Commit 873937e7 authored by Mikulas Patocka's avatar Mikulas Patocka Committed by Mike Snitzer
Browse files

dm thin: don't allow changing data device during thin-pool reload 

The existing code allows changing the data device when the thin-pool
target is reloaded.

This capability is not required and only complicates device lifetime
guarantees. This can cause crashes like the one reported here:
	https://bugzilla.redhat.com/show_bug.cgi?id=1788596


where the kernel tries to issue a flush bio located in a structure that
was already freed.

Take the first step to simplifying the thin-pool's data device lifetime
by disallowing changing it. Like the thin-pool's metadata device, the
data device is now set in pool_create() and it cannot be changed for a
given thin-pool.

Signed-off-by: default avatarMikulas Patocka <mpatocka@redhat.com>
Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
parent a4a8d286

drivers/md/dm-thin.c

+13 −5
Original line number Diff line number Diff line
@@ -231,6 +231,7 @@ struct pool { 
	struct dm_target *ti;	/* Only set if a pool target is bound */



	struct mapped_device *pool_md;

	struct block_device *data_dev;

	struct block_device *md_dev;

	struct dm_pool_metadata *pmd;
@@ -2933,6 +2934,7 @@ static struct kmem_cache *_new_mapping_cache; 


static struct pool *pool_create(struct mapped_device *pool_md,

				struct block_device *metadata_dev,

				struct block_device *data_dev,

				unsigned long block_size,

				int read_only, char **error)

{
@@ -3040,6 +3042,7 @@ static struct pool *pool_create(struct mapped_device *pool_md, 
	pool->last_commit_jiffies = jiffies;

	pool->pool_md = pool_md;

	pool->md_dev = metadata_dev;

	pool->data_dev = data_dev;

	__pool_table_insert(pool);



	return pool;
@@ -3081,6 +3084,7 @@ static void __pool_dec(struct pool *pool) 


static struct pool *__pool_find(struct mapped_device *pool_md,

				struct block_device *metadata_dev,

				struct block_device *data_dev,

				unsigned long block_size, int read_only,

				char **error, int *created)

{
@@ -3091,19 +3095,23 @@ static struct pool *__pool_find(struct mapped_device *pool_md, 
			*error = "metadata device already in use by a pool";

			return ERR_PTR(-EBUSY);

		}

		if (pool->data_dev != data_dev) {

			*error = "data device already in use by a pool";

			return ERR_PTR(-EBUSY);

		}

		__pool_inc(pool);



	} else {

		pool = __pool_table_lookup(pool_md);

		if (pool) {

			if (pool->md_dev != metadata_dev) {

			if (pool->md_dev != metadata_dev || pool->data_dev != data_dev) {

				*error = "different pool cannot replace a pool";

				return ERR_PTR(-EINVAL);

			}

			__pool_inc(pool);



		} else {

			pool = pool_create(pool_md, metadata_dev, block_size, read_only, error);

			pool = pool_create(pool_md, metadata_dev, data_dev, block_size, read_only, error);

			*created = 1;

		}

	}
@@ -3356,7 +3364,7 @@ static int pool_ctr(struct dm_target *ti, unsigned argc, char **argv) 
		goto out;

	}



	pool = __pool_find(dm_table_get_md(ti->table), metadata_dev->bdev,

	pool = __pool_find(dm_table_get_md(ti->table), metadata_dev->bdev, data_dev->bdev,

			   block_size, pf.mode == PM_READ_ONLY, &ti->error, &pool_created);

	if (IS_ERR(pool)) {

		r = PTR_ERR(pool);
@@ -4098,7 +4106,7 @@ static struct target_type pool_target = { 
	.name = "thin-pool",

	.features = DM_TARGET_SINGLETON | DM_TARGET_ALWAYS_WRITEABLE |

		    DM_TARGET_IMMUTABLE,

	.version = {1, 21, 0},

	.version = {1, 22, 0},

	.module = THIS_MODULE,

	.ctr = pool_ctr,

	.dtr = pool_dtr,
@@ -4475,7 +4483,7 @@ static void thin_io_hints(struct dm_target *ti, struct queue_limits *limits) 


static struct target_type thin_target = {

	.name = "thin",

	.version = {1, 21, 0},

	.version = {1, 22, 0},

	.module	= THIS_MODULE,

	.ctr = thin_ctr,

	.dtr = thin_dtr,

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