rbd: don't take extra bio reference for osd client

Currently, if the OSD client finds an osd request has had a bio list
attached to it, it drops a reference to it (or rather, to the first
entry on that list) when the request is released.

The code that added that reference (i.e., the rbd client) is
therefore required to take an extra reference to that first bio
structure.

The osd client doesn't really do anything with the bio pointer other
than transfer it from the osd request structure to outgoing (for
writes) and ingoing (for reads) messages.  So it really isn't the
right place to be taking or dropping references.

Furthermore, the rbd client already holds references to all bio
structures it passes to the osd client, and holds them until the
request is completed.  So there's no need for this extra reference
whatsoever.

So remove the bio_put() call in ceph_osdc_release_request(), as
well as its matching bio_get() call in rbd_osd_req_create().

This change could lead to a crash if old libceph.ko was used with
new rbd.ko.  Add a compatibility check at rbd initialization time to
avoid this possibilty.

This resolves:
    http://tracker.ceph.com/issues/3798    and
    http://tracker.ceph.com/issues/3799

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 ed0c91d810639477a26663ef4b44924837fa1834..3ba4836f024c5a9377d26be1f01ae14f90e69f04 100644 (file)
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -1342,7 +1342,6 @@ static struct ceph_osd_request *rbd_osd_req_create(
        case OBJ_REQUEST_BIO:
                rbd_assert(obj_request->bio_list != NULL);
                osd_req->r_bio = obj_request->bio_list;
-               bio_get(osd_req->r_bio);
                /* osd client requires "num pages" even for bio */
                osd_req->r_num_pages = calc_pages_for(offset, length);
                break;
@@ -4149,6 +4148,11 @@ int __init rbd_init(void)
 {
        int rc;
 
+       if (!libceph_compatible(NULL)) {
+               rbd_warn(NULL, "libceph incompatibility (quitting)");
+
+               return -EINVAL;
+       }
        rc = rbd_sysfs_init();
        if (rc)
                return rc;

diff --git a/net/ceph/ceph_common.c b/net/ceph/ceph_common.c
index a98c03ff853f98d541d351c2d1470e4aac04b8e5..c236c235c4a2499e11996c38ea8e806d78e6621a 100644 (file)
--- a/net/ceph/ceph_common.c
+++ b/net/ceph/ceph_common.c
@@ -39,7 +39,7 @@
  */
 bool libceph_compatible(void *data)
 {
-       return false;
+       return true;
 }
 EXPORT_SYMBOL(libceph_compatible);
 

diff --git a/net/ceph/osd_client.c b/net/ceph/osd_client.c
index 500ae8b493216a43251822eb728459c10a417093..ba03648533c06fd57755ea5eeca139e492a60944 100644 (file)
--- a/net/ceph/osd_client.c
+++ b/net/ceph/osd_client.c
@@ -147,10 +147,6 @@ void ceph_osdc_release_request(struct kref *kref)
        if (req->r_own_pages)
                ceph_release_page_vector(req->r_pages,
                                         req->r_num_pages);
-#ifdef CONFIG_BLOCK
-       if (req->r_bio)
-               bio_put(req->r_bio);
-#endif
        ceph_put_snap_context(req->r_snapc);
        ceph_pagelist_release(&req->r_trail);
        if (req->r_mempool)