[FUSE] cow: Cleanup, comments, fixes, minor refactoring

- Use the term "cluster" for a group of dnbd3-blocks instead of also
  calling them blocks.
- Use term "table" instead of "array" for the L1 and L2 tables.
- Use term "index" instead of "offset" when addressing those tables
- Fix a few logic bugs, use-after-free
- Add TODOs for parts that need better comments

3 files changed, 21 insertions, 16 deletions

diff --git a/inc/dnbd3/config.h b/inc/dnbd3/config.h
index df9d0e0..eb4b8b1 100644
--- a/inc/dnbd3/config.h
+++ b/inc/dnbd3/config.h
@@ -40,20 +40,4 @@
 // +++++ Block Device +++++
 #define DNBD3_BLOCK_SIZE ((uint64_t)4096) // NEVER CHANGE THIS OR THE WORLD WILL END!
 
-// +++++ COW +++++
-#define COW_BITFIELD_SIZE 40 // NEVER CHANGE THIS OR THE WORLD WILL ALSO END!
-#define COW_FILE_META_MAGIC_VALUE ((uint64_t)0xEBE44D6E72F7825E) // Magic Value to recognize a Cow meta file
-#define COW_FILE_DATA_MAGIC_VALUE ((uint64_t)0xEBE44D6E72F7825F) // Magic Value to recognize a Cow data file
-#define COW_MIN_UPLOAD_DELAY 60 // in seconds
-#define COW_STATS_UPDATE_TIME 5 // time in seconds the cow status files gets updated (while uploading blocks)
-#define COW_MAX_PARALLEL_UPLOADS 10 // maximum number of parallel uploads
-#define COW_MAX_PARALLEL_BACKGROUND_UPLOADS 2 // maximum number of parallel uploads while the image is still mounted
-#define COW_URL_STRING_SIZE 500 // Max string size for an url
-#define COW_SHOW_UL_SPEED 1 // enable display of ul speed in cow status file
-#define COW_MAX_IMAGE_SIZE 1000LL * 1000LL * 1000LL * 1000LL; // Maximum size an image can have(tb*gb*mb*kb)
-// +++++ COW API Endpoints +++++
-#define COW_API_CREATE "%s/api/File/Create"
-#define COW_API_UPDATE "%s/api/File/Update?guid=%s&BlockNumber=%lu"
-#define COW_API_START_MERGE "%s/api/File/StartMerge"
-
 #endif /* CONFIG_H_ */
diff --git a/inc/dnbd3/config/cow.h b/inc/dnbd3/config/cow.h
new file mode 100644
index 0000000..9ed59a0
--- /dev/null
+++ b/inc/dnbd3/config/cow.h
@@ -0,0 +1,20 @@
+#ifndef _COW_CONFIG_H_
+#define _COW_CONFIG_H_
+
+// +++++ COW +++++
+#define COW_BITFIELD_SIZE 40 // NEVER CHANGE THIS OR THE WORLD WILL ALSO END!
+#define COW_FILE_META_MAGIC_VALUE ((uint64_t)0xEBE44D6E72F7825E) // Magic Value to recognize a Cow meta file
+#define COW_FILE_DATA_MAGIC_VALUE ((uint64_t)0xEBE44D6E72F7825F) // Magic Value to recognize a Cow data file
+#define COW_MIN_UPLOAD_DELAY 60 // in seconds
+#define COW_STATS_UPDATE_TIME 5 // time in seconds the cow status files gets updated (while uploading blocks)
+#define COW_MAX_PARALLEL_UPLOADS 10 // maximum number of parallel uploads
+#define COW_MAX_PARALLEL_BACKGROUND_UPLOADS 2 // maximum number of parallel uploads while the image is still mounted
+#define COW_URL_STRING_SIZE 500 // Max string size for an url
+#define COW_SHOW_UL_SPEED 1 // enable display of ul speed in cow status file
+#define COW_MAX_IMAGE_SIZE 1000LL * 1000LL * 1000LL * 1000LL; // Maximum size an image can have(tb*gb*mb*kb)
+// +++++ COW API Endpoints +++++
+#define COW_API_CREATE "%s/api/file/create"
+#define COW_API_UPDATE "%s/api/file/update?guid=%s&clusterindex=%lu"
+#define COW_API_START_MERGE "%s/api/file/merge"
+
+#endif
diff --git a/inc/dnbd3/types.h b/inc/dnbd3/types.h
index 699fa68..bd15f4e 100644
--- a/inc/dnbd3/types.h
+++ b/inc/dnbd3/types.h
@@ -30,6 +30,7 @@
 #include <stdbool.h>
 #include <stddef.h>
 #include <string.h>
+#define container_of( ptr, type, member ) ( (type *)( (char *)( ptr ) - (char *)&( ( (type *)NULL )->member ) ) )
 #endif
 
 #ifndef MIN