sunrpc: add debugfs file for displaying client rpc_task queue
It's possible to get a dump of the RPC task queue by writing a value to
/proc/sys/sunrpc/rpc_debug. If you write any value to that file, you get
a dump of the RPC client task list into the log buffer. This is a rather
inconvenient interface however, and makes it hard to get immediate info
about the task queue.
Add a new directory hierarchy under debugfs:
sunrpc/
rpc_clnt/
<clientid>/
Within each clientid directory we create a new "tasks" file that will
dump info similar to what shows up in the log buffer, but with a few
small differences -- we avoid printing raw kernel addresses in favor of
symbolic names and the XID is also displayed.
Signed-off-by: Jeff Layton <jlayton@primarydata.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
diff --git a/net/sunrpc/debugfs.c b/net/sunrpc/debugfs.c
new file mode 100644
index 0000000..3d77456
--- /dev/null
+++ b/net/sunrpc/debugfs.c
@@ -0,0 +1,191 @@
+/**
+ * debugfs interface for sunrpc
+ *
+ * (c) 2014 Jeff Layton <jlayton@primarydata.com>
+ */
+
+#include <linux/debugfs.h>
+#include <linux/sunrpc/sched.h>
+#include <linux/sunrpc/clnt.h>
+#include "netns.h"
+
+static struct dentry *topdir;
+static struct dentry *rpc_clnt_dir;
+
+struct rpc_clnt_iter {
+ struct rpc_clnt *clnt;
+ loff_t pos;
+};
+
+static int
+tasks_show(struct seq_file *f, void *v)
+{
+ u32 xid = 0;
+ struct rpc_task *task = v;
+ struct rpc_clnt *clnt = task->tk_client;
+ const char *rpc_waitq = "none";
+
+ if (RPC_IS_QUEUED(task))
+ rpc_waitq = rpc_qname(task->tk_waitqueue);
+
+ if (task->tk_rqstp)
+ xid = be32_to_cpu(task->tk_rqstp->rq_xid);
+
+ seq_printf(f, "%5u %04x %6d 0x%x 0x%x %8ld %ps %sv%u %s a:%ps q:%s\n",
+ task->tk_pid, task->tk_flags, task->tk_status,
+ clnt->cl_clid, xid, task->tk_timeout, task->tk_ops,
+ clnt->cl_program->name, clnt->cl_vers, rpc_proc_name(task),
+ task->tk_action, rpc_waitq);
+ return 0;
+}
+
+static void *
+tasks_start(struct seq_file *f, loff_t *ppos)
+ __acquires(&clnt->cl_lock)
+{
+ struct rpc_clnt_iter *iter = f->private;
+ loff_t pos = *ppos;
+ struct rpc_clnt *clnt = iter->clnt;
+ struct rpc_task *task;
+
+ iter->pos = pos + 1;
+ spin_lock(&clnt->cl_lock);
+ list_for_each_entry(task, &clnt->cl_tasks, tk_task)
+ if (pos-- == 0)
+ return task;
+ return NULL;
+}
+
+static void *
+tasks_next(struct seq_file *f, void *v, loff_t *pos)
+{
+ struct rpc_clnt_iter *iter = f->private;
+ struct rpc_clnt *clnt = iter->clnt;
+ struct rpc_task *task = v;
+ struct list_head *next = task->tk_task.next;
+
+ ++iter->pos;
+ ++*pos;
+
+ /* If there's another task on list, return it */
+ if (next == &clnt->cl_tasks)
+ return NULL;
+ return list_entry(next, struct rpc_task, tk_task);
+}
+
+static void
+tasks_stop(struct seq_file *f, void *v)
+ __releases(&clnt->cl_lock)
+{
+ struct rpc_clnt_iter *iter = f->private;
+ struct rpc_clnt *clnt = iter->clnt;
+
+ spin_unlock(&clnt->cl_lock);
+}
+
+static const struct seq_operations tasks_seq_operations = {
+ .start = tasks_start,
+ .next = tasks_next,
+ .stop = tasks_stop,
+ .show = tasks_show,
+};
+
+static int tasks_open(struct inode *inode, struct file *filp)
+{
+ int ret = seq_open_private(filp, &tasks_seq_operations,
+ sizeof(struct rpc_clnt_iter));
+
+ if (!ret) {
+ struct seq_file *seq = filp->private_data;
+ struct rpc_clnt_iter *iter = seq->private;
+
+ iter->clnt = inode->i_private;
+
+ if (!atomic_inc_not_zero(&iter->clnt->cl_count)) {
+ seq_release_private(inode, filp);
+ ret = -EINVAL;
+ }
+ }
+
+ return ret;
+}
+
+static int
+tasks_release(struct inode *inode, struct file *filp)
+{
+ struct seq_file *seq = filp->private_data;
+ struct rpc_clnt_iter *iter = seq->private;
+
+ rpc_release_client(iter->clnt);
+ return seq_release_private(inode, filp);
+}
+
+static const struct file_operations tasks_fops = {
+ .owner = THIS_MODULE,
+ .open = tasks_open,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = tasks_release,
+};
+
+int
+rpc_clnt_debugfs_register(struct rpc_clnt *clnt)
+{
+ int len;
+ char name[9]; /* 8 for hex digits + NULL terminator */
+
+ /* Already registered? */
+ if (clnt->cl_debugfs)
+ return 0;
+
+ len = snprintf(name, sizeof(name), "%x", clnt->cl_clid);
+ if (len >= sizeof(name))
+ return -EINVAL;
+
+ /* make the per-client dir */
+ clnt->cl_debugfs = debugfs_create_dir(name, rpc_clnt_dir);
+ if (!clnt->cl_debugfs)
+ return -ENOMEM;
+
+ /* make tasks file */
+ 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;
+ }
+
+ return 0;
+}
+
+void
+rpc_clnt_debugfs_unregister(struct rpc_clnt *clnt)
+{
+ debugfs_remove_recursive(clnt->cl_debugfs);
+ clnt->cl_debugfs = NULL;
+}
+
+void __exit
+sunrpc_debugfs_exit(void)
+{
+ debugfs_remove_recursive(topdir);
+}
+
+int __init
+sunrpc_debugfs_init(void)
+{
+ topdir = debugfs_create_dir("sunrpc", NULL);
+ if (!topdir)
+ goto out;
+
+ rpc_clnt_dir = debugfs_create_dir("rpc_clnt", topdir);
+ if (!rpc_clnt_dir)
+ goto out_remove;
+
+ return 0;
+out_remove:
+ debugfs_remove_recursive(topdir);
+ topdir = NULL;
+out:
+ return -ENOMEM;
+}