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-rw-r--r--Documentation/device-mapper/thin-provisioning.txt8
-rw-r--r--drivers/md/dm-thin.c135
2 files changed, 115 insertions, 28 deletions
diff --git a/Documentation/device-mapper/thin-provisioning.txt b/Documentation/device-mapper/thin-provisioning.txt
index 310c1201d621..3370bc4d7b98 100644
--- a/Documentation/device-mapper/thin-provisioning.txt
+++ b/Documentation/device-mapper/thin-provisioning.txt
@@ -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.
diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c
index 703bbbc4f16f..213ae32a0fc4 100644
--- a/drivers/md/dm-thin.c
+++ b/drivers/md/dm-thin.c
@@ -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);
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.