Commit 67e2e2b2 authored by Joe Thornber's avatar Joe Thornber Committed by Alasdair G Kergon
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dm thin: add pool target flags to control discard



Add dm thin target arguments to control discard support.

ignore_discard: Disables discard support

no_discard_passdown: Don't pass discards down to the underlying data
device, but just remove the mapping within the thin provisioning target.
Signed-off-by: default avatarJoe Thornber <ejt@redhat.com>
Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
Signed-off-by: default avatarAlasdair G Kergon <agk@redhat.com>
parent 104655fd
......@@ -223,7 +223,13 @@ i) Constructor
<low water mark (blocks)> [<number of feature args> [<arg>]*]
Optional feature arguments:
- 'skip_block_zeroing': skips the zeroing of newly-provisioned blocks.
skip_block_zeroing: Skip the zeroing of newly-provisioned blocks.
ignore_discard: Disable discard support.
no_discard_passdown: Don't pass discards down to the underlying
data device, but just remove the mapping.
Data block size must be between 64KB (128 sectors) and 1GB
(2097152 sectors) inclusive.
......
......@@ -489,6 +489,13 @@ static void build_virtual_key(struct dm_thin_device *td, dm_block_t b,
* devices.
*/
struct new_mapping;
struct pool_features {
unsigned zero_new_blocks:1;
unsigned discard_enabled:1;
unsigned discard_passdown:1;
};
struct pool {
struct list_head list;
struct dm_target *ti; /* Only set if a pool target is bound */
......@@ -502,7 +509,7 @@ struct pool {
dm_block_t offset_mask;
dm_block_t low_water_blocks;
unsigned zero_new_blocks:1;
struct pool_features pf;
unsigned low_water_triggered:1; /* A dm event has been sent */
unsigned no_free_space:1; /* A -ENOSPC warning has been issued */
......@@ -543,7 +550,7 @@ struct pool_c {
struct dm_target_callbacks callbacks;
dm_block_t low_water_blocks;
unsigned zero_new_blocks:1;
struct pool_features pf;
};
/*
......@@ -1051,7 +1058,7 @@ static void schedule_zero(struct thin_c *tc, dm_block_t virt_block,
* zeroing pre-existing data, we can issue the bio immediately.
* Otherwise we use kcopyd to zero the data first.
*/
if (!pool->zero_new_blocks)
if (!pool->pf.zero_new_blocks)
process_prepared_mapping(m);
else if (io_overwrites_block(pool, bio)) {
......@@ -1202,7 +1209,7 @@ static void process_discard(struct thin_c *tc, struct bio *bio)
*/
m = get_next_mapping(pool);
m->tc = tc;
m->pass_discard = !lookup_result.shared;
m->pass_discard = (!lookup_result.shared) & pool->pf.discard_passdown;
m->virt_block = block;
m->data_block = lookup_result.block;
m->cell = cell;
......@@ -1617,7 +1624,7 @@ static int bind_control_target(struct pool *pool, struct dm_target *ti)
pool->ti = ti;
pool->low_water_blocks = pt->low_water_blocks;
pool->zero_new_blocks = pt->zero_new_blocks;
pool->pf = pt->pf;
return 0;
}
......@@ -1631,6 +1638,14 @@ static void unbind_control_target(struct pool *pool, struct dm_target *ti)
/*----------------------------------------------------------------
* Pool creation
*--------------------------------------------------------------*/
/* Initialize pool features. */
static void pool_features_init(struct pool_features *pf)
{
pf->zero_new_blocks = 1;
pf->discard_enabled = 1;
pf->discard_passdown = 1;
}
static void __pool_destroy(struct pool *pool)
{
__pool_table_remove(pool);
......@@ -1678,7 +1693,7 @@ static struct pool *pool_create(struct mapped_device *pool_md,
pool->block_shift = ffs(block_size) - 1;
pool->offset_mask = block_size - 1;
pool->low_water_blocks = 0;
pool->zero_new_blocks = 1;
pool_features_init(&pool->pf);
pool->prison = prison_create(PRISON_CELLS);
if (!pool->prison) {
*error = "Error creating pool's bio prison";
......@@ -1775,7 +1790,8 @@ static void __pool_dec(struct pool *pool)
static struct pool *__pool_find(struct mapped_device *pool_md,
struct block_device *metadata_dev,
unsigned long block_size, char **error)
unsigned long block_size, char **error,
int *created)
{
struct pool *pool = __pool_table_lookup_metadata_dev(metadata_dev);
......@@ -1791,8 +1807,10 @@ static struct pool *__pool_find(struct mapped_device *pool_md,
return ERR_PTR(-EINVAL);
__pool_inc(pool);
} else
} else {
pool = pool_create(pool_md, metadata_dev, block_size, error);
*created = 1;
}
}
return pool;
......@@ -1816,10 +1834,6 @@ static void pool_dtr(struct dm_target *ti)
mutex_unlock(&dm_thin_pool_table.mutex);
}
struct pool_features {
unsigned zero_new_blocks:1;
};
static int parse_pool_features(struct dm_arg_set *as, struct pool_features *pf,
struct dm_target *ti)
{
......@@ -1828,7 +1842,7 @@ static int parse_pool_features(struct dm_arg_set *as, struct pool_features *pf,
const char *arg_name;
static struct dm_arg _args[] = {
{0, 1, "Invalid number of pool feature arguments"},
{0, 3, "Invalid number of pool feature arguments"},
};
/*
......@@ -1848,6 +1862,12 @@ static int parse_pool_features(struct dm_arg_set *as, struct pool_features *pf,
if (!strcasecmp(arg_name, "skip_block_zeroing")) {
pf->zero_new_blocks = 0;
continue;
} else if (!strcasecmp(arg_name, "ignore_discard")) {
pf->discard_enabled = 0;
continue;
} else if (!strcasecmp(arg_name, "no_discard_passdown")) {
pf->discard_passdown = 0;
continue;
}
ti->error = "Unrecognised pool feature requested";
......@@ -1865,10 +1885,12 @@ static int parse_pool_features(struct dm_arg_set *as, struct pool_features *pf,
*
* Optional feature arguments are:
* skip_block_zeroing: skips the zeroing of newly-provisioned blocks.
* ignore_discard: disable discard
* no_discard_passdown: don't pass discards down to the data device
*/
static int pool_ctr(struct dm_target *ti, unsigned argc, char **argv)
{
int r;
int r, pool_created = 0;
struct pool_c *pt;
struct pool *pool;
struct pool_features pf;
......@@ -1928,8 +1950,7 @@ static int pool_ctr(struct dm_target *ti, unsigned argc, char **argv)
/*
* Set default pool features.
*/
memset(&pf, 0, sizeof(pf));
pf.zero_new_blocks = 1;
pool_features_init(&pf);
dm_consume_args(&as, 4);
r = parse_pool_features(&as, &pf, ti);
......@@ -1943,21 +1964,58 @@ static int pool_ctr(struct dm_target *ti, unsigned argc, char **argv)
}
pool = __pool_find(dm_table_get_md(ti->table), metadata_dev->bdev,
block_size, &ti->error);
block_size, &ti->error, &pool_created);
if (IS_ERR(pool)) {
r = PTR_ERR(pool);
goto out_free_pt;
}
/*
* 'pool_created' reflects whether this is the first table load.
* Top level discard support is not allowed to be changed after
* initial load. This would require a pool reload to trigger thin
* device changes.
*/
if (!pool_created && pf.discard_enabled != pool->pf.discard_enabled) {
ti->error = "Discard support cannot be disabled once enabled";
r = -EINVAL;
goto out_flags_changed;
}
/*
* If discard_passdown was enabled verify that the data device
* supports discards. Disable discard_passdown if not; otherwise
* -EOPNOTSUPP will be returned.
*/
if (pf.discard_passdown) {
struct request_queue *q = bdev_get_queue(data_dev->bdev);
if (!q || !blk_queue_discard(q)) {
DMWARN("Discard unsupported by data device: Disabling discard passdown.");
pf.discard_passdown = 0;
}
}
pt->pool = pool;
pt->ti = ti;
pt->metadata_dev = metadata_dev;
pt->data_dev = data_dev;
pt->low_water_blocks = low_water_blocks;
pt->zero_new_blocks = pf.zero_new_blocks;
pt->pf = pf;
ti->num_flush_requests = 1;
ti->num_discard_requests = 1;
ti->discards_supported = 1;
/*
* Only need to enable discards if the pool should pass
* them down to the data device. The thin device's discard
* processing will cause mappings to be removed from the btree.
*/
if (pf.discard_enabled && pf.discard_passdown) {
ti->num_discard_requests = 1;
/*
* Setting 'discards_supported' circumvents the normal
* stacking of discard limits (this keeps the pool and
* thin devices' discard limits consistent).
*/
ti->discards_supported = 1;
}
ti->private = pt;
pt->callbacks.congested_fn = pool_is_congested;
......@@ -1967,6 +2025,8 @@ static int pool_ctr(struct dm_target *ti, unsigned argc, char **argv)
return 0;
out_flags_changed:
__pool_dec(pool);
out_free_pt:
kfree(pt);
out:
......@@ -2255,7 +2315,7 @@ static int pool_message(struct dm_target *ti, unsigned argc, char **argv)
static int pool_status(struct dm_target *ti, status_type_t type,
char *result, unsigned maxlen)
{
int r;
int r, count;
unsigned sz = 0;
uint64_t transaction_id;
dm_block_t nr_free_blocks_data;
......@@ -2318,10 +2378,19 @@ static int pool_status(struct dm_target *ti, status_type_t type,
(unsigned long)pool->sectors_per_block,
(unsigned long long)pt->low_water_blocks);
DMEMIT("%u ", !pool->zero_new_blocks);
count = !pool->pf.zero_new_blocks + !pool->pf.discard_enabled +
!pool->pf.discard_passdown;
DMEMIT("%u ", count);
if (!pool->zero_new_blocks)
if (!pool->pf.zero_new_blocks)
DMEMIT("skip_block_zeroing ");
if (!pool->pf.discard_enabled)
DMEMIT("ignore_discard ");
if (!pool->pf.discard_passdown)
DMEMIT("no_discard_passdown ");
break;
}
......@@ -2352,6 +2421,9 @@ static int pool_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
static void set_discard_limits(struct pool *pool, struct queue_limits *limits)
{
/*
* FIXME: these limits may be incompatible with the pool's data device
*/
limits->max_discard_sectors = pool->sectors_per_block;
/*
......@@ -2359,6 +2431,7 @@ static void set_discard_limits(struct pool *pool, struct queue_limits *limits)
* bios that overlap 2 blocks.
*/
limits->discard_granularity = pool->sectors_per_block << SECTOR_SHIFT;
limits->discard_zeroes_data = pool->pf.zero_new_blocks;
}
static void pool_io_hints(struct dm_target *ti, struct queue_limits *limits)
......@@ -2368,14 +2441,15 @@ static void pool_io_hints(struct dm_target *ti, struct queue_limits *limits)
blk_limits_io_min(limits, 0);
blk_limits_io_opt(limits, pool->sectors_per_block << SECTOR_SHIFT);
set_discard_limits(pool, limits);
if (pool->pf.discard_enabled)
set_discard_limits(pool, limits);
}
static struct target_type pool_target = {
.name = "thin-pool",
.features = DM_TARGET_SINGLETON | DM_TARGET_ALWAYS_WRITEABLE |
DM_TARGET_IMMUTABLE,
.version = {1, 0, 0},
.version = {1, 1, 0},
.module = THIS_MODULE,
.ctr = pool_ctr,
.dtr = pool_dtr,
......@@ -2417,6 +2491,9 @@ static void thin_dtr(struct dm_target *ti)
* pool_dev: the path to the pool (eg, /dev/mapper/my_pool)
* dev_id: the internal device identifier
* origin_dev: a device external to the pool that should act as the origin
*
* If the pool device has discards disabled, they get disabled for the thin
* device as well.
*/
static int thin_ctr(struct dm_target *ti, unsigned argc, char **argv)
{
......@@ -2485,8 +2562,12 @@ static int thin_ctr(struct dm_target *ti, unsigned argc, char **argv)
ti->split_io = tc->pool->sectors_per_block;
ti->num_flush_requests = 1;
ti->num_discard_requests = 1;
ti->discards_supported = 1;
/* In case the pool supports discards, pass them on. */
if (tc->pool->pf.discard_enabled) {
ti->discards_supported = 1;
ti->num_discard_requests = 1;
}
dm_put(pool_md);
......
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