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author | Linus Torvalds <torvalds@linux-foundation.org> | 2010-08-10 15:38:19 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2010-08-10 15:38:19 -0700 |
commit | 3d30701b58970425e1d45994d6cb82f828924fdd (patch) | |
tree | 8b14cf462628bebf8548c1b8c205a674564052d1 /lib/raid6/raid6recov.c | |
parent | 8cbd84f2dd4e52a8771b191030c374ba3e56d291 (diff) | |
parent | fd8aa2c1811bf60ccb2d5de0579c6f62aec1772d (diff) | |
download | linux-next-3d30701b58970425e1d45994d6cb82f828924fdd.tar.gz |
Merge branch 'for-linus' of git://neil.brown.name/md
* 'for-linus' of git://neil.brown.name/md: (24 commits)
md: clean up do_md_stop
md: fix another deadlock with removing sysfs attributes.
md: move revalidate_disk() back outside open_mutex
md/raid10: fix deadlock with unaligned read during resync
md/bitmap: separate out loading a bitmap from initialising the structures.
md/bitmap: prepare for storing write-intent-bitmap via dm-dirty-log.
md/bitmap: optimise scanning of empty bitmaps.
md/bitmap: clean up plugging calls.
md/bitmap: reduce dependence on sysfs.
md/bitmap: white space clean up and similar.
md/raid5: export raid5 unplugging interface.
md/plug: optionally use plugger to unplug an array during resync/recovery.
md/raid5: add simple plugging infrastructure.
md/raid5: export is_congested test
raid5: Don't set read-ahead when there is no queue
md: add support for raising dm events.
md: export various start/stop interfaces
md: split out md_rdev_init
md: be more careful setting MD_CHANGE_CLEAN
md/raid5: ensure we create a unique name for kmem_cache when mddev has no gendisk
...
Diffstat (limited to 'lib/raid6/raid6recov.c')
-rw-r--r-- | lib/raid6/raid6recov.c | 132 |
1 files changed, 132 insertions, 0 deletions
diff --git a/lib/raid6/raid6recov.c b/lib/raid6/raid6recov.c new file mode 100644 index 000000000000..2609f00e0d61 --- /dev/null +++ b/lib/raid6/raid6recov.c @@ -0,0 +1,132 @@ +/* -*- linux-c -*- ------------------------------------------------------- * + * + * Copyright 2002 H. Peter Anvin - All Rights Reserved + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation, Inc., 53 Temple Place Ste 330, + * Boston MA 02111-1307, USA; either version 2 of the License, or + * (at your option) any later version; incorporated herein by reference. + * + * ----------------------------------------------------------------------- */ + +/* + * raid6recov.c + * + * RAID-6 data recovery in dual failure mode. In single failure mode, + * use the RAID-5 algorithm (or, in the case of Q failure, just reconstruct + * the syndrome.) + */ + +#include <linux/raid/pq.h> + +/* Recover two failed data blocks. */ +void raid6_2data_recov(int disks, size_t bytes, int faila, int failb, + void **ptrs) +{ + u8 *p, *q, *dp, *dq; + u8 px, qx, db; + const u8 *pbmul; /* P multiplier table for B data */ + const u8 *qmul; /* Q multiplier table (for both) */ + + p = (u8 *)ptrs[disks-2]; + q = (u8 *)ptrs[disks-1]; + + /* Compute syndrome with zero for the missing data pages + Use the dead data pages as temporary storage for + delta p and delta q */ + dp = (u8 *)ptrs[faila]; + ptrs[faila] = (void *)raid6_empty_zero_page; + ptrs[disks-2] = dp; + dq = (u8 *)ptrs[failb]; + ptrs[failb] = (void *)raid6_empty_zero_page; + ptrs[disks-1] = dq; + + raid6_call.gen_syndrome(disks, bytes, ptrs); + + /* Restore pointer table */ + ptrs[faila] = dp; + ptrs[failb] = dq; + ptrs[disks-2] = p; + ptrs[disks-1] = q; + + /* Now, pick the proper data tables */ + pbmul = raid6_gfmul[raid6_gfexi[failb-faila]]; + qmul = raid6_gfmul[raid6_gfinv[raid6_gfexp[faila]^raid6_gfexp[failb]]]; + + /* Now do it... */ + while ( bytes-- ) { + px = *p ^ *dp; + qx = qmul[*q ^ *dq]; + *dq++ = db = pbmul[px] ^ qx; /* Reconstructed B */ + *dp++ = db ^ px; /* Reconstructed A */ + p++; q++; + } +} +EXPORT_SYMBOL_GPL(raid6_2data_recov); + +/* Recover failure of one data block plus the P block */ +void raid6_datap_recov(int disks, size_t bytes, int faila, void **ptrs) +{ + u8 *p, *q, *dq; + const u8 *qmul; /* Q multiplier table */ + + p = (u8 *)ptrs[disks-2]; + q = (u8 *)ptrs[disks-1]; + + /* Compute syndrome with zero for the missing data page + Use the dead data page as temporary storage for delta q */ + dq = (u8 *)ptrs[faila]; + ptrs[faila] = (void *)raid6_empty_zero_page; + ptrs[disks-1] = dq; + + raid6_call.gen_syndrome(disks, bytes, ptrs); + + /* Restore pointer table */ + ptrs[faila] = dq; + ptrs[disks-1] = q; + + /* Now, pick the proper data tables */ + qmul = raid6_gfmul[raid6_gfinv[raid6_gfexp[faila]]]; + + /* Now do it... */ + while ( bytes-- ) { + *p++ ^= *dq = qmul[*q ^ *dq]; + q++; dq++; + } +} +EXPORT_SYMBOL_GPL(raid6_datap_recov); + +#ifndef __KERNEL__ +/* Testing only */ + +/* Recover two failed blocks. */ +void raid6_dual_recov(int disks, size_t bytes, int faila, int failb, void **ptrs) +{ + if ( faila > failb ) { + int tmp = faila; + faila = failb; + failb = tmp; + } + + if ( failb == disks-1 ) { + if ( faila == disks-2 ) { + /* P+Q failure. Just rebuild the syndrome. */ + raid6_call.gen_syndrome(disks, bytes, ptrs); + } else { + /* data+Q failure. Reconstruct data from P, + then rebuild syndrome. */ + /* NOT IMPLEMENTED - equivalent to RAID-5 */ + } + } else { + if ( failb == disks-2 ) { + /* data+P failure. */ + raid6_datap_recov(disks, bytes, faila, ptrs); + } else { + /* data+data failure. */ + raid6_2data_recov(disks, bytes, faila, failb, ptrs); + } + } +} + +#endif |