+Pranith ----- Original Message ----- > From: "Raghavendra Gowdappa" <rgowdapp@xxxxxxxxxx> > To: "Raghavendra Bhat" <rabhat@xxxxxxxxxx> > Cc: "Anand Avati" <aavati@xxxxxxxxxx>, "Gluster Devel" <gluster-devel@xxxxxxxxxxx> > Sent: Thursday, December 18, 2014 12:58:27 PM > Subject: Re: explicit lookup of inods linked via readdirp > > > > ----- Original Message ----- > > From: "Raghavendra Bhat" <rabhat@xxxxxxxxxx> > > To: "Gluster Devel" <gluster-devel@xxxxxxxxxxx> > > Cc: "Anand Avati" <aavati@xxxxxxxxxx> > > Sent: Thursday, December 18, 2014 12:31:41 PM > > Subject: explicit lookup of inods linked via readdirp > > > > > > Hi, > > > > In fuse I saw, that as part of resolving a inode, an explicit lookup is > > done on it if the inode is found to be linked via readdirp (At the time > > of linking in readdirp, fuse sets a flag in the inode context). It is > > done because, many xlators such as afr depend upon lookup call for many > > things such as healing. > > Yes. But the lookup is a nameless lookup and hence is not sufficient enough. > Some of the functionalities that get affected AFAIK are: > 1. dht cannot create/heal directories and their layouts. > 2. afr cannot identify gfid mismatch of a file across its subvolumes, since > to identify a gfid mismatch we need a name. > > From what I heard, afr relies on crawls done by self-heal daemon for > named-lookups. But dht is worst hit in terms of maintaining directory > structure on newly added bricks (this problem is slightly different, since > we don't hit this because of nameless lookup after readdirp. Instead it is > because of a lack of named-lookup on the file after a graph switch. > Neverthless I am clubbing both because a named lookup would've solved the > issue). I've a feeling that different components have built their own way of > handling what is essentially same issue. Its better we devise a single > comprehensive solution. > > > > > But that logic is not there in gfapi. I am thinking of introducing that > > mechanism in gfapi as well, where as part of resolve it checks if the > > inode is linked from readdirp. And if so it will do an explicit lookup > > on that inode. > > As you've mentioned a lookup gives a chance to afr to heal the file. So, its > needed in gfapi too. However you've to speak to afr folks to discuss whether > nameless lookup is sufficient enough. > > > > > NOTE: It can be done in NFS server as well. > > Dht in NFS setup is also hit because of lack of named-lookups resulting in > non-healing of directories on newly added brick. > > > > > Please provide feedback. > > > > Regards, > > Raghavendra Bhat > > _______________________________________________ > > Gluster-devel mailing list > > Gluster-devel@xxxxxxxxxxx > > http://supercolony.gluster.org/mailman/listinfo/gluster-devel > > > _______________________________________________ > Gluster-devel mailing list > Gluster-devel@xxxxxxxxxxx > http://supercolony.gluster.org/mailman/listinfo/gluster-devel > _______________________________________________ Gluster-devel mailing list Gluster-devel@xxxxxxxxxxx http://supercolony.gluster.org/mailman/listinfo/gluster-devel
