linux-stable/fs/exofs/Kconfig.ore
Boaz Harrosh ce5d36aac2 ore: Support for raid 6
This simple patch adds support for raid6 to the ORE.
Most operations and calculations where already for the general
case. Only things left:
* call async_gen_syndrome() in the case of raid6
  (NOTE that the raid6 math is the one supported by the Linux Kernel
   see: crypto/async_tx/async_pq.c)
* call _ore_add_parity_unit() twice with only last call generating
  the redundancy pages.

* Fix couple BUGS in old code
  a. In reads when parity==2 it can happen that per_dev->length=0
     but per_dev->offset was set and adjusted by _ore_add_sg_seg().
     Don't let it be overwritten.
  b. The all 'cur_comp > starting_dev' thing to determine if:
       "per_dev->offset is in the current stripe number or the
       next one."
     Was a complete raid5/4 accident. When parity==2 this is not
     at all true usually. All we need to do is increment si->ob_offset
     once we pass by the first parity device.
     (This also greatly simplifies the code, amen)
  c. Calculation of si->dev rotation can overflow when parity==2.

* Then last enable raid6 in ore_verify_layout()

I want to deeply thank Daniel Gryniewicz who found first all the
bugs in the old raid code, and inspired these patches:
	Inspired-by Daniel Gryniewicz <dang@linuxbox.com>

Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
2014-05-22 14:48:15 +03:00

14 lines
495 B
Text

# ORE - Objects Raid Engine (libore.ko)
#
# Note ORE needs to "select ASYNC_XOR". So Not to force multiple selects
# for every ORE user we do it like this. Any user should add itself here
# at the "depends on EXOFS_FS || ..." with an ||. The dependencies are
# selected here, and we default to "ON". So in effect it is like been
# selected by any of the users.
config ORE
tristate
depends on EXOFS_FS || PNFS_OBJLAYOUT
select ASYNC_XOR
select RAID6_PQ
select ASYNC_PQ
default SCSI_OSD_ULD