[dm-devel] [PATCH] fix mirror device creation with lvcreate failed

[Liuhua Wang]

Hi, Alasdair

>>> On 9/17/2014 at 07:21 AM, in message
<20140916232104.GC2407 at agk-dp.fab.redhat.com>, Alasdair G Kergon
<agk at redhat.com> wrote: 
> On Wed, Aug 27, 2014 at 04:18:25PM +0800, Liuhua Wang wrote:
> >  On some devices, 
> 
> Which devices?  What is the necessary condition to trigger the problem?
> 
When using dasd device formated with bocksize of 4096bytes.
the problem occurs, while formated with blocksie of 512bytes,
no problem.

> > when create mirror device with lvcreate, it fails.
> >  device-mapper: reload ioctl on  failed: Invalid argument
> >  Failed to activate new LV.
>  
> What exactly causes this error?
> - Do you get a kernel error message too?
There are error messages:
---------------------
[22798.077877] end_request: I/O error, dev dasdd, sector 2240
[22798.077902] device-mapper: raid: Failed to read superblock of device at position 1
[23087.875420] type=1006 audit(1404313201.346:28): pid=1596 uid=0 old auid=4294967295 new auid=0 old ses=4294967295 new ses=27 res=1
[23127.707296] dasd-eckd.d2bf98: 0.0.141d: ERP 0000000036ab1e40 has run out of retries and failed
----------------------

> >  We can use read size 4096 since md always use 4096.
>  
> How is that connected to problem?
> Why does it fix it?
> 
> > +++ b/drivers/md/dm-raid.c
> > @@ -860,7 +860,7 @@ static int super_load(struct md_rdev *rdev, struct 
> md_rdev *refdev)
> >  	rdev->sb_start = 0;
> >  	rdev->sb_size = sizeof(*sb);
>   
> What should sb_size really be?
512bytes
> 
> > -	ret = read_disk_sb(rdev, rdev->sb_size);
> > +	ret = read_disk_sb(rdev, 4096);
> 
> Why aren't they both MD_SB_BYTES?
> (Strictly, does sb_size need recalculating after the read?)
> 
> Alasdair
> 

Best regards,
Liuhua