Re: [PATCH 5/6] f2fs: add a kernel thread to issue discard commands asynchronously

[Christoph Hellwig]

On Thu, Jan 12, 2017 at 02:44:06PM -0800, Jaegeuk Kim wrote:
> This patch adds a kernel thread to issue discard commands.
> It proposes three states, D_PREP, D_SUBMIT, and D_DONE to identify current
> bio status.

Why?  Instead of creating the complexity of a thread you should look
into issuing the discard bios asynchronously, which should help to
simplify a lot of the discard logic in f2fs.