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Commit e5aea7b4 authored by Joe Thornber's avatar Joe Thornber Committed by Mike Snitzer
Browse files

dm thin: relax external origin size constraints 



Track the size of any external origin.  Previously the external origin's
size had to be a multiple of the thin-pool's block size, that is no
longer a requirement.  In addition, snapshots that are larger than the
external origin are now supported.

Signed-off-by: default avatarJoe Thornber <ejt@redhat.com>
Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
parent 50f3c3ef

drivers/md/dm-thin.c

+115 −43
Original line number Diff line number Diff line
@@ -227,6 +227,7 @@ struct thin_c { 
	struct list_head list;

	struct dm_dev *pool_dev;

	struct dm_dev *origin_dev;

	sector_t origin_size;

	dm_thin_id dev_id;



	struct pool *pool;
@@ -590,31 +591,31 @@ static void __complete_mapping_preparation(struct dm_thin_new_mapping *m) 
	}

}



static void copy_complete(int read_err, unsigned long write_err, void *context)

static void complete_mapping_preparation(struct dm_thin_new_mapping *m)

{

	unsigned long flags;

	struct dm_thin_new_mapping *m = context;

	struct pool *pool = m->tc->pool;



	m->err = read_err || write_err ? -EIO : 0;



	spin_lock_irqsave(&pool->lock, flags);

	__complete_mapping_preparation(m);

	spin_unlock_irqrestore(&pool->lock, flags);

}



static void copy_complete(int read_err, unsigned long write_err, void *context)

{

	struct dm_thin_new_mapping *m = context;



	m->err = read_err || write_err ? -EIO : 0;

	complete_mapping_preparation(m);

}



static void overwrite_endio(struct bio *bio, int err)

{

	unsigned long flags;

	struct dm_thin_endio_hook *h = dm_per_bio_data(bio, sizeof(struct dm_thin_endio_hook));

	struct dm_thin_new_mapping *m = h->overwrite_mapping;

	struct pool *pool = m->tc->pool;



	m->err = err;



	spin_lock_irqsave(&pool->lock, flags);

	__complete_mapping_preparation(m);

	spin_unlock_irqrestore(&pool->lock, flags);

	complete_mapping_preparation(m);

}



/*----------------------------------------------------------------*/
@@ -824,10 +825,31 @@ static struct dm_thin_new_mapping *get_next_mapping(struct pool *pool) 
	return m;

}



static void ll_zero(struct thin_c *tc, struct dm_thin_new_mapping *m,

		    sector_t begin, sector_t end)

{

	int r;

	struct dm_io_region to;



	to.bdev = tc->pool_dev->bdev;

	to.sector = begin;

	to.count = end - begin;



	r = dm_kcopyd_zero(tc->pool->copier, 1, &to, 0, copy_complete, m);

	if (r < 0) {

		DMERR_LIMIT("dm_kcopyd_zero() failed");

		copy_complete(1, 1, m);

	}

}



/*

 * A partial copy also needs to zero the uncopied region.

 */

static void schedule_copy(struct thin_c *tc, dm_block_t virt_block,

			  struct dm_dev *origin, dm_block_t data_origin,

			  dm_block_t data_dest,

			  struct dm_bio_prison_cell *cell, struct bio *bio)

			  struct dm_bio_prison_cell *cell, struct bio *bio,

			  sector_t len)

{

	int r;

	struct pool *pool = tc->pool;
@@ -838,10 +860,15 @@ static void schedule_copy(struct thin_c *tc, dm_block_t virt_block, 
	m->data_block = data_dest;

	m->cell = cell;



	/*

	 * quiesce action + copy action + an extra reference held for the

	 * duration of this function (we may need to inc later for a

	 * partial zero).

	 */

	atomic_set(&m->prepare_actions, 3);



	if (!dm_deferred_set_add_work(pool->shared_read_ds, &m->list))

		atomic_set(&m->prepare_actions, 1); /* copy only */

	else

		atomic_set(&m->prepare_actions, 2); /* quiesce + copy */

		complete_mapping_preparation(m); /* already quiesced */



	/*

	 * IO to pool_dev remaps to the pool target's data_dev.
@@ -862,36 +889,47 @@ static void schedule_copy(struct thin_c *tc, dm_block_t virt_block, 


		from.bdev = origin->bdev;

		from.sector = data_origin * pool->sectors_per_block;

		from.count = pool->sectors_per_block;

		from.count = len;



		to.bdev = tc->pool_dev->bdev;

		to.sector = data_dest * pool->sectors_per_block;

		to.count = pool->sectors_per_block;

		to.count = len;



		r = dm_kcopyd_copy(pool->copier, &from, 1, &to,

				   0, copy_complete, m);

		if (r < 0) {

			mempool_free(m, pool->mapping_pool);

			DMERR_LIMIT("dm_kcopyd_copy() failed");

			cell_error(pool, cell);

			copy_complete(1, 1, m);



			/*

			 * We allow the zero to be issued, to simplify the

			 * error path.  Otherwise we'd need to start

			 * worrying about decrementing the prepare_actions

			 * counter.

			 */

		}



		/*

		 * Do we need to zero a tail region?

		 */

		if (len < pool->sectors_per_block && pool->pf.zero_new_blocks) {

			atomic_inc(&m->prepare_actions);

			ll_zero(tc, m,

				data_dest * pool->sectors_per_block + len,

				(data_dest + 1) * pool->sectors_per_block);

		}

	}



	complete_mapping_preparation(m); /* drop our ref */

}



static void schedule_internal_copy(struct thin_c *tc, dm_block_t virt_block,

				   dm_block_t data_origin, dm_block_t data_dest,

				   struct dm_bio_prison_cell *cell, struct bio *bio)

{

	schedule_copy(tc, virt_block, tc->pool_dev,

		      data_origin, data_dest, cell, bio);

}



static void schedule_external_copy(struct thin_c *tc, dm_block_t virt_block,

				   dm_block_t data_dest,

				   struct dm_bio_prison_cell *cell, struct bio *bio)

{

	schedule_copy(tc, virt_block, tc->origin_dev,

		      virt_block, data_dest, cell, bio);

		      data_origin, data_dest, cell, bio,

		      tc->pool->sectors_per_block);

}



static void schedule_zero(struct thin_c *tc, dm_block_t virt_block,
@@ -923,21 +961,33 @@ static void schedule_zero(struct thin_c *tc, dm_block_t virt_block, 
		save_and_set_endio(bio, &m->saved_bi_end_io, overwrite_endio);

		inc_all_io_entry(pool, bio);

		remap_and_issue(tc, bio, data_block);

	} else {

		int r;

		struct dm_io_region to;



		to.bdev = tc->pool_dev->bdev;

		to.sector = data_block * pool->sectors_per_block;

		to.count = pool->sectors_per_block;



		r = dm_kcopyd_zero(pool->copier, 1, &to, 0, copy_complete, m);

		if (r < 0) {

			mempool_free(m, pool->mapping_pool);

			DMERR_LIMIT("dm_kcopyd_zero() failed");

			cell_error(pool, cell);

		}

	} else

		ll_zero(tc, m,

			data_block * pool->sectors_per_block,

			(data_block + 1) * pool->sectors_per_block);

}



static void schedule_external_copy(struct thin_c *tc, dm_block_t virt_block,

				   dm_block_t data_dest,

				   struct dm_bio_prison_cell *cell, struct bio *bio)

{

	struct pool *pool = tc->pool;

	sector_t virt_block_begin = virt_block * pool->sectors_per_block;

	sector_t virt_block_end = (virt_block + 1) * pool->sectors_per_block;



	if (virt_block_end <= tc->origin_size)

		schedule_copy(tc, virt_block, tc->origin_dev,

			      virt_block, data_dest, cell, bio,

			      pool->sectors_per_block);



	else if (virt_block_begin < tc->origin_size)

		schedule_copy(tc, virt_block, tc->origin_dev,

			      virt_block, data_dest, cell, bio,

			      tc->origin_size - virt_block_begin);



	else

		schedule_zero(tc, virt_block, data_dest, cell, bio);

}



/*
@@ -1319,7 +1369,18 @@ static void process_bio(struct thin_c *tc, struct bio *bio) 
			inc_all_io_entry(pool, bio);

			cell_defer_no_holder(tc, cell);



			if (bio_end_sector(bio) <= tc->origin_size)

				remap_to_origin_and_issue(tc, bio);



			else if (bio->bi_iter.bi_sector < tc->origin_size) {

				zero_fill_bio(bio);

				bio->bi_iter.bi_size = (tc->origin_size - bio->bi_iter.bi_sector) << SECTOR_SHIFT;

				remap_to_origin_and_issue(tc, bio);



			} else {

				zero_fill_bio(bio);

				bio_endio(bio, 0);

			}

		} else

			provision_block(tc, bio, block, cell);

		break;
@@ -3145,7 +3206,7 @@ static struct target_type pool_target = { 
	.name = "thin-pool",

	.features = DM_TARGET_SINGLETON | DM_TARGET_ALWAYS_WRITEABLE |

		    DM_TARGET_IMMUTABLE,

	.version = {1, 12, 0},

	.version = {1, 13, 0},

	.module = THIS_MODULE,

	.ctr = pool_ctr,

	.dtr = pool_dtr,
@@ -3404,6 +3465,16 @@ static void thin_postsuspend(struct dm_target *ti) 
	noflush_work(tc, do_noflush_stop);

}



static int thin_preresume(struct dm_target *ti)

{

	struct thin_c *tc = ti->private;



	if (tc->origin_dev)

		tc->origin_size = get_dev_size(tc->origin_dev->bdev);



	return 0;

}



/*

 * <nr mapped sectors> <highest mapped sector>

 */
@@ -3486,12 +3557,13 @@ static int thin_iterate_devices(struct dm_target *ti, 


static struct target_type thin_target = {

	.name = "thin",

	.version = {1, 12, 0},

	.version = {1, 13, 0},

	.module	= THIS_MODULE,

	.ctr = thin_ctr,

	.dtr = thin_dtr,

	.map = thin_map,

	.end_io = thin_endio,

	.preresume = thin_preresume,

	.presuspend = thin_presuspend,

	.postsuspend = thin_postsuspend,

	.status = thin_status,