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authorAlex Elder <elder@inktank.com>2013-01-30 11:13:33 -0600
committerSage Weil <sage@inktank.com>2013-02-13 18:29:11 -0800
commit72fe25e3460c8673984370208e0e6261101372d6 (patch)
treefae2e1db42c35f14db6c1f952f460b49dcffea89 /net/ceph
parentb82d167be64b3e88d9434d8a98ce83c83a07aa48 (diff)
downloadlinux-72fe25e3460c8673984370208e0e6261101372d6.tar.gz
libceph: add a compatibility check interface
An upcoming change implements semantic change that could lead to a crash if an old version of the libceph kernel module is used with a new version of the rbd kernel module. In order to preclude that possibility, this adds a compatibilty check interface. If this interface doesn't exist, the modules are obviously not compatible. But if it does exist, this provides a way of letting the caller know whether it will operate properly with this libceph module. Perhaps confusingly, it returns false right now. The semantic change mentioned above will make it return true. This resolves: http://tracker.ceph.com/issues/3800 Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
Diffstat (limited to 'net/ceph')
-rw-r--r--net/ceph/ceph_common.c16
1 files changed, 16 insertions, 0 deletions
diff --git a/net/ceph/ceph_common.c b/net/ceph/ceph_common.c
index ee71ea26777..a98c03ff853 100644
--- a/net/ceph/ceph_common.c
+++ b/net/ceph/ceph_common.c
@@ -26,6 +26,22 @@
#include "crypto.h"
+/*
+ * Module compatibility interface. For now it doesn't do anything,
+ * but its existence signals a certain level of functionality.
+ *
+ * The data buffer is used to pass information both to and from
+ * libceph. The return value indicates whether libceph determines
+ * it is compatible with the caller (from another kernel module),
+ * given the provided data.
+ *
+ * The data pointer can be null.
+ */
+bool libceph_compatible(void *data)
+{
+ return false;
+}
+EXPORT_SYMBOL(libceph_compatible);
/*
* find filename portion of a path (/foo/bar/baz -> baz)