linux/fs/exofs/ore_raid.h
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

63 lines
2.2 KiB
C

/*
* Copyright (C) from 2011
* Boaz Harrosh <bharrosh@panasas.com>
*
* This file is part of the objects raid engine (ore).
*
* It is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as published
* by the Free Software Foundation.
*
* You should have received a copy of the GNU General Public License
* along with "ore". If not, write to the Free Software Foundation, Inc:
* "Free Software Foundation <info@fsf.org>"
*/
#include <scsi/osd_ore.h>
#define ORE_ERR(fmt, a...) printk(KERN_ERR "ore: " fmt, ##a)
#ifdef CONFIG_EXOFS_DEBUG
#define ORE_DBGMSG(fmt, a...) \
printk(KERN_NOTICE "ore @%s:%d: " fmt, __func__, __LINE__, ##a)
#else
#define ORE_DBGMSG(fmt, a...) \
do { if (0) printk(fmt, ##a); } while (0)
#endif
/* u64 has problems with printk this will cast it to unsigned long long */
#define _LLU(x) (unsigned long long)(x)
#define ORE_DBGMSG2(M...) do {} while (0)
/* #define ORE_DBGMSG2 ORE_DBGMSG */
/* ios_raid.c stuff needed by ios.c */
int _ore_post_alloc_raid_stuff(struct ore_io_state *ios);
void _ore_free_raid_stuff(struct ore_io_state *ios);
void _ore_add_sg_seg(struct ore_per_dev_state *per_dev, unsigned cur_len,
bool not_last);
int _ore_add_parity_unit(struct ore_io_state *ios, struct ore_striping_info *si,
struct ore_per_dev_state *per_dev, unsigned cur_len,
bool do_xor);
void _ore_add_stripe_page(struct __stripe_pages_2d *sp2d,
struct ore_striping_info *si, struct page *page);
static inline void _add_stripe_page(struct __stripe_pages_2d *sp2d,
struct ore_striping_info *si, struct page *page)
{
if (!sp2d) /* Inline the fast path */
return; /* Hay no raid stuff */
_ore_add_stripe_page(sp2d, si, page);
}
/* ios.c stuff needed by ios_raid.c */
int _ore_get_io_state(struct ore_layout *layout,
struct ore_components *oc, unsigned numdevs,
unsigned sgs_per_dev, unsigned num_par_pages,
struct ore_io_state **pios);
int _ore_add_stripe_unit(struct ore_io_state *ios, unsigned *cur_pg,
unsigned pgbase, struct page **pages,
struct ore_per_dev_state *per_dev, int cur_len);
int _ore_read_mirror(struct ore_io_state *ios, unsigned cur_comp);
int ore_io_execute(struct ore_io_state *ios);