[v3,2/3] dm: Add support for block provisioning
Commit Message
Add support to dm devices for REQ_OP_PROVISION. The default mode
is to passthrough the request to the underlying device, if it
supports it. 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.
Signed-off-by: Sarthak Kukreti <sarthakkukreti@chromium.org>
---
drivers/md/dm-crypt.c | 4 +-
drivers/md/dm-linear.c | 1 +
drivers/md/dm-snap.c | 7 +++
drivers/md/dm-table.c | 25 ++++++++
drivers/md/dm-thin.c | 110 +++++++++++++++++++++++++++++++---
drivers/md/dm.c | 4 ++
include/linux/device-mapper.h | 11 ++++
7 files changed, 153 insertions(+), 9 deletions(-)
Comments
On Fri, Apr 14 2023 at 9:32P -0400,
Joe Thornber <thornber@redhat.com> wrote:
> On Fri, Apr 14, 2023 at 7:52 AM Sarthak Kukreti <sarthakkukreti@chromium.org>
> wrote:
>
> > Add support to dm devices for REQ_OP_PROVISION. The default mode
> > is to passthrough the request to the underlying device, if it
> > supports it. 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.
> >
>
> I see two issue with this patch:
>
> i) You use get_bio_block_range() to see which blocks the provision bio
> covers. But this function only returns
> complete blocks that are covered (it was designed for discard). Unlike
> discard, provision is not a hint so those
> partial blocks will need to be provisioned too.
>
> ii) You are setting off multiple dm_thin_new_mapping operations in flight
> at once. Each of these receives
> the same virt_cell and frees it when it completes. So I think we have
> multiple frees occuring? In addition you also
> release the cell yourself in process_provision_cell(). Fixing this is not
> trivial, you'll need to reference count the cells,
> and aggregate the mapping operation results.
>
> I think it would be far easier to restrict the size of the provision bio to
> be no bigger than one thinp block (as we do for normal io). This way dm
> core can split the bios, chain the child bios rather than having to
> reference count mapping ops, and aggregate the results.
I happened to be looking at implementing WRITE_ZEROES support for DM
thinp yesterday and reached the same conclussion relative to it (both
of Joe's points above, for me "ii)" was: the dm-bio-prison-v1 range
locking we do for discards needs work for other types of IO).
We can work to make REQ_OP_PROVISION spanning multiple thinp blocks
possible as follow-on optimization; but in the near-term DM thinp
needs REQ_OP_PROVISION to be split on a thinp block boundary.
This splitting can be assisted by block core in terms of a new
'provision_granularity' (which for thinp, it'd be set to the thinp
blocksize). But I don't know that we need to go that far (I'm
thinking its fine to have DM do the splitting it needs and only
elevate related code to block core if/when needed in the future).
DM core can take on conditionally imposing its max_io_len() to handle
splitting REQ_OP_PROVISION as needed on a per-target basis. This DM
core commit I've staged for 6.4 makes this quite a simple change:
https://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm.git/commit/?h=dm-6.4&id=13f6facf3faeed34ca381aef4c9b153c7aed3972
So please rebase on linux-dm.git's dm-6.4 branch, and for
REQ_OP_PROVISION dm.c:__process_abnormal_io() you'd add this:
case REQ_OP_PROVISION:
num_bios = ti->num_provision_bios;
if (ti->max_provision_granularity)
max_granularity = limits->max_provision_sectors;
break;
I'll reply again later today (to patch 2's actual code changes),
because I caught at least one other thing worth mentioning.
Thanks,
Mike
On Thu, Apr 13 2023 at 8:02P -0400,
Sarthak Kukreti <sarthakkukreti@chromium.org> wrote:
> Add support to dm devices for REQ_OP_PROVISION. The default mode
> is to passthrough the request to the underlying device, if it
> supports it. 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.
>
> Signed-off-by: Sarthak Kukreti <sarthakkukreti@chromium.org>
> ---
> drivers/md/dm-crypt.c | 4 +-
> drivers/md/dm-linear.c | 1 +
> drivers/md/dm-snap.c | 7 +++
Have you tested REQ_OP_PROVISION with these targets? Just want to
make sure you have an explicit need (and vested interest) for them
passing through REQ_OP_PROVISION.
> diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
> index 2055a758541d..5985343384a7 100644
> --- a/drivers/md/dm-table.c
> +++ b/drivers/md/dm-table.c
> @@ -1850,6 +1850,26 @@ static bool dm_table_supports_write_zeroes(struct dm_table *t)
> return true;
> }
>
> +static int device_provision_capable(struct dm_target *ti, struct dm_dev *dev,
> + sector_t start, sector_t len, void *data)
> +{
> + return !bdev_max_provision_sectors(dev->bdev);
> +}
> +
> +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->provision_supported ||
> + (ti->type->iterate_devices &&
> + ti->type->iterate_devices(ti, device_provision_capable, NULL)))
> + 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)
> {
> @@ -1983,6 +2003,11 @@ 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);
This doesn't seem correct in that it'll override whatever
max_provision_sectors was set by a target (like thinp).
I think you only need the if (!dm_table_supports_provision)) case:
> + 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 13d4677baafd..b08b7ae617be 100644
> --- a/drivers/md/dm-thin.c
> +++ b/drivers/md/dm-thin.c
I think it'll make the most sense to split out the dm-thin.c changes
in a separate patch.
> @@ -909,7 +909,8 @@ 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);
> @@ -1013,6 +1014,15 @@ static void process_prepared_mapping(struct dm_thin_new_mapping *m)
> goto out;
> }
>
> + /*
> + * For provision requests, once the prepared block has been inserted
> + * into the mapping btree, return.
> + */
> + if (bio && bio_op(bio) == REQ_OP_PROVISION) {
> + bio_endio(bio);
> + return;
> + }
> +
> /*
> * Release any bios held while the block was being provisioned.
> * If we are processing a write bio that completely covers the block,
> @@ -1241,7 +1251,7 @@ 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) &&
> + return (bio_data_dir(bio) == WRITE) && bio_op(bio) != REQ_OP_PROVISION &&
> io_overlaps_block(pool, bio);
> }
>
> @@ -1334,10 +1344,11 @@ static void schedule_copy(struct thin_c *tc, dm_block_t virt_block,
> /*
> * IO to pool_dev remaps to the pool target's data_dev.
> *
> - * If the whole block of data is being overwritten, we can issue the
> - * bio immediately. Otherwise we use kcopyd to clone the data first.
> + * If the whole block of data is being overwritten and if this is not a
> + * provision request, we can issue the bio immediately.
> + * Otherwise we use kcopyd to clone the data first.
> */
> - if (io_overwrites_block(pool, bio))
> + if (io_overwrites_block(pool, bio) && bio_op(bio) != REQ_OP_PROVISION)
> remap_and_issue_overwrite(tc, bio, data_dest, m);
> else {
> struct dm_io_region from, to;
> @@ -1356,7 +1367,8 @@ static void schedule_copy(struct thin_c *tc, dm_block_t virt_block,
> /*
> * Do we need to zero a tail region?
> */
> - if (len < pool->sectors_per_block && pool->pf.zero_new_blocks) {
> + if (len < pool->sectors_per_block && pool->pf.zero_new_blocks &&
> + bio_op(bio) != REQ_OP_PROVISION) {
> atomic_inc(&m->prepare_actions);
> ll_zero(tc, m,
> data_dest * pool->sectors_per_block + len,
> @@ -1390,6 +1402,10 @@ static void schedule_zero(struct thin_c *tc, dm_block_t virt_block,
> m->data_block = data_block;
> m->cell = cell;
>
> + /* Provision requests are chained on the original bio. */
> + 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.
> @@ -1865,7 +1881,8 @@ static void process_shared_bio(struct thin_c *tc, struct bio *bio,
>
> if (bio_data_dir(bio) == WRITE && bio->bi_iter.bi_size) {
> break_sharing(tc, bio, block, &key, lookup_result, data_cell);
> - cell_defer_no_holder(tc, virt_cell);
> + if (bio_op(bio) != REQ_OP_PROVISION)
> + cell_defer_no_holder(tc, virt_cell);
> } else {
> struct dm_thin_endio_hook *h = dm_per_bio_data(bio, sizeof(struct dm_thin_endio_hook));
>
Not confident in the above changes given the request that we only
handle REQ_OP_PROVISION one thinp block at a time. So I'll gloss over
them for now.
> @@ -1982,6 +1999,73 @@ 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:
> + if (lookup_result.shared)
> + process_shared_bio(tc, bio, begin,
> + &lookup_result, cell);
> + begin++;
> + break;
> + case -ENODATA:
> + bio_inc_remaining(bio);
> + 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;
> + }
Like Joe mentioned, this pattern was fine for discards because they
are advisory/optional. But we need to make sure we don't truncate
REQ_OP_PROVISION -- so we need to round up if we partially bleed into
the blocks to the left or right.
BUT ranged REQ_OP_PROVISION support is for later, this can be dealt
with more simply in that each REQ_OP_PROVISION will be handled a block
at a time initially. SO you'll want to honor _all_ REQ_OP_PROVISION,
never returning early.
> +
> + 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;
> @@ -2202,6 +2286,8 @@ 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);
This should be pool->process_provision() (or ->process_provision_bio
if you like). Point is, you need to be switching these methods
if/when the pool_mode transitions in set_pool_mode().
> else
> pool->process_bio(tc, bio);
>
> @@ -2723,7 +2809,8 @@ 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;
> }
> @@ -3370,6 +3457,8 @@ 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;
>
> /*
> * Only need to enable discards if the pool should pass
> @@ -4068,6 +4157,7 @@ static void pool_io_hints(struct dm_target *ti, struct queue_limits *limits)
> blk_limits_io_opt(limits, pool->sectors_per_block << SECTOR_SHIFT);
> }
>
> +
Please fix this extra whitespace damage.
> /*
> * pt->adjusted_pf is a staging area for the actual features to use.
> * They get transferred to the live pool in bind_control_target()
> @@ -4261,6 +4351,9 @@ static int thin_ctr(struct dm_target *ti, unsigned int argc, char **argv)
> ti->num_discard_bios = 1;
> }
>
> + ti->num_provision_bios = 1;
> + ti->provision_supported = true;
> +
> mutex_unlock(&dm_thin_pool_table.mutex);
>
> spin_lock_irq(&tc->pool->lock);
> @@ -4475,6 +4568,7 @@ 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 */
Building on my previous reply, with suggested update to
dm.c:__process_abnormal_io(), once you rebase on dm-6.4's dm-thin.c
you'll want to instead:
limits->max_provision_sectors = pool->sectors_per_block << SECTOR_SHIFT;
And you'll want to drop any of the above code that deals with handling
bio-prison range locking and processing of REQ_OP_PROVISION for
multiple thinp blocks at once.
Simple REQ_OP_PROVISION processing one thinp block at a time first and
then we can worry about handling REQ_OP_PROVISION that span blocks
later.
> static struct target_type thin_target = {
> diff --git a/drivers/md/dm.c b/drivers/md/dm.c
> index dfde0088147a..d8f1803062b7 100644
> --- a/drivers/md/dm.c
> +++ b/drivers/md/dm.c
> @@ -1593,6 +1593,7 @@ 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;
> @@ -1617,6 +1618,9 @@ 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;
> }
Please be sure to include my suggested __process_abnormal_io change
from my previous reply.
> diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h
> index 7975483816e4..e9f687521ae6 100644
> --- a/include/linux/device-mapper.h
> +++ b/include/linux/device-mapper.h
> @@ -334,6 +334,12 @@ struct dm_target {
> */
> unsigned int 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 int num_provision_bios;
> +
> /*
> * The minimum number of extra bytes allocated in each io for the
> * target to use.
> @@ -358,6 +364,11 @@ struct dm_target {
> */
> bool discards_supported:1;
>
> + /* Set if this target needs to receive provision requests regardless of
> + * whether or not its underlying devices have support.
> + */
> + bool provision_supported:1;
> +
> /*
> * Set if we need to limit the number of in-flight bios when swapping.
> */
You'll need to add max_provision_granularity bool too (as implied by
the dm.c:__process_abnormal_io() change suggested in my first reply to
this patch).
I'm happy to wait for you to consume the v3 feedback we've provided so
you can create a v4. I'm thinking I can base dm-thin.c's WRITE_ZEROES
support ontop of your REQ_OP_PROVISION v4 changes -- they should be
complementary.
Thanks,
Mike
On Fri, Apr 14, 2023 at 2:58 PM Mike Snitzer <snitzer@kernel.org> wrote:
>
> On Thu, Apr 13 2023 at 8:02P -0400,
> Sarthak Kukreti <sarthakkukreti@chromium.org> wrote:
>
> > Add support to dm devices for REQ_OP_PROVISION. The default mode
> > is to passthrough the request to the underlying device, if it
> > supports it. 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.
> >
> > Signed-off-by: Sarthak Kukreti <sarthakkukreti@chromium.org>
> > ---
> > drivers/md/dm-crypt.c | 4 +-
> > drivers/md/dm-linear.c | 1 +
> > drivers/md/dm-snap.c | 7 +++
>
> Have you tested REQ_OP_PROVISION with these targets? Just want to
> make sure you have an explicit need (and vested interest) for them
> passing through REQ_OP_PROVISION.
>
Yes. I have a vested interest in dm-linear and dm-crypt; I kept
dm-snap support mostly for consistency with thin snapshots.
> > diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
> > index 2055a758541d..5985343384a7 100644
> > --- a/drivers/md/dm-table.c
> > +++ b/drivers/md/dm-table.c
> > @@ -1850,6 +1850,26 @@ static bool dm_table_supports_write_zeroes(struct dm_table *t)
> > return true;
> > }
> >
> > +static int device_provision_capable(struct dm_target *ti, struct dm_dev *dev,
> > + sector_t start, sector_t len, void *data)
> > +{
> > + return !bdev_max_provision_sectors(dev->bdev);
> > +}
> > +
> > +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->provision_supported ||
> > + (ti->type->iterate_devices &&
> > + ti->type->iterate_devices(ti, device_provision_capable, NULL)))
> > + 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)
> > {
> > @@ -1983,6 +2003,11 @@ 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);
>
> This doesn't seem correct in that it'll override whatever
> max_provision_sectors was set by a target (like thinp).
>
> I think you only need the if (!dm_table_supports_provision)) case:
>
Done
> > + 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 13d4677baafd..b08b7ae617be 100644
> > --- a/drivers/md/dm-thin.c
> > +++ b/drivers/md/dm-thin.c
>
> I think it'll make the most sense to split out the dm-thin.c changes
> in a separate patch.
>
Separated the dm-thin changes into a separate patch that follows this one in v4.
> > @@ -909,7 +909,8 @@ 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);
> > @@ -1013,6 +1014,15 @@ static void process_prepared_mapping(struct dm_thin_new_mapping *m)
> > goto out;
> > }
> >
> > + /*
> > + * For provision requests, once the prepared block has been inserted
> > + * into the mapping btree, return.
> > + */
> > + if (bio && bio_op(bio) == REQ_OP_PROVISION) {
> > + bio_endio(bio);
> > + return;
> > + }
> > +
> > /*
> > * Release any bios held while the block was being provisioned.
> > * If we are processing a write bio that completely covers the block,
> > @@ -1241,7 +1251,7 @@ 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) &&
> > + return (bio_data_dir(bio) == WRITE) && bio_op(bio) != REQ_OP_PROVISION &&
> > io_overlaps_block(pool, bio);
> > }
> >
> > @@ -1334,10 +1344,11 @@ static void schedule_copy(struct thin_c *tc, dm_block_t virt_block,
> > /*
> > * IO to pool_dev remaps to the pool target's data_dev.
> > *
> > - * If the whole block of data is being overwritten, we can issue the
> > - * bio immediately. Otherwise we use kcopyd to clone the data first.
> > + * If the whole block of data is being overwritten and if this is not a
> > + * provision request, we can issue the bio immediately.
> > + * Otherwise we use kcopyd to clone the data first.
> > */
> > - if (io_overwrites_block(pool, bio))
> > + if (io_overwrites_block(pool, bio) && bio_op(bio) != REQ_OP_PROVISION)
> > remap_and_issue_overwrite(tc, bio, data_dest, m);
> > else {
> > struct dm_io_region from, to;
> > @@ -1356,7 +1367,8 @@ static void schedule_copy(struct thin_c *tc, dm_block_t virt_block,
> > /*
> > * Do we need to zero a tail region?
> > */
> > - if (len < pool->sectors_per_block && pool->pf.zero_new_blocks) {
> > + if (len < pool->sectors_per_block && pool->pf.zero_new_blocks &&
> > + bio_op(bio) != REQ_OP_PROVISION) {
> > atomic_inc(&m->prepare_actions);
> > ll_zero(tc, m,
> > data_dest * pool->sectors_per_block + len,
> > @@ -1390,6 +1402,10 @@ static void schedule_zero(struct thin_c *tc, dm_block_t virt_block,
> > m->data_block = data_block;
> > m->cell = cell;
> >
> > + /* Provision requests are chained on the original bio. */
> > + 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.
> > @@ -1865,7 +1881,8 @@ static void process_shared_bio(struct thin_c *tc, struct bio *bio,
> >
> > if (bio_data_dir(bio) == WRITE && bio->bi_iter.bi_size) {
> > break_sharing(tc, bio, block, &key, lookup_result, data_cell);
> > - cell_defer_no_holder(tc, virt_cell);
> > + if (bio_op(bio) != REQ_OP_PROVISION)
> > + cell_defer_no_holder(tc, virt_cell);
> > } else {
> > struct dm_thin_endio_hook *h = dm_per_bio_data(bio, sizeof(struct dm_thin_endio_hook));
> >
>
> Not confident in the above changes given the request that we only
> handle REQ_OP_PROVISION one thinp block at a time. So I'll gloss over
> them for now.
>
Yeah, the majority of this got removed in v4. I added a check in
io_overwrites_block() to return false for all provision requests.
> > @@ -1982,6 +1999,73 @@ 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:
> > + if (lookup_result.shared)
> > + process_shared_bio(tc, bio, begin,
> > + &lookup_result, cell);
> > + begin++;
> > + break;
> > + case -ENODATA:
> > + bio_inc_remaining(bio);
> > + 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;
> > + }
>
> Like Joe mentioned, this pattern was fine for discards because they
> are advisory/optional. But we need to make sure we don't truncate
> REQ_OP_PROVISION -- so we need to round up if we partially bleed into
> the blocks to the left or right.
>
> BUT ranged REQ_OP_PROVISION support is for later, this can be dealt
> with more simply in that each REQ_OP_PROVISION will be handled a block
> at a time initially. SO you'll want to honor _all_ REQ_OP_PROVISION,
> never returning early.
>
Thanks. The next patch in the series has the simplified version. It
had a lot in common with process_bio() so there was a possibility for
merging the two code paths, but I opted to keep it like this to make
ranged handling and passdown support easier to implement.
> > +
> > + 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;
> > @@ -2202,6 +2286,8 @@ 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);
>
> This should be pool->process_provision() (or ->process_provision_bio
> if you like). Point is, you need to be switching these methods
> if/when the pool_mode transitions in set_pool_mode().
>
Done
> > else
> > pool->process_bio(tc, bio);
> >
> > @@ -2723,7 +2809,8 @@ 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;
> > }
> > @@ -3370,6 +3457,8 @@ 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;
> >
> > /*
> > * Only need to enable discards if the pool should pass
> > @@ -4068,6 +4157,7 @@ static void pool_io_hints(struct dm_target *ti, struct queue_limits *limits)
> > blk_limits_io_opt(limits, pool->sectors_per_block << SECTOR_SHIFT);
> > }
> >
> > +
>
> Please fix this extra whitespace damage.
>
Done
> > /*
> > * pt->adjusted_pf is a staging area for the actual features to use.
> > * They get transferred to the live pool in bind_control_target()
> > @@ -4261,6 +4351,9 @@ static int thin_ctr(struct dm_target *ti, unsigned int argc, char **argv)
> > ti->num_discard_bios = 1;
> > }
> >
> > + ti->num_provision_bios = 1;
> > + ti->provision_supported = true;
> > +
> > mutex_unlock(&dm_thin_pool_table.mutex);
> >
> > spin_lock_irq(&tc->pool->lock);
> > @@ -4475,6 +4568,7 @@ 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 */
>
> Building on my previous reply, with suggested update to
> dm.c:__process_abnormal_io(), once you rebase on dm-6.4's dm-thin.c
> you'll want to instead:
>
> limits->max_provision_sectors = pool->sectors_per_block << SECTOR_SHIFT;
>
> And you'll want to drop any of the above code that deals with handling
> bio-prison range locking and processing of REQ_OP_PROVISION for
> multiple thinp blocks at once.
>
> Simple REQ_OP_PROVISION processing one thinp block at a time first and
> then we can worry about handling REQ_OP_PROVISION that span blocks
> later.
>
Thanks, done in v4.
> > static struct target_type thin_target = {
> > diff --git a/drivers/md/dm.c b/drivers/md/dm.c
> > index dfde0088147a..d8f1803062b7 100644
> > --- a/drivers/md/dm.c
> > +++ b/drivers/md/dm.c
> > @@ -1593,6 +1593,7 @@ 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;
> > @@ -1617,6 +1618,9 @@ 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;
> > }
>
> Please be sure to include my suggested __process_abnormal_io change
> from my previous reply.
>
Done.
> > diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h
> > index 7975483816e4..e9f687521ae6 100644
> > --- a/include/linux/device-mapper.h
> > +++ b/include/linux/device-mapper.h
> > @@ -334,6 +334,12 @@ struct dm_target {
> > */
> > unsigned int 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 int num_provision_bios;
> > +
> > /*
> > * The minimum number of extra bytes allocated in each io for the
> > * target to use.
> > @@ -358,6 +364,11 @@ struct dm_target {
> > */
> > bool discards_supported:1;
> >
> > + /* Set if this target needs to receive provision requests regardless of
> > + * whether or not its underlying devices have support.
> > + */
> > + bool provision_supported:1;
> > +
> > /*
> > * Set if we need to limit the number of in-flight bios when swapping.
> > */
>
> You'll need to add max_provision_granularity bool too (as implied by
> the dm.c:__process_abnormal_io() change suggested in my first reply to
> this patch).
>
> I'm happy to wait for you to consume the v3 feedback we've provided so
> you can create a v4. I'm thinking I can base dm-thin.c's WRITE_ZEROES
> support ontop of your REQ_OP_PROVISION v4 changes -- they should be
> complementary.
>
Done. Thanks for the review and guidance!
Best
Sarthak
> Thanks,
> Mike
@@ -3087,6 +3087,8 @@ 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) {
@@ -3390,7 +3392,7 @@ 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 +
@@ -62,6 +62,7 @@ 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;
@@ -1358,6 +1358,7 @@ static int snapshot_ctr(struct dm_target *ti, unsigned int argc, char **argv)
if (s->discard_zeroes_cow)
ti->num_discard_bios = (s->discard_passdown_origin ? 2 : 1);
ti->per_io_data_size = sizeof(struct dm_snap_tracked_chunk);
+ ti->num_provision_bios = 1;
/* Add snapshot to the list of snapshots for this origin */
/* Exceptions aren't triggered till snapshot_resume() is called */
@@ -2003,6 +2004,11 @@ static int snapshot_map(struct dm_target *ti, struct bio *bio)
/* If the block is already remapped - use that, else remap it */
e = dm_lookup_exception(&s->complete, chunk);
if (e) {
+ if (unlikely(bio_op(bio) == REQ_OP_PROVISION)) {
+ bio_endio(bio);
+ r = DM_MAPIO_SUBMITTED;
+ goto out_unlock;
+ }
remap_exception(s, e, bio, chunk);
if (unlikely(bio_op(bio) == REQ_OP_DISCARD) &&
io_overlaps_chunk(s, bio)) {
@@ -2413,6 +2419,7 @@ static void snapshot_io_hints(struct dm_target *ti, struct queue_limits *limits)
/* All discards are split on chunk_size boundary */
limits->discard_granularity = snap->store->chunk_size;
limits->max_discard_sectors = snap->store->chunk_size;
+ limits->max_provision_sectors = snap->store->chunk_size;
up_read(&_origins_lock);
}
@@ -1850,6 +1850,26 @@ static bool dm_table_supports_write_zeroes(struct dm_table *t)
return true;
}
+static int device_provision_capable(struct dm_target *ti, struct dm_dev *dev,
+ sector_t start, sector_t len, void *data)
+{
+ return !bdev_max_provision_sectors(dev->bdev);
+}
+
+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->provision_supported ||
+ (ti->type->iterate_devices &&
+ ti->type->iterate_devices(ti, device_provision_capable, NULL)))
+ 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)
{
@@ -1983,6 +2003,11 @@ 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);
/*
@@ -909,7 +909,8 @@ 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);
@@ -1013,6 +1014,15 @@ static void process_prepared_mapping(struct dm_thin_new_mapping *m)
goto out;
}
+ /*
+ * For provision requests, once the prepared block has been inserted
+ * into the mapping btree, return.
+ */
+ if (bio && bio_op(bio) == REQ_OP_PROVISION) {
+ bio_endio(bio);
+ return;
+ }
+
/*
* Release any bios held while the block was being provisioned.
* If we are processing a write bio that completely covers the block,
@@ -1241,7 +1251,7 @@ 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) &&
+ return (bio_data_dir(bio) == WRITE) && bio_op(bio) != REQ_OP_PROVISION &&
io_overlaps_block(pool, bio);
}
@@ -1334,10 +1344,11 @@ static void schedule_copy(struct thin_c *tc, dm_block_t virt_block,
/*
* IO to pool_dev remaps to the pool target's data_dev.
*
- * If the whole block of data is being overwritten, we can issue the
- * bio immediately. Otherwise we use kcopyd to clone the data first.
+ * If the whole block of data is being overwritten and if this is not a
+ * provision request, we can issue the bio immediately.
+ * Otherwise we use kcopyd to clone the data first.
*/
- if (io_overwrites_block(pool, bio))
+ if (io_overwrites_block(pool, bio) && bio_op(bio) != REQ_OP_PROVISION)
remap_and_issue_overwrite(tc, bio, data_dest, m);
else {
struct dm_io_region from, to;
@@ -1356,7 +1367,8 @@ static void schedule_copy(struct thin_c *tc, dm_block_t virt_block,
/*
* Do we need to zero a tail region?
*/
- if (len < pool->sectors_per_block && pool->pf.zero_new_blocks) {
+ if (len < pool->sectors_per_block && pool->pf.zero_new_blocks &&
+ bio_op(bio) != REQ_OP_PROVISION) {
atomic_inc(&m->prepare_actions);
ll_zero(tc, m,
data_dest * pool->sectors_per_block + len,
@@ -1390,6 +1402,10 @@ static void schedule_zero(struct thin_c *tc, dm_block_t virt_block,
m->data_block = data_block;
m->cell = cell;
+ /* Provision requests are chained on the original bio. */
+ 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.
@@ -1865,7 +1881,8 @@ static void process_shared_bio(struct thin_c *tc, struct bio *bio,
if (bio_data_dir(bio) == WRITE && bio->bi_iter.bi_size) {
break_sharing(tc, bio, block, &key, lookup_result, data_cell);
- cell_defer_no_holder(tc, virt_cell);
+ if (bio_op(bio) != REQ_OP_PROVISION)
+ cell_defer_no_holder(tc, virt_cell);
} else {
struct dm_thin_endio_hook *h = dm_per_bio_data(bio, sizeof(struct dm_thin_endio_hook));
@@ -1982,6 +1999,73 @@ 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:
+ if (lookup_result.shared)
+ process_shared_bio(tc, bio, begin,
+ &lookup_result, cell);
+ begin++;
+ break;
+ case -ENODATA:
+ bio_inc_remaining(bio);
+ 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;
@@ -2202,6 +2286,8 @@ 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);
@@ -2723,7 +2809,8 @@ 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;
}
@@ -3370,6 +3457,8 @@ 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;
/*
* Only need to enable discards if the pool should pass
@@ -4068,6 +4157,7 @@ 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()
@@ -4261,6 +4351,9 @@ static int thin_ctr(struct dm_target *ti, unsigned int argc, char **argv)
ti->num_discard_bios = 1;
}
+ ti->num_provision_bios = 1;
+ ti->provision_supported = true;
+
mutex_unlock(&dm_thin_pool_table.mutex);
spin_lock_irq(&tc->pool->lock);
@@ -4475,6 +4568,7 @@ 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 = {
@@ -1593,6 +1593,7 @@ 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;
@@ -1617,6 +1618,9 @@ 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;
}
@@ -334,6 +334,12 @@ struct dm_target {
*/
unsigned int 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 int num_provision_bios;
+
/*
* The minimum number of extra bytes allocated in each io for the
* target to use.
@@ -358,6 +364,11 @@ struct dm_target {
*/
bool discards_supported:1;
+ /* Set if this target needs to receive provision requests regardless of
+ * whether or not its underlying devices have support.
+ */
+ bool provision_supported:1;
+
/*
* Set if we need to limit the number of in-flight bios when swapping.
*/