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;