Re: [RFC PATCH 1/3] fs: add AT_REPLACE flag for linkat() which replaces the target

On Tue, Nov 22, 2016, at 03:25 AM, Omar Sandoval wrote:

From: Omar Sandoval <redacted>

One of the most common uses of temporary files is the classic atomic
replacement pattern, i.e.,

- write temporary file
- fsync temporary file
- rename temporary file over real file
- fsync parent directory

Now, we have O_TMPFILE, which gives us a much better way to create
temporary files, but it's not possible to use it for this pattern.

FWIW, I have some userspace code that indeed wants exactly this:

https://github.com/GNOME/libglnx/blob/36396b49ad6636c9959f3dfac5e04d41584b1a92/glnx-fdio.c#L232

So if we add this, I'd presumably change the code to try it and
fall back on EINVAL as usual?