Great development! I'm certainly all for this becoming the standard/default. Unfortunately for those relying on fsync() flushing the whole file system (which one shouldn't) syncfs() isn't a great replacement. Last time I tested that it didn't return errors on failure nor was it making certain all changes to the file system before syncfs() made it to disk.<p>Btrfs had this "fast fsync" for a while already btw. (out of necessity -- otherwise fsync would be even more unbearably slow on btrfs). This seemed to be difficult to implement (lots of corner cases). Every release there were "fast fsync" bug fixes such as e.g. <a href="https://lore.kernel.org/linux-btrfs/20200220132949.20571-1-fdmanana@kernel.org/" rel="nofollow">https://lore.kernel.org/linux-btrfs/20200220132949.20571-1-f...</a> <a href="https://lore.kernel.org/linux-btrfs/20200722112837.15516-1-fdmanana@kernel.org/" rel="nofollow">https://lore.kernel.org/linux-btrfs/20200722112837.15516-1-f...</a> . Let's hope the ext4 version of this has less initial issues.