OverlayFS On Linux 5.15 Improves Performance, Copies Up More Attributes

OverlayFS continues to be used by Linux IoT/embedded devices and other use-cases as a union mount file-system. With Linux 5.15 the OverlayFS file-system continues to improve.

OverlayFS on Linux 5.15 should deliver some performance improvements thanks to RCU look-ups now being enabled. While no performance figures were provided as part of the patch, OverlayFS' lack of RCU usage for getting ACLs had yielded "a big performance hit in certain situations." That should now be squared away with Linux 5.15.

OverlayFS also now handles copying up immutable/append/sync/noatime attributes. This takes care of some inconsistent behavior currently seen by OverlayFS along with patches for other file attribute fixes.

More details on the OverlayFS changes for Linux 5.15 via this pull request sent in last week and merged.