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From: Alexander Motin <mav@FreeBSD.org>
Date: Sun, 6 Feb 2011 08:46:37 +0000 (UTC)
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Subject: svn commit: r218364 - projects/graid/head/sys/geom/raid
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Author: mav
Date: Sun Feb  6 08:46:37 2011
New Revision: 218364
URL: http://svn.freebsd.org/changeset/base/218364

Log:
  Use circular comparision of generations. If (unlikely) generations counter
  will ever wrap around, such logic may give a bit more reliable detection
  of the newest metadata copy. It is based on assumtion that all disk's
  metadata updated same time and should stay close and no disk should rejoin
  the array after being offline/failed/stale for more then half of generation
  counter wrap period. In last case this question just has no valid answer.

Modified:
  projects/graid/head/sys/geom/raid/md_intel.c

Modified: projects/graid/head/sys/geom/raid/md_intel.c
==============================================================================
--- projects/graid/head/sys/geom/raid/md_intel.c	Sun Feb  6 07:41:27 2011	(r218363)
+++ projects/graid/head/sys/geom/raid/md_intel.c	Sun Feb  6 08:46:37 2011	(r218364)
@@ -964,7 +964,7 @@ g_raid_md_intel_new_disk(struct g_raid_d
 	} else {
 		/* If we haven't started yet - check metadata freshness. */
 		if (mdi->mdio_meta == NULL ||
-		    pdmeta->generation > mdi->mdio_generation) {
+		    ((int32_t)(pdmeta->generation - mdi->mdio_generation)) > 0) {
 			G_RAID_DEBUG(1, "Newer disk");
 			if (mdi->mdio_meta != NULL)
 				free(mdi->mdio_meta, M_MD_INTEL);