md-cluster: Improve md_reload_sb to be less error prone
md_reload_sb is too simplistic and it explicitly needs to determine
the changes made by the writing node. However, there are multiple areas
where a simple reload could fail.
Instead, read the superblock of one of the "good" rdevs and update
the necessary information:
- read the superblock into a newly allocated page, by temporarily
swapping out rdev->sb_page and calling ->load_super.
- if that fails return
- if it succeeds, call check_sb_changes
1. iterates over list of active devices and checks the matching
dev_roles[] value.
If that is 'faulty', the device must be marked as faulty
- call md_error to mark the device as faulty. Make sure
not to set CHANGE_DEVS and wakeup mddev->thread or else
it would initiate a resync process, which is the responsibility
of the "primary" node.
- clear the Blocked bit
- Call remove_and_add_spares() to hot remove the device.
If the device is 'spare':
- call remove_and_add_spares() to get the number of spares
added in this operation.
- Reduce mddev->degraded to mark the array as not degraded.
2. reset recovery_cp
- read the rest of the rdevs to update recovery_offset. If recovery_offset
is equal to MaxSector, call spare_active() to set it In_sync
This required that recovery_offset be initialized to MaxSector, as
opposed to zero so as to communicate the end of sync for a rdev.
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
diff --git a/drivers/md/md.c b/drivers/md/md.c
index e21a2fe..12cc28a 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -8924,25 +8924,118 @@
return ret;
}
-void md_reload_sb(struct mddev *mddev)
+static void check_sb_changes(struct mddev *mddev, struct md_rdev *rdev)
{
- struct md_rdev *rdev, *tmp;
+ struct mdp_superblock_1 *sb = page_address(rdev->sb_page);
+ struct md_rdev *rdev2;
+ int role, ret;
+ char b[BDEVNAME_SIZE];
- rdev_for_each_safe(rdev, tmp, mddev) {
- rdev->sb_loaded = 0;
- ClearPageUptodate(rdev->sb_page);
- }
- mddev->raid_disks = 0;
- analyze_sbs(mddev);
- rdev_for_each_safe(rdev, tmp, mddev) {
- struct mdp_superblock_1 *sb = page_address(rdev->sb_page);
- /* since we don't write to faulty devices, we figure out if the
- * disk is faulty by comparing events
- */
- if (mddev->events > sb->events)
- set_bit(Faulty, &rdev->flags);
+ /* Check for change of roles in the active devices */
+ rdev_for_each(rdev2, mddev) {
+ if (test_bit(Faulty, &rdev2->flags))
+ continue;
+
+ /* Check if the roles changed */
+ role = le16_to_cpu(sb->dev_roles[rdev2->desc_nr]);
+ if (role != rdev2->raid_disk) {
+ /* got activated */
+ if (rdev2->raid_disk == -1 && role != 0xffff) {
+ rdev2->saved_raid_disk = role;
+ ret = remove_and_add_spares(mddev, rdev2);
+ pr_info("Activated spare: %s\n",
+ bdevname(rdev2->bdev,b));
+ continue;
+ }
+ /* device faulty
+ * We just want to do the minimum to mark the disk
+ * as faulty. The recovery is performed by the
+ * one who initiated the error.
+ */
+ if ((role == 0xfffe) || (role == 0xfffd)) {
+ md_error(mddev, rdev2);
+ clear_bit(Blocked, &rdev2->flags);
+ }
+ }
}
+ /* recovery_cp changed */
+ if (le64_to_cpu(sb->resync_offset) != mddev->recovery_cp)
+ mddev->recovery_cp = le64_to_cpu(sb->resync_offset);
+
+ /* Finally set the event to be up to date */
+ mddev->events = le64_to_cpu(sb->events);
+}
+
+static int read_rdev(struct mddev *mddev, struct md_rdev *rdev)
+{
+ int err;
+ struct page *swapout = rdev->sb_page;
+ struct mdp_superblock_1 *sb;
+
+ /* Store the sb page of the rdev in the swapout temporary
+ * variable in case we err in the future
+ */
+ rdev->sb_page = NULL;
+ alloc_disk_sb(rdev);
+ ClearPageUptodate(rdev->sb_page);
+ rdev->sb_loaded = 0;
+ err = super_types[mddev->major_version].load_super(rdev, NULL, mddev->minor_version);
+
+ if (err < 0) {
+ pr_warn("%s: %d Could not reload rdev(%d) err: %d. Restoring old values\n",
+ __func__, __LINE__, rdev->desc_nr, err);
+ put_page(rdev->sb_page);
+ rdev->sb_page = swapout;
+ rdev->sb_loaded = 1;
+ return err;
+ }
+
+ sb = page_address(rdev->sb_page);
+ /* Read the offset unconditionally, even if MD_FEATURE_RECOVERY_OFFSET
+ * is not set
+ */
+
+ if ((le32_to_cpu(sb->feature_map) & MD_FEATURE_RECOVERY_OFFSET))
+ rdev->recovery_offset = le64_to_cpu(sb->recovery_offset);
+
+ /* The other node finished recovery, call spare_active to set
+ * device In_sync and mddev->degraded
+ */
+ if (rdev->recovery_offset == MaxSector &&
+ !test_bit(In_sync, &rdev->flags) &&
+ mddev->pers->spare_active(mddev))
+ sysfs_notify(&mddev->kobj, NULL, "degraded");
+
+ put_page(swapout);
+ return 0;
+}
+
+void md_reload_sb(struct mddev *mddev, int nr)
+{
+ struct md_rdev *rdev;
+ int err;
+
+ /* Find the rdev */
+ rdev_for_each_rcu(rdev, mddev) {
+ if (rdev->desc_nr == nr)
+ break;
+ }
+
+ if (!rdev || rdev->desc_nr != nr) {
+ pr_warn("%s: %d Could not find rdev with nr %d\n", __func__, __LINE__, nr);
+ return;
+ }
+
+ err = read_rdev(mddev, rdev);
+ if (err < 0)
+ return;
+
+ check_sb_changes(mddev, rdev);
+
+ /* Read all rdev's to update recovery_offset */
+ rdev_for_each_rcu(rdev, mddev)
+ read_rdev(mddev, rdev);
}
EXPORT_SYMBOL(md_reload_sb);