, pool->sectors_per_block << SECTOR_SHIFT);
}

+
/*
* pt->adjusted_pf is a staging area for the actual features to use.
* They get transferred to the live pool in bind_control_target()
@@ -4233,6 +4308,8 @@ static int thin_ctr(struct dm_target *ti, unsigned argc, char **argv)
ti->num_discard_bios = 1;
}

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

spin_lock_irq(&tc->pool->lock);
@@ -4447,6 +4524,7 @@ static void thin_io_hints(struct dm_target *ti, struct queue_limits *limits)

limits->discard_granularity = pool->sectors_per_block << SECTOR_SHIFT;
limits->max_discard_sectors = 2048 * 1024 * 16; /* 16G */
+ limits->max_provision_sectors = 2048 * 1024 * 16; /* 16G */
}

static struct target_type thin_target = {
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 60549b65c799..3fe524800f5a 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1600,6 +1600,7 @@ static bool is_abnormal_io(struct bio *bio)
case REQ_OP_DISCARD:
case REQ_OP_SECURE_ERASE:
case REQ_OP_WRITE_ZEROES:
+ case REQ_OP_PROVISION:
return true;
default:
break;
@@ -1624,6 +1625,9 @@ static blk_status_t __process_abnormal_io(struct clone_info *ci,
case REQ_OP_WRITE_ZEROES:
num_bios = ti->num_write_zeroes_bios;
break;
+ case REQ_OP_PROVISION:
+ num_bios = ti->num_provision_bios;
+ break;
default:
break;
}
diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h
index 04c6acf7faaa..edeb47195b6f 100644
--- a/include/linux/device-mapper.h
+++ b/include/linux/device-mapper.h
@@ -333,6 +333,12 @@ struct dm_target {
*/
unsigned num_write_zeroes_bios;

+ /*
+ * The number of PROVISION bios that will be submitted to the target.
+ * The bio number can be accessed with dm_bio_get_target_bio_nr.
+ */
+ unsigned num_provision_bios;
+
/*
* The minimum number of extra bytes allocated in each io for the
* target to use.
--
2.31.0