rf_pqdeg.c revision 1.4 
1/*	$NetBSD: rf_pqdeg.c,v 1.4 1999/08/15 02:36:40 oster Exp $	*/
2/*
3 * Copyright (c) 1995 Carnegie-Mellon University.
4 * All rights reserved.
5 *
6 * Author: Daniel Stodolsky
7 *
8 * Permission to use, copy, modify and distribute this software and
9 * its documentation is hereby granted, provided that both the copyright
10 * notice and this permission notice appear in all copies of the
11 * software, derivative works or modified versions, and any portions
12 * thereof, and that both notices appear in supporting documentation.
13 *
14 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
15 * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
16 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
17 *
18 * Carnegie Mellon requests users of this software to return to
19 *
20 *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
21 *  School of Computer Science
22 *  Carnegie Mellon University
23 *  Pittsburgh PA 15213-3890
24 *
25 * any improvements or extensions that they make and grant Carnegie the
26 * rights to redistribute these changes.
27 */
28
29#include "rf_archs.h"
30
31#if (RF_INCLUDE_DECL_PQ > 0) || (RF_INCLUDE_RAID6 > 0)
32
33#include "rf_types.h"
34#include "rf_raid.h"
35#include "rf_dag.h"
36#include "rf_dagutils.h"
37#include "rf_dagfuncs.h"
38#include "rf_dagffrd.h"
39#include "rf_dagffwr.h"
40#include "rf_dagdegrd.h"
41#include "rf_dagdegwr.h"
42#include "rf_threadid.h"
43#include "rf_etimer.h"
44#include "rf_pqdeg.h"
45#include "rf_general.h"
46#include "rf_pqdegdags.h"
47#include "rf_pq.h"
48
49/*
50   Degraded mode dag functions for P+Q calculations.
51
52   The following nomenclature is used.
53
54   PQ_<D><P><Q>_Create{Large,Small}<Write|Read>DAG
55
56   where <D><P><Q> are single digits representing the number of failed
57   data units <D> (0,1,2), parity units <P> (0,1), and Q units <Q>, effecting
58   the I/O. The reads have only  PQ_<D><P><Q>_CreateReadDAG variants, while
59   the single fault writes have both large and small write versions. (Single fault
60   PQ is equivalent to normal mode raid 5 in many aspects.
61
62   Some versions degenerate into the same case, and are grouped together below.
63*/
64
65/* Reads, single failure
66
67   we have parity, so we can do a raid 5
68   reconstruct read.
69*/
70
71RF_CREATE_DAG_FUNC_DECL(rf_PQ_100_CreateReadDAG)
72{
73	rf_CreateDegradedReadDAG(raidPtr, asmap, dag_h, bp, flags, allocList, &rf_pRecoveryFuncs);
74}
75/* Reads double failure  */
76
77/*
78   Q is lost, but not parity
79   so we can a raid 5 reconstruct read.
80*/
81
82RF_CREATE_DAG_FUNC_DECL(rf_PQ_101_CreateReadDAG)
83{
84	rf_CreateDegradedReadDAG(raidPtr, asmap, dag_h, bp, flags, allocList, &rf_pRecoveryFuncs);
85}
86/*
87  parity is lost, so we need to
88  do a reconstruct read and recompute
89  the data with Q.
90*/
91
92RF_CREATE_DAG_FUNC_DECL(rf_PQ_110_CreateReadDAG)
93{
94	RF_PhysDiskAddr_t *temp;
95	/* swap P and Q pointers to fake out the DegradedReadDAG code */
96	temp = asmap->parityInfo;
97	asmap->parityInfo = asmap->qInfo;
98	asmap->qInfo = temp;
99	rf_CreateDegradedReadDAG(raidPtr, asmap, dag_h, bp, flags, allocList, &rf_qRecoveryFuncs);
100}
101/*
102  Two data units are dead in this stripe, so we will need read
103  both P and Q to reconstruct the data. Note that only
104  one data unit we are reading may actually be missing.
105*/
106RF_CREATE_DAG_FUNC_DECL(rf_CreateDoubleDegradedReadDAG);
107RF_CREATE_DAG_FUNC_DECL(rf_CreateDoubleDegradedReadDAG)
108{
109	rf_PQ_DoubleDegRead(raidPtr, asmap, dag_h, bp, flags, allocList);
110}
111RF_CREATE_DAG_FUNC_DECL(rf_PQ_200_CreateReadDAG);
112RF_CREATE_DAG_FUNC_DECL(rf_PQ_200_CreateReadDAG)
113{
114	rf_CreateDoubleDegradedReadDAG(raidPtr, asmap, dag_h, bp, flags, allocList);
115}
116/* Writes, single failure */
117
118RF_CREATE_DAG_FUNC_DECL(rf_PQ_100_CreateWriteDAG);
119RF_CREATE_DAG_FUNC_DECL(rf_PQ_100_CreateWriteDAG)
120{
121	if (asmap->numStripeUnitsAccessed != 1 &&
122	    asmap->failedPDAs[0]->numSector !=
123	    raidPtr->Layout.sectorsPerStripeUnit)
124		RF_PANIC();
125	rf_CommonCreateSimpleDegradedWriteDAG(raidPtr, asmap, dag_h, bp,
126		      flags, allocList, 2,
127		      (int (*) (RF_DagNode_t *)) rf_Degraded_100_PQFunc,
128		      RF_FALSE);
129}
130/* Dead  P - act like a RAID 5 small write with parity = Q */
131RF_CREATE_DAG_FUNC_DECL(rf_PQ_010_CreateSmallWriteDAG)
132{
133	RF_PhysDiskAddr_t *temp;
134	/* swap P and Q pointers to fake out the DegradedReadDAG code */
135	temp = asmap->parityInfo;
136	asmap->parityInfo = asmap->qInfo;
137	asmap->qInfo = temp;
138	rf_CommonCreateSmallWriteDAG(raidPtr, asmap, dag_h, bp, flags,
139				     allocList, &rf_qFuncs, NULL);
140}
141/* Dead Q - act like a RAID 5 small write */
142RF_CREATE_DAG_FUNC_DECL(rf_PQ_001_CreateSmallWriteDAG)
143{
144	rf_CommonCreateSmallWriteDAG(raidPtr, asmap, dag_h, bp, flags,
145				     allocList, &rf_pFuncs, NULL);
146}
147/* Dead P - act like a RAID 5 large write but for Q */
148RF_CREATE_DAG_FUNC_DECL(rf_PQ_010_CreateLargeWriteDAG)
149{
150	RF_PhysDiskAddr_t *temp;
151	/* swap P and Q pointers to fake out the code */
152	temp = asmap->parityInfo;
153	asmap->parityInfo = asmap->qInfo;
154	asmap->qInfo = temp;
155	rf_CommonCreateLargeWriteDAG(raidPtr, asmap, dag_h, bp, flags,
156				     allocList, 1, rf_RegularQFunc, RF_FALSE);
157}
158/* Dead Q - act like a RAID 5 large write */
159RF_CREATE_DAG_FUNC_DECL(rf_PQ_001_CreateLargeWriteDAG)
160{
161	rf_CommonCreateLargeWriteDAG(raidPtr, asmap, dag_h, bp, flags,
162				     allocList, 1, rf_RegularPFunc, RF_FALSE);
163}
164
165
166/*
167 * writes, double failure
168 */
169
170/*
171 * Lost P & Q - do a nonredundant write
172 */
173RF_CREATE_DAG_FUNC_DECL(rf_PQ_011_CreateWriteDAG)
174{
175	rf_CreateNonRedundantWriteDAG(raidPtr, asmap, dag_h, bp, flags, allocList,
176	    RF_IO_TYPE_WRITE);
177}
178/*
179   In the two cases below,
180   A nasty case arises when the write a (strict) portion of a failed stripe unit
181   and parts of another su. For now, we do not support this.
182*/
183
184/*
185  Lost Data and  P - do a Q write.
186*/
187RF_CREATE_DAG_FUNC_DECL(rf_PQ_110_CreateWriteDAG)
188{
189	RF_PhysDiskAddr_t *temp;
190
191	if (asmap->numStripeUnitsAccessed != 1 &&
192	    asmap->failedPDAs[0]->numSector != raidPtr->Layout.sectorsPerStripeUnit) {
193		RF_PANIC();
194	}
195	/* swap P and Q to fake out parity code */
196	temp = asmap->parityInfo;
197	asmap->parityInfo = asmap->qInfo;
198	asmap->qInfo = temp;
199	rf_CommonCreateSimpleDegradedWriteDAG(raidPtr, asmap, dag_h, bp, flags,
200		      allocList, 1,
201		      (int (*) (RF_DagNode_t *)) rf_PQ_DegradedWriteQFunc,
202		      RF_FALSE);
203	/* is the regular Q func the right one to call? */
204}
205/*
206   Lost Data and Q - do degraded mode P write
207*/
208RF_CREATE_DAG_FUNC_DECL(rf_PQ_101_CreateWriteDAG)
209{
210	if (asmap->numStripeUnitsAccessed != 1 &&
211	    asmap->failedPDAs[0]->numSector != raidPtr->Layout.sectorsPerStripeUnit)
212		RF_PANIC();
213	rf_CommonCreateSimpleDegradedWriteDAG(raidPtr, asmap, dag_h, bp, flags,
214	    allocList, 1, rf_RecoveryXorFunc, RF_FALSE);
215}
216#endif				/* (RF_INCLUDE_DECL_PQ > 0) ||
217				 * (RF_INCLUDE_RAID6 > 0) */
218