ceph: use rbtree for mds requests

The rbtree is a more appropriate data structure than a radix_tree.  It
avoids extra memory usage and simplifies the code.

It also fixes a bug where the debugfs 'mdsc' file wasn't including the
most recent mds request.

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

3 files changed, 97 insertions, 69 deletions

diff --git a/fs/ceph/debugfs.c b/fs/ceph/debugfs.c
index fba44b2a6086..cd5dd805e4be 100644
--- a/fs/ceph/debugfs.c
+++ b/fs/ceph/debugfs.c
@@ -142,21 +142,16 @@ static int monc_show(struct seq_file *s, void *p)
 static int mdsc_show(struct seq_file *s, void *p)
 {
         struct ceph_client *client = s->private;
-        struct ceph_mds_request *req;
-        u64 nexttid = 0;
-        int got;
         struct ceph_mds_client *mdsc = &client->mdsc;
+        struct ceph_mds_request *req;
+        struct rb_node *rp;
         int pathlen;
         u64 pathbase;
         char *path;
 
         mutex_lock(&mdsc->mutex);
-        while (nexttid < mdsc->last_tid) {
-                got = radix_tree_gang_lookup(&mdsc->request_tree,
-                                             (void **)&req, nexttid, 1);
-                if (got == 0)
-                        break;
-                nexttid = req->r_tid + 1;
+        for (rp = rb_first(&mdsc->request_tree); rp; rp = rb_next(rp)) {
+                req = rb_entry(rp, struct ceph_mds_request, r_node);
 
                 if (req->r_request)
                         seq_printf(s, "%lld\tmds%d\t", req->r_tid, req->r_mds);
diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
index aa8506bad42d..81840d6b68a4 100644
--- a/fs/ceph/mds_client.c
+++ b/fs/ceph/mds_client.c
@@ -255,6 +255,7 @@ static const char *session_state_name(int s)
         case CEPH_MDS_SESSION_OPEN: return "open";
         case CEPH_MDS_SESSION_HUNG: return "hung";
         case CEPH_MDS_SESSION_CLOSING: return "closing";
+        case CEPH_MDS_SESSION_RESTARTING: return "restarting";
         case CEPH_MDS_SESSION_RECONNECTING: return "reconnecting";
         default: return "???";
         }
@@ -448,10 +449,42 @@ static struct ceph_mds_request *__lookup_request(struct ceph_mds_client *mdsc,
                                              u64 tid)
 {
         struct ceph_mds_request *req;
-        req = radix_tree_lookup(&mdsc->request_tree, tid);
-        if (req)
-                ceph_mdsc_get_request(req);
-        return req;
+        struct rb_node *n = mdsc->request_tree.rb_node;
+
+        while (n) {
+                req = rb_entry(n, struct ceph_mds_request, r_node);
+                if (tid < req->r_tid)
+                        n = n->rb_left;
+                else if (tid > req->r_tid)
+                        n = n->rb_right;
+                else {
+                        ceph_mdsc_get_request(req);
+                        return req;
+                }
+        }
+        return NULL;
+}
+
+static void __insert_request(struct ceph_mds_client *mdsc,
+                             struct ceph_mds_request *new)
+{
+        struct rb_node **p = &mdsc->request_tree.rb_node;
+        struct rb_node *parent = NULL;
+        struct ceph_mds_request *req = NULL;
+
+        while (*p) {
+                parent = *p;
+                req = rb_entry(parent, struct ceph_mds_request, r_node);
+                if (new->r_tid < req->r_tid)
+                        p = &(*p)->rb_left;
+                else if (new->r_tid > req->r_tid)
+                        p = &(*p)->rb_right;
+                else
+                        BUG();
+        }
+
+        rb_link_node(&new->r_node, parent, p);
+        rb_insert_color(&new->r_node, &mdsc->request_tree);
 }
 
 /*
@@ -469,7 +502,7 @@ static void __register_request(struct ceph_mds_client *mdsc,
                 ceph_reserve_caps(&req->r_caps_reservation, req->r_num_caps);
         dout("__register_request %p tid %lld\n", req, req->r_tid);
         ceph_mdsc_get_request(req);
-        radix_tree_insert(&mdsc->request_tree, req->r_tid, (void *)req);
+        __insert_request(mdsc, req);
 
         if (dir) {
                 struct ceph_inode_info *ci = ceph_inode(dir);
@@ -485,7 +518,7 @@ static void __unregister_request(struct ceph_mds_client *mdsc,
                                  struct ceph_mds_request *req)
 {
         dout("__unregister_request %p tid %lld\n", req, req->r_tid);
-        radix_tree_delete(&mdsc->request_tree, req->r_tid);
+        rb_erase(&req->r_node, &mdsc->request_tree);
         ceph_mdsc_put_request(req);
 
         if (req->r_unsafe_dir) {
@@ -1115,17 +1148,25 @@ ceph_mdsc_create_request(struct ceph_mds_client *mdsc, int op, int mode)
 }
 
 /*
- * return oldest (lowest) tid in request tree, 0 if none.
+ * return oldest (lowest) request, tid in request tree, 0 if none.
  *
  * called under mdsc->mutex.
  */
+static struct ceph_mds_request *__get_oldest_req(struct ceph_mds_client *mdsc)
+{
+        if (RB_EMPTY_ROOT(&mdsc->request_tree))
+                return NULL;
+        return rb_entry(rb_first(&mdsc->request_tree),
+                        struct ceph_mds_request, r_node);
+}
+
 static u64 __get_oldest_tid(struct ceph_mds_client *mdsc)
 {
-        struct ceph_mds_request *first;
-        if (radix_tree_gang_lookup(&mdsc->request_tree,
-                                   (void **)&first, 0, 1) <= 0)
-                return 0;
-        return first->r_tid;
+        struct ceph_mds_request *req = __get_oldest_req(mdsc);
+
+        if (req)
+                return req->r_tid;
+        return 0;
 }
 
 /*
@@ -1540,26 +1581,19 @@ static void __wake_requests(struct ceph_mds_client *mdsc,
  */
 static void kick_requests(struct ceph_mds_client *mdsc, int mds, int all)
 {
-        struct ceph_mds_request *reqs[10];
-        u64 nexttid = 0;
-        int i, got;
+        struct ceph_mds_request *req;
+        struct rb_node *p;
 
         dout("kick_requests mds%d\n", mds);
-        while (nexttid <= mdsc->last_tid) {
-                got = radix_tree_gang_lookup(&mdsc->request_tree,
-                                             (void **)&reqs, nexttid, 10);
-                if (got == 0)
-                        break;
-                nexttid = reqs[got-1]->r_tid + 1;
-                for (i = 0; i < got; i++) {
-                        if (reqs[i]->r_got_unsafe)
-                                continue;
-                        if (reqs[i]->r_session &&
-                            reqs[i]->r_session->s_mds == mds) {
-                                dout(" kicking tid %llu\n", reqs[i]->r_tid);
-                                put_request_session(reqs[i]);
-                                __do_request(mdsc, reqs[i]);
-                        }
+        for (p = rb_first(&mdsc->request_tree); p; p = rb_next(p)) {
+                req = rb_entry(p, struct ceph_mds_request, r_node);
+                if (req->r_got_unsafe)
+                        continue;
+                if (req->r_session &&
+                    req->r_session->s_mds == mds) {
+                        dout(" kicking tid %llu\n", req->r_tid);
+                        put_request_session(req);
+                        __do_request(mdsc, req);
                 }
         }
 }
@@ -1748,7 +1782,7 @@ static void handle_reply(struct ceph_mds_session *session, struct ceph_msg *msg)
                         list_del_init(&req->r_unsafe_item);
 
                         /* last unsafe request during umount? */
-                        if (mdsc->stopping && !__get_oldest_tid(mdsc))
+                        if (mdsc->stopping && !__get_oldest_req(mdsc))
                                 complete(&mdsc->safe_umount_waiters);
                         mutex_unlock(&mdsc->mutex);
                         goto out;
@@ -2573,7 +2607,7 @@ int ceph_mdsc_init(struct ceph_mds_client *mdsc, struct ceph_client *client)
         INIT_LIST_HEAD(&mdsc->snap_empty);
         spin_lock_init(&mdsc->snap_empty_lock);
         mdsc->last_tid = 0;
-        INIT_RADIX_TREE(&mdsc->request_tree, GFP_NOFS);
+        mdsc->request_tree = RB_ROOT;
         INIT_DELAYED_WORK(&mdsc->delayed_work, delayed_work);
         mdsc->last_renew_caps = jiffies;
         INIT_LIST_HEAD(&mdsc->cap_delay_list);
@@ -2600,20 +2634,19 @@ static void wait_requests(struct ceph_mds_client *mdsc)
         struct ceph_client *client = mdsc->client;
 
         mutex_lock(&mdsc->mutex);
-        if (__get_oldest_tid(mdsc)) {
+        if (__get_oldest_req(mdsc)) {
                 mutex_unlock(&mdsc->mutex);
+
                 dout("wait_requests waiting for requests\n");
                 wait_for_completion_timeout(&mdsc->safe_umount_waiters,
                                     client->mount_args->mount_timeout * HZ);
-                mutex_lock(&mdsc->mutex);
 
                 /* tear down remaining requests */
-                while (radix_tree_gang_lookup(&mdsc->request_tree,
-                                              (void **)&req, 0, 1)) {
+                mutex_lock(&mdsc->mutex);
+                while ((req = __get_oldest_req(mdsc))) {
                         dout("wait_requests timed out on tid %llu\n",
                              req->r_tid);
-                        radix_tree_delete(&mdsc->request_tree, req->r_tid);
-                        ceph_mdsc_put_request(req);
+                        __unregister_request(mdsc, req);
                 }
         }
         mutex_unlock(&mdsc->mutex);
@@ -2639,31 +2672,29 @@ void ceph_mdsc_pre_umount(struct ceph_mds_client *mdsc)
  */
 static void wait_unsafe_requests(struct ceph_mds_client *mdsc, u64 want_tid)
 {
-        struct ceph_mds_request *req;
-        u64 next_tid = 0;
-        int got;
+        struct ceph_mds_request *req = NULL;
+        struct rb_node *n;
 
         mutex_lock(&mdsc->mutex);
         dout("wait_unsafe_requests want %lld\n", want_tid);
-        while (1) {
-                got = radix_tree_gang_lookup(&mdsc->request_tree, (void **)&req,
-                                             next_tid, 1);
-                if (!got)
-                        break;
-                if (req->r_tid > want_tid)
+        req = __get_oldest_req(mdsc);
+        while (req && req->r_tid <= want_tid) {
+                if ((req->r_op & CEPH_MDS_OP_WRITE)) {
+                        /* write op */
+                        ceph_mdsc_get_request(req);
+                        mutex_unlock(&mdsc->mutex);
+                        dout("wait_unsafe_requests  wait on %llu (want %llu)\n",
+                             req->r_tid, want_tid);
+                        wait_for_completion(&req->r_safe_completion);
+                        mutex_lock(&mdsc->mutex);
+                        n = rb_next(&req->r_node);
+                        ceph_mdsc_put_request(req);
+                } else {
+                        n = rb_next(&req->r_node);
+                }
+                if (!n)
                         break;
-
-                next_tid = req->r_tid + 1;
-                if ((req->r_op & CEPH_MDS_OP_WRITE) == 0)
-                        continue;  /* not a write op */
-
-                ceph_mdsc_get_request(req);
-                mutex_unlock(&mdsc->mutex);
-                dout("wait_unsafe_requests  wait on %llu (want %llu)\n",
-                     req->r_tid, want_tid);
-                wait_for_completion(&req->r_safe_completion);
-                mutex_lock(&mdsc->mutex);
-                ceph_mdsc_put_request(req);
+                req = rb_entry(n, struct ceph_mds_request, r_node);
         }
         mutex_unlock(&mdsc->mutex);
         dout("wait_unsafe_requests done\n");
diff --git a/fs/ceph/mds_client.h b/fs/ceph/mds_client.h
index ee71495e27c4..98f09cd06006 100644
--- a/fs/ceph/mds_client.h
+++ b/fs/ceph/mds_client.h
@@ -6,6 +6,7 @@
 #include <linux/list.h>
 #include <linux/mutex.h>
 #include <linux/radix-tree.h>
+#include <linux/rbtree.h>
 #include <linux/spinlock.h>
 
 #include "types.h"
@@ -150,6 +151,7 @@ typedef void (*ceph_mds_request_callback_t) (struct ceph_mds_client *mdsc,
  */
 struct ceph_mds_request {
         u64 r_tid;                   /* transaction id */
+        struct rb_node r_node;
 
         int r_op;                    /* mds op code */
         int r_mds;
@@ -249,7 +251,7 @@ struct ceph_mds_client {
         spinlock_t              snap_empty_lock;  /* protect snap_empty */
 
         u64                    last_tid;      /* most recent mds request */
-        struct radix_tree_root request_tree;  /* pending mds requests */
+        struct rb_root         request_tree;  /* pending mds requests */
         struct delayed_work    delayed_work;  /* delayed work */
         unsigned long    last_renew_caps;  /* last time we renewed our caps */
         struct list_head cap_delay_list;   /* caps with delayed release */