[2.6.20.17 review 43/58] dm snapshot: permit invalid activation

Willy Tarreau
2007-08-22T09:02:32Z

[-- Attachment #1: 0043-dm-snapshot-permit-invalid-activation.patch --]
[-- Type: text/plain, Size: 1916 bytes --]

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.

Signed-off-by: Milan Broz <mbroz@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Willy Tarreau <w@1wt.eu>
---
drivers/md/dm-exception-store.c | 11 ++++++-----
drivers/md/dm-snap.c | 5 ++++-
2 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/drivers/md/dm-exception-store.c b/drivers/md/dm-exception-store.c
index 99cdffa..fc496fc 100644
--- a/drivers/md/dm-exception-store.c
+++ b/drivers/md/dm-exception-store.c
@@ -453,11 +453,6 @@ 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);
@@ -465,6 +460,12 @@ static int persistent_read_metadata(struct exception_store *store)
}

/*
+ * Metadata are valid, but snapshot is invalidated
+ */
+ if (!ps->valid)
+ return 1;
+
+ /*
* Read the metadata.
*/
r = read_exceptions(ps);
diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c
index 0821a2b..9227ba4 100644
--- a/drivers/md/dm-snap.c
+++ b/drivers/md/dm-snap.c
@@ -522,9 +522,12 @@ 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);
--
1.5.2.5

--