1 files changed, 37 insertions, 30 deletions

diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index b67ecda1e7ef..fcef63c2c30b 100644
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -1873,7 +1873,7 @@ static struct rbd_img_request *rbd_img_request_create(
 	}
 	if (child_request)
 		img_request_child_set(img_request);
-	if (rbd_dev->parent_spec)
+	if (rbd_dev->parent_overlap)
 		img_request_layered_set(img_request);
 	spin_lock_init(&img_request->completion_lock);
 	img_request->next_completion = 0;
@@ -3613,6 +3613,7 @@ static int rbd_dev_v2_parent_info(struct rbd_device *rbd_dev)
 	__le64 snapid;
 	void *p;
 	void *end;
+	u64 pool_id;
 	char *image_id;
 	u64 overlap;
 	int ret;
@@ -3643,18 +3644,19 @@ static int rbd_dev_v2_parent_info(struct rbd_device *rbd_dev)
 	p = reply_buf;
 	end = reply_buf + ret;
 	ret = -ERANGE;
-	ceph_decode_64_safe(&p, end, parent_spec->pool_id, out_err);
-	if (parent_spec->pool_id == CEPH_NOPOOL)
+	ceph_decode_64_safe(&p, end, pool_id, out_err);
+	if (pool_id == CEPH_NOPOOL)
 		goto out;	/* No parent?  No problem. */
 
 	/* The ceph file layout needs to fit pool id in 32 bits */
 
 	ret = -EIO;
-	if (parent_spec->pool_id > (u64)U32_MAX) {
+	if (pool_id > (u64)U32_MAX) {
 		rbd_warn(NULL, "parent pool id too large (%llu > %u)\n",
-			(unsigned long long)parent_spec->pool_id, U32_MAX);
+			(unsigned long long)pool_id, U32_MAX);
 		goto out_err;
 	}
+	parent_spec->pool_id = pool_id;
 
 	image_id = ceph_extract_encoded_string(&p, end, NULL, GFP_KERNEL);
 	if (IS_ERR(image_id)) {
@@ -3666,6 +3668,7 @@ static int rbd_dev_v2_parent_info(struct rbd_device *rbd_dev)
 	ceph_decode_64_safe(&p, end, overlap, out_err);
 
 	if (overlap) {
+		rbd_spec_put(rbd_dev->parent_spec);
 		rbd_dev->parent_spec = parent_spec;
 		parent_spec = NULL;	/* rbd_dev now owns this */
 		rbd_dev->parent_overlap = overlap;
@@ -4034,17 +4037,43 @@ static int rbd_dev_v2_header_info(struct rbd_device *rbd_dev)
 			goto out;
 	}
 
+	/*
+	 * If the image supports layering, get the parent info.  We
+	 * need to probe the first time regardless.  Thereafter we
+	 * only need to if there's a parent, to see if it has
+	 * disappeared due to the mapped image getting flattened.
+	 */
+	if (rbd_dev->header.features & RBD_FEATURE_LAYERING &&
+			(first_time || rbd_dev->parent_spec)) {
+		bool warn;
+
+		ret = rbd_dev_v2_parent_info(rbd_dev);
+		if (ret)
+			goto out;
+
+		/*
+		 * Print a warning if this is the initial probe and
+		 * the image has a parent.  Don't print it if the
+		 * image now being probed is itself a parent.  We
+		 * can tell at this point because we won't know its
+		 * pool name yet (just its pool id).
+		 */
+		warn = rbd_dev->parent_spec && rbd_dev->spec->pool_name;
+		if (first_time && warn)
+			rbd_warn(rbd_dev, "WARNING: kernel layering "
+					"is EXPERIMENTAL!");
+	}
+
 	ret = rbd_dev_v2_image_size(rbd_dev);
 	if (ret)
 		goto out;
+
 	if (rbd_dev->spec->snap_id == CEPH_NOSNAP)
 		if (rbd_dev->mapping.size != rbd_dev->header.image_size)
 			rbd_dev->mapping.size = rbd_dev->header.image_size;
 
 	ret = rbd_dev_v2_snap_context(rbd_dev);
 	dout("rbd_dev_v2_snap_context returned %d\n", ret);
-	if (ret)
-		goto out;
 out:
 	up_write(&rbd_dev->header_rwsem);
 
@@ -4498,24 +4527,6 @@ static int rbd_dev_v2_header_onetime(struct rbd_device *rbd_dev)
 	if (ret)
 		goto out_err;
 
-	/* If the image supports layering, get the parent info */
-
-	if (rbd_dev->header.features & RBD_FEATURE_LAYERING) {
-		ret = rbd_dev_v2_parent_info(rbd_dev);
-		if (ret)
-			goto out_err;
-		/*
-		 * Print a warning if this image has a parent.
-		 * Don't print it if the image now being probed
-		 * is itself a parent.  We can tell at this point
-		 * because we won't know its pool name yet (just its
-		 * pool id).
-		 */
-		if (rbd_dev->parent_spec && rbd_dev->spec->pool_name)
-			rbd_warn(rbd_dev, "WARNING: kernel layering "
-					"is EXPERIMENTAL!");
-	}
-
 	/* If the image supports fancy striping, get its parameters */
 
 	if (rbd_dev->header.features & RBD_FEATURE_STRIPINGV2) {
@@ -4527,11 +4538,7 @@ static int rbd_dev_v2_header_onetime(struct rbd_device *rbd_dev)
 
 	return 0;
 out_err:
-	rbd_dev->parent_overlap = 0;
-	rbd_spec_put(rbd_dev->parent_spec);
-	rbd_dev->parent_spec = NULL;
-	kfree(rbd_dev->header_name);
-	rbd_dev->header_name = NULL;
+	rbd_dev->header.features = 0;
 	kfree(rbd_dev->header.object_prefix);
 	rbd_dev->header.object_prefix = NULL;