Re: [PATCH v7 0/5] Support for Open-Channel SSDs

From: Dongsheng Yang
Date: Tue Sep 01 2015 - 23:57:57 EST


On 08/07/2015 10:29 PM, Matias BjÃrling wrote:
These patches implement support for Open-Channel SSDs.

Applies against axboe's linux-block/for-4.3/drivers and can be found
in the lkml_v7 branch at https://github.com/OpenChannelSSD/linux

Any feedback is greatly appreciated.

Hi Matias,
After a reading of your code, that's a great idea.
I tried it with null_nvm and qemu-nvm. I have two questions
here.
(1), Why we name it lightnvm? IIUC, this framework
can work for other flashes not only NVMe protocol.
(2), There are gc and bm, but where is the wear leveling?
In hardware?

Thanx
Yang

Changes since v6:
- Multipage support (Javier Gonzalez)
- General code cleanups
- Fixed memleak on register failure

Changes since v5:
Feedback from Christoph Hellwig.
- Created new null_nvm from null_blk to register itself as a lightnvm
device.
- Changed the interface of register/unregister to only take disk_name.
The gendisk alloc in nvme is kept. Most instantiations will
involve the device gendisk, therefore wait with refactoring to a
later time.
- Renamed global parameters in core.c and rrpc.c

Changes since v4:
- Remove gendisk->nvm dependency
- Remove device driver rq private field dependency.
- Update submission and completion. The flow is now
Target -> Block Manager -> Device Driver, replacing callbacks in
device driver.
- Abstracted out the block manager into its own module. Other block
managers can now be implemented. For example to support fully
host-based SSDs.
- No longer exposes the device driver gendisk to user-space.
- Management is moved into /sys/modules/lnvm/parameters/configure_debug

Changes since v3:

- Remove dependency on REQ_NVM_GC
- Refactor nvme integration to use nvme_submit_sync_cmd for
internal commands.
- Fix race condition bug on multiple threads on RRPC target.
- Rename sysfs entry under the block device from nvm to lightnvm.
The configuration is found in /sys/block/*/lightnvm/

Changes since v2:

Feedback from Paul Bolle:
- Fix license to GPLv2, documentation, compilation.
Feedback from Keith Busch:
- nvme: Move lightnvm out and into nvme-lightnvm.c.
- nvme: Set controller css on lightnvm command set.
- nvme: Remove OACS.
Feedback from Christoph Hellwig:
- lightnvm: Move out of block layer into /drivers/lightnvm/core.c
- lightnvm: refactor request->phys_sector into device drivers.
- lightnvm: refactor prep/unprep into device drivers.
- lightnvm: move nvm_dev from request_queue to gendisk.

New
- Bad block table support (From Javier).
- Update maintainers file.

Changes since v1:

- Splitted LightNVM into two parts. A get/put interface for flash
blocks and the respective targets that implement flash translation
layer logic.
- Updated the patches according to the LightNVM specification changes.
- Added interface to add/remove targets for a block device.

Thanks to Jens Axboe, Christoph Hellwig, Keith Busch, Paul Bolle,
Javier Gonzalez and Jesper Madsen for discussions and contributions.

Matias BjÃrling (5):
lightnvm: Support for Open-Channel SSDs
lightnvm: Hybrid Open-Channel SSD RRPC target
lightnvm: Hybrid Open-Channel SSD block manager
null_nvm: Lightnvm test driver
nvme: LightNVM support

MAINTAINERS | 8 +
drivers/Kconfig | 2 +
drivers/Makefile | 5 +
drivers/block/Makefile | 2 +-
drivers/block/nvme-core.c | 23 +-
drivers/block/nvme-lightnvm.c | 568 ++++++++++++++++++
drivers/lightnvm/Kconfig | 36 ++
drivers/lightnvm/Makefile | 8 +
drivers/lightnvm/bm_hb.c | 366 ++++++++++++
drivers/lightnvm/bm_hb.h | 46 ++
drivers/lightnvm/core.c | 591 +++++++++++++++++++
drivers/lightnvm/null_nvm.c | 481 +++++++++++++++
drivers/lightnvm/rrpc.c | 1296 +++++++++++++++++++++++++++++++++++++++++
drivers/lightnvm/rrpc.h | 236 ++++++++
include/linux/lightnvm.h | 334 +++++++++++
include/linux/nvme.h | 6 +
include/uapi/linux/nvme.h | 3 +
17 files changed, 4007 insertions(+), 4 deletions(-)
create mode 100644 drivers/block/nvme-lightnvm.c
create mode 100644 drivers/lightnvm/Kconfig
create mode 100644 drivers/lightnvm/Makefile
create mode 100644 drivers/lightnvm/bm_hb.c
create mode 100644 drivers/lightnvm/bm_hb.h
create mode 100644 drivers/lightnvm/core.c
create mode 100644 drivers/lightnvm/null_nvm.c
create mode 100644 drivers/lightnvm/rrpc.c
create mode 100644 drivers/lightnvm/rrpc.h
create mode 100644 include/linux/lightnvm.h


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