libceph: support crush tunables

The server side recently added support for tuning some magic
crush variables. Decode these variables if they are present, or use the
default values if they are not present.

Corresponds to ceph.git commit 89af369c25f274fe62ef730e5e8aad0c54f1e5a5.

Signed-off-by: caleb miles <caleb.miles@inktank.com>
Reviewed-by: Sage Weil <sage@inktank.com>
Reviewed-by: Alex Elder <elder@inktank.com>
Reviewed-by: Yehuda Sadeh <yehuda@inktank.com>

1 files changed, 39 insertions, 0 deletions

diff --git a/net/ceph/osdmap.c b/net/ceph/osdmap.c
index 9600674c2c39..3124b71a8883 100644
--- a/net/ceph/osdmap.c
+++ b/net/ceph/osdmap.c
@@ -135,6 +135,21 @@ bad:
         return -EINVAL;
 }
 
+static int skip_name_map(void **p, void *end)
+{
+        int len;
+        ceph_decode_32_safe(p, end, len ,bad);
+        while (len--) {
+                int strlen;
+                *p += sizeof(u32);
+                ceph_decode_32_safe(p, end, strlen, bad);
+                *p += strlen;
+}
+        return 0;
+bad:
+        return -EINVAL;
+}
+
 static struct crush_map *crush_decode(void *pbyval, void *end)
 {
         struct crush_map *c;
@@ -143,6 +158,7 @@ static struct crush_map *crush_decode(void *pbyval, void *end)
         void **p = &pbyval;
         void *start = pbyval;
         u32 magic;
+        u32 num_name_maps;
 
         dout("crush_decode %p to %p len %d\n", *p, end, (int)(end - *p));
 
@@ -150,6 +166,11 @@ static struct crush_map *crush_decode(void *pbyval, void *end)
         if (c == NULL)
                 return ERR_PTR(-ENOMEM);
 
+        /* set tunables to default values */
+        c->choose_local_tries = 2;
+        c->choose_local_fallback_tries = 5;
+        c->choose_total_tries = 19;
+
         ceph_decode_need(p, end, 4*sizeof(u32), bad);
         magic = ceph_decode_32(p);
         if (magic != CRUSH_MAGIC) {
@@ -297,7 +318,25 @@ static struct crush_map *crush_decode(void *pbyval, void *end)
         }
 
         /* ignore trailing name maps. */
+        for (num_name_maps = 0; num_name_maps < 3; num_name_maps++) {
+                err = skip_name_map(p, end);
+                if (err < 0)
+                        goto done;
+        }
+
+        /* tunables */
+        ceph_decode_need(p, end, 3*sizeof(u32), done);
+        c->choose_local_tries = ceph_decode_32(p);
+        c->choose_local_fallback_tries =  ceph_decode_32(p);
+        c->choose_total_tries = ceph_decode_32(p);
+        dout("crush decode tunable choose_local_tries = %d",
+             c->choose_local_tries);
+        dout("crush decode tunable choose_local_fallback_tries = %d",
+             c->choose_local_fallback_tries);
+        dout("crush decode tunable choose_total_tries = %d",
+             c->choose_total_tries);
 
+done:
         dout("crush_decode success\n");
         return c;