os/filestore: improve error message of aio write failure

e.g. when we encountered an AIO error, the output is not
very human-readable, as below:

    -1> 2016-04-19 12:07:57.387805 7f192e320700 -1 journal aio to 53059584~1744896 wrote 18446744073709551611
     0> 2016-04-19 12:07:57.389205 7f192e320700 -1 os/FileJournal.cc: In function 'void FileJournal::write_finish_thread_entry()' th
read 7f192e320700 time 2016-04-19 12:07:57.387831

Signed-off-by: xie xingguo <xie.xingguo@zte.com.cn>

diff --git a/src/os/filestore/FileJournal.cc b/src/os/filestore/FileJournal.cc
index 9e403101c35bd98a237883601234be56a71c3900..5a77be0fd1f1a1856b753bf927b96eb8c1524a41 100644 (file)
--- a/src/os/filestore/FileJournal.cc
+++ b/src/os/filestore/FileJournal.cc
@@ -1537,7 +1537,7 @@ void FileJournal::write_finish_thread_entry()
        aio_info *ai = (aio_info *)event[i].obj;
        if (event[i].res != ai->len) {
          derr << "aio to " << ai->off << "~" << ai->len
-              << " wrote " << event[i].res << dendl;
+              << " returned: " << (int)event[i].res << dendl;
          assert(0 == "unexpected aio error");
        }
        dout(10) << "write_finish_thread_entry aio " << ai->off