Re: [PATCH 2/2] block: remove the per-bio/request write hint

[Jens Axboe <axboe@kernel.dk>]

On 3/6/22 11:01 AM, Christoph Hellwig wrote:
> On Sun, Mar 06, 2022 at 10:11:46AM -0700, Jens Axboe wrote:
>> 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

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.

-- 
Jens Axboe