Add a bakvol module in UBI layer for MLC paired page power loss issue

From: BeanHuo <[email protected]>

These patches aim to solve MLC NAND paired page power loss issue,by adding a bakvol(backup volume) module in UBI layer.

MLC NAND paired page power loss issue is a known issue so far, MLC NAND pages are coupled in a sense that if you cut power while writing to a page, you corrupt not only this page, but also one of the previous pages which is paired with the current one.
http://www.linux-mtd.infradead.org/doc/ubifs.html#L_ubifs_mlc

This paired page power loss solution is based on NAND multiple plane program feature. Dual plane page program method can program two different plane pages at the same time. as for this solution, there are three main steps:

1. initialization
While UBI attach process, if ubi first attach MTD to ubi device,
bakvol will be created, and reserve 20 PEBs for bakvol. if not, scan every PEB to find out bakvol PEB, update a bakvol PEB table in RAM.
2. recovery
While UBIFS mount, and if there is a power loss, bakvol module will check if there are lower pages being dameged by last power loss, if yes, bakvol will apply for one new PEB, move uncorrupted data to this PEB, and recover dameged data by backup page data in bakvol PEB.
3. backup
if UBI proggrams one lower page, bakvol module will duplicate this lower page data,and then program source page data and backup page data into two different plane pages(one is user data volume and another is backup volume) at the same time through dual plane program command.
If UBI porgrams upper page data, still uses mtd_write() to program. In another word, backup only implements while program lower page.

These patches have already been tested on Micron 70s/80s MLC NAND.

Any suggestions and comments welcomed.

This version patches based on Linux kernel 4.2-rc7.

v2:
1.Add CRC32 protection for user OOB area data. 2.Move recovery action from attach step to ubifs mount step. 3.Add more comments for some key function. 4.standard multi-plane program function. 5.Standard send-mail patches

Bean Huo (17):
include:mtd:add multi-plane page program command include:mtd:add multi-plane program in mtd_info drivers:mtd:add multi-plane page program support in partition layer drivers:mtd:nand:enable dual plane page program function drivers:mtd:ubi:add bakvol on-flash and RAM data structures drivers:mtd:ubi:add bakvol function define in ubi layer fs:ubifs:add bakvol function define in ubifs layer drivers:mtd:ubi:disable bakvol function while writing volume table drivers:mtd:ubi:get PEB according to specfied plane number drivers:mtd:ubi:enable bakvol function for fastmap operation drivers:mtd:ubi:add disable/enable bakvol while ubi write drivers:mtd:ubi:add disable bakvol while ubi detach drivers:mtd:ubi:add bakvol init while attach ubi drivers:mtd:ubi:add backup operation in ubi_io_write fs:ubifs:enable bakvol module and recover operation driver:mtd:ubi:add new bakvol module in ubi layer drivers:mtd:ubi: Kconfig Makefile

 drivers/mtd/mtdpart.c        |   19 +
 drivers/mtd/nand/nand_base.c |  405 +++++++++++++
 drivers/mtd/ubi/Kconfig      |   15 +
 drivers/mtd/ubi/Makefile     |    2 +-
 drivers/mtd/ubi/attach.c     |   24 +-
 drivers/mtd/ubi/bakvol.c     | 1296 ++++++++++++++++++++++++++++++++++++++++++
 drivers/mtd/ubi/build.c      |    2 +
 drivers/mtd/ubi/eba.c        |   13 +-
 drivers/mtd/ubi/fastmap.c    |    2 +-
 drivers/mtd/ubi/io.c         |   73 ++-
 drivers/mtd/ubi/ubi-media.h  |   64 +++
 drivers/mtd/ubi/ubi.h        |   23 +-
 drivers/mtd/ubi/vtbl.c       |    2 +-
 drivers/mtd/ubi/wl.c         |  140 +++++
 fs/ubifs/super.c             |   11 +
 fs/ubifs/ubifs.h             |    2 +
 include/linux/mtd/mtd.h      |   19 +
 include/linux/mtd/nand.h     |    4 +
 18 files changed, 2091 insertions(+), 25 deletions(-)
 create mode 100644 drivers/mtd/ubi/bakvol.c

1.9.1