sunrpc: add a debugfs rpc_xprt directory with an info file in it

Add a new directory heirarchy under the debugfs sunrpc/ directory:

    sunrpc/
        rpc_xprt/
            <xprt id>/

Within that directory, we can put files that give info about the
xprts. We do have the (minor) problem that there is no succinct,
unique identifier for rpc_xprts. So we generate them synthetically
with a static atomic_t counter.

For now, this directory just holds an "info" file, but we may add
other files to it in the future.

Signed-off-by: Jeff Layton <jlayton@primarydata.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>

1 files changed, 108 insertions, 7 deletions

diff --git a/net/sunrpc/debugfs.c b/net/sunrpc/debugfs.c
index 3d7745683ca3..e811f390f9f6 100644
--- a/net/sunrpc/debugfs.c
+++ b/net/sunrpc/debugfs.c
@@ -11,6 +11,7 @@
 
 static struct dentry *topdir;
 static struct dentry *rpc_clnt_dir;
+static struct dentry *rpc_xprt_dir;
 
 struct rpc_clnt_iter {
         struct rpc_clnt *clnt;
@@ -131,8 +132,8 @@ static const struct file_operations tasks_fops = {
 int
 rpc_clnt_debugfs_register(struct rpc_clnt *clnt)
 {
-        int len;
-        char name[9]; /* 8 for hex digits + NULL terminator */
+        int len, err;
+        char name[24]; /* enough for "../../rpc_xprt/ + 8 hex digits + NULL */
 
         /* Already registered? */
         if (clnt->cl_debugfs)
@@ -148,14 +149,28 @@ rpc_clnt_debugfs_register(struct rpc_clnt *clnt)
                 return -ENOMEM;
 
         /* make tasks file */
+        err = -ENOMEM;
         if (!debugfs_create_file("tasks", S_IFREG | S_IRUSR, clnt->cl_debugfs,
-                                 clnt, &tasks_fops)) {
-                debugfs_remove_recursive(clnt->cl_debugfs);
-                clnt->cl_debugfs = NULL;
-                return -ENOMEM;
-        }
+                                 clnt, &tasks_fops))
+                goto out_err;
+
+        err = -EINVAL;
+        rcu_read_lock();
+        len = snprintf(name, sizeof(name), "../../rpc_xprt/%s",
+                        rcu_dereference(clnt->cl_xprt)->debugfs->d_name.name);
+        rcu_read_unlock();
+        if (len >= sizeof(name))
+                goto out_err;
+
+        err = -ENOMEM;
+        if (!debugfs_create_symlink("xprt", clnt->cl_debugfs, name))
+                goto out_err;
 
         return 0;
+out_err:
+        debugfs_remove_recursive(clnt->cl_debugfs);
+        clnt->cl_debugfs = NULL;
+        return err;
 }
 
 void
@@ -165,6 +180,88 @@ rpc_clnt_debugfs_unregister(struct rpc_clnt *clnt)
         clnt->cl_debugfs = NULL;
 }
 
+static int
+xprt_info_show(struct seq_file *f, void *v)
+{
+        struct rpc_xprt *xprt = f->private;
+
+        seq_printf(f, "netid: %s\n", xprt->address_strings[RPC_DISPLAY_NETID]);
+        seq_printf(f, "addr:  %s\n", xprt->address_strings[RPC_DISPLAY_ADDR]);
+        seq_printf(f, "port:  %s\n", xprt->address_strings[RPC_DISPLAY_PORT]);
+        seq_printf(f, "state: 0x%lx\n", xprt->state);
+        return 0;
+}
+
+static int
+xprt_info_open(struct inode *inode, struct file *filp)
+{
+        int ret;
+        struct rpc_xprt *xprt = inode->i_private;
+
+        ret = single_open(filp, xprt_info_show, xprt);
+
+        if (!ret) {
+                if (!xprt_get(xprt)) {
+                        single_release(inode, filp);
+                        ret = -EINVAL;
+                }
+        }
+        return ret;
+}
+
+static int
+xprt_info_release(struct inode *inode, struct file *filp)
+{
+        struct rpc_xprt *xprt = inode->i_private;
+
+        xprt_put(xprt);
+        return single_release(inode, filp);
+}
+
+static const struct file_operations xprt_info_fops = {
+        .owner          = THIS_MODULE,
+        .open           = xprt_info_open,
+        .read           = seq_read,
+        .llseek         = seq_lseek,
+        .release        = xprt_info_release,
+};
+
+int
+rpc_xprt_debugfs_register(struct rpc_xprt *xprt)
+{
+        int len, id;
+        static atomic_t cur_id;
+        char            name[9]; /* 8 hex digits + NULL term */
+
+        id = (unsigned int)atomic_inc_return(&cur_id);
+
+        len = snprintf(name, sizeof(name), "%x", id);
+        if (len >= sizeof(name))
+                return -EINVAL;
+
+        /* make the per-client dir */
+        xprt->debugfs = debugfs_create_dir(name, rpc_xprt_dir);
+        if (!xprt->debugfs)
+                return -ENOMEM;
+
+        /* make tasks file */
+        if (!debugfs_create_file("info", S_IFREG | S_IRUSR, xprt->debugfs,
+                                 xprt, &xprt_info_fops)) {
+                debugfs_remove_recursive(xprt->debugfs);
+                xprt->debugfs = NULL;
+                return -ENOMEM;
+        }
+
+        return 0;
+}
+
+void
+rpc_xprt_debugfs_unregister(struct rpc_xprt *xprt)
+{
+        debugfs_remove_recursive(xprt->debugfs);
+        xprt->debugfs = NULL;
+}
+
 void __exit
 sunrpc_debugfs_exit(void)
 {
@@ -182,6 +279,10 @@ sunrpc_debugfs_init(void)
         if (!rpc_clnt_dir)
                 goto out_remove;
 
+        rpc_xprt_dir = debugfs_create_dir("rpc_xprt", topdir);
+        if (!rpc_xprt_dir)
+                goto out_remove;
+
         return 0;
 out_remove:
         debugfs_remove_recursive(topdir);