dm thin: add pool target flags to control discard (67e2e2b2) · Commits · 戴 / test

Documentation/device-mapper/thin-provisioning.txt

+7 −1

Original line number	Diff line number	Diff line
		@@ -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.

drivers/md/dm-thin.c

+108 −27

Original line number	Diff line number	Diff line
		@@ -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;
		/*
		* 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)
		@@ -2368,6 +2441,7 @@ 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);
		if (pool->pf.discard_enabled)
		set_discard_limits(pool, limits);
		}

		@@ -2375,7 +2449,7 @@ 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;

		/* 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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