Improved Case-Insensitive File Handling Coming To Linux 6.9

The optional case-insensitive file/folder handling under Linux that's hooked up for various file-systems like EXT4 and F2FS will benefit from improved performance on the upcoming Linux 6.9 kernel cycle.

Microsoft engineer Christian Brauner sent out the VFS misc pull request ahead of the Linux 6.9 merge window being opened. Most interesting with that miscellaneous VFS work for Linux 6.9 is enhancing the case-insensitive code. Christian explained:

"Finally merge the case-insensitive improvement series Gabriel has been working on for a long time. This cleanly propagates case insensitive operations through s_d_op which in turn allows us to remove the quite ugly generic_set_encrypted_ci_d_ops() operations. It also improves performance by trying a case-sensitive comparison first and then fallback to case-insensitive lookup if that fails. This also fixes a bug where overlayfs would be able to be mounted over a case insensitive directory which would lead to all sort of odd behaviors."

There are also various bug fixes and other code improvements with this code pending for Linux 6.9.