Re: report a bug that panic when grow size for external bitmap

[Zhilong Liu <zlliu@suse.com>]

On 08/31/2017 08:27 AM, NeilBrown wrote:
> On Wed, Aug 30 2017, Zhilong Liu wrote:
>
>> On 08/29/2017 06:47 PM, NeilBrown wrote:
>>> Thanks.  I see what I missed. Please try this patch instead.
>> Hi, Neil;
>>       I have tested the following patch, I still got the call-trace after
>> I built with it.
>> If you need other infos, I would append.
>
> Thanks for testing.
> I looked more completely and I think it is easiest just to disable the
> functionality rather than try to fix it.
> Resizing the file in the kernel is extra complexity that I don't
> want to get in to.
> We could adjust the bitmap chunk size so that the file doesn't
> need to grow, but it started getting more complicated than I really
> wanted to deal with.
> If there is anyone actually using file-backed bitmaps who wants to
> be able to resize the array without removing the bitmap first, then
> we can look at the problem again.  For now I've sent a patch which
> just returns an error instead of crashing when someone tries to resize
> an array with a file-backed bitmap.

Hi, Neil;
     Shall update the "SIZE CHANGES" under "GROW MODE" of man-page for
resize like following after kernel patch merged?

Thanks,
-Zhilong

diff --git a/mdadm.8.in b/mdadm.8.in
index e0747fb..f0fd1fc 100644
--- a/mdadm.8.in
+++ b/mdadm.8.in
@@ -2758,6 +2758,11 @@ Also the size of an array cannot be changed while 
it has an active
  bitmap.  If an array has a bitmap, it must be removed before the size
  can be changed. Once the change is complete a new bitmap can be created.

+.PP
+Note:
+.B "--grow --size"
+is not yet supported for external file bitmap.
+
  .SS RAID\-DEVICES CHANGES

  A RAID1 array can work with any number of devices from 1 upwards

> Thanks,
> NeilBrown