/* /proc interface for AFS
 *
 * Copyright (C) 2002 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */

#include <linux/slab.h>
#include <linux/module.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/sched.h>
#include <linux/uaccess.h>
#include "internal.h"

static inline struct afs_net *afs_proc2net(struct file *f)
{
        return &__afs_net;
}

static inline struct afs_net *afs_seq2net(struct seq_file *m)
{
        return &__afs_net; // TODO: use seq_file_net(m)
}

static int afs_proc_cells_open(struct inode *inode, struct file *file);
static void *afs_proc_cells_start(struct seq_file *p, loff_t *pos);
static void *afs_proc_cells_next(struct seq_file *p, void *v, loff_t *pos);
static void afs_proc_cells_stop(struct seq_file *p, void *v);
static int afs_proc_cells_show(struct seq_file *m, void *v);
static ssize_t afs_proc_cells_write(struct file *file, const char __user *buf,
                                    size_t size, loff_t *_pos);

static const struct seq_operations afs_proc_cells_ops = {
        .start  = afs_proc_cells_start,
        .next   = afs_proc_cells_next,
        .stop   = afs_proc_cells_stop,
        .show   = afs_proc_cells_show,
};

static const struct file_operations afs_proc_cells_fops = {
        .open           = afs_proc_cells_open,
        .read           = seq_read,
        .write          = afs_proc_cells_write,
        .llseek         = seq_lseek,
        .release        = seq_release,
};

static ssize_t afs_proc_rootcell_read(struct file *file, char __user *buf,
                                      size_t size, loff_t *_pos);
static ssize_t afs_proc_rootcell_write(struct file *file,
                                       const char __user *buf,
                                       size_t size, loff_t *_pos);

static const struct file_operations afs_proc_rootcell_fops = {
        .read           = afs_proc_rootcell_read,
        .write          = afs_proc_rootcell_write,
        .llseek         = no_llseek,
};

static int afs_proc_cell_volumes_open(struct inode *inode, struct file *file);
static void *afs_proc_cell_volumes_start(struct seq_file *p, loff_t *pos);
static void *afs_proc_cell_volumes_next(struct seq_file *p, void *v,
                                        loff_t *pos);
static void afs_proc_cell_volumes_stop(struct seq_file *p, void *v);
static int afs_proc_cell_volumes_show(struct seq_file *m, void *v);

static const struct seq_operations afs_proc_cell_volumes_ops = {
        .start  = afs_proc_cell_volumes_start,
        .next   = afs_proc_cell_volumes_next,
        .stop   = afs_proc_cell_volumes_stop,
        .show   = afs_proc_cell_volumes_show,
};

static const struct file_operations afs_proc_cell_volumes_fops = {
        .open           = afs_proc_cell_volumes_open,
        .read           = seq_read,
        .llseek         = seq_lseek,
        .release        = seq_release,
};

static int afs_proc_cell_vlservers_open(struct inode *inode,
                                        struct file *file);
static void *afs_proc_cell_vlservers_start(struct seq_file *p, loff_t *pos);
static void *afs_proc_cell_vlservers_next(struct seq_file *p, void *v,
                                          loff_t *pos);
static void afs_proc_cell_vlservers_stop(struct seq_file *p, void *v);
static int afs_proc_cell_vlservers_show(struct seq_file *m, void *v);

static const struct seq_operations afs_proc_cell_vlservers_ops = {
        .start  = afs_proc_cell_vlservers_start,
        .next   = afs_proc_cell_vlservers_next,
        .stop   = afs_proc_cell_vlservers_stop,
        .show   = afs_proc_cell_vlservers_show,
};

static const struct file_operations afs_proc_cell_vlservers_fops = {
        .open           = afs_proc_cell_vlservers_open,
        .read           = seq_read,
        .llseek         = seq_lseek,
        .release        = seq_release,
};

static int afs_proc_servers_open(struct inode *inode, struct file *file);
static void *afs_proc_servers_start(struct seq_file *p, loff_t *pos);
static void *afs_proc_servers_next(struct seq_file *p, void *v,
                                        loff_t *pos);
static void afs_proc_servers_stop(struct seq_file *p, void *v);
static int afs_proc_servers_show(struct seq_file *m, void *v);

static const struct seq_operations afs_proc_servers_ops = {
        .start  = afs_proc_servers_start,
        .next   = afs_proc_servers_next,
        .stop   = afs_proc_servers_stop,
        .show   = afs_proc_servers_show,
};

static const struct file_operations afs_proc_servers_fops = {
        .open           = afs_proc_servers_open,
        .read           = seq_read,
        .llseek         = seq_lseek,
        .release        = seq_release,
};

static int afs_proc_sysname_open(struct inode *inode, struct file *file);
static int afs_proc_sysname_release(struct inode *inode, struct file *file);
static void *afs_proc_sysname_start(struct seq_file *p, loff_t *pos);
static void *afs_proc_sysname_next(struct seq_file *p, void *v,
                                        loff_t *pos);
static void afs_proc_sysname_stop(struct seq_file *p, void *v);
static int afs_proc_sysname_show(struct seq_file *m, void *v);
static ssize_t afs_proc_sysname_write(struct file *file,
                                      const char __user *buf,
                                      size_t size, loff_t *_pos);

static const struct seq_operations afs_proc_sysname_ops = {
        .start  = afs_proc_sysname_start,
        .next   = afs_proc_sysname_next,
        .stop   = afs_proc_sysname_stop,
        .show   = afs_proc_sysname_show,
};

static const struct file_operations afs_proc_sysname_fops = {
        .open           = afs_proc_sysname_open,
        .read           = seq_read,
        .llseek         = seq_lseek,
        .release        = afs_proc_sysname_release,
        .write          = afs_proc_sysname_write,
};

static const struct file_operations afs_proc_stats_fops;

/*
 * initialise the /proc/fs/afs/ directory
 */
int afs_proc_init(struct afs_net *net)
{
        _enter("");

        net->proc_afs = proc_mkdir("fs/afs", NULL);
        if (!net->proc_afs)
                goto error_dir;

        if (!proc_create("cells", 0644, net->proc_afs, &afs_proc_cells_fops) ||
            !proc_create("rootcell", 0644, net->proc_afs, &afs_proc_rootcell_fops) ||
            !proc_create("servers", 0644, net->proc_afs, &afs_proc_servers_fops) ||
            !proc_create("stats", 0644, net->proc_afs, &afs_proc_stats_fops) ||
            !proc_create("sysname", 0644, net->proc_afs, &afs_proc_sysname_fops))
                goto error_tree;

        _leave(" = 0");
        return 0;

error_tree:
        proc_remove(net->proc_afs);
error_dir:
        _leave(" = -ENOMEM");
        return -ENOMEM;
}

/*
 * clean up the /proc/fs/afs/ directory
 */
void afs_proc_cleanup(struct afs_net *net)
{
        proc_remove(net->proc_afs);
        net->proc_afs = NULL;
}

/*
 * open "/proc/fs/afs/cells" which provides a summary of extant cells
 */
static int afs_proc_cells_open(struct inode *inode, struct file *file)
{
        struct seq_file *m;
        int ret;

        ret = seq_open(file, &afs_proc_cells_ops);
        if (ret < 0)
                return ret;

        m = file->private_data;
        m->private = PDE_DATA(inode);
        return 0;
}

/*
 * set up the iterator to start reading from the cells list and return the
 * first item
 */
static void *afs_proc_cells_start(struct seq_file *m, loff_t *_pos)
        __acquires(rcu)
{
        struct afs_net *net = afs_seq2net(m);

        rcu_read_lock();
        return seq_list_start_head(&net->proc_cells, *_pos);
}

/*
 * move to next cell in cells list
 */
static void *afs_proc_cells_next(struct seq_file *m, void *v, loff_t *pos)
{
        struct afs_net *net = afs_seq2net(m);

        return seq_list_next(v, &net->proc_cells, pos);
}

/*
 * clean up after reading from the cells list
 */
static void afs_proc_cells_stop(struct seq_file *m, void *v)
        __releases(rcu)
{
        rcu_read_unlock();
}

/*
 * display a header line followed by a load of cell lines
 */
static int afs_proc_cells_show(struct seq_file *m, void *v)
{
        struct afs_cell *cell = list_entry(v, struct afs_cell, proc_link);
        struct afs_net *net = afs_seq2net(m);

        if (v == &net->proc_cells) {
                /* display header on line 1 */
                seq_puts(m, "USE NAME\n");
                return 0;
        }

        /* display one cell per line on subsequent lines */
        seq_printf(m, "%3u %s\n", atomic_read(&cell->usage), cell->name);
        return 0;
}

/*
 * handle writes to /proc/fs/afs/cells
 * - to add cells: echo "add <cellname> <IP>[:<IP>][:<IP>]"
 */
static ssize_t afs_proc_cells_write(struct file *file, const char __user *buf,
                                    size_t size, loff_t *_pos)
{
        struct afs_net *net = afs_proc2net(file);
        char *kbuf, *name, *args;
        int ret;

        /* start by dragging the command into memory */
        if (size <= 1 || size >= PAGE_SIZE)
                return -EINVAL;

        kbuf = memdup_user_nul(buf, size);
        if (IS_ERR(kbuf))
                return PTR_ERR(kbuf);

        /* trim to first NL */
        name = memchr(kbuf, '\n', size);
        if (name)
                *name = 0;

        /* split into command, name and argslist */
        name = strchr(kbuf, ' ');
        if (!name)
                goto inval;
        do {
                *name++ = 0;
        } while(*name == ' ');
        if (!*name)
                goto inval;

        args = strchr(name, ' ');
        if (!args)
                goto inval;
        do {
                *args++ = 0;
        } while(*args == ' ');
        if (!*args)
                goto inval;

        /* determine command to perform */
        _debug("cmd=%s name=%s args=%s", kbuf, name, args);

        if (strcmp(kbuf, "add") == 0) {
                struct afs_cell *cell;

                cell = afs_lookup_cell(net, name, strlen(name), args, true);
                if (IS_ERR(cell)) {
                        ret = PTR_ERR(cell);
                        goto done;
                }

                if (test_and_set_bit(AFS_CELL_FL_NO_GC, &cell->flags))
                        afs_put_cell(net, cell);
                printk("kAFS: Added new cell '%s'\n", name);
        } else {
                goto inval;
        }

        ret = size;

done:
        kfree(kbuf);
        _leave(" = %d", ret);
        return ret;

inval:
        ret = -EINVAL;
        printk("kAFS: Invalid Command on /proc/fs/afs/cells file\n");
        goto done;
}

static ssize_t afs_proc_rootcell_read(struct file *file, char __user *buf,
                                      size_t size, loff_t *_pos)
{
        struct afs_cell *cell;
        struct afs_net *net = afs_proc2net(file);
        unsigned int seq = 0;
        char name[AFS_MAXCELLNAME + 1];
        int len;

        if (*_pos > 0)
                return 0;
        if (!net->ws_cell)
                return 0;

        rcu_read_lock();
        do {
                read_seqbegin_or_lock(&net->cells_lock, &seq);
                len = 0;
                cell = rcu_dereference_raw(net->ws_cell);
                if (cell) {
                        len = cell->name_len;
                        memcpy(name, cell->name, len);
                }
        } while (need_seqretry(&net->cells_lock, seq));
        done_seqretry(&net->cells_lock, seq);
        rcu_read_unlock();

        if (!len)
                return 0;

        name[len++] = '\n';
        if (len > size)
                len = size;
        if (copy_to_user(buf, name, len) != 0)
                return -EFAULT;
        *_pos = 1;
        return len;
}

/*
 * handle writes to /proc/fs/afs/rootcell
 * - to initialize rootcell: echo "cell.name:192.168.231.14"
 */
static ssize_t afs_proc_rootcell_write(struct file *file,
                                       const char __user *buf,
                                       size_t size, loff_t *_pos)
{
        struct afs_net *net = afs_proc2net(file);
        char *kbuf, *s;
        int ret;

        /* start by dragging the command into memory */
        if (size <= 1 || size >= PAGE_SIZE)
                return -EINVAL;

        kbuf = memdup_user_nul(buf, size);
        if (IS_ERR(kbuf))
                return PTR_ERR(kbuf);

        ret = -EINVAL;
        if (kbuf[0] == '.')
                goto out;
        if (memchr(kbuf, '/', size))
                goto out;

        /* trim to first NL */
        s = memchr(kbuf, '\n', size);
        if (s)
                *s = 0;

        /* determine command to perform */
        _debug("rootcell=%s", kbuf);

        ret = afs_cell_init(net, kbuf);
        if (ret >= 0)
                ret = size;     /* consume everything, always */

out:
        kfree(kbuf);
        _leave(" = %d", ret);
        return ret;
}

/*
 * initialise /proc/fs/afs/<cell>/
 */
int afs_proc_cell_setup(struct afs_net *net, struct afs_cell *cell)
{
        struct proc_dir_entry *dir;

        _enter("%p{%s},%p", cell, cell->name, net->proc_afs);

        dir = proc_mkdir(cell->name, net->proc_afs);
        if (!dir)
                goto error_dir;

        if (!proc_create_data("vlservers", 0, dir,
                              &afs_proc_cell_vlservers_fops, cell) ||
            !proc_create_data("volumes", 0, dir,
                              &afs_proc_cell_volumes_fops, cell))
                goto error_tree;

        _leave(" = 0");
        return 0;

error_tree:
        remove_proc_subtree(cell->name, net->proc_afs);
error_dir:
        _leave(" = -ENOMEM");
        return -ENOMEM;
}

/*
 * remove /proc/fs/afs/<cell>/
 */
void afs_proc_cell_remove(struct afs_net *net, struct afs_cell *cell)
{
        _enter("");

        remove_proc_subtree(cell->name, net->proc_afs);

        _leave("");
}

/*
 * open "/proc/fs/afs/<cell>/volumes" which provides a summary of extant cells
 */
static int afs_proc_cell_volumes_open(struct inode *inode, struct file *file)
{
        struct afs_cell *cell;
        struct seq_file *m;
        int ret;

        cell = PDE_DATA(inode);
        if (!cell)
                return -ENOENT;

        ret = seq_open(file, &afs_proc_cell_volumes_ops);
        if (ret < 0)
                return ret;

        m = file->private_data;
        m->private = cell;

        return 0;
}

/*
 * set up the iterator to start reading from the cells list and return the
 * first item
 */
static void *afs_proc_cell_volumes_start(struct seq_file *m, loff_t *_pos)
        __acquires(cell->proc_lock)
{
        struct afs_cell *cell = m->private;

        _enter("cell=%p pos=%Ld", cell, *_pos);

        read_lock(&cell->proc_lock);
        return seq_list_start_head(&cell->proc_volumes, *_pos);
}

/*
 * move to next cell in cells list
 */
static void *afs_proc_cell_volumes_next(struct seq_file *p, void *v,
                                        loff_t *_pos)
{
        struct afs_cell *cell = p->private;

        _enter("cell=%p pos=%Ld", cell, *_pos);
        return seq_list_next(v, &cell->proc_volumes, _pos);
}

/*
 * clean up after reading from the cells list
 */
static void afs_proc_cell_volumes_stop(struct seq_file *p, void *v)
        __releases(cell->proc_lock)
{
        struct afs_cell *cell = p->private;

        read_unlock(&cell->proc_lock);
}

static const char afs_vol_types[3][3] = {
        [AFSVL_RWVOL]   = "RW",
        [AFSVL_ROVOL]   = "RO",
        [AFSVL_BACKVOL] = "BK",
};

/*
 * display a header line followed by a load of volume lines
 */
static int afs_proc_cell_volumes_show(struct seq_file *m, void *v)
{
        struct afs_cell *cell = m->private;
        struct afs_volume *vol = list_entry(v, struct afs_volume, proc_link);

        /* Display header on line 1 */
        if (v == &cell->proc_volumes) {
                seq_puts(m, "USE VID      TY\n");
                return 0;
        }

        seq_printf(m, "%3d %08x %s\n",
                   atomic_read(&vol->usage), vol->vid,
                   afs_vol_types[vol->type]);

        return 0;
}

/*
 * open "/proc/fs/afs/<cell>/vlservers" which provides a list of volume
 * location server
 */
static int afs_proc_cell_vlservers_open(struct inode *inode, struct file *file)
{
        struct afs_cell *cell;
        struct seq_file *m;
        int ret;

        cell = PDE_DATA(inode);
        if (!cell)
                return -ENOENT;

        ret = seq_open(file, &afs_proc_cell_vlservers_ops);
        if (ret<0)
                return ret;

        m = file->private_data;
        m->private = cell;

        return 0;
}

/*
 * set up the iterator to start reading from the cells list and return the
 * first item
 */
static void *afs_proc_cell_vlservers_start(struct seq_file *m, loff_t *_pos)
        __acquires(rcu)
{
        struct afs_addr_list *alist;
        struct afs_cell *cell = m->private;
        loff_t pos = *_pos;

        rcu_read_lock();

        alist = rcu_dereference(cell->vl_addrs);

        /* allow for the header line */
        if (!pos)
                return (void *) 1;
        pos--;

        if (!alist || pos >= alist->nr_addrs)
                return NULL;

        return alist->addrs + pos;
}

/*
 * move to next cell in cells list
 */
static void *afs_proc_cell_vlservers_next(struct seq_file *p, void *v,
                                          loff_t *_pos)
{
        struct afs_addr_list *alist;
        struct afs_cell *cell = p->private;
        loff_t pos;

        alist = rcu_dereference(cell->vl_addrs);

        pos = *_pos;
        (*_pos)++;
        if (!alist || pos >= alist->nr_addrs)
                return NULL;

        return alist->addrs + pos;
}

/*
 * clean up after reading from the cells list
 */
static void afs_proc_cell_vlservers_stop(struct seq_file *p, void *v)
        __releases(rcu)
{
        rcu_read_unlock();
}

/*
 * display a header line followed by a load of volume lines
 */
static int afs_proc_cell_vlservers_show(struct seq_file *m, void *v)
{
        struct sockaddr_rxrpc *addr = v;

        /* display header on line 1 */
        if (v == (void *)1) {
                seq_puts(m, "ADDRESS\n");
                return 0;
        }

        /* display one cell per line on subsequent lines */
        seq_printf(m, "%pISp\n", &addr->transport);
        return 0;
}

/*
 * open "/proc/fs/afs/servers" which provides a summary of active
 * servers
 */
static int afs_proc_servers_open(struct inode *inode, struct file *file)
{
        return seq_open(file, &afs_proc_servers_ops);
}

/*
 * Set up the iterator to start reading from the server list and return the
 * first item.
 */
static void *afs_proc_servers_start(struct seq_file *m, loff_t *_pos)
        __acquires(rcu)
{
        struct afs_net *net = afs_seq2net(m);

        rcu_read_lock();
        return seq_hlist_start_head_rcu(&net->fs_proc, *_pos);
}

/*
 * move to next cell in cells list
 */
static void *afs_proc_servers_next(struct seq_file *m, void *v, loff_t *_pos)
{
        struct afs_net *net = afs_seq2net(m);

        return seq_hlist_next_rcu(v, &net->fs_proc, _pos);
}

/*
 * clean up after reading from the cells list
 */
static void afs_proc_servers_stop(struct seq_file *p, void *v)
        __releases(rcu)
{
        rcu_read_unlock();
}

/*
 * display a header line followed by a load of volume lines
 */
static int afs_proc_servers_show(struct seq_file *m, void *v)
{
        struct afs_server *server;
        struct afs_addr_list *alist;

        if (v == SEQ_START_TOKEN) {
                seq_puts(m, "UUID                                 USE ADDR\n");
                return 0;
        }

        server = list_entry(v, struct afs_server, proc_link);
        alist = rcu_dereference(server->addresses);
        seq_printf(m, "%pU %3d %pISp\n",
                   &server->uuid,
                   atomic_read(&server->usage),
                   &alist->addrs[alist->index].transport);
        return 0;
}

void afs_put_sysnames(struct afs_sysnames *sysnames)
{
        int i;

        if (sysnames && refcount_dec_and_test(&sysnames->usage)) {
                for (i = 0; i < sysnames->nr; i++)
                        if (sysnames->subs[i] != afs_init_sysname &&
                            sysnames->subs[i] != sysnames->blank)
                                kfree(sysnames->subs[i]);
        }
}

/*
 * Handle opening of /proc/fs/afs/sysname.  If it is opened for writing, we
 * assume the caller wants to change the substitution list and we allocate a
 * buffer to hold the list.
 */
static int afs_proc_sysname_open(struct inode *inode, struct file *file)
{
        struct afs_sysnames *sysnames;
        struct seq_file *m;
        int ret;

        ret = seq_open(file, &afs_proc_sysname_ops);
        if (ret < 0)
                return ret;

        if (file->f_mode & FMODE_WRITE) {
                sysnames = kzalloc(sizeof(*sysnames), GFP_KERNEL);
                if (!sysnames) {
                        seq_release(inode, file);
                        return -ENOMEM;
                }

                refcount_set(&sysnames->usage, 1);
                m = file->private_data;
                m->private = sysnames;
        }

        return 0;
}

/*
 * Handle writes to /proc/fs/afs/sysname to set the @sys substitution.
 */
static ssize_t afs_proc_sysname_write(struct file *file,
                                      const char __user *buf,
                                      size_t size, loff_t *_pos)
{
        struct afs_sysnames *sysnames;
        struct seq_file *m = file->private_data;
        char *kbuf = NULL, *s, *p, *sub;
        int ret, len;

        sysnames = m->private;
        if (!sysnames)
                return -EINVAL;
        if (sysnames->error)
                return sysnames->error;

        if (size >= PAGE_SIZE - 1) {
                sysnames->error = -EINVAL;
                return -EINVAL;
        }
        if (size == 0)
                return 0;

        kbuf = memdup_user_nul(buf, size);
        if (IS_ERR(kbuf))
                return PTR_ERR(kbuf);

        inode_lock(file_inode(file));

        p = kbuf;
        while ((s = strsep(&p, " \t\n"))) {
                len = strlen(s);
                if (len == 0)
                        continue;
                ret = -ENAMETOOLONG;
                if (len >= AFSNAMEMAX)
                        goto error;

                if (len >= 4 &&
                    s[len - 4] == '@' &&
                    s[len - 3] == 's' &&
                    s[len - 2] == 'y' &&
                    s[len - 1] == 's')
                        /* Protect against recursion */
                        goto invalid;

                if (s[0] == '.' &&
                    (len < 2 || (len == 2 && s[1] == '.')))
                        goto invalid;

                if (memchr(s, '/', len))
                        goto invalid;

                ret = -EFBIG;
                if (sysnames->nr >= AFS_NR_SYSNAME)
                        goto out;

                if (strcmp(s, afs_init_sysname) == 0) {
                        sub = (char *)afs_init_sysname;
                } else {
                        ret = -ENOMEM;
                        sub = kmemdup(s, len + 1, GFP_KERNEL);
                        if (!sub)
                                goto out;
                }

                sysnames->subs[sysnames->nr] = sub;
                sysnames->nr++;
        }

        ret = size;     /* consume everything, always */
out:
        inode_unlock(file_inode(file));
        kfree(kbuf);
        return ret;

invalid:
        ret = -EINVAL;
error:
        sysnames->error = ret;
        goto out;
}

static int afs_proc_sysname_release(struct inode *inode, struct file *file)
{
        struct afs_sysnames *sysnames, *kill = NULL;
        struct seq_file *m = file->private_data;
        struct afs_net *net = afs_seq2net(m);

        sysnames = m->private;
        if (sysnames) {
                if (!sysnames->error) {
                        kill = sysnames;
                        if (sysnames->nr == 0) {
                                sysnames->subs[0] = sysnames->blank;
                                sysnames->nr++;
                        }
                        write_lock(&net->sysnames_lock);
                        kill = net->sysnames;
                        net->sysnames = sysnames;
                        write_unlock(&net->sysnames_lock);
                }
                afs_put_sysnames(kill);
        }

        return seq_release(inode, file);
}

static void *afs_proc_sysname_start(struct seq_file *m, loff_t *pos)
        __acquires(&net->sysnames_lock)
{
        struct afs_net *net = afs_seq2net(m);
        struct afs_sysnames *names = net->sysnames;

        read_lock(&net->sysnames_lock);

        if (*pos >= names->nr)
                return NULL;
        return (void *)(unsigned long)(*pos + 1);
}

static void *afs_proc_sysname_next(struct seq_file *m, void *v, loff_t *pos)
{
        struct afs_net *net = afs_seq2net(m);
        struct afs_sysnames *names = net->sysnames;

        *pos += 1;
        if (*pos >= names->nr)
                return NULL;
        return (void *)(unsigned long)(*pos + 1);
}

static void afs_proc_sysname_stop(struct seq_file *m, void *v)
        __releases(&net->sysnames_lock)
{
        struct afs_net *net = afs_seq2net(m);

        read_unlock(&net->sysnames_lock);
}

static int afs_proc_sysname_show(struct seq_file *m, void *v)
{
        struct afs_net *net = afs_seq2net(m);
        struct afs_sysnames *sysnames = net->sysnames;
        unsigned int i = (unsigned long)v - 1;

        if (i < sysnames->nr)
                seq_printf(m, "%s\n", sysnames->subs[i]);
        return 0;
}

/*
 * Display general per-net namespace statistics
 */
static int afs_proc_stats_show(struct seq_file *m, void *v)
{
        struct afs_net *net = afs_seq2net(m);

        seq_puts(m, "kAFS statistics\n");

        seq_printf(m, "dir-mgmt: look=%u reval=%u inval=%u relpg=%u\n",
                   atomic_read(&net->n_lookup),
                   atomic_read(&net->n_reval),
                   atomic_read(&net->n_inval),
                   atomic_read(&net->n_relpg));

        seq_printf(m, "dir-data: rdpg=%u\n",
                   atomic_read(&net->n_read_dir));

        seq_printf(m, "dir-edit: cr=%u rm=%u\n",
                   atomic_read(&net->n_dir_cr),
                   atomic_read(&net->n_dir_rm));

        seq_printf(m, "file-rd : n=%u nb=%lu\n",
                   atomic_read(&net->n_fetches),
                   atomic_long_read(&net->n_fetch_bytes));
        seq_printf(m, "file-wr : n=%u nb=%lu\n",
                   atomic_read(&net->n_stores),
                   atomic_long_read(&net->n_store_bytes));
        return 0;
}

/*
 * Open "/proc/fs/afs/stats" to allow reading of the stat counters.
 */
static int afs_proc_stats_open(struct inode *inode, struct file *file)
{
        return single_open(file, afs_proc_stats_show, NULL);
}

static const struct file_operations afs_proc_stats_fops = {
        .open           = afs_proc_stats_open,
        .read           = seq_read,
        .llseek         = seq_lseek,
        .release        = single_release,
};