Hi, I have looked into this on another system earlier and this is what I have so far:
1. The test involves moving and renaming directories and files within those dirs. 2. A rename dir operation failed on one subvol. So we have 3 subvols where the directory has the new name and one where it has the old name. 3. Some operation - perhaps a revalidate - has added a dentry with the old name to the inode . So there are now 2 dentries for the same inode for a directory. 4. Renaming a file inside that directory calls an inode_link which end up traversing the dentry list for each entry all the way up to the root in the __foreach_ancestor_dentry function. If there are multiple deep directories with the same problem in the path, this takes a very long time (hours) because of the number of times the function is called. I do not know why the rename dir failed. However, is the following a correct/acceptable fix for the traversal issue? 1. A directory should never have more than one dentry 2. __foreach_ancestor_dentry uses the dentry list of the parent inode. Parent inode will always be a directory. 3. Can we just take the first dentry in the list for the cycle check as we are really only comparing inodes? In the scenarios I have tried, all the dentries in the dentry_list always have the same inode. This would prevent the hang. If there is more than one dentry for a directory, flag an error somehow. 4. Is there any chance that a dentry in the list can have a different inode? If yes, that is a different problem and 3 does not apply. It would work like this: last_parent_inode = NULL; list_for_each_entry (each, &parent->dentry_list, inode_list) { //Since we are only using the each->parent to check, stop if we have already checked it if(each->parent != last_parent_inode) { ret = __foreach_ancestor_dentry (each, per_dentry_fn, data); if (ret) goto out; } last_parent_inode = each->parent; } This would prevent the hang but leads to other issues which would exist in the current code anyway - mainly, which dentry is the correct one and how do we recover? Regards, Nithya On Wed, May 11, 2016 at 7:09 PM, Niels de Vos <nde...@redhat.com> wrote: > Could someone look into this busy loop? > https://paste.fedoraproject.org/365207/29732171/raw/ > > This was happening in a regression-test burn-in run, occupying a Jenkins > slave for 2+ days: > https://build.gluster.org/job/regression-test-burn-in/936/ > (run with commit f0ade919006b2581ae192f997a8ae5bacc2892af from master) > > A coredump of the mount process is available from here: > http://slave20.cloud.gluster.org/archived_builds/crash.tar.gz > > Thanks misc for reporting and gathering the debugging info. > Niels > > _______________________________________________ > Gluster-devel mailing list > Gluster-devel@gluster.org > http://www.gluster.org/mailman/listinfo/gluster-devel >
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