md/md-cluster: handle REMOVE message earlier

Commit a1fd37f97808 ("md: Don't wait for MD_RECOVERY_NEEDED for
HOT_REMOVE_DISK ioctl") introduced a regression in the md_cluster
module. (Failed cases 02r1_Manage_re-add & 02r10_Manage_re-add)

Consider a 2-node cluster:
- node1 set faulty & remove command on a disk.
- node2 must correctly update the array metadata.

Before a1fd37f97808, on node1, the delay between msg:METADATA_UPDATED
(triggered by faulty) and msg:REMOVE was sufficient for node2 to
reload the disk info (written by node1).
After a1fd37f97808, node1 no longer waits between faulty and remove,
causing it to send msg:REMOVE while node2 is still reloading disk info.
This often results in node2 failing to remove the faulty disk.

== how to trigger ==

set up a 2-node cluster (node1 & node2) with disks vdc & vdd.

on node1:
mdadm -CR /dev/md0 -l1 -b clustered -n2 /dev/vdc /dev/vdd --assume-clean
ssh node2-ip mdadm -A /dev/md0 /dev/vdc /dev/vdd
mdadm --manage /dev/md0 --fail /dev/vdc --remove /dev/vdc

check array status on both nodes with "mdadm -D /dev/md0".
node1 output:
    Number   Major   Minor   RaidDevice State
       -       0        0        0      removed
       1     254       48        1      active sync   /dev/vdd
node2 output:
    Number   Major   Minor   RaidDevice State
       -       0        0        0      removed
       1     254       48        1      active sync   /dev/vdd

       0     254       32        -      faulty   /dev/vdc

Fixes: a1fd37f97808 ("md: Don't wait for MD_RECOVERY_NEEDED for HOT_REMOVE_DISK ioctl")
Signed-off-by: Heming Zhao <heming.zhao@suse.com>
Reviewed-by: Su Yue <glass.su@suse.com>
Link: https://lore.kernel.org/linux-raid/20250728042145.9989-1-heming.zhao@suse.com
Signed-off-by: Yu Kuai <yukuai3@huawei.com>

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 2716d5c59517ab3bcc8f500b26ba755791017957..8af97ef80ec524b0f82d934dc1ba026fe5623849 100644 (file)
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -9777,8 +9777,8 @@ void md_check_recovery(struct mddev *mddev)
                         * remove disk.
                         */
                        rdev_for_each_safe(rdev, tmp, mddev) {
-                               if (test_and_clear_bit(ClusterRemove, &rdev->flags) &&
-                                               rdev->raid_disk < 0)
+                               if (rdev->raid_disk < 0 &&
+                                   test_and_clear_bit(ClusterRemove, &rdev->flags))
                                        md_kick_rdev_from_array(rdev);
                        }
                }
@@ -10084,8 +10084,11 @@ static void check_sb_changes(struct mddev *mddev, struct md_rdev *rdev)
 
        /* Check for change of roles in the active devices */
        rdev_for_each_safe(rdev2, tmp, mddev) {
-               if (test_bit(Faulty, &rdev2->flags))
+               if (test_bit(Faulty, &rdev2->flags)) {
+                       if (test_bit(ClusterRemove, &rdev2->flags))
+                               set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
                        continue;
+               }
 
                /* Check if the roles changed */
                role = le16_to_cpu(sb->dev_roles[rdev2->desc_nr]);