dm snapshot: track suspended state in target

Keep track of whether or not the device is suspended within the snapshot
target module, the same as we do in dm-raid1.

We will use this later to enforce the correct sequence of ioctls to
transfer the in-core exceptions from a snapshot target instance in
one table to a replacement one capable of merging them back
into the origin.

Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

1 files changed, 16 insertions, 1 deletions

diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c
index dc500a6f6232..fd04caa90340 100644
--- a/drivers/md/dm-snap.c
+++ b/drivers/md/dm-snap.c
@@ -72,6 +72,9 @@ struct dm_snapshot {
         /* Origin writes don't trigger exceptions until this is set */
         int active;
 
+        /* Whether or not owning mapped_device is suspended */
+        int suspended;
+
         mempool_t *pending_pool;
 
         atomic_t pending_exceptions_count;
@@ -656,6 +659,7 @@ static int snapshot_ctr(struct dm_target *ti, unsigned int argc, char **argv)
         s->ti = ti;
         s->valid = 1;
         s->active = 0;
+        s->suspended = 0;
         atomic_set(&s->pending_exceptions_count, 0);
         init_rwsem(&s->lock);
         spin_lock_init(&s->pe_lock);
@@ -1175,12 +1179,22 @@ static int snapshot_end_io(struct dm_target *ti, struct bio *bio,
         return 0;
 }
 
+static void snapshot_postsuspend(struct dm_target *ti)
+{
+        struct dm_snapshot *s = ti->private;
+
+        down_write(&s->lock);
+        s->suspended = 1;
+        up_write(&s->lock);
+}
+
 static void snapshot_resume(struct dm_target *ti)
 {
         struct dm_snapshot *s = ti->private;
 
         down_write(&s->lock);
         s->active = 1;
+        s->suspended = 0;
         up_write(&s->lock);
 }
 
@@ -1489,12 +1503,13 @@ static struct target_type origin_target = {
 
 static struct target_type snapshot_target = {
         .name    = "snapshot",
-        .version = {1, 8, 0},
+        .version = {1, 9, 0},
         .module  = THIS_MODULE,
         .ctr     = snapshot_ctr,
         .dtr     = snapshot_dtr,
         .map     = snapshot_map,
         .end_io  = snapshot_end_io,
+        .postsuspend = snapshot_postsuspend,
         .resume  = snapshot_resume,
         .status  = snapshot_status,
         .iterate_devices = snapshot_iterate_devices,