Hello, Kent.

On Mon, Sep 10, 2012 at 05:22:30PM -0700, Kent Overstreet wrote:

A bunch of what __blk_queue_bounce() was doing was problematic for the
immutable bvec work; this cleans that up and the code is quite a bit
smaller, too.

The __bio_for_each_segment() in copy_to_high_bio_irq() was changed
because that one's looping over the original bio, not the bounce bio -
since the bounce code doesn't own that bio the __ version wasn't
correct.

I do like the new implementation.  I think the function is broken
before and after tho.  Allocating from fs_bio_set from block layer is
never safe and nothing seems to prevent multiple allocators compete in
the bounce page mempool.  This will need a separate bioset and the
multiple mempool allocation would have to be put inside a mutex.

Also, how was this tested?

Thanks.

-- 
tejun