[md PATCH 11/14] md/raid5: don't test ->writes_pending in raid5_remove_disk

NeilBrown
2017-02-16T04:39:02Z

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. This allows read requests
to interfere so it might make removal of the journal device
harder, but it is safer.

Signed-off-by: NeilBrown <neilb@suse.com>
---
drivers/md/raid5.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index c96fca2c6a98..4de03479cdce 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -7279,10 +7279,14 @@ 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.
*/
- if (atomic_read(&mddev->writes_pending))
+ lock_all_device_hash_locks_irq(conf);
+ if (atomic_read(&conf->active_stripes)) {
+ unlock_all_device_hash_locks_irq(conf);
return -EBUSY;
+ }
log = conf->log;
conf->log = NULL;
+ unlock_all_device_hash_locks_irq(conf);
synchronize_rcu();
r5l_exit_log(log);
return 0;