From: Milan Broz <mbroz@redhat.com>
Date: Thu, 12 Jul 2007 16:28:13 +0000 (+0100)
Subject: dm snapshot: permit invalid activation
X-Git-Tag: v2.6.23-rc1~1093
X-Git-Url: http://pilppa.com/gitweb/?a=commitdiff_plain;h=0764147b111b8ca886e4f2e9c9e019106b09b657;p=linux-2.6-omap-h63xx.git

dm snapshot: permit invalid activation

Allow invalid snapshots to be activated instead of failing.

This allows userspace to reinstate any given snapshot state - for
example after an unscheduled reboot - and clean up the invalid snapshot
at its leisure.

Cc: stable@kernel.org
Signed-off-by: Milan Broz <mbroz@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

diff --git a/drivers/md/dm-exception-store.c b/drivers/md/dm-exception-store.c
index 8c25c2ff724..3d65917a1bb 100644
--- a/drivers/md/dm-exception-store.c
+++ b/drivers/md/dm-exception-store.c
@@ -489,17 +489,18 @@ static int persistent_read_metadata(struct exception_store *store)
 		/*
 		 * Sanity checks.
 		 */
-		if (!ps->valid) {
-			DMWARN("snapshot is marked invalid");
-			return -EINVAL;
-		}
-
 		if (ps->version != SNAPSHOT_DISK_VERSION) {
 			DMWARN("unable to handle snapshot disk version %d",
 			       ps->version);
 			return -EINVAL;
 		}
 
+		/*
+		 * Metadata are valid, but snapshot is invalidated
+		 */
+		if (!ps->valid)
+			return 1;
+
 		/*
 		 * Read the metadata.
 		 */
diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c
index 1da41229fbf..854891d07b5 100644
--- a/drivers/md/dm-snap.c
+++ b/drivers/md/dm-snap.c
@@ -523,9 +523,12 @@ static int snapshot_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 
 	/* Metadata must only be loaded into one table at once */
 	r = s->store.read_metadata(&s->store);
-	if (r) {
+	if (r < 0) {
 		ti->error = "Failed to read snapshot metadata";
 		goto bad6;
+	} else if (r > 0) {
+		s->valid = 0;
+		DMWARN("Snapshot is marked invalid.");
 	}
 
 	bio_list_init(&s->queued_bios);