libceph: allocate the locator string with GFP_NOFAIL

calc_target() isn't supposed to fail with anything but POOL_DNE, in
which case we report that the pool doesn't exist and fail the request
with -ENOENT.  Doing this for -ENOMEM is at the very least confusing
and also harmful -- as the preceding requests complete, a short-lived
locator string allocation is likely to succeed after a wait.

(We used to call ceph_object_locator_to_pg() for a pi lookup.  In
theory that could fail with -ENOENT, hence the "ret != -ENOENT" warning
being removed.)
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

include/linux/ceph/osdmap.h

@@ -279,7 +279,7 @@ bool ceph_osds_changed(const struct ceph_osds *old_acting,
 		       const struct ceph_osds *new_acting,
 		       bool any_change);
 
-int __ceph_object_locator_to_pg(struct ceph_pg_pool_info *pi,
+void __ceph_object_locator_to_pg(struct ceph_pg_pool_info *pi,
 				 const struct ceph_object_id *oid,
 				 const struct ceph_object_locator *oloc,
 				 struct ceph_pg *raw_pgid);

net/ceph/osd_client.c

@@ -1430,7 +1430,6 @@ static enum calc_target_result calc_target(struct ceph_osd_client *osdc,
 	bool recovery_deletes = ceph_osdmap_flag(osdc,
 						 CEPH_OSDMAP_RECOVERY_DELETES);
 	enum calc_target_result ct_res;
-	int ret;
 
 	t->epoch = osdc->osdmap->epoch;
 	pi = ceph_pg_pool_by_id(osdc->osdmap, t->base_oloc.pool);
@@ -1466,14 +1465,7 @@ static enum calc_target_result calc_target(struct ceph_osd_client *osdc,
 		}
 	}
 
-	ret = __ceph_object_locator_to_pg(pi, &t->target_oid, &t->target_oloc,
-					  &pgid);
-	if (ret) {
-		WARN_ON(ret != -ENOENT);
-		t->osd = CEPH_HOMELESS_OSD;
-		ct_res = CALC_TARGET_POOL_DNE;
-		goto out;
-	}
+	__ceph_object_locator_to_pg(pi, &t->target_oid, &t->target_oloc, &pgid);
 	last_pgid.pool = pgid.pool;
 	last_pgid.seed = ceph_stable_mod(pgid.seed, t->pg_num, t->pg_num_mask);
 

net/ceph/osdmap.c

@@ -2145,7 +2145,7 @@ bool ceph_osds_changed(const struct ceph_osds *old_acting,
  * Should only be called with target_oid and target_oloc (as opposed to
  * base_oid and base_oloc), since tiering isn't taken into account.
  */
-int __ceph_object_locator_to_pg(struct ceph_pg_pool_info *pi,
+void __ceph_object_locator_to_pg(struct ceph_pg_pool_info *pi,
 				 const struct ceph_object_id *oid,
 				 const struct ceph_object_locator *oloc,
 				 struct ceph_pg *raw_pgid)
@@ -2164,11 +2164,8 @@ int __ceph_object_locator_to_pg(struct ceph_pg_pool_info *pi,
 		int nsl = oloc->pool_ns->len;
 		size_t total = nsl + 1 + oid->name_len;
 
-		if (total > sizeof(stack_buf)) {
-			buf = kmalloc(total, GFP_NOIO);
-			if (!buf)
-				return -ENOMEM;
-		}
+		if (total > sizeof(stack_buf))
+			buf = kmalloc(total, GFP_NOIO | __GFP_NOFAIL);
 		memcpy(buf, oloc->pool_ns->str, nsl);
 		buf[nsl] = '\037';
 		memcpy(buf + nsl + 1, oid->name, oid->name_len);
@@ -2180,7 +2177,6 @@ int __ceph_object_locator_to_pg(struct ceph_pg_pool_info *pi,
 		     oid->name, nsl, oloc->pool_ns->str,
 		     raw_pgid->pool, raw_pgid->seed);
 	}
-	return 0;
 }
 
 int ceph_object_locator_to_pg(struct ceph_osdmap *osdmap,
@@ -2194,7 +2190,8 @@ int ceph_object_locator_to_pg(struct ceph_osdmap *osdmap,
 	if (!pi)
 		return -ENOENT;
 
-	return __ceph_object_locator_to_pg(pi, oid, oloc, raw_pgid);
+	__ceph_object_locator_to_pg(pi, oid, oloc, raw_pgid);
+	return 0;
 }
 EXPORT_SYMBOL(ceph_object_locator_to_pg);