----- Original Message ----- > From: "Pranith Kumar Karampuri" <pkarampu@xxxxxxxxxx> > To: "Ashish Pandey" <aspandey@xxxxxxxxxx> > Cc: "Gluster Devel" <gluster-devel@xxxxxxxxxxx>, "Shyam Ranganathan" <srangana@xxxxxxxxxx>, "Nithya Balachandran" > <nbalacha@xxxxxxxxxx>, "Xavier Hernandez" <xhernandez@xxxxxxxxxx>, "Raghavendra Gowdappa" <rgowdapp@xxxxxxxxxx> > Sent: Tuesday, December 13, 2016 9:29:46 PM > Subject: Re: 1402538 : Assertion failure during rebalance of symbolic links > > On Tue, Dec 13, 2016 at 2:45 PM, Ashish Pandey <aspandey@xxxxxxxxxx> wrote: > > > Hi All, > > > > We have been seeing an issue where re balancing symbolic links leads to an > > assertion failure in EC volume. > > > > The root cause of this is that while migrating symbolic links to other sub > > volume, it creates a link file (with attributes .........T) . > > This file is a regular file. > > Now, during migration a setattr comes to this link and because of possible > > race, posix_stat return stats of this "T" file. > > In ec_manager_seattr, we receive callbacks and check the type of entry. If > > it is a regular file we try to get size and if it is not there, we raise an > > assert. > > So, basically we are checking a size of the link (which will not have > > size) which has been returned as regular file and we are ending up when > > this condition > > becomes TRUE. > > > > Now, this looks like a problem with re balance and difficult to fix at > > this point (as per the discussion). > > We have an alternative to fix it in EC but that will be more like a hack > > than an actual fix. We should not modify EC > > to deal with an individual issue which is in other translator. I am afraid, dht doesn't have a better way of handling this. While DHT maintains abstraction (of a symbolic link) to layers above, the layers below it cannot be shielded from seeing the details like a linkto file etc. If the concern really is that the file is changing its type in a span of single fop, we can probably explore the option of locking (or other synchronization mechanisms) to prevent migration taking place, while a fop is in progress. But, I assume there will be performance penalties for that too. > > > > Now the question is how to proceed with this? Any suggestions? > > > > Raghavendra/Nithya, > Could one of you explain the difficulties in fixing this issue in > DHT so that Xavi will also be caught up with why we should add this change > in EC in the short term. > > > > > > Details on this bug can be found here - > > https://bugzilla.redhat.com/show_bug.cgi?id=1402538 > > > > ---- > > Ashish > > > > > > > > > > > -- > Pranith > _______________________________________________ Gluster-devel mailing list Gluster-devel@xxxxxxxxxxx http://www.gluster.org/mailman/listinfo/gluster-devel
