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

[ Upstream commit 873937e75f9a8ea231a502c3d29d9cb6ad91b3ef ]

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: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c
index 69201bdf7f4c67732b374c53047cc3fa88ae7cdd..1b2c98b43519f1ffa9afbda5b7547dafac43d0ca 100644 (file)
--- a/drivers/md/dm-thin.c
+++ b/drivers/md/dm-thin.c
@@ -231,6 +231,7 @@ struct pool {
        struct dm_target *ti;   /* Only set if a pool target is bound */
 
        struct mapped_device *pool_md;
        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;
 
        struct block_device *md_dev;
        struct dm_pool_metadata *pmd;
 


@@ -2945,6 +2946,7 @@ static struct kmem_cache *_new_mapping_cache;
 
 static struct pool *pool_create(struct mapped_device *pool_md,
                                struct block_device *metadata_dev,
 
 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)
 {
                                unsigned long block_size,
                                int read_only, char **error)
 {


@@ -3052,6 +3054,7 @@ 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->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;
        __pool_table_insert(pool);
 
        return pool;


@@ -3093,6 +3096,7 @@ static void __pool_dec(struct pool *pool)
 
 static struct pool *__pool_find(struct mapped_device *pool_md,
                                struct block_device *metadata_dev,
 
 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)
 {
                                unsigned long block_size, int read_only,
                                char **error, int *created)
 {


@@ -3103,19 +3107,23 @@ static struct pool *__pool_find(struct mapped_device *pool_md,
                        *error = "metadata device already in use by a pool";
                        return ERR_PTR(-EBUSY);
                }
                        *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) {
                __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 {
                                *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;
                }
        }
                        *created = 1;
                }
        }


@@ -3368,7 +3376,7 @@ static int pool_ctr(struct dm_target *ti, unsigned argc, char **argv)
                goto out;
        }
 
                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);
                           block_size, pf.mode == PM_READ_ONLY, &ti->error, &pool_created);
        if (IS_ERR(pool)) {
                r = PTR_ERR(pool);


@@ -4114,7 +4122,7 @@ static struct target_type pool_target = {
        .name = "thin-pool",
        .features = DM_TARGET_SINGLETON | DM_TARGET_ALWAYS_WRITEABLE |
                    DM_TARGET_IMMUTABLE,
        .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,
        .module = THIS_MODULE,
        .ctr = pool_ctr,
        .dtr = pool_dtr,


@@ -4493,7 +4501,7 @@ static void thin_io_hints(struct dm_target *ti, struct queue_limits *limits)
 
 static struct target_type thin_target = {
        .name = "thin",
 
 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,
        .module = THIS_MODULE,
        .ctr = thin_ctr,
        .dtr = thin_dtr,