From 6090368abcb40554c660c8c3140ce19ff0f8f66f Mon Sep 17 00:00:00 2001
From: Li Nan <linan122@huawei.com>
Date: Sat, 27 May 2023 17:20:07 +0800
Subject: [PATCH] md/raid10: prioritize adding disk to 'removed' mirror
Git-commit: 6090368abcb40554c660c8c3140ce19ff0f8f66f
Patch-mainline: v6.5-rc1
References: git-fixes
When add a new disk to raid10, it will traverse conf->mirror from start
and find one of the following mirror to add:
1. mirror->rdev is set to WantReplacement and it have no replacement,
set new disk to mirror->replacement.
2. no mirror->rdev, set new disk to mirror->rdev.
There is a array as below (sda is set to WantReplacement):
Number Major Minor RaidDevice State
0 8 0 0 active sync set-A /dev/sda
- 0 0 1 removed
2 8 32 2 active sync set-A /dev/sdc
3 8 48 3 active sync set-B /dev/sdd
Use 'mdadm --add' to add a new disk to this array, the new disk will
become sda's replacement instead of add to removed position, which is
confusing for users. Meanwhile, after new disk recovery success, sda
will be set to Faulty.
Prioritize adding disk to 'removed' mirror is a better choice. In the
above scenario, the behavior is the same as before, except sda will not
be deleted. Before other disks are added, continued use sda is more
reliable.
Signed-off-by: Li Nan <linan122@huawei.com>
Signed-off-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20230527092007.3008856-1-linan666@huaweicloud.com
Signed-off-by: Coly Li <colyli@suse.de>
---
drivers/md/raid10.c | 35 ++++++++++++++++++++---------------
1 file changed, 20 insertions(+), 15 deletions(-)
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -1796,9 +1796,10 @@ static int raid10_add_disk(struct mddev
{
struct r10conf *conf = mddev->private;
int err = -EEXIST;
- int mirror;
+ int mirror, repl_slot = -1;
int first = 0;
int last = conf->geo.raid_disks - 1;
+ struct raid10_info *p;
if (mddev->recovery_cp < MaxSector)
/* only hot-add to in-sync arrays, as recovery is
@@ -1821,23 +1822,14 @@ static int raid10_add_disk(struct mddev
else
mirror = first;
for ( ; mirror <= last ; mirror++) {
- struct raid10_info *p = &conf->mirrors[mirror];
+ p = &conf->mirrors[mirror];
if (p->recovery_disabled == mddev->recovery_disabled)
continue;
if (p->rdev) {
- if (!test_bit(WantReplacement, &p->rdev->flags) ||
- p->replacement != NULL)
- continue;
- clear_bit(In_sync, &rdev->flags);
- set_bit(Replacement, &rdev->flags);
- rdev->raid_disk = mirror;
- err = 0;
- if (mddev->gendisk)
- disk_stack_limits(mddev->gendisk, rdev->bdev,
- rdev->data_offset << 9);
- conf->fullsync = 1;
- rcu_assign_pointer(p->replacement, rdev);
- break;
+ if (test_bit(WantReplacement, &p->rdev->flags) &&
+ p->replacement == NULL && repl_slot < 0)
+ repl_slot = mirror;
+ continue;
}
if (mddev->gendisk)
@@ -1856,6 +1848,19 @@ static int raid10_add_disk(struct mddev
if (mddev->queue && blk_queue_discard(bdev_get_queue(rdev->bdev)))
blk_queue_flag_set(QUEUE_FLAG_DISCARD, mddev->queue);
+ if (err && repl_slot >= 0) {
+ p = &conf->mirrors[repl_slot];
+ clear_bit(In_sync, &rdev->flags);
+ set_bit(Replacement, &rdev->flags);
+ rdev->raid_disk = repl_slot;
+ err = 0;
+ if (mddev->gendisk)
+ disk_stack_limits(mddev->gendisk, rdev->bdev,
+ rdev->data_offset << 9);
+ conf->fullsync = 1;
+ rcu_assign_pointer(p->replacement, rdev);
+ }
+
print_conf(conf);
return err;
}