Wine Reflink Support Continues To Be Worked On For Significant Space Savings

Last month I wrote about the proposed reflink support for Wine that would provide significant space savings for those having multiple Windows games/applications on Linux installed where Wine and derivatives like Crossover and Steam Play (Proton) generally maintain a separate "prefix" per software installation. Fortunately, that reflink support continues to be worked on for Wine where it can lead to savings up to several hundred megabytes per Wine prefix.

Wine currently has around 150MB of mostly redundant DLLs for each Wine 32-bit prefix created and around 300MB for each Wine 64-bit prefix. Most prefixes have these various system libraries byte-for-byte identical and in those cases the reflink support can lead to additional prefixes taking 1MB or less for actual on-disk storage. For those installing many games and Windows applications, this can potentially mean significant space-savings if/when this reflink support is merged into Wine.

The reflink support takes care of the scenario where if any of the shared libraries in a given prefix are modified, the original copy is not manipulated as would be the case if Wine was just doing hard/symbolic linking between the different symlinks.

While this reflink de-duplication support is great, it does require support from the underlying file-system. File-systems like Btrfs and XFS support reflinks but notably not having the support is EXT4.

Sent out today were the v3 patches of the Wine reflink support that improve the error handling of the new code. Hopefully this reflink support will be ready for mainlining soon.