[src/trunk]: src/sys/dev/raidframe Add logic to the main reconstruction loop ...

[oster <oster%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/5357190e2341
branches:  trunk
changeset: 777495:5357190e2341
user:      oster <oster%NetBSD.org@localhost>
date:      Mon Feb 20 22:42:52 2012 +0000

description:
Add logic to the main reconstruction loop to handle RAID5 with rotated
spares.  While here, observe that we were actually doing one more
stripe than we thought we were, and correct that too (it didn't matter
for non-RAID5_RS, but it definitely does for RAID5_RS).  Add some
bounds-checking at the beginning to handle the case where the number
of stripes in the set is smaller than the sliding reconstruction window.

XXX: this problem likely needs to be fixed for PARITY_DECLUSTERING too.

diffstat:

 sys/dev/raidframe/rf_reconstruct.c |  66 +++++++++++++++++++++++++++++++++++--
 1 files changed, 61 insertions(+), 5 deletions(-)

diffs (115 lines):

diff -r c8c75fc33585 -r 5357190e2341 sys/dev/raidframe/rf_reconstruct.c
--- a/sys/dev/raidframe/rf_reconstruct.c        Mon Feb 20 22:42:05 2012 +0000
+++ b/sys/dev/raidframe/rf_reconstruct.c        Mon Feb 20 22:42:52 2012 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: rf_reconstruct.c,v 1.117 2011/10/14 09:23:30 hannken Exp $     */
+/*     $NetBSD: rf_reconstruct.c,v 1.118 2012/02/20 22:42:52 oster Exp $       */
 /*
  * Copyright (c) 1995 Carnegie-Mellon University.
  * All rights reserved.
@@ -33,7 +33,7 @@
  ************************************************************/
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: rf_reconstruct.c,v 1.117 2011/10/14 09:23:30 hannken Exp $");
+__KERNEL_RCSID(0, "$NetBSD: rf_reconstruct.c,v 1.118 2012/02/20 22:42:52 oster Exp $");
 
 #include <sys/param.h>
 #include <sys/time.h>
@@ -570,6 +570,9 @@
        RF_ReconCtrl_t *tmp_reconctrl;
        RF_ReconEvent_t *event;
        RF_StripeCount_t incPSID,lastPSID,num_writes,pending_writes,prev;
+#if RF_INCLUDE_RAID5_RS > 0
+       RF_StripeCount_t startPSID,endPSID,aPSID,bPSID,offPSID;
+#endif
        RF_ReconUnitCount_t RUsPerPU;
        struct timeval etime, elpsd;
        unsigned long xor_s, xor_resid_us;
@@ -622,7 +625,17 @@
        recon_error = 0;
        write_error = 0;
        pending_writes = incPSID;
-       raidPtr->reconControl->lastPSID = incPSID;
+       raidPtr->reconControl->lastPSID = incPSID - 1;
+
+       /* bounds check raidPtr->reconControl->lastPSID and
+          pending_writes so that we don't attempt to wait for more IO
+          than can possibly happen */
+
+       if (raidPtr->reconControl->lastPSID > lastPSID)
+               raidPtr->reconControl->lastPSID = lastPSID;
+
+       if (pending_writes > lastPSID)
+               pending_writes = lastPSID;
 
        /* start the actual reconstruction */
 
@@ -636,6 +649,49 @@
                }
 
                num_writes = 0;
+
+#if RF_INCLUDE_RAID5_RS > 0
+               /* For RAID5 with Rotated Spares we will be 'short'
+                  some number of writes since no writes will get
+                  issued for stripes where the spare is on the
+                  component being rebuilt.  Account for the shortage
+                  here so that we don't hang indefinitely below
+                  waiting for writes to complete that were never
+                  scheduled.
+
+                  XXX: Should be fixed for PARITY_DECLUSTERING and
+                  others too! 
+
+               */
+
+               if (raidPtr->Layout.numDataCol < 
+                   raidPtr->numCol - raidPtr->Layout.numParityCol) {
+                       /* numDataCol is at least 2 less than numCol, so
+                          should be RAID 5 with Rotated Spares */
+
+                       /* XXX need to update for RAID 6 */
+                       
+                       startPSID = raidPtr->reconControl->lastPSID - pending_writes + 1;
+                       endPSID = raidPtr->reconControl->lastPSID;
+                       
+                       offPSID = raidPtr->numCol - col - 1;
+                       
+                       aPSID = startPSID - startPSID % raidPtr->numCol + offPSID;
+                       if (aPSID < startPSID) {
+                               aPSID += raidPtr->numCol;
+                       }
+                       
+                       bPSID = endPSID - ((endPSID - offPSID) % raidPtr->numCol);
+                       
+                       if (aPSID < endPSID) {
+                               num_writes = ((bPSID - aPSID) / raidPtr->numCol) + 1;
+                       }
+                       
+                       if ((aPSID == endPSID) && (bPSID == endPSID)) {
+                               num_writes++;
+                       }
+               }
+#endif
                
                /* issue a read for each surviving disk */
                
@@ -714,7 +770,7 @@
 #endif
                }
 
-               /* reads done, wakup any waiters, and then wait for writes */
+               /* reads done, wakeup any waiters, and then wait for writes */
 
                rf_WakeupHeadSepCBWaiters(raidPtr);
 
@@ -1134,7 +1190,7 @@
                        ctrl->ru_count = 0;
                        /* code left over from when head-sep was based on
                         * parity stripe id */
-                       if (ctrl->curPSID >= raidPtr->reconControl->lastPSID) {
+                       if (ctrl->curPSID > raidPtr->reconControl->lastPSID) {
                                CheckForNewMinHeadSep(raidPtr, ++(ctrl->headSepCounter));
                                return (RF_RECON_DONE_READS);   /* finito! */
                        }