On Mon, Jan 06, 2025 at 11:17:32AM -0500, Theodore Ts'o wrote: > Yes. And we might decide that it should be done using some kind of > ioctl, such as BLKDISCARD, as opposed to a new fallocate operation, > since it really isn't a filesystem metadata operation, just as > BLKDISARD isn't. The other side of the argument is that ioctls are > ugly, and maybe all new such operations should be plumbed through via > fallocate as opposed to adding a new ioctl. I don't have strong > feelings on this, although I *do* belive that whatever interface we > use, whether it be fallocate or ioctl, it should be supported by block > devices and files in a file system, to make life easier for those > databases that want to support running on a raw block device (for > full-page advertisements on the back cover of the Businessweek > magazine) or on files (which is how 99.9% of all real-world users > actually run enterprise databases. :-) If you want the operation to work for files it needs to be routed through the file system as otherwise you can't make it actually work coherently. While you could add a new ioctl that works on a file fallocate seems like a much better interface. Supporting it on a block device is trivial, as it can mostly (or even entirely depending on the exact definition of the interface) reuse the existing zero range / punch hole code.
