On Tue, Mar 31, 2020 at 07:11:11AM +0200, Miklos Szeredi wrote: > On Mon, Mar 30, 2020 at 11:17 PM Christian Brauner > <christian.brauner@xxxxxxxxxx> wrote: > > > Fwiw, putting down my kernel hat and speaking as someone who maintains > > two container runtimes and various other low-level bits and pieces in > > userspace who'd make heavy use of this stuff I would prefer the fd-based > > fsinfo() approach especially in the light of across namespace > > operations, querying all properties of a mount atomically all-at-once, > > fsinfo(2) doesn't meet the atomically all-at-once requirement. I guess your /proc based idea have exactly the same problem... I see two possible ways: - after open("/mnt", O_PATH) create copy-on-write object in kernel to represent mount node -- kernel will able to modify it, but userspace will get unchanged data from the FD until to close() - improve fsinfo() to provide set (list) of the attributes by one call Karel -- Karel Zak <kzak@xxxxxxxxxx> http://karelzak.blogspot.com