Hi all
The reshape can be stuck during raid5 reshape when raid5 journal misses. It can
be reproduced 100%
The test steps are:
1. mdadm -CR /dev/md0 -l5 -n4 /dev/sd[b-e]1 --write-journal /dev/sdf1
2. mdadm --wait /dev/md0
3. mdadm /dev/md0 -f /dev/sdf1
4. mdadm /dev/md0 -r /dev/sdf1
5. mdadm /dev/md0 -a /dev/sdf1
6. mdadm -G -n5 /dev/md0
Reshape request has 4 steps:
1. read data for source stripes
2. write source strips data to target stripes
3. calculate parity for target stripes
4. write target stripes to disks.
After step3:
sh->reconstruct_state is reconstruct_state_result
sh->state is STRIPE_EXPANDING | STRIPE_EXPAND_READY
Now it needs to write data to disks. And it needs to execute this part code:
/* Finish reconstruct operations initiated by the expansion process */
if (sh->reconstruct_state == reconstruct_state_result) {
But the journal disk is removed, it execute this part code:
if (s.failed > conf->max_degraded ||
(s.log_failed && s.injournal == 0)) {
sh->check_state = 0;
sh->reconstruct_state = 0;
After setting sh->reconstruct_state to zero, it will go to calculate the parity again.
Now it's stuck in a dead loop.
Can we allow the reshape happen in this case? Is it ok just to return failure for command
`mdadm -G -n5 /dev/md0` in this case?
Best Regards
Xiao
