Running e2fsck on an MDT with a large number of striped directories shows a large number of disconnected directory entries. On several different systems this is showing a large number of errors during e2fsck, resulting in tens or hundreds of thousands of entries that need to be connected to list+found:
This doesn't appear to be caused by filesystem errors, as it has been seen repeatedly, so it is more likely to be a bug in the code (eg. rename doesn't connect striped directories properly, maybe if the rename source was on a remote MDT and the target is on the local MDT, or the reverse, or during "lfs migrate -m" or similar.
This might be related to
LU-15388, since REMOTE_PARENT_DIR entries have the wrong ".." entry, so updates to that directory will be incorrect.