The merge window for Linux 5.18 ends this weekend after Microsoft’s exFAT filesystem received a Pull Request. There are only two patches for exFAT this cycle, but both changes are important.
First, exFAT on Linux 5.18+ adds an option to allow access to paths with trailing dots. Until now, the exFAT driver unconditionally stripped trailing periods in path components, and in Linux 5.18, this practice was relaxed.
This patch adds an exFAT “keep_last_dots” mount option to control whether trailing sentences are stripped. The motivation for this work was to discover that the FUSE exFAT driver allows trailing dots, but the Linux kernel driver does not. See this patch for more details.
Another patch for Linux 5.18 no longer clears VolumeDirty on writeback, an important change to avoid shortening the lifespan of storage devices. Before this commit, if ‘dirsync’ or ‘sync’ was not enabled, VolumeDirty was cleared on writeback. If there is a sudden power loss after clearing VolumeDirty, but no other updates have been written, the exFAT filesystem will not be able to detect the power loss on the next mount.
And when the parent directory is updated, VolumeDirty will be set again but not cleared. This means that the boot sector will be written at least once per writeback, which will shorten the life of the device.