Re: [patch 1/2]block: handle merged discard request

[Mike Snitzer]

On Mon, Aug 20 2012 at  9:58am -0400,
Christoph Hellwig <hch@xxxxxxxxxxxxx> wrote:

> On Mon, Aug 20, 2012 at 09:57:39AM -0400, Mike Snitzer wrote:
> > But I haven't put my finger on _why_ a discard bio has bio->bi_io_vec
> > (but given my use of DM, bio comes from bio_alloc_bioset, and DM passes
> > original bio->bi_max_vecs for nr_iovecs).
> 
> TRIM has a payload and we cheay by preallocation a data page for it.

Thought we pushed that down?  Hence sd_setup_discard_cmnd's
alloc_page + blk_add_request_payload hack.
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