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>

diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index ad26502..b895613 100644 (file)
--- 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);