- * sleep. The flush semaphore is set to the number of in-core buffers and
- * decremented around disk syncing. Therefore, if all buffers are syncing,
- * this semaphore will cause new writes to sleep until a sync completes.
- * Otherwise, this code just does p() followed by v(). This approximates
- * a sleep/wakeup except we can't race.
+ * sleep. We wait on the flush queue on the head iclog as that should be
+ * the first iclog to complete flushing. Hence if all iclogs are syncing,
+ * we will wait here and all new writes will sleep until a sync completes.