ceph: use strong hash function for mapping objects to pgs

We were using the (weak) dcache hash function, but it was leaving lower
bits consecutive for consecutive (inode) objects.  We really want to make
the object to pg mapping random and uniform, so use a proper hash function
here.

This is Robert Jenkin's public domain hash function (with some minor
cleanup):
	http://burtleburtle.net/bob/hash/evahash.html

This is a protocol revision.

Signed-off-by: Sage Weil <sage@newdream.net>

1 files changed, 1 insertions, 1 deletions

diff --git a/fs/ceph/ceph_fs.h b/fs/ceph/ceph_fs.h
index ae523828c538..25fc537f4140 100644
--- a/fs/ceph/ceph_fs.h
+++ b/fs/ceph/ceph_fs.h
@@ -38,7 +38,7 @@
 #define CEPH_OSD_PROTOCOL     7 /* cluster internal */
 #define CEPH_MDS_PROTOCOL     9 /* cluster internal */
 #define CEPH_MON_PROTOCOL     5 /* cluster internal */
-#define CEPH_OSDC_PROTOCOL   21 /* server/client */
+#define CEPH_OSDC_PROTOCOL   22 /* server/client */
 #define CEPH_MDSC_PROTOCOL   29 /* server/client */
 #define CEPH_MONC_PROTOCOL   15 /* server/client */