[PATCH v5 14/16] md/raid10: Add error message when setting MD_BROKEN

[Kenta Akagi <k@mgml.me>]

Once MD_BROKEN is set on an array, no further writes can be performed.
The user must be informed that the array cannot continue operation.

Add error logging when MD_BROKEN flag is set on raid10 arrays to improve
debugging and system administration visibility.

Signed-off-by: Kenta Akagi <k@mgml.me>
---
 drivers/md/raid10.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index aa9d328fe875..369def3413c0 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -2031,6 +2031,10 @@ static void raid10_error(struct mddev *mddev, struct md_rdev *rdev)
 
 	if (test_bit(In_sync, &rdev->flags) && !enough(conf, rdev->raid_disk)) {
 		set_bit(MD_BROKEN, &mddev->flags);
+		pr_crit("md/raid10:%s: Disk failure on %pg, this is the last device.\n"
+			"md/raid10:%s: Cannot continue operation (%d/%d failed).\n",
+			mdname(mddev), rdev->bdev,
+			mdname(mddev), mddev->degraded + 1, conf->geo.raid_disks);
 
 		if (!mddev->fail_last_dev)
 			return;
-- 
2.50.1