MD request counter broken on 4.0-rc5 RAID1

MD request counter broken on 4.0-rc5 RAID1

[Simon Kirby]

Hello :)

I'm seeing "iostat -x -k 1" print this after a RAID1 rebuild on 4.0-rc5.
It's not abnormal other than it's 3-disk, with one being SSD (sdc) and
the other two being write-mostly:

Device:         rrqm/s   wrqm/s     r/s     w/s    rkB/s    wkB/s avgrq-sz avgqu-sz   await r_await w_await  svctm  %util
sda               0.00     0.00    0.00    0.00     0.00     0.00     0.00     0.00    0.00    0.00    0.00   0.00   0.00
sdb               0.00     0.00    0.00    0.00     0.00     0.00     0.00     0.00    0.00    0.00    0.00   0.00   0.00
sdc               0.00     0.00    0.00    0.00     0.00     0.00     0.00     0.00    0.00    0.00    0.00   0.00   0.00
md0               0.00     0.00    0.00    0.00     0.00     0.00     0.00   345.00    0.00    0.00    0.00   0.00 100.00
md2               0.00     0.00    0.00    0.00     0.00     0.00     0.00 58779.00    0.00    0.00    0.00   0.00 100.00
md1               0.00     0.00    0.00    0.00     0.00     0.00     0.00    12.00    0.00    0.00    0.00   0.00 100.00

This was working on 3.18. Shall I bisect, or is it obvious?

It seems to just be leaking as the counters were going up gradually while
it was rebuilding.

Personalities : [linear] [raid0] [raid1] [raid10]
md1 : active raid1 sdb2[1](W) sda2[0](W) sdc2[2]
      530048 blocks [3/3] [UUU]

md2 : active raid1 sdb3[0](W) sdc3[2] sda3[1](W)
      153613440 blocks [3/3] [UUU]

md0 : active raid1 sdb1[0](W) sdc1[2] sda1[1](W)
      2104384 blocks [3/3] [UUU]

unused devices: <none>

Simo-

Re: MD request counter broken on 4.0-rc5 RAID1

[NeilBrown]

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On Tue, 24 Mar 2015 17:04:03 -0700 Simon Kirby <sim@hostway.ca> wrote:

> Hello :)
> 
> I'm seeing "iostat -x -k 1" print this after a RAID1 rebuild on 4.0-rc5.
> It's not abnormal other than it's 3-disk, with one being SSD (sdc) and
> the other two being write-mostly:
> 
> Device:         rrqm/s   wrqm/s     r/s     w/s    rkB/s    wkB/s avgrq-sz avgqu-sz   await r_await w_await  svctm  %util
> sda               0.00     0.00    0.00    0.00     0.00     0.00     0.00     0.00    0.00    0.00    0.00   0.00   0.00
> sdb               0.00     0.00    0.00    0.00     0.00     0.00     0.00     0.00    0.00    0.00    0.00   0.00   0.00
> sdc               0.00     0.00    0.00    0.00     0.00     0.00     0.00     0.00    0.00    0.00    0.00   0.00   0.00
> md0               0.00     0.00    0.00    0.00     0.00     0.00     0.00   345.00    0.00    0.00    0.00   0.00 100.00
> md2               0.00     0.00    0.00    0.00     0.00     0.00     0.00 58779.00    0.00    0.00    0.00   0.00 100.00
> md1               0.00     0.00    0.00    0.00     0.00     0.00     0.00    12.00    0.00    0.00    0.00   0.00 100.00
> 
> This was working on 3.18. Shall I bisect, or is it obvious?

Almost certainly 18c0b223cf9901727ef3b02da6711ac930b4e5d4 in 3.19.

It adds 'part_inc_in_flight' and never decrements it.

Complain to the author.

Thanks,
NeilBrown

> 
> It seems to just be leaking as the counters were going up gradually while
> it was rebuilding.
> 
> Personalities : [linear] [raid0] [raid1] [raid10]
> md1 : active raid1 sdb2[1](W) sda2[0](W) sdc2[2]
>       530048 blocks [3/3] [UUU]
> 
> md2 : active raid1 sdb3[0](W) sdc3[2] sda3[1](W)
>       153613440 blocks [3/3] [UUU]
> 
> md0 : active raid1 sdb1[0](W) sdc1[2] sda1[1](W)
>       2104384 blocks [3/3] [UUU]
> 
> unused devices: <none>
> 
> Simo-
> --
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