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

Christoph Hellwig
2022-03-05T05:19:49Z

On Sat, Mar 05, 2022 at 09:12:55AM +1100, Dave Chinner wrote:
> AFAICT, all the filesystem/IO path passthrough plumbing for hints is
> now gone, and no hardware will ever receive hints. Doesn't this
> mean that file_write_hint(), file->f_write_hint and iocb->ki_hint
> are now completely unused, too?

No, for the reason tha you state below. f2fs still uses it.

> AFAICT, this patch leaves just the f2fs allocator usage of
> inode->i_rw_hint to select a segment to allocate from as the
> remaining consumer of this entire plumbing and user API. Is that
> used by applications anywhere, or can that be removed and so the
> rest of the infrastructure get removed and the fcntl()s no-op'd or
> -EOPNOTSUPP?

I was told it is used quite heavily in android.