On 02/25/2016 11:08 PM, NeilBrown wrote:
> On Fri, Feb 26 2016, Shaohua Li wrote:
>
>> check_reshape() is called from raid5d thread. raid5d thread shouldn't
>> call mddev_suspend(), because mddev_suspend() waits for all IO finish
>> but IO is handled in raid5d thread, we could easily deadlock here.
>>
>> Artur,
>> It would be great if you can verify this works for your test.
>>
>> Reported-by: Artur Paszkiewicz <artur.paszkiewicz@xxxxxxxxx>
>> Cc: NeilBrown <neilb@xxxxxxxx>
>> Signed-off-by: Shaohua Li <shli@xxxxxx>
>> ---
>> drivers/md/raid5.c | 18 ++++++++++++++++++
>> drivers/md/raid5.h | 2 ++
>> 2 files changed, 20 insertions(+)
>>
>> diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
>> index 7f770b0..c7fd070 100644
>> --- a/drivers/md/raid5.c
>> +++ b/drivers/md/raid5.c
>> @@ -2089,6 +2089,14 @@ static int resize_chunks(struct r5conf *conf, int new_disks, int new_sectors)
>> unsigned long cpu;
>> int err = 0;
>>
>> + /*
>> + * Never shrink. And mddev_suspend() could deadlock if this is called
>> + * from raid5d. In that case, scribble_disks and scribble_sectors
>> + * should equal to new_disks and new_sectors
>> + */
>> + if (conf->scribble_disks >= new_disks &&
>> + conf->scribble_sectors >= new_sectors)
>> + return 0;
>> mddev_suspend(conf->mddev);
>> get_online_cpus();
>> for_each_present_cpu(cpu) {
>> @@ -2110,6 +2118,10 @@ static int resize_chunks(struct r5conf *conf, int new_disks, int new_sectors)
>> }
>> put_online_cpus();
>> mddev_resume(conf->mddev);
>> + if (!err) {
>> + conf->scribble_disks = new_disks;
>> + conf->scribble_sectors = new_sectors;
>> + }
>> return err;
>> }
>>
>> @@ -6413,6 +6425,12 @@ static int raid5_alloc_percpu(struct r5conf *conf)
>> }
>> put_online_cpus();
>>
>> + if (!err) {
>> + conf->scribble_disks = max(conf->raid_disks,
>> + conf->previous_raid_disks);
>> + conf->scribble_sectors = max(conf->chunk_sectors,
>> + conf->prev_chunk_sectors) / STRIPE_SECTORS;
>
> Here we set ->scribble_sectors to a number of stripes rather than a
> number of sectors. I think you need to remove the "/ STRIPE_SECTORS".
That's correct. I've tested the patch and it works well but only without
the "/ STRIPE_SECTORS".
Thanks,
Artur
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