[Gluster-devel] Fencing FOPs on data-split-brained files

[Ravishankar N]

Hi,

Currenly in glusterfs, when there is a data splt-brain (only) on a file, 
we disallow the following operations from the mount-point by returning 
EIO to the application:
- Writes to the file (truncate, dd, echo, cp etc)
- Reads to the file (cat)
- Reading extended attributes (getfattr) [1]

However we do permit the following operations:
-creating hardlinks
-creating symlinks
-mv
-setattr
-chmod
-chown
--touch
-ls
-stat

While it makes sense to allow `ls` and `stat`, is it okay to  add checks 
in the FOPS to disallow the other operations? Allowing creation of links 
and changing file attributes only seems to complicate things before the 
admin can go to the backend bricks and resolve the splitbrain (by 
deleteing all but the healthy copy of the file including hardlinks). 
More so if the file is renamed before addressing the split-brain.
Please share your thoughs.

Thanks,
Ravi

[1] http://review.gluster.org/#/c/5988/