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

On 08/31/2017 08:27 AM, NeilBrown wrote:

On Wed, Aug 30 2017, Zhilong Liu wrote:

quoted

On 08/29/2017 06:47 PM, NeilBrown wrote:

quoted

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