libceph: add support for HASHPSPOOL pool flag

The legacy behavior adds the pgid seed and pool together as the input for
CRUSH.  That is problematic because each pool's PGs end up mapping to the
same OSDs: 1.5 == 2.4 == 3.3 == ...

Instead, if the HASHPSPOOL flag is set, we has the ps and pool together and
feed that into CRUSH.  This ensures that two adjacent pools will map to
an independent pseudorandom set of OSDs.

Advertise our support for this via a protocol feature flag.

Signed-off-by: Sage Weil <sage@inktank.com>
Reviewed-by: Alex Elder <elder@inktank.com>

1 files changed, 3 insertions, 1 deletions

diff --git a/include/linux/ceph/ceph_features.h b/include/linux/ceph/ceph_features.h
index ab0a54286e0d..76554cecaab2 100644
--- a/include/linux/ceph/ceph_features.h
+++ b/include/linux/ceph/ceph_features.h
@@ -34,6 +34,7 @@
 #define CEPH_FEATURE_REPLY_CREATE_INODE   (1<<27)
 #define CEPH_FEATURE_OSD_HBMSGS     (1<<28)
 #define CEPH_FEATURE_MDSENC         (1<<29)
+#define CEPH_FEATURE_OSDHASHPSPOOL  (1<<30)
 
 /*
  * Features supported.
@@ -45,7 +46,8 @@
          CEPH_FEATURE_OSDENC |                  \
          CEPH_FEATURE_CRUSH_TUNABLES |          \
          CEPH_FEATURE_CRUSH_TUNABLES2 |         \
-         CEPH_FEATURE_REPLY_CREATE_INODE)
+         CEPH_FEATURE_REPLY_CREATE_INODE |      \
+         CEPH_FEATURE_OSDHASHPSPOOL)
 
 #define CEPH_FEATURES_REQUIRED_DEFAULT   \
         (CEPH_FEATURE_NOSRCADDR |        \