On Sun, ddMar 06, 2022 at 11:06:12AM -0700, Jens Axboe wrote:

quoted

On 3/6/22 11:01 AM, Christoph Hellwig wrote:

quoted

On Sun, Mar 06, 2022 at 10:11:46AM -0700, Jens Axboe wrote:

quoted

Yes, I think we should kill it. If we retain the inode hint, the f2fs
doesn't need a any changes. And it should be safe to make the per-file
fcntl hints return EINVAL, which they would on older kernels anyway.
Untested, but something like the below.

I've sent this off to the testing farm this morning, but EINVAL might
be even better:

http://git.infradead.org/users/hch/block.git/shortlog/refs/heads/more-hint-removal

Yup, I like that.

quoted

I do think EINVAL is better, as it just tells the app it's not available
like we would've done before. With just doing zeroes, that might break
applications that set-and-verify. Of course there's also the risk of
that since we retain inode hints (so they work), but fail file hints.
That's a lesser risk though, and we only know of the inode hints being
used.

Agreed, I think EINVAL would be better here - jsut make it behave
like it would on a kernel that never supported this functionality in
the first place. Seems simpler to me for user applications if we do
that.

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com

Currently, UFS device also supports hot/cold data separation 
and uses existing write_hint code.

In other words, the function is also being used in storage other than NVMe,
and if it is removed, it is thought that there will be an operation problem.

If the code is removed, I am worried about how other devices
that use the function.

Is there a good alternative?