rbd: re-submit write request for flattened clone

Add code to rbd_img_parent_read_full_callback() to detect when a
clone's parent image has disappeared, and re-submit the original
write request in that case.  (See the previous commit for more
reasoning about why this is appropriate.)

Rename some variables in rbd_img_obj_parent_read_full_callback()
to match the convention used in the previous patch.

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

1 files changed, 22 insertions, 7 deletions

diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index 4edcb6d85f01..5c2731859e8a 100644
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -2319,7 +2319,7 @@ rbd_img_obj_parent_read_full_callback(struct rbd_img_request *img_request)
         struct rbd_device *rbd_dev;
         struct page **pages;
         u32 page_count;
-        int result;
+        int img_result;
         u64 parent_length;
         u64 offset;
         u64 length;
@@ -2338,7 +2338,7 @@ rbd_img_obj_parent_read_full_callback(struct rbd_img_request *img_request)
         orig_request = img_request->obj_request;
         rbd_assert(orig_request != NULL);
         rbd_assert(obj_request_type_valid(orig_request->type));
-        result = img_request->result;
+        img_result = img_request->result;
         parent_length = img_request->length;
         rbd_assert(parent_length == img_request->xferred);
         rbd_img_request_put(img_request);
@@ -2347,7 +2347,22 @@ rbd_img_obj_parent_read_full_callback(struct rbd_img_request *img_request)
         rbd_dev = orig_request->img_request->rbd_dev;
         rbd_assert(rbd_dev);
 
-        if (result)
+        /*
+         * If the overlap has become 0 (most likely because the
+         * image has been flattened) we need to free the pages
+         * and re-submit the original write request.
+         */
+        if (!rbd_dev->parent_overlap) {
+                struct ceph_osd_client *osdc;
+
+                ceph_release_page_vector(pages, page_count);
+                osdc = &rbd_dev->rbd_client->client->osdc;
+                img_result = rbd_obj_request_submit(osdc, orig_request);
+                if (!img_result)
+                        return;
+        }
+
+        if (img_result)
                 goto out_err;
 
         /*
@@ -2356,7 +2371,7 @@ rbd_img_obj_parent_read_full_callback(struct rbd_img_request *img_request)
          * request.  Allocate the new copyup osd request for the
          * original request, and release the old one.
          */
-        result = -ENOMEM;
+        img_result = -ENOMEM;
         osd_req = rbd_osd_req_create_copyup(orig_request);
         if (!osd_req)
                 goto out_err;
@@ -2391,13 +2406,13 @@ rbd_img_obj_parent_read_full_callback(struct rbd_img_request *img_request)
 
         orig_request->callback = rbd_img_obj_copyup_callback;
         osdc = &rbd_dev->rbd_client->client->osdc;
-        result = rbd_obj_request_submit(osdc, orig_request);
-        if (!result)
+        img_result = rbd_obj_request_submit(osdc, orig_request);
+        if (!img_result)
                 return;
 out_err:
         /* Record the error code and complete the request */
 
-        orig_request->result = result;
+        orig_request->result = img_result;
         orig_request->xferred = 0;
         obj_request_done_set(orig_request);
         rbd_obj_request_complete(orig_request);