Zack's Kernel News
Zack's Kernel News

Chronicler Zack Brown reports on the latest news, views, dilemmas, and developments within the Linux kernel community.
Status of OverlayFS and Union Filesystems in General
Recently, Miklos Szeredi requested that OverlayFS be included in the main kernel tree. OverlayFS allows two directory trees to appear as one. Two files with the same path on each tree would appear to occupy the same directory in the overlayed filesystem. The project has been in existence for several years, but this time Linus Torvalds replied, "Yes, I think we should just do it. It's in use, it's pretty small, and the other alternatives are worse. Let's just plan on getting this thing done with."
Al Viro said he'd start reviewing the code, but he also suggested that if they were going to merge a union filesystem such as OverlayFS, they might as well consider merging other similar projects, such as Unionmount and Aufs. Unionmount in particular, he said, had been getting some good work lately from David Howells.
Meanwhile, Sedat Dilek jumped for joy at seeing OverlayFS close to acceptance. Al also replied again with his initial review. He'd identified some security issues and other technical problems, and he went back and forth with Miklos about them. The two at first didn't see eye-to-eye about how to fix the issues, or even whether a given issue was really a problem.
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