Determine the data offset using a variable specified within the softraid

metadata. This allows us to implement seamless transitions from the
previous metadata version to the current version, avoiding the need to
recreate the softraid volume.

Joint work with marco@ during c2k10.

ok marco@

1 files changed, 36 insertions, 9 deletions

diff --git a/sys/dev/softraid.c b/sys/dev/softraid.c
index ad03205b17a..196370de27f 100644
--- a/sys/dev/softraid.c
+++ b/sys/dev/softraid.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: softraid.c,v 1.207 2010/06/28 18:31:01 krw Exp $ */
+/* $OpenBSD: softraid.c,v 1.208 2010/07/02 09:20:26 jsing Exp $ */
 /*
  * Copyright (c) 2007, 2008, 2009 Marco Peereboom <marco@peereboom.us>
  * Copyright (c) 2008 Chris Kuethe <ckuethe@openbsd.org>
@@ -538,6 +538,7 @@ sr_meta_init(struct sr_discipline *sd, struct sr_chunk_head *cl)
 	sm->ssdi.ssd_version = SR_META_VERSION;
 	sm->ssd_ondisk = 0;
 	sm->ssdi.ssd_flags = sd->sd_meta_flags;
+	sm->ssd_data_offset = SR_DATA_OFFSET;
 
 	/* get uuid from chunk 0 */
 	bcopy(&sd->sd_vol.sv_chunks[0]->src_meta.scmi.scm_uuid,
@@ -815,20 +816,43 @@ sr_meta_validate(struct sr_discipline *sd, dev_t dev, struct sr_metadata *sm,
 		goto done;
 	}
 
-	if (sm->ssdi.ssd_version != SR_META_VERSION) {
-		printf("%s: %s can not read metadata version %u, expected %u\n",
-		    DEVNAME(sc), devname, sm->ssdi.ssd_version,
-		    SR_META_VERSION);
-		goto done;
-	}
-
+	/* Verify metadata checksum. */
 	sr_checksum(sc, sm, &checksum, sizeof(struct sr_meta_invariant));
 	if (bcmp(&checksum, &sm->ssd_checksum, sizeof(checksum))) {
 		printf("%s: invalid metadata checksum\n", DEVNAME(sc));
 		goto done;
 	}
 
-	/* XXX do other checksums */
+	/* Handle changes between versions. */
+	if (sm->ssdi.ssd_version == 3) {
+
+		/*
+		 * Version 3 - update metadata version and fix up data offset
+		 * value since this did not exist in version 3.
+		 */
+		sm->ssdi.ssd_version = SR_META_VERSION;
+		snprintf(sm->ssdi.ssd_revision, sizeof(sm->ssdi.ssd_revision),
+		    "%03d", SR_META_VERSION);
+		if (sm->ssd_data_offset == 0)
+			sm->ssd_data_offset = SR_META_V3_DATA_OFFSET;
+
+	} else if (sm->ssdi.ssd_version == SR_META_VERSION) {
+
+		/* 
+		 * Version 4 - original metadata format did not store
+		 * data offset so fix this up if necessary.
+		 */
+		if (sm->ssd_data_offset == 0)
+			sm->ssd_data_offset = SR_DATA_OFFSET;
+
+	} else {
+
+		printf("%s: %s can not read metadata version %u, expected %u\n",
+		    DEVNAME(sc), devname, sm->ssdi.ssd_version,
+		    SR_META_VERSION);
+		goto done;
+
+	}
 
 #ifdef SR_DEBUG
 	/* warn if disk changed order */
@@ -3718,6 +3742,9 @@ sr_validate_io(struct sr_workunit *wu, daddr64_t *blk, char *func)
 	DNPRINTF(SR_D_DIS, "%s: %s 0x%02x\n", DEVNAME(sd->sd_sc), func,
 	    xs->cmd->opcode);
 
+	if (sd->sd_meta->ssd_data_offset == 0)
+		panic("invalid data offset");
+
 	if (sd->sd_vol_status == BIOC_SVOFFLINE) {
 		DNPRINTF(SR_D_DIS, "%s: %s device offline\n",
 		    DEVNAME(sd->sd_sc), func);