Remove atomic from locking ideas, clarify cleaning locks

sftl.c

@@ -172,36 +172,47 @@ static void sftl_make_request(struct request_queue *q, struct bio *bio)
 		// ** Modify translation maps
 		// ** Unlock translation maps
 		// * If insufficient:
-		// ** Check if someone is already flushing using an increment of atomic variable
-		// ** If yes:
+		// ** Check flush flag (no need for atomic/etc as already within buffer lock)
+		// ** If someone is already flushing:
 		// *** Unlock buffer
 		// *** Wait until flushing ends using an event
 		// *** Goto (Start)
-		// ** If not:
-		// *** (Flush) Remember current bio and initiate flushing
+		// ** If no one is flushing yet:
+		// *** Set flush flag
+		// *** Remember current bio and initiate (Flush) operation
 		// * Unlock buffer
 		//
 		// After (Flush) operation ends:
-		// * Take write lock on the buffer (writers are already blocked, this is for readers)
+		// * Take write lock on the buffer (writers are already blocked, this is to block readers)
 		// * Clear buffer
 		// * If the free sequence pointer can be moved without cleaning:
 		// ** Move pointer
 		// ** Perform own remembered write operation
+		// ** Unset flush flag
 		// ** Unlock buffer
 		// ** Wake up waiting writers
 		// * If not:
 		// ** Initiate cleaning process
 		// ** Unlock buffer
 		//
-		// After cleaning:
+		// After cleaning operation ends:
 		// * Take write lock on translation maps
 		// * Modify translation maps
 		// * Unlock translation maps
 		// * Take write lock on the buffer
 		// * Move free sequence pointer
-		// * Perform own remembered write operation
-		// * Unlock buffer
-		// * Wake up waiting writers
+		// * If there are no more pending cleaning operations:
+		// ** Perform own remembered write operation:
+		// *** Take write lock on translation maps so readers won't get them partially modified
+		// *** Write current bio into buffer
+		// *** Modify translation maps
+		// *** Unlock translation maps
+		// ** Unset flush flag
+		// ** Unlock buffer
+		// ** Wake up waiting writers
+		// * Else:
+		// ** Initiate next cleaning operation
+		// ** Unlock buffer
 		struct sftl_map *buf_map = (struct sftl_map *)(sftl->buf + seg_clust*clust_sz) + sftl->buf_size;
 		char *buffer = __bio_kmap_atomic(bio, 0, KM_USER0);
 		memcpy(sftl->buf + clust_sz*sftl->buf_size, buffer, clust_sz);