On 04/05/2017 12:17 AM, NeilBrown wrote:
[snip]
>> diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
>> index 7d67235..0554110 100644
>> --- a/drivers/md/raid1.c
>> +++ b/drivers/md/raid1.c
>> @@ -1986,11 +1986,13 @@ static int fix_sync_read_error(struct r1bio *r1_bio)
>> /* Don't try recovering from here - just fail it
>> * ... unless it is the last working device of course */
>> md_error(mddev, rdev);
>> - if (test_bit(Faulty, &rdev->flags))
>> + if (test_bit(Faulty, &rdev->flags)) {
>> /* Don't try to read from here, but make sure
>> * put_buf does it's thing
>> */
>> bio->bi_end_io = end_sync_write;
>> + bio->bi_next = NULL;
>> + }
>> }
>>
>> while(sectors) {
>
>
> Ah - I see what is happening now. I was looking at the vanilla 4.4
> code, which doesn't have the failfast changes.
My bad to forgot mention... yes our md stuff is very much close to the
upstream.
>
> I don't think your patch is correct though. We really shouldn't be
> re-using that bio, and setting bi_next to NULL just hides the bug. It
> doesn't fix it.
> As the rdev is now Faulty, it doesn't make sense for
> sync_request_write() to submit a write request to it.
Make sense, while still have concerns regarding the design:
* in this case since the read_disk already abandoned, is it fine to
keep r1_bio->read_disk recording the faulty device index?
* we assign the 'end_sync_write' to the original read bio in this
case, but when is this supposed to be called?
>
> Can you confirm that this works please.
Yes, it works.
Tested-by: Michael Wang <yun.wang@xxxxxxxxxxxxxxxx>
Regards,
Michael Wang
>
> diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
> index d2d8b8a5bd56..219f1e1f1d1d 100644
> --- a/drivers/md/raid1.c
> +++ b/drivers/md/raid1.c
> @@ -2180,6 +2180,8 @@ static void sync_request_write(struct mddev *mddev, struct r1bio *r1_bio)
> (i == r1_bio->read_disk ||
> !test_bit(MD_RECOVERY_SYNC, &mddev->recovery))))
> continue;
> + if (test_bit(Faulty, &conf->mirrors[i].rdev->flags))
> + continue;
>
> bio_set_op_attrs(wbio, REQ_OP_WRITE, 0);
> if (test_bit(FailFast, &conf->mirrors[i].rdev->flags))
>
>
> Thanks,
> NeilBrown
>
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