biolatency.py: use blk_account_io_done instead of blk_account_io_comp…

…letion (iovisor#2109)

The biolatency tool attaches kprobe at blk_account_io_completion() function
to check when a request is finished. But sometimes request can be finished
partially and blk_account_io_completion() is called again.
The blk_account_io_done() is called when a request is finally
finished and biolatency tool should attach blk_account_io_done(), not
blk_account_io_completion().

Signed-off-by: Gioh Kim <[email protected]>

tools/biolatency.py

@@ -67,7 +67,7 @@
 }
 
 // output
-int trace_req_completion(struct pt_regs *ctx, struct request *req)
+int trace_req_done(struct pt_regs *ctx, struct request *req)
 {
  u64 *tsp, delta;
 
@@ -119,8 +119,8 @@
  if BPF.get_kprobe_functions(b'blk_start_request'):
  b.attach_kprobe(event="blk_start_request", fn_name="trace_req_start")
  b.attach_kprobe(event="blk_mq_start_request", fn_name="trace_req_start")
-b.attach_kprobe(event="blk_account_io_completion",
- fn_name="trace_req_completion")
+b.attach_kprobe(event="blk_account_io_done",
+ fn_name="trace_req_done")
 
 print("Tracing block device I/O... Hit Ctrl-C to end.")