kclient: avoid starvation when fsync on dir

diff --git a/src/kernel/dir.c b/src/kernel/dir.c
index c4c80235c421402a7ebde1e6127e70e9023e14c1..8a1fa803ca46d7caa67df58a5eb17104e66ed448 100644 (file)
--- a/src/kernel/dir.c
+++ b/src/kernel/dir.c
@@ -862,14 +862,31 @@ static int ceph_dir_fsync(struct file *file, struct dentry *dentry, int datasync
        struct inode *inode = dentry->d_inode;
        struct ceph_inode_info *ci = ceph_inode(inode);
        int ret, err;
-       struct list_head *p, *n;
+       struct list_head *p, *n, *head;
+       struct ceph_mds_request *req;
+       u64 last_tid;
 
        ret = 0;
-       dout(0, "sync on directory\n");
+       dout(10, "sync on directory\n");
+
+       head = &ci->i_listener_list;
+
        spin_lock(&ci->i_listener_lock);
-       list_for_each_safe(p, n, &ci->i_listener_list) {
-               struct ceph_mds_request *req =
-                        list_entry(p, struct ceph_mds_request, r_listener_item);
+
+       if (list_empty(head))
+               goto out;
+
+       req = list_entry(head->prev,
+                        struct ceph_mds_request, r_listener_item);
+       last_tid = req->r_tid;
+
+       list_for_each_safe(p, n, head) {
+               req = list_entry(p, struct ceph_mds_request, r_listener_item);
+
+               /* avoid starvation */
+               if (req->r_tid > last_tid)
+                       goto out;
+
                ceph_mdsc_get_request(req);
                spin_unlock(&ci->i_listener_lock);
                if (req->r_timeout) {
@@ -884,8 +901,8 @@ static int ceph_dir_fsync(struct file *file, struct dentry *dentry, int datasync
 
                ceph_mdsc_put_request(req);
        }
+out:
        spin_unlock(&ci->i_listener_lock);
-
        return ret;
 }