xfs: enable buffer deadlock postmortem diagnosis via ftrace

Create a second buf_trylock tracepoint so that we can distinguish
between a successful and a failed trylock.  With this piece, we can
use a script to look at the ftrace output to detect buffer deadlocks.

[dchinner: update to if/else as per hch's suggestion]

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dave Chinner <david@fromorbit.com>
This commit is contained in:
Darrick J. Wong 2016-06-21 11:53:28 +10:00 committed by Dave Chinner
parent 3f94c441e2
commit 479c641273
2 changed files with 6 additions and 3 deletions

View file

@ -944,10 +944,12 @@ xfs_buf_trylock(
int locked;
locked = down_trylock(&bp->b_sema) == 0;
if (locked)
if (locked) {
XB_SET_OWNER(bp);
trace_xfs_buf_trylock(bp, _RET_IP_);
trace_xfs_buf_trylock(bp, _RET_IP_);
} else {
trace_xfs_buf_trylock_fail(bp, _RET_IP_);
}
return locked;
}

View file

@ -354,6 +354,7 @@ DEFINE_BUF_EVENT(xfs_buf_submit_wait);
DEFINE_BUF_EVENT(xfs_buf_bawrite);
DEFINE_BUF_EVENT(xfs_buf_lock);
DEFINE_BUF_EVENT(xfs_buf_lock_done);
DEFINE_BUF_EVENT(xfs_buf_trylock_fail);
DEFINE_BUF_EVENT(xfs_buf_trylock);
DEFINE_BUF_EVENT(xfs_buf_unlock);
DEFINE_BUF_EVENT(xfs_buf_iowait);