From 6090368abcb40554c660c8c3140ce19ff0f8f66f Mon Sep 17 00:00:00 2001 From: Li Nan Date: Sat, 27 May 2023 17:20:07 +0800 Subject: [PATCH] md/raid10: prioritize adding disk to 'removed' mirror 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 Signed-off-by: Song Liu Link: https://lore.kernel.org/r/20230527092007.3008856-1-linan666@huaweicloud.com --- drivers/md/raid10.c | 35 ++++++++++++++++++++--------------- 1 file changed, 20 insertions(+), 15 deletions(-) diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c index 8eda799..ab0e248 100644 --- a/drivers/md/raid10.c +++ b/drivers/md/raid10.c @@ -2151,9 +2151,10 @@ static int raid10_add_disk(struct mddev *mddev, struct md_rdev *rdev) { 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 @@ -2176,23 +2177,14 @@ static int raid10_add_disk(struct mddev *mddev, struct md_rdev *rdev) 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) @@ -2209,6 +2201,19 @@ static int raid10_add_disk(struct mddev *mddev, struct md_rdev *rdev) break; } + 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; } -- 2.7.4