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ce5d36aac2
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>
14 lines
495 B
Text
14 lines
495 B
Text
# ORE - Objects Raid Engine (libore.ko)
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#
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# Note ORE needs to "select ASYNC_XOR". So Not to force multiple selects
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# for every ORE user we do it like this. Any user should add itself here
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# at the "depends on EXOFS_FS || ..." with an ||. The dependencies are
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# selected here, and we default to "ON". So in effect it is like been
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# selected by any of the users.
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config ORE
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tristate
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depends on EXOFS_FS || PNFS_OBJLAYOUT
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select ASYNC_XOR
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select RAID6_PQ
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select ASYNC_PQ
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default SCSI_OSD_ULD
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