[Gluster-devel] Regards to highlight the change in behavior of metadata operation for directory

[Mohit Agrawal]

Hi All,

   As we know in glusterfs we have one known issue specific to preserve
metadata consistency for directory in
   pure distributed environment.

Problem:

   After brick stop if application do any metadata operation(like
permission,uid/gid change, xattr change) on directory and restart
   the brick, metadata is not consistent on stopped brick because dht is
not able to heal it properly.We have tried to fix
   this problem from the patch https://review.gluster.org/#/c/15468/ and we
would like to highlight the change in behavior after
   merge this patch.

Solution:
   This patch will change the current behavior of metadata operation on
directory.

   As of now we don't restrict application to run any metadata operation on
directory if brick is stopped even brick is belong to the hash
   sub-volume for that directory but after apply this patch we would not
allow metadata operation(attribute,xattr change) on directory
   if hashed subvolume (MDS) is down for that directory.

   After merge this patch we will consider hash sub-volume as a MDS for
that directory  and before wind any fop call at dht level to next xlator
  we do check the status of MDS, if stopped brick is the MDS of that
directory we will not allow to run the operation on directory otherwise
  dht wind a call to next xlator.



Regards
Mohit Agrawal
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