Linux 5.14 Works Around Compatibility With Some Digital Camera exFAT File-Systems

Merged back in Linux 5.4 in late 2019 was the exFAT file-system driver that has proven to be quite mature at this stage with the work led by Samsung under the blessing of Microsoft. There hasn't been much in the way of exFAT file-system driver changes in recent kernel releases given its maturity. Even with Linux 5.14 there are just two exFAT patches but end up being notable at least for some users due to fixing file-system compatibility with some digital cameras.

Linux 5.14's exFAT brings improved compatibility with the exFAT file-systems from some digital cameras. In particular, when mounting an exFAT file-system from select digital cameras under Linux, in some cases not all of the files would show up under Linux.

This issue appears to be ultimately with the digital camera's firmware and not Linux in that the data length in the stream entry of the directory is not getting updated under some conditions. This meant Linux wasn't showing all of the files in a given directory when the data length wasn't being updated.

Now with the patches for the exFAT driver in Linux 5.14 is a patch to handle the wrong stream entry size in the exFAT read directory function. This fix/workaround will also be back-ported to stable kernels.

This issue of "missing files" appears to happen with at least some Fuji digital cameras while it remains to be seen if the vendor will update their exFAT file-system as they appear to be the one out of spec in this case.