[PATCH 1/4] xfs: don't nest icloglock inside ic_callback_lock

Dave Chinner
2021-06-22T04:06:14Z

From: Dave Chinner <dchinner@redhat.com>

It's completely unnecessary because callbacks are added to iclogs
without holding the icloglock, hence no amount of ordering between
the icloglock and ic_callback_lock will order the removal of
callbacks from the iclog.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
---
fs/xfs/xfs_log.c | 18 ++++--------------
1 file changed, 4 insertions(+), 14 deletions(-)

diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c
index e93cac6b5378..bb4390942275 100644
--- a/fs/xfs/xfs_log.c
+++ b/fs/xfs/xfs_log.c
@@ -2773,11 +2773,8 @@ static void
xlog_state_do_iclog_callbacks(
struct xlog *log,
struct xlog_in_core *iclog)
- __releases(&log->l_icloglock)
- __acquires(&log->l_icloglock)
{
trace_xlog_iclog_callbacks_start(iclog, _RET_IP_);
- spin_unlock(&log->l_icloglock);
spin_lock(&iclog->ic_callback_lock);
while (!list_empty(&iclog->ic_callbacks)) {
LIST_HEAD(tmp);
@@ -2789,12 +2786,6 @@ xlog_state_do_iclog_callbacks(
spin_lock(&iclog->ic_callback_lock);
}

- /*
- * Pick up the icloglock while still holding the callback lock so we
- * serialise against anyone trying to add more callbacks to this iclog
- * now we've finished processing.
- */
- spin_lock(&log->l_icloglock);
spin_unlock(&iclog->ic_callback_lock);
trace_xlog_iclog_callbacks_done(iclog, _RET_IP_);
}
@@ -2836,13 +2827,12 @@ xlog_state_do_callback(
iclog = iclog->ic_next;
continue;
}
+ spin_unlock(&log->l_icloglock);

- /*
- * Running callbacks will drop the icloglock which means
- * we'll have to run at least one more complete loop.
- */
- cycled_icloglock = true;
xlog_state_do_iclog_callbacks(log, iclog);
+ cycled_icloglock = true;
+
+ spin_lock(&log->l_icloglock);
if (XLOG_FORCED_SHUTDOWN(log))
wake_up_all(&iclog->ic_force_wait);
else
--
2.31.1