BeFS was the last real one i'm aware of at the complexity you are talking about (plenty of FSen have some very basic indexed support for say file sizes , but no

BeFS was the last real one i'm aware of at the complexity you are talking about (plenty of FSen have some very basic indexed support for say file sizes , but not the kind of generic tagging you are talking about) At this point, the view seems to be "attributes happen in the file system, indexing happens in user space". Especially on linux. Part of the reason is, as i understand it, the surface/complexity of including query languages in the kernel, which is not horribly unreasonable So all the common FSen have reasonable xattr support, and inotify/etc that support notification of attribute changes. The expectation seems to be that the fact that inotify might drop events now and then is not a dealbreaker. The modern queue length is usually 16384 anyway. I'm not saying there aren't tradeoffs here, but this seems to be the direction taken overall. I actually would love to have an FS with native indexed xattr and a way to get at them. I just don't think we'll get back there again anytime soon.