hi,
 I cannot possible give any consideration to this caching layer until I'm
 happy with the code I got from you for stripe batching, and I'm not.

I asked:

Subject: Re: [PATCH 7/7] md/raid5: fix handling of degraded stripes in batches.
Date: Wed, 13 May 2015 10:56:04 +1000

What exactly do you expect to happen after the stripes in a batch after they
have been split up?

and haven't received a reply yet.
Did you not get that email?

Thanks,
NeilBrown



On Mon, 18 May 2015 19:57:28 -0700 Shaohua Li [off-list ref] wrote:

Hi,

This is the second version of the raid5/6 caching layer patches. The patches add a
caching layer for raid5/6. The caching layer uses a SSD as a cache for a raid
5/6. It works like the similar way of a hardware raid controller. The purpose
is to improve raid performance (reduce read-modify-write) and fix write hole
issue. The main patch is patch 3 and the description has all details about the
implementation.

Main changes of V2 are to improve performance. Meta data write doesn't use FUA
any more. Discard request is only dispatched when discard range is big enough.
Also have some bug fixing and code cleanup. Please review!

Thanks,
Shaohua


Shaohua Li (5):
  raid5: directly use mddev->queue
  raid5: A caching layer for RAID5/6
  raid5: add some sysfs entries
  md: don't allow resize/reshape with cache support
  raid5: skip resync if caching is enabled

Song Liu (1):
  MD: add a new disk role to present cache device

 drivers/md/Makefile            |    2 +-
 drivers/md/md.c                |   14 +-
 drivers/md/md.h                |    4 +
 drivers/md/raid5-cache.c       | 3519 ++++++++++++++++++++++++++++++++++++++++
 drivers/md/raid5.c             |   97 +-
 drivers/md/raid5.h             |   16 +-
 include/uapi/linux/raid/md_p.h |   73 +
 7 files changed, 3705 insertions(+), 20 deletions(-)
 create mode 100644 drivers/md/raid5-cache.c