Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/shli/md

Pull MD updates from Shaohua Li:
 - A bunch of patches from Neil Brown to fix RCU usage
 - Two performance improvement patches from Tomasz Majchrzak
 - Alexey Obitotskiy fixes module refcount issue
 - Arnd Bergmann fixes time granularity
 - Cong Wang fixes a list corruption issue
 - Guoqing Jiang fixes a deadlock in md-cluster
 - A null pointer deference fix from me
 - Song Liu fixes misuse of raid6 rmw
 - Other trival/cleanup fixes from Guoqing Jiang and Xiao Ni

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/shli/md: (28 commits)
  MD: fix null pointer deference
  raid10: improve random reads performance
  md: add missing sysfs_notify on array_state update
  Fix kernel module refcount handling
  md: use seconds granularity for error logging
  md: reduce the number of synchronize_rcu() calls when multiple devices fail.
  md: be extra careful not to take a reference to a Faulty device.
  md/multipath: add rcu protection to rdev access in multipath_status.
  md/raid5: add rcu protection to rdev accesses in raid5_status.
  md/raid5: add rcu protection to rdev accesses in want_replace
  md/raid5: add rcu protection to rdev accesses in handle_failed_sync.
  md/raid1: add rcu protection to rdev in fix_read_error
  md/raid1: small code cleanup in end_sync_write
  md/raid1: small cleanup in raid1_end_read/write_request
  md/raid10: simplify print_conf a little.
  md/raid10: minor code improvement in fix_read_error()
  md/raid10: add rcu protection to rdev access during reshape.
  md/raid10: add rcu protection to rdev access in raid10_sync_request.
  md/raid10: add rcu protection in raid10_status.
  md/raid10: fix refounct imbalance when resyncing an array with a replacement device.
  ...

1 files changed, 17 insertions, 12 deletions

diff --git a/drivers/md/multipath.c b/drivers/md/multipath.c
index 72ea98e89e57..4974682842ae 100644
--- a/drivers/md/multipath.c
+++ b/drivers/md/multipath.c
@@ -43,7 +43,8 @@ static int multipath_map (struct mpconf *conf)
 	rcu_read_lock();
 	for (i = 0; i < disks; i++) {
 		struct md_rdev *rdev = rcu_dereference(conf->multipaths[i].rdev);
-		if (rdev && test_bit(In_sync, &rdev->flags)) {
+		if (rdev && test_bit(In_sync, &rdev->flags) &&
+		    !test_bit(Faulty, &rdev->flags)) {
 			atomic_inc(&rdev->nr_pending);
 			rcu_read_unlock();
 			return i;
@@ -141,17 +142,19 @@ static void multipath_make_request(struct mddev *mddev, struct bio * bio)
 	return;
 }
 
-static void multipath_status (struct seq_file *seq, struct mddev *mddev)
+static void multipath_status(struct seq_file *seq, struct mddev *mddev)
 {
 	struct mpconf *conf = mddev->private;
 	int i;
 
 	seq_printf (seq, " [%d/%d] [", conf->raid_disks,
 		    conf->raid_disks - mddev->degraded);
-	for (i = 0; i < conf->raid_disks; i++)
-		seq_printf (seq, "%s",
-			       conf->multipaths[i].rdev &&
-			       test_bit(In_sync, &conf->multipaths[i].rdev->flags) ? "U" : "_");
+	rcu_read_lock();
+	for (i = 0; i < conf->raid_disks; i++) {
+		struct md_rdev *rdev = rcu_dereference(conf->multipaths[i].rdev);
+		seq_printf (seq, "%s", rdev && test_bit(In_sync, &rdev->flags) ? "U" : "_");
+	}
+	rcu_read_unlock();
 	seq_printf (seq, "]");
 }
 
@@ -295,12 +298,14 @@ static int multipath_remove_disk(struct mddev *mddev, struct md_rdev *rdev)
 			goto abort;
 		}
 		p->rdev = NULL;
-		synchronize_rcu();
-		if (atomic_read(&rdev->nr_pending)) {
-			/* lost the race, try later */
-			err = -EBUSY;
-			p->rdev = rdev;
-			goto abort;
+		if (!test_bit(RemoveSynchronized, &rdev->flags)) {
+			synchronize_rcu();
+			if (atomic_read(&rdev->nr_pending)) {
+				/* lost the race, try later */
+				err = -EBUSY;
+				p->rdev = rdev;
+				goto abort;
+			}
 		}
 		err = md_integrity_register(mddev);
 	}