ceph: enable readahead

Initialized bdi->ra_pages to enable readahead.  Use 512KB default.
Signed-off-by: Sage Weil <sage@newdream.net>

fs/ceph/super.c

@@ -327,6 +327,7 @@ static int parse_mount_args(struct ceph_client *client,
 	args->mount_timeout = CEPH_MOUNT_TIMEOUT_DEFAULT; /* seconds */
 	args->caps_wanted_delay_min = CEPH_CAPS_WANTED_DELAY_MIN_DEFAULT;
 	args->caps_wanted_delay_max = CEPH_CAPS_WANTED_DELAY_MAX_DEFAULT;
+	args->rsize = CEPH_MOUNT_RSIZE_DEFAULT;
 	args->snapdir_name = kstrdup(CEPH_SNAPDIRNAME_DEFAULT, GFP_KERNEL);
 	args->cap_release_safety = CEPH_CAPS_PER_RELEASE * 4;
 	args->max_readdir = 1024;

fs/ceph/super.h

@@ -69,7 +69,7 @@ struct ceph_mount_args {
  * defaults
  */
 #define CEPH_MOUNT_TIMEOUT_DEFAULT  60
-#define CEPH_MOUNT_RSIZE_DEFAULT    (128*1024) /* readahead */
+#define CEPH_MOUNT_RSIZE_DEFAULT    (512*1024) /* readahead */
 
 #define CEPH_MSG_MAX_FRONT_LEN	(16*1024*1024)
 #define CEPH_MSG_MAX_DATA_LEN	(16*1024*1024)