/**
 * 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_fault_dir;
static struct dentry *rpc_clnt_dir;
static struct dentry *rpc_xprt_dir;

unsigned int rpc_inject_disconnect;

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,
};

void
rpc_clnt_debugfs_register(struct rpc_clnt *clnt)
{
        int len;
        char name[24]; /* enough for "../../rpc_xprt/ + 8 hex digits + NULL */
        struct rpc_xprt *xprt;

        /* Already registered? */
        if (clnt->cl_debugfs || !rpc_clnt_dir)
                return;

        len = snprintf(name, sizeof(name), "%x", clnt->cl_clid);
        if (len >= sizeof(name))
                return;

        /* make the per-client dir */
        clnt->cl_debugfs = debugfs_create_dir(name, rpc_clnt_dir);
        if (!clnt->cl_debugfs)
                return;

        /* make tasks file */
        if (!debugfs_create_file("tasks", S_IFREG | S_IRUSR, clnt->cl_debugfs,
                                 clnt, &tasks_fops))
                goto out_err;

        rcu_read_lock();
        xprt = rcu_dereference(clnt->cl_xprt);
        /* no "debugfs" dentry? Don't bother with the symlink. */
        if (!xprt->debugfs) {
                rcu_read_unlock();
                return;
        }
        len = snprintf(name, sizeof(name), "../../rpc_xprt/%s",
                        xprt->debugfs->d_name.name);
        rcu_read_unlock();

        if (len >= sizeof(name))
                goto out_err;

        if (!debugfs_create_symlink("xprt", clnt->cl_debugfs, name))
                goto out_err;

        return;
out_err:
        debugfs_remove_recursive(clnt->cl_debugfs);
        clnt->cl_debugfs = NULL;
}

void
rpc_clnt_debugfs_unregister(struct rpc_clnt *clnt)
{
        debugfs_remove_recursive(clnt->cl_debugfs);
        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,
};

void
rpc_xprt_debugfs_register(struct rpc_xprt *xprt)
{
        int len, id;
        static atomic_t cur_id;
        char            name[9]; /* 8 hex digits + NULL term */

        if (!rpc_xprt_dir)
                return;

        id = (unsigned int)atomic_inc_return(&cur_id);

        len = snprintf(name, sizeof(name), "%x", id);
        if (len >= sizeof(name))
                return;

        /* make the per-client dir */
        xprt->debugfs = debugfs_create_dir(name, rpc_xprt_dir);
        if (!xprt->debugfs)
                return;

        /* 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;
        }

        atomic_set(&xprt->inject_disconnect, rpc_inject_disconnect);
}

void
rpc_xprt_debugfs_unregister(struct rpc_xprt *xprt)
{
        debugfs_remove_recursive(xprt->debugfs);
        xprt->debugfs = NULL;
}

static int
fault_open(struct inode *inode, struct file *filp)
{
        filp->private_data = kmalloc(128, GFP_KERNEL);
        if (!filp->private_data)
                return -ENOMEM;
        return 0;
}

static int
fault_release(struct inode *inode, struct file *filp)
{
        kfree(filp->private_data);
        return 0;
}

static ssize_t
fault_disconnect_read(struct file *filp, char __user *user_buf,
                      size_t len, loff_t *offset)
{
        char *buffer = (char *)filp->private_data;
        size_t size;

        size = sprintf(buffer, "%u\n", rpc_inject_disconnect);
        return simple_read_from_buffer(user_buf, len, offset, buffer, size);
}

static ssize_t
fault_disconnect_write(struct file *filp, const char __user *user_buf,
                       size_t len, loff_t *offset)
{
        char buffer[16];

        if (len >= sizeof(buffer))
                len = sizeof(buffer) - 1;
        if (copy_from_user(buffer, user_buf, len))
                return -EFAULT;
        buffer[len] = '\0';
        if (kstrtouint(buffer, 10, &rpc_inject_disconnect))
                return -EINVAL;
        return len;
}

static const struct file_operations fault_disconnect_fops = {
        .owner          = THIS_MODULE,
        .open           = fault_open,
        .read           = fault_disconnect_read,
        .write          = fault_disconnect_write,
        .release        = fault_release,
};

static struct dentry *
inject_fault_dir(struct dentry *topdir)
{
        struct dentry *faultdir;

        faultdir = debugfs_create_dir("inject_fault", topdir);
        if (!faultdir)
                return NULL;

        if (!debugfs_create_file("disconnect", S_IFREG | S_IRUSR, faultdir,
                                 NULL, &fault_disconnect_fops))
                return NULL;

        return faultdir;
}

void __exit
sunrpc_debugfs_exit(void)
{
        debugfs_remove_recursive(topdir);
        topdir = NULL;
        rpc_fault_dir = NULL;
        rpc_clnt_dir = NULL;
        rpc_xprt_dir = NULL;
}

void __init
sunrpc_debugfs_init(void)
{
        topdir = debugfs_create_dir("sunrpc", NULL);
        if (!topdir)
                return;

        rpc_fault_dir = inject_fault_dir(topdir);
        if (!rpc_fault_dir)
                goto out_remove;

        rpc_clnt_dir = debugfs_create_dir("rpc_clnt", topdir);
        if (!rpc_clnt_dir)
                goto out_remove;

        rpc_xprt_dir = debugfs_create_dir("rpc_xprt", topdir);
        if (!rpc_xprt_dir)
                goto out_remove;

        return;
out_remove:
        debugfs_remove_recursive(topdir);
        topdir = NULL;
        rpc_fault_dir = NULL;
        rpc_clnt_dir = NULL;
}