mbcache: remove unnecessary module_get/module_put

When mbcache is built as a module, any modules that use it (ext2 and/or
ext4) will depend on its symbols directly, incrementing its reference
count.  Therefore, there is no need to do module_get/module_put.

Also note that since the module_get/module_put were in the mbcache
module itself, executing those lines of code was already dependent on
another reference to the mbcache module being held.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Jan Kara <jack@suse.cz>

fs/mbcache.c

@@ -344,9 +344,6 @@ struct mb_cache *mb_cache_create(int bucket_bits)
 	int bucket_count = 1 << bucket_bits;
 	int i;
 
-	if (!try_module_get(THIS_MODULE))
-		return NULL;
-
 	cache = kzalloc(sizeof(struct mb_cache), GFP_KERNEL);
 	if (!cache)
 		goto err_out;
@@ -377,7 +374,6 @@ struct mb_cache *mb_cache_create(int bucket_bits)
 	return cache;
 
 err_out:
-	module_put(THIS_MODULE);
 	return NULL;
 }
 EXPORT_SYMBOL(mb_cache_create);
@@ -411,7 +407,6 @@ void mb_cache_destroy(struct mb_cache *cache)
 	}
 	kfree(cache->c_hash);
 	kfree(cache);
-	module_put(THIS_MODULE);
 }
 EXPORT_SYMBOL(mb_cache_destroy);