On Sun, Jan 12, 2025 at 12:27:43AM -0500, Theodore Ts'o wrote: > So yes, it basically exists, although in practice, it doesn't work as > well as you might think, because of the need to read potentially a > large number of the metdata blocks. But for example, if you make sure > that all of the inode information is already cached, e.g.: > > ls -lR /path/to/large/tree > /dev/null > > Then the operation to do a bulk update will be fast: > > time chown -R root:root /path/to/large/tree > > This demonstrates that the bottleneck tends to be *reading* the > metdata blocks, not *writing* the metadata blocks. So if we presented more of the operations to the kernel at once, it could pipeline the reading of the metadata, providing a user-visible win. However, I don't know that we need a new user API to do it. This is something that could be done in the "rm" tool; it has the information it needs, and it's better to put heuristics like "how far to read ahead" in userspace than the kernel.
