[md PATCH 11/15] md/raid5: don't test ->writes_pending in raid5_remove_disk

NeilBrown
2017-03-15T03:05:14Z

This test on ->writes_pending cannot be safe as the counter
can be incremented at any moment and cannot be locked against.

Change it to test conf->active_stripes, which at least
can be locked against. More changes are still needed.

A future patch will change ->writes_pending, and testing it here will
be very inconvenient.

Signed-off-by: NeilBrown <neilb@suse.com>
---
drivers/md/raid5.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 4e906e5903e8..5eb3764bafd3 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -7528,9 +7528,12 @@ static int raid5_remove_disk(struct mddev *mddev, struct md_rdev *rdev)
/*
* we can't wait pending write here, as this is called in
* raid5d, wait will deadlock.
+ * neilb: there is no locking about new writes here,
+ * so this cannot be safe.
*/
- if (atomic_read(&mddev->writes_pending))
+ if (atomic_read(&conf->active_stripes)) {
return -EBUSY;
+ }
log_exit(conf);
return 0;
}