rbd: support data returned from OSD methods

An OSD object method call can be made using rbd_req_sync_exec().
Until now this has only been used for creating a new RBD snapshot,
and that has only required sending data out, not receiving anything
back from the OSD.

We will now need to get data back from an OSD on a method call, so
add parameters to rbd_req_sync_exec() that allow a buffer into which
returned data should be placed to be specified, along with its size.

Previously, rbd_req_sync_exec() passed a null pointer and zero
size to rbd_req_sync_op(); change this so the new inbound buffer
information is provided instead.

Rename the "buf" and "len" parameters in rbd_req_sync_op() to
make it more obvious they are describing inbound data.

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

1 files changed, 11 insertions, 8 deletions

diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index ad26502f4b0f..b8956131950c 100644
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -1098,8 +1098,8 @@ static int rbd_req_sync_op(struct rbd_device *rbd_dev,
                            int flags,
                            struct ceph_osd_req_op *ops,
                            const char *object_name,
-                           u64 ofs, u64 len,
-                           char *buf,
+                           u64 ofs, u64 inbound_size,
+                           char *inbound,
                            struct ceph_osd_request **linger_req,
                            u64 *ver)
 {
@@ -1109,13 +1109,13 @@ static int rbd_req_sync_op(struct rbd_device *rbd_dev,
 
         rbd_assert(ops != NULL);
 
-        num_pages = calc_pages_for(ofs , len);
+        num_pages = calc_pages_for(ofs, inbound_size);
         pages = ceph_alloc_page_vector(num_pages, GFP_KERNEL);
         if (IS_ERR(pages))
                 return PTR_ERR(pages);
 
         ret = rbd_do_request(NULL, rbd_dev, snapc, snapid,
-                          object_name, ofs, len, NULL,
+                          object_name, ofs, inbound_size, NULL,
                           pages, num_pages,
                           flags,
                           ops,
@@ -1125,8 +1125,8 @@ static int rbd_req_sync_op(struct rbd_device *rbd_dev,
         if (ret < 0)
                 goto done;
 
-        if ((flags & CEPH_OSD_FLAG_READ) && buf)
-                ret = ceph_copy_from_page_vector(pages, buf, ofs, ret);
+        if ((flags & CEPH_OSD_FLAG_READ) && inbound)
+                ret = ceph_copy_from_page_vector(pages, inbound, ofs, ret);
 
 done:
         ceph_release_page_vector(pages, num_pages);
@@ -1445,6 +1445,8 @@ static int rbd_req_sync_exec(struct rbd_device *rbd_dev,
                              const char *method_name,
                              const char *outbound,
                              size_t outbound_size,
+                             char *inbound,
+                             size_t inbound_size,
                              int flags,
                              u64 *ver)
 {
@@ -1478,7 +1480,8 @@ static int rbd_req_sync_exec(struct rbd_device *rbd_dev,
         ret = rbd_req_sync_op(rbd_dev, NULL,
                                CEPH_NOSNAP,
                                flags, ops,
-                               object_name, 0, 0, NULL, NULL, ver);
+                               object_name, 0, inbound_size, inbound,
+                               NULL, ver);
 
         rbd_destroy_ops(ops);
 
@@ -1789,7 +1792,7 @@ static int rbd_header_add_snap(struct rbd_device *rbd_dev,
 
         ret = rbd_req_sync_exec(rbd_dev, rbd_dev->header_name,
                                 "rbd", "snap_add",
-                                data, (size_t) (p - data),
+                                data, (size_t) (p - data), NULL, 0,
                                 CEPH_OSD_FLAG_WRITE | CEPH_OSD_FLAG_ONDISK,
                                 NULL);