dm snapshot: do not use map_context
Eliminate struct map_info from dm-snap.
map_info->ptr was used in dm-snap to indicate if the bio was tracked.
If map_info->ptr was non-NULL, the bio was linked in tracked_chunk_hash.
This patch removes the use of map_info->ptr. We determine if the bio was
tracked based on hlist_unhashed(&c->node). If hlist_unhashed is true,
the bio is not tracked, if it is false, the bio is tracked.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c
index b7e179c..e1ecacf 100644
--- a/drivers/md/dm-snap.c
+++ b/drivers/md/dm-snap.c
@@ -190,9 +190,19 @@
chunk_t chunk;
};
-static struct dm_snap_tracked_chunk *track_chunk(struct dm_snapshot *s,
- struct bio *bio,
- chunk_t chunk)
+static void init_tracked_chunk(struct bio *bio)
+{
+ struct dm_snap_tracked_chunk *c = dm_per_bio_data(bio, sizeof(struct dm_snap_tracked_chunk));
+ INIT_HLIST_NODE(&c->node);
+}
+
+static bool is_bio_tracked(struct bio *bio)
+{
+ struct dm_snap_tracked_chunk *c = dm_per_bio_data(bio, sizeof(struct dm_snap_tracked_chunk));
+ return !hlist_unhashed(&c->node);
+}
+
+static void track_chunk(struct dm_snapshot *s, struct bio *bio, chunk_t chunk)
{
struct dm_snap_tracked_chunk *c = dm_per_bio_data(bio, sizeof(struct dm_snap_tracked_chunk));
@@ -202,13 +212,11 @@
hlist_add_head(&c->node,
&s->tracked_chunk_hash[DM_TRACKED_CHUNK_HASH(chunk)]);
spin_unlock_irq(&s->tracked_chunk_lock);
-
- return c;
}
-static void stop_tracking_chunk(struct dm_snapshot *s,
- struct dm_snap_tracked_chunk *c)
+static void stop_tracking_chunk(struct dm_snapshot *s, struct bio *bio)
{
+ struct dm_snap_tracked_chunk *c = dm_per_bio_data(bio, sizeof(struct dm_snap_tracked_chunk));
unsigned long flags;
spin_lock_irqsave(&s->tracked_chunk_lock, flags);
@@ -1568,6 +1576,8 @@
chunk_t chunk;
struct dm_snap_pending_exception *pe = NULL;
+ init_tracked_chunk(bio);
+
if (bio->bi_rw & REQ_FLUSH) {
bio->bi_bdev = s->cow->bdev;
return DM_MAPIO_REMAPPED;
@@ -1652,7 +1662,7 @@
}
} else {
bio->bi_bdev = s->origin->bdev;
- map_context->ptr = track_chunk(s, bio, chunk);
+ track_chunk(s, bio, chunk);
}
out_unlock:
@@ -1681,12 +1691,13 @@
int r = DM_MAPIO_REMAPPED;
chunk_t chunk;
+ init_tracked_chunk(bio);
+
if (bio->bi_rw & REQ_FLUSH) {
if (!dm_bio_get_target_request_nr(bio))
bio->bi_bdev = s->origin->bdev;
else
bio->bi_bdev = s->cow->bdev;
- map_context->ptr = NULL;
return DM_MAPIO_REMAPPED;
}
@@ -1715,7 +1726,7 @@
remap_exception(s, e, bio, chunk);
if (bio_rw(bio) == WRITE)
- map_context->ptr = track_chunk(s, bio, chunk);
+ track_chunk(s, bio, chunk);
goto out_unlock;
}
@@ -1737,10 +1748,9 @@
int error, union map_info *map_context)
{
struct dm_snapshot *s = ti->private;
- struct dm_snap_tracked_chunk *c = map_context->ptr;
- if (c)
- stop_tracking_chunk(s, c);
+ if (is_bio_tracked(bio))
+ stop_tracking_chunk(s, bio);
return 0;
}