Case Insensitive Trees in CephFS

Like most POSIX file systems, CephFS has always been a case-sensitive file system. However, it has become a priority to improve integration with gateways like Samba which present a case-insensitive view of some tree in the file system. In order to present that view, Samba requires expensive checks for file name lookups to locate a directory entry with the computed case-insensitive folding. It is also necessary to politely handle interoperating with other clients that are using normal case-sensitive names. To address this gap, CephFS now provides a mechanism for enforcing case-insensitive operations on a directory tree for all clients by simply setting a Ceph extended attribute. This talk will walk through the challenges for Samba's gateway on CephFS, the changes to the CephFS metadata server and clients, the interfaces used by other well-known file systems, and the expectations users may have going forward.