ceph: use rbtree for mon statfs requests

An rbtree is lighter weight, particularly given we will generally have
very few in-flight statfs requests.

Signed-off-by: Sage Weil <sage@newdream.net>

3 files changed, 54 insertions, 32 deletions

diff --git a/fs/ceph/debugfs.c b/fs/ceph/debugfs.c
index cd5dd805e4be..b58bd9188692 100644
--- a/fs/ceph/debugfs.c
+++ b/fs/ceph/debugfs.c
@@ -112,9 +112,8 @@ static int monc_show(struct seq_file *s, void *p)
 {
         struct ceph_client *client = s->private;
         struct ceph_mon_statfs_request *req;
-        u64 nexttid = 0;
-        int got;
         struct ceph_mon_client *monc = &client->monc;
+        struct rb_node *rp;
 
         mutex_lock(&monc->mutex);
 
@@ -125,17 +124,12 @@ static int monc_show(struct seq_file *s, void *p)
         if (monc->want_next_osdmap)
                 seq_printf(s, "want next osdmap\n");
 
-        while (nexttid < monc->last_tid) {
-                got = radix_tree_gang_lookup(&monc->statfs_request_tree,
-                                             (void **)&req, nexttid, 1);
-                if (got == 0)
-                        break;
-                nexttid = req->tid + 1;
-
+        for (rp = rb_first(&monc->statfs_request_tree); rp; rp = rb_next(rp)) {
+                req = rb_entry(rp, struct ceph_mon_statfs_request, node);
                 seq_printf(s, "%lld statfs\n", req->tid);
         }
-        mutex_unlock(&monc->mutex);
 
+        mutex_unlock(&monc->mutex);
         return 0;
 }
 
diff --git a/fs/ceph/mon_client.c b/fs/ceph/mon_client.c
index fec41a0eff86..542276e60798 100644
--- a/fs/ceph/mon_client.c
+++ b/fs/ceph/mon_client.c
@@ -343,6 +343,46 @@ out:
 /*
  * statfs
  */
+static struct ceph_mon_statfs_request *__lookup_statfs(
+        struct ceph_mon_client *monc, u64 tid)
+{
+        struct ceph_mon_statfs_request *req;
+        struct rb_node *n = monc->statfs_request_tree.rb_node;
+
+        while (n) {
+                req = rb_entry(n, struct ceph_mon_statfs_request, node);
+                if (tid < req->tid)
+                        n = n->rb_left;
+                else if (tid > req->tid)
+                        n = n->rb_right;
+                else
+                        return req;
+        }
+        return NULL;
+}
+
+static void __insert_statfs(struct ceph_mon_client *monc,
+                            struct ceph_mon_statfs_request *new)
+{
+        struct rb_node **p = &monc->statfs_request_tree.rb_node;
+        struct rb_node *parent = NULL;
+        struct ceph_mon_statfs_request *req = NULL;
+
+        while (*p) {
+                parent = *p;
+                req = rb_entry(parent, struct ceph_mon_statfs_request, node);
+                if (new->tid < req->tid)
+                        p = &(*p)->rb_left;
+                else if (new->tid > req->tid)
+                        p = &(*p)->rb_right;
+                else
+                        BUG();
+        }
+
+        rb_link_node(&new->node, parent, p);
+        rb_insert_color(&new->node, &monc->statfs_request_tree);
+}
+
 static void handle_statfs_reply(struct ceph_mon_client *monc,
                                 struct ceph_msg *msg)
 {
@@ -356,7 +396,7 @@ static void handle_statfs_reply(struct ceph_mon_client *monc,
         dout("handle_statfs_reply %p tid %llu\n", msg, tid);
 
         mutex_lock(&monc->mutex);
-        req = radix_tree_lookup(&monc->statfs_request_tree, tid);
+        req = __lookup_statfs(monc, tid);
         if (req) {
                 *req->buf = reply->st;
                 req->result = 0;
@@ -416,11 +456,7 @@ int ceph_monc_do_statfs(struct ceph_mon_client *monc, struct ceph_statfs *buf)
         req.tid = ++monc->last_tid;
         req.last_attempt = jiffies;
         req.delay = BASE_DELAY_INTERVAL;
-        if (radix_tree_insert(&monc->statfs_request_tree, req.tid, &req) < 0) {
-                mutex_unlock(&monc->mutex);
-                pr_err("ENOMEM in do_statfs\n");
-                return -ENOMEM;
-        }
+        __insert_statfs(monc, &req);
         monc->num_statfs_requests++;
         mutex_unlock(&monc->mutex);
 
@@ -430,7 +466,7 @@ int ceph_monc_do_statfs(struct ceph_mon_client *monc, struct ceph_statfs *buf)
                 err = wait_for_completion_interruptible(&req.completion);
 
         mutex_lock(&monc->mutex);
-        radix_tree_delete(&monc->statfs_request_tree, req.tid);
+        rb_erase(&req.node, &monc->statfs_request_tree);
         monc->num_statfs_requests--;
         ceph_msgpool_resv(&monc->msgpool_statfs_reply, -1);
         mutex_unlock(&monc->mutex);
@@ -445,20 +481,11 @@ int ceph_monc_do_statfs(struct ceph_mon_client *monc, struct ceph_statfs *buf)
  */
 static void __resend_statfs(struct ceph_mon_client *monc)
 {
-        u64 next_tid = 0;
-        int got;
-        int did = 0;
         struct ceph_mon_statfs_request *req;
+        struct rb_node *p;
 
-        while (1) {
-                got = radix_tree_gang_lookup(&monc->statfs_request_tree,
-                                             (void **)&req,
-                                             next_tid, 1);
-                if (got == 0)
-                        break;
-                did++;
-                next_tid = req->tid + 1;
-
+        for (p = rb_first(&monc->statfs_request_tree); p; p = rb_next(p)) {
+                req = rb_entry(p, struct ceph_mon_statfs_request, node);
                 send_statfs(monc, req);
         }
 }
@@ -578,7 +605,7 @@ int ceph_monc_init(struct ceph_mon_client *monc, struct ceph_client *cl)
         monc->sub_sent = 0;
 
         INIT_DELAYED_WORK(&monc->delayed_work, delayed_work);
-        INIT_RADIX_TREE(&monc->statfs_request_tree, GFP_NOFS);
+        monc->statfs_request_tree = RB_ROOT;
         monc->num_statfs_requests = 0;
         monc->last_tid = 0;
 
diff --git a/fs/ceph/mon_client.h b/fs/ceph/mon_client.h
index 5ca8e48d4379..b958ad5afa06 100644
--- a/fs/ceph/mon_client.h
+++ b/fs/ceph/mon_client.h
@@ -2,7 +2,7 @@
 #define _FS_CEPH_MON_CLIENT_H
 
 #include <linux/completion.h>
-#include <linux/radix-tree.h>
+#include <linux/rbtree.h>
 
 #include "messenger.h"
 #include "msgpool.h"
@@ -45,6 +45,7 @@ struct ceph_mon_request {
  */
 struct ceph_mon_statfs_request {
         u64 tid;
+        struct rb_node node;
         int result;
         struct ceph_statfs *buf;
         struct completion completion;
@@ -75,7 +76,7 @@ struct ceph_mon_client {
         struct ceph_msgpool msgpool_auth_reply;
 
         /* pending statfs requests */
-        struct radix_tree_root statfs_request_tree;
+        struct rb_root statfs_request_tree;
         int num_statfs_requests;
         u64 last_tid;