ceph: drop support for preferred_osd pgs

This was an ill-conceived feature that has been removed from Ceph.  Do
this gracefully:

 - reject attempts to specify a preferred_osd via the ioctl
 - stop exposing this information via virtual xattrs
 - always fill in -1 for requests, in case we talk to an older server
 - don't calculate preferred_osd placements/pgids

Reviewed-by: Alex Elder <elder@inktank.com>
Signed-off-by: Sage Weil <sage@inktank.com>
diff --git a/net/ceph/osdmap.c b/net/ceph/osdmap.c
index 29ad46e..7d39f3c 100644
--- a/net/ceph/osdmap.c
+++ b/net/ceph/osdmap.c
@@ -1000,7 +1000,6 @@
 {
 	unsigned num, num_mask;
 	struct ceph_pg pgid;
-	s32 preferred = (s32)le32_to_cpu(fl->fl_pg_preferred);
 	int poolid = le32_to_cpu(fl->fl_pg_pool);
 	struct ceph_pg_pool_info *pool;
 	unsigned ps;
@@ -1011,23 +1010,13 @@
 	if (!pool)
 		return -EIO;
 	ps = ceph_str_hash(pool->v.object_hash, oid, strlen(oid));
-	if (preferred >= 0) {
-		ps += preferred;
-		num = le32_to_cpu(pool->v.lpg_num);
-		num_mask = pool->lpg_num_mask;
-	} else {
-		num = le32_to_cpu(pool->v.pg_num);
-		num_mask = pool->pg_num_mask;
-	}
+	num = le32_to_cpu(pool->v.pg_num);
+	num_mask = pool->pg_num_mask;
 
 	pgid.ps = cpu_to_le16(ps);
-	pgid.preferred = cpu_to_le16(preferred);
+	pgid.preferred = cpu_to_le16(-1);
 	pgid.pool = fl->fl_pg_pool;
-	if (preferred >= 0)
-		dout("calc_object_layout '%s' pgid %d.%xp%d\n", oid, poolid, ps,
-		     (int)preferred);
-	else
-		dout("calc_object_layout '%s' pgid %d.%x\n", oid, poolid, ps);
+	dout("calc_object_layout '%s' pgid %d.%x\n", oid, poolid, ps);
 
 	ol->ol_pgid = pgid;
 	ol->ol_stripe_unit = fl->fl_object_stripe_unit;
@@ -1046,23 +1035,17 @@
 	struct ceph_pg_pool_info *pool;
 	int ruleno;
 	unsigned poolid, ps, pps, t;
-	int preferred;
 
 	poolid = le32_to_cpu(pgid.pool);
 	ps = le16_to_cpu(pgid.ps);
-	preferred = (s16)le16_to_cpu(pgid.preferred);
 
 	pool = __lookup_pg_pool(&osdmap->pg_pools, poolid);
 	if (!pool)
 		return NULL;
 
 	/* pg_temp? */
-	if (preferred >= 0)
-		t = ceph_stable_mod(ps, le32_to_cpu(pool->v.lpg_num),
-				    pool->lpgp_num_mask);
-	else
-		t = ceph_stable_mod(ps, le32_to_cpu(pool->v.pg_num),
-				    pool->pgp_num_mask);
+	t = ceph_stable_mod(ps, le32_to_cpu(pool->v.pg_num),
+			    pool->pgp_num_mask);
 	pgid.ps = cpu_to_le16(t);
 	pg = __lookup_pg_mapping(&osdmap->pg_temp, pgid);
 	if (pg) {
@@ -1080,23 +1063,13 @@
 		return NULL;
 	}
 
-	/* don't forcefeed bad device ids to crush */
-	if (preferred >= osdmap->max_osd ||
-	    preferred >= osdmap->crush->max_devices)
-		preferred = -1;
-
-	if (preferred >= 0)
-		pps = ceph_stable_mod(ps,
-				      le32_to_cpu(pool->v.lpgp_num),
-				      pool->lpgp_num_mask);
-	else
-		pps = ceph_stable_mod(ps,
-				      le32_to_cpu(pool->v.pgp_num),
-				      pool->pgp_num_mask);
+	pps = ceph_stable_mod(ps,
+			      le32_to_cpu(pool->v.pgp_num),
+			      pool->pgp_num_mask);
 	pps += poolid;
 	*num = crush_do_rule(osdmap->crush, ruleno, pps, osds,
 			     min_t(int, pool->v.size, *num),
-			     preferred, osdmap->osd_weight);
+			     -1, osdmap->osd_weight);
 	return osds;
 }