Re: [PATCH 28/33] vfs: syscall: Add fsconfig() for configuring and managing a context [ver #11]

From: David Howells
Date: Thu Aug 09 2018 - 12:33:24 EST

Miklos Szeredi <miklos@xxxxxxxxxx> wrote:

> > However, as I have said, I *am* willing to add one of more flags to help
> > with this, but I can't make any "legacy" fs honour them as this requires
> > the fs_context to be passed down to sget_fc() and the filesystem - which
> > is why I was considering leaving it for later.
> You can determine at fsopen() time whether the filesystem is able to
> support the O_EXCL behavior? If so, then it's trivial to enable this
> conditionally. I think that's what Eric is asking for, it's obviously
> not fair to ask for a change in behavior of the legacy interface.

What do you mean by "enable it conditionally"? It cannot be enabled for
filesystems that don't pass fs_context down to sget().

mount(2) mustn't enable it lest it break userspace.

fsopen(2) can let userspace set a flag to enable it.