rpc_pipe.c

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/*
 * net/sunrpc/rpc_pipe.c
 *
 * Userland/kernel interface for rpcauth_gss.
 * Code shamelessly plagiarized from fs/nfsd/nfsctl.c
 * and fs/sysfs/inode.c
 *
 * Copyright (c) 2002, Trond Myklebust <[email protected]>
 *
 */
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/pagemap.h>
#include <linux/mount.h>
#include <linux/namei.h>
#include <linux/fsnotify.h>
#include <linux/kernel.h>
#include <linux/rcupdate.h>

#include <asm/ioctls.h>
#include <linux/poll.h>
#include <linux/wait.h>
#include <linux/seq_file.h>

#include <linux/sunrpc/clnt.h>
#include <linux/workqueue.h>
#include <linux/sunrpc/rpc_pipe_fs.h>
#include <linux/sunrpc/cache.h>
#include <linux/nsproxy.h>
#include <linux/notifier.h>

#include "netns.h"
#include "sunrpc.h"

#define RPCDBG_FACILITY RPCDBG_DEBUG

#define NET_NAME(net)   ((net == &init_net) ? " (init_net)" : "")

static struct file_system_type rpc_pipe_fs_type;


static struct kmem_cache *rpc_inode_cachep __read_mostly;

#define RPC_UPCALL_TIMEOUT (30*HZ)

static BLOCKING_NOTIFIER_HEAD(rpc_pipefs_notifier_list);

int rpc_pipefs_notifier_register(struct notifier_block *nb)
{
    return blocking_notifier_chain_cond_register(&rpc_pipefs_notifier_list, nb);
}
EXPORT_SYMBOL_GPL(rpc_pipefs_notifier_register);

void rpc_pipefs_notifier_unregister(struct notifier_block *nb)
{
    blocking_notifier_chain_unregister(&rpc_pipefs_notifier_list, nb);
}
EXPORT_SYMBOL_GPL(rpc_pipefs_notifier_unregister);

static void rpc_purge_list(wait_queue_head_t *waitq, struct list_head *head,
        void (*destroy_msg)(struct rpc_pipe_msg *), int err)
{
    struct rpc_pipe_msg *msg;

    if (list_empty(head))
        return;
    do {
        msg = list_entry(head->next, struct rpc_pipe_msg, list);
        list_del_init(&msg->list);
        msg->errno = err;
        destroy_msg(msg);
    } while (!list_empty(head));

    if (waitq)
        wake_up(waitq);
}

static void
rpc_timeout_upcall_queue(struct work_struct *work)
{
    LIST_HEAD(free_list);
    struct rpc_pipe *pipe =
        container_of(work, struct rpc_pipe, queue_timeout.work);
    void (*destroy_msg)(struct rpc_pipe_msg *);
    struct dentry *dentry;

    spin_lock(&pipe->lock);
    destroy_msg = pipe->ops->destroy_msg;
    if (pipe->nreaders == 0) {
        list_splice_init(&pipe->pipe, &free_list);
        pipe->pipelen = 0;
    }
    dentry = dget(pipe->dentry);
    spin_unlock(&pipe->lock);
    rpc_purge_list(dentry ? &RPC_I(dentry->d_inode)->waitq : NULL,
            &free_list, destroy_msg, -ETIMEDOUT);
    dput(dentry);
}

ssize_t rpc_pipe_generic_upcall(struct file *filp, struct rpc_pipe_msg *msg,
                char __user *dst, size_t buflen)
{
    char *data = (char *)msg->data + msg->copied;
    size_t mlen = min(msg->len - msg->copied, buflen);
    unsigned long left;

    left = copy_to_user(dst, data, mlen);
    if (left == mlen) {
        msg->errno = -EFAULT;
        return -EFAULT;
    }

    mlen -= left;
    msg->copied += mlen;
    msg->errno = 0;
    return mlen;
}
EXPORT_SYMBOL_GPL(rpc_pipe_generic_upcall);

int
rpc_queue_upcall(struct rpc_pipe *pipe, struct rpc_pipe_msg *msg)
{
    int res = -EPIPE;
    struct dentry *dentry;

    spin_lock(&pipe->lock);
    if (pipe->nreaders) {
        list_add_tail(&msg->list, &pipe->pipe);
        pipe->pipelen += msg->len;
        res = 0;
    } else if (pipe->flags & RPC_PIPE_WAIT_FOR_OPEN) {
        if (list_empty(&pipe->pipe))
            queue_delayed_work(rpciod_workqueue,
                    &pipe->queue_timeout,
                    RPC_UPCALL_TIMEOUT);
        list_add_tail(&msg->list, &pipe->pipe);
        pipe->pipelen += msg->len;
        res = 0;
    }
    dentry = dget(pipe->dentry);
    spin_unlock(&pipe->lock);
    if (dentry) {
        wake_up(&RPC_I(dentry->d_inode)->waitq);
        dput(dentry);
    }
    return res;
}
EXPORT_SYMBOL_GPL(rpc_queue_upcall);

static inline void
rpc_inode_setowner(struct inode *inode, void *private)
{
    RPC_I(inode)->private = private;
}

static void
rpc_close_pipes(struct inode *inode)
{
    struct rpc_pipe *pipe = RPC_I(inode)->pipe;
    int need_release;
    LIST_HEAD(free_list);

    mutex_lock(&inode->i_mutex);
    spin_lock(&pipe->lock);
    need_release = pipe->nreaders != 0 || pipe->nwriters != 0;
    pipe->nreaders = 0;
    list_splice_init(&pipe->in_upcall, &free_list);
    list_splice_init(&pipe->pipe, &free_list);
    pipe->pipelen = 0;
    pipe->dentry = NULL;
    spin_unlock(&pipe->lock);
    rpc_purge_list(&RPC_I(inode)->waitq, &free_list, pipe->ops->destroy_msg, -EPIPE);
    pipe->nwriters = 0;
    if (need_release && pipe->ops->release_pipe)
        pipe->ops->release_pipe(inode);
    cancel_delayed_work_sync(&pipe->queue_timeout);
    rpc_inode_setowner(inode, NULL);
    RPC_I(inode)->pipe = NULL;
    mutex_unlock(&inode->i_mutex);
}

static struct inode *
rpc_alloc_inode(struct super_block *sb)
{
    struct rpc_inode *rpci;
    rpci = (struct rpc_inode *)kmem_cache_alloc(rpc_inode_cachep, GFP_KERNEL);
    if (!rpci)
        return NULL;
    return &rpci->vfs_inode;
}

static void
rpc_i_callback(struct rcu_head *head)
{
    struct inode *inode = container_of(head, struct inode, i_rcu);
    kmem_cache_free(rpc_inode_cachep, RPC_I(inode));
}

static void
rpc_destroy_inode(struct inode *inode)
{
    call_rcu(&inode->i_rcu, rpc_i_callback);
}

static int
rpc_pipe_open(struct inode *inode, struct file *filp)
{
    struct rpc_pipe *pipe;
    int first_open;
    int res = -ENXIO;

    mutex_lock(&inode->i_mutex);
    pipe = RPC_I(inode)->pipe;
    if (pipe == NULL)
        goto out;
    first_open = pipe->nreaders == 0 && pipe->nwriters == 0;
    if (first_open && pipe->ops->open_pipe) {
        res = pipe->ops->open_pipe(inode);
        if (res)
            goto out;
    }
    if (filp->f_mode & FMODE_READ)
        pipe->nreaders++;
    if (filp->f_mode & FMODE_WRITE)
        pipe->nwriters++;
    res = 0;
out:
    mutex_unlock(&inode->i_mutex);
    return res;
}

static int
rpc_pipe_release(struct inode *inode, struct file *filp)
{
    struct rpc_pipe *pipe;
    struct rpc_pipe_msg *msg;
    int last_close;

    mutex_lock(&inode->i_mutex);
    pipe = RPC_I(inode)->pipe;
    if (pipe == NULL)
        goto out;
    msg = filp->private_data;
    if (msg != NULL) {
        spin_lock(&pipe->lock);
        msg->errno = -EAGAIN;
        list_del_init(&msg->list);
        spin_unlock(&pipe->lock);
        pipe->ops->destroy_msg(msg);
    }
    if (filp->f_mode & FMODE_WRITE)
        pipe->nwriters --;
    if (filp->f_mode & FMODE_READ) {
        pipe->nreaders --;
        if (pipe->nreaders == 0) {
            LIST_HEAD(free_list);
            spin_lock(&pipe->lock);
            list_splice_init(&pipe->pipe, &free_list);
            pipe->pipelen = 0;
            spin_unlock(&pipe->lock);
            rpc_purge_list(&RPC_I(inode)->waitq, &free_list,
                    pipe->ops->destroy_msg, -EAGAIN);
        }
    }
    last_close = pipe->nwriters == 0 && pipe->nreaders == 0;
    if (last_close && pipe->ops->release_pipe)
        pipe->ops->release_pipe(inode);
out:
    mutex_unlock(&inode->i_mutex);
    return 0;
}

static ssize_t
rpc_pipe_read(struct file *filp, char __user *buf, size_t len, loff_t *offset)
{
    struct inode *inode = filp->f_path.dentry->d_inode;
    struct rpc_pipe *pipe;
    struct rpc_pipe_msg *msg;
    int res = 0;

    mutex_lock(&inode->i_mutex);
    pipe = RPC_I(inode)->pipe;
    if (pipe == NULL) {
        res = -EPIPE;
        goto out_unlock;
    }
    msg = filp->private_data;
    if (msg == NULL) {
        spin_lock(&pipe->lock);
        if (!list_empty(&pipe->pipe)) {
            msg = list_entry(pipe->pipe.next,
                    struct rpc_pipe_msg,
                    list);
            list_move(&msg->list, &pipe->in_upcall);
            pipe->pipelen -= msg->len;
            filp->private_data = msg;
            msg->copied = 0;
        }
        spin_unlock(&pipe->lock);
        if (msg == NULL)
            goto out_unlock;
    }
    /* NOTE: it is up to the callback to update msg->copied */
    res = pipe->ops->upcall(filp, msg, buf, len);
    if (res < 0 || msg->len == msg->copied) {
        filp->private_data = NULL;
        spin_lock(&pipe->lock);
        list_del_init(&msg->list);
        spin_unlock(&pipe->lock);
        pipe->ops->destroy_msg(msg);
    }
out_unlock:
    mutex_unlock(&inode->i_mutex);
    return res;
}

static ssize_t
rpc_pipe_write(struct file *filp, const char __user *buf, size_t len, loff_t *offset)
{
    struct inode *inode = filp->f_path.dentry->d_inode;
    int res;

    mutex_lock(&inode->i_mutex);
    res = -EPIPE;
    if (RPC_I(inode)->pipe != NULL)
        res = RPC_I(inode)->pipe->ops->downcall(filp, buf, len);
    mutex_unlock(&inode->i_mutex);
    return res;
}

static unsigned int
rpc_pipe_poll(struct file *filp, struct poll_table_struct *wait)
{
    struct inode *inode = filp->f_path.dentry->d_inode;
    struct rpc_inode *rpci = RPC_I(inode);
    unsigned int mask = POLLOUT | POLLWRNORM;

    poll_wait(filp, &rpci->waitq, wait);

    mutex_lock(&inode->i_mutex);
    if (rpci->pipe == NULL)
        mask |= POLLERR | POLLHUP;
    else if (filp->private_data || !list_empty(&rpci->pipe->pipe))
        mask |= POLLIN | POLLRDNORM;
    mutex_unlock(&inode->i_mutex);
    return mask;
}

static long
rpc_pipe_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
{
    struct inode *inode = filp->f_path.dentry->d_inode;
    struct rpc_pipe *pipe;
    int len;

    switch (cmd) {
    case FIONREAD:
        mutex_lock(&inode->i_mutex);
        pipe = RPC_I(inode)->pipe;
        if (pipe == NULL) {
            mutex_unlock(&inode->i_mutex);
            return -EPIPE;
        }
        spin_lock(&pipe->lock);
        len = pipe->pipelen;
        if (filp->private_data) {
            struct rpc_pipe_msg *msg;
            msg = filp->private_data;
            len += msg->len - msg->copied;
        }
        spin_unlock(&pipe->lock);
        mutex_unlock(&inode->i_mutex);
        return put_user(len, (int __user *)arg);
    default:
        return -EINVAL;
    }
}

static const struct file_operations rpc_pipe_fops = {
    .owner      = THIS_MODULE,
    .llseek     = no_llseek,
    .read       = rpc_pipe_read,
    .write      = rpc_pipe_write,
    .poll       = rpc_pipe_poll,
    .unlocked_ioctl = rpc_pipe_ioctl,
    .open       = rpc_pipe_open,
    .release    = rpc_pipe_release,
};

static int
rpc_show_info(struct seq_file *m, void *v)
{
    struct rpc_clnt *clnt = m->private;

    rcu_read_lock();
    seq_printf(m, "RPC server: %s\n",
            rcu_dereference(clnt->cl_xprt)->servername);
    seq_printf(m, "service: %s (%d) version %d\n", clnt->cl_protname,
            clnt->cl_prog, clnt->cl_vers);
    seq_printf(m, "address: %s\n", rpc_peeraddr2str(clnt, RPC_DISPLAY_ADDR));
    seq_printf(m, "protocol: %s\n", rpc_peeraddr2str(clnt, RPC_DISPLAY_PROTO));
    seq_printf(m, "port: %s\n", rpc_peeraddr2str(clnt, RPC_DISPLAY_PORT));
    rcu_read_unlock();
    return 0;
}

static int
rpc_info_open(struct inode *inode, struct file *file)
{
    struct rpc_clnt *clnt = NULL;
    int ret = single_open(file, rpc_show_info, NULL);

    if (!ret) {
        struct seq_file *m = file->private_data;

        spin_lock(&file->f_path.dentry->d_lock);
        if (!d_unhashed(file->f_path.dentry))
            clnt = RPC_I(inode)->private;
        if (clnt != NULL && atomic_inc_not_zero(&clnt->cl_count)) {
            spin_unlock(&file->f_path.dentry->d_lock);
            m->private = clnt;
        } else {
            spin_unlock(&file->f_path.dentry->d_lock);
            single_release(inode, file);
            ret = -EINVAL;
        }
    }
    return ret;
}

static int
rpc_info_release(struct inode *inode, struct file *file)
{
    struct seq_file *m = file->private_data;
    struct rpc_clnt *clnt = (struct rpc_clnt *)m->private;

    if (clnt)
        rpc_release_client(clnt);
    return single_release(inode, file);
}

static const struct file_operations rpc_info_operations = {
    .owner      = THIS_MODULE,
    .open       = rpc_info_open,
    .read       = seq_read,
    .llseek     = seq_lseek,
    .release    = rpc_info_release,
};


/*
 * Description of fs contents.
 */
struct rpc_filelist {
    const char *name;
    const struct file_operations *i_fop;
    umode_t mode;
};

static int rpc_delete_dentry(const struct dentry *dentry)
{
    return 1;
}

static const struct dentry_operations rpc_dentry_operations = {
    .d_delete = rpc_delete_dentry,
};

static struct inode *
rpc_get_inode(struct super_block *sb, umode_t mode)
{
    struct inode *inode = new_inode(sb);
    if (!inode)
        return NULL;
    inode->i_ino = get_next_ino();
    inode->i_mode = mode;
    inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
    switch (mode & S_IFMT) {
    case S_IFDIR:
        inode->i_fop = &simple_dir_operations;
        inode->i_op = &simple_dir_inode_operations;
        inc_nlink(inode);
    default:
        break;
    }
    return inode;
}

static int __rpc_create_common(struct inode *dir, struct dentry *dentry,
                   umode_t mode,
                   const struct file_operations *i_fop,
                   void *private)
{
    struct inode *inode;

    d_drop(dentry);
    inode = rpc_get_inode(dir->i_sb, mode);
    if (!inode)
        goto out_err;
    inode->i_ino = iunique(dir->i_sb, 100);
    if (i_fop)
        inode->i_fop = i_fop;
    if (private)
        rpc_inode_setowner(inode, private);
    d_add(dentry, inode);
    return 0;
out_err:
    printk(KERN_WARNING "%s: %s failed to allocate inode for dentry %s\n",
            __FILE__, __func__, dentry->d_name.name);
    dput(dentry);
    return -ENOMEM;
}

static int __rpc_create(struct inode *dir, struct dentry *dentry,
            umode_t mode,
            const struct file_operations *i_fop,
            void *private)
{
    int err;

    err = __rpc_create_common(dir, dentry, S_IFREG | mode, i_fop, private);
    if (err)
        return err;
    fsnotify_create(dir, dentry);
    return 0;
}

static int __rpc_mkdir(struct inode *dir, struct dentry *dentry,
               umode_t mode,
               const struct file_operations *i_fop,
               void *private)
{
    int err;

    err = __rpc_create_common(dir, dentry, S_IFDIR | mode, i_fop, private);
    if (err)
        return err;
    inc_nlink(dir);
    fsnotify_mkdir(dir, dentry);
    return 0;
}

static void
init_pipe(struct rpc_pipe *pipe)
{
    pipe->nreaders = 0;
    pipe->nwriters = 0;
    INIT_LIST_HEAD(&pipe->in_upcall);
    INIT_LIST_HEAD(&pipe->in_downcall);
    INIT_LIST_HEAD(&pipe->pipe);
    pipe->pipelen = 0;
    INIT_DELAYED_WORK(&pipe->queue_timeout,
                rpc_timeout_upcall_queue);
    pipe->ops = NULL;
    spin_lock_init(&pipe->lock);
    pipe->dentry = NULL;
}

void rpc_destroy_pipe_data(struct rpc_pipe *pipe)
{
    kfree(pipe);
}
EXPORT_SYMBOL_GPL(rpc_destroy_pipe_data);

struct rpc_pipe *rpc_mkpipe_data(const struct rpc_pipe_ops *ops, int flags)
{
    struct rpc_pipe *pipe;

    pipe = kzalloc(sizeof(struct rpc_pipe), GFP_KERNEL);
    if (!pipe)
        return ERR_PTR(-ENOMEM);
    init_pipe(pipe);
    pipe->ops = ops;
    pipe->flags = flags;
    return pipe;
}
EXPORT_SYMBOL_GPL(rpc_mkpipe_data);

static int __rpc_mkpipe_dentry(struct inode *dir, struct dentry *dentry,
                   umode_t mode,
                   const struct file_operations *i_fop,
                   void *private,
                   struct rpc_pipe *pipe)
{
    struct rpc_inode *rpci;
    int err;

    err = __rpc_create_common(dir, dentry, S_IFIFO | mode, i_fop, private);
    if (err)
        return err;
    rpci = RPC_I(dentry->d_inode);
    rpci->private = private;
    rpci->pipe = pipe;
    fsnotify_create(dir, dentry);
    return 0;
}

static int __rpc_rmdir(struct inode *dir, struct dentry *dentry)
{
    int ret;

    dget(dentry);
    ret = simple_rmdir(dir, dentry);
    d_delete(dentry);
    dput(dentry);
    return ret;
}

int rpc_rmdir(struct dentry *dentry)
{
    struct dentry *parent;
    struct inode *dir;
    int error;

    parent = dget_parent(dentry);
    dir = parent->d_inode;
    mutex_lock_nested(&dir->i_mutex, I_MUTEX_PARENT);
    error = __rpc_rmdir(dir, dentry);
    mutex_unlock(&dir->i_mutex);
    dput(parent);
    return error;
}
EXPORT_SYMBOL_GPL(rpc_rmdir);

static int __rpc_unlink(struct inode *dir, struct dentry *dentry)
{
    int ret;

    dget(dentry);
    ret = simple_unlink(dir, dentry);
    d_delete(dentry);
    dput(dentry);
    return ret;
}

static int __rpc_rmpipe(struct inode *dir, struct dentry *dentry)
{
    struct inode *inode = dentry->d_inode;

    rpc_close_pipes(inode);
    return __rpc_unlink(dir, dentry);
}

static struct dentry *__rpc_lookup_create_exclusive(struct dentry *parent,
                      struct qstr *name)
{
    struct dentry *dentry;

    dentry = d_lookup(parent, name);
    if (!dentry) {
        dentry = d_alloc(parent, name);
        if (!dentry)
            return ERR_PTR(-ENOMEM);
    }
    if (dentry->d_inode == NULL) {
        d_set_d_op(dentry, &rpc_dentry_operations);
        return dentry;
    }
    dput(dentry);
    return ERR_PTR(-EEXIST);
}

/*
 * FIXME: This probably has races.
 */
static void __rpc_depopulate(struct dentry *parent,
                 const struct rpc_filelist *files,
                 int start, int eof)
{
    struct inode *dir = parent->d_inode;
    struct dentry *dentry;
    struct qstr name;
    int i;

    for (i = start; i < eof; i++) {
        name.name = files[i].name;
        name.len = strlen(files[i].name);
        name.hash = full_name_hash(name.name, name.len);
        dentry = d_lookup(parent, &name);

        if (dentry == NULL)
            continue;
        if (dentry->d_inode == NULL)
            goto next;
        switch (dentry->d_inode->i_mode & S_IFMT) {
            default:
                BUG();
            case S_IFREG:
                __rpc_unlink(dir, dentry);
                break;
            case S_IFDIR:
                __rpc_rmdir(dir, dentry);
        }
next:
        dput(dentry);
    }
}

static void rpc_depopulate(struct dentry *parent,
               const struct rpc_filelist *files,
               int start, int eof)
{
    struct inode *dir = parent->d_inode;

    mutex_lock_nested(&dir->i_mutex, I_MUTEX_CHILD);
    __rpc_depopulate(parent, files, start, eof);
    mutex_unlock(&dir->i_mutex);
}

static int rpc_populate(struct dentry *parent,
            const struct rpc_filelist *files,
            int start, int eof,
            void *private)
{
    struct inode *dir = parent->d_inode;
    struct dentry *dentry;
    int i, err;

    mutex_lock(&dir->i_mutex);
    for (i = start; i < eof; i++) {
        struct qstr q;

        q.name = files[i].name;
        q.len = strlen(files[i].name);
        q.hash = full_name_hash(q.name, q.len);
        dentry = __rpc_lookup_create_exclusive(parent, &q);
        err = PTR_ERR(dentry);
        if (IS_ERR(dentry))
            goto out_bad;
        switch (files[i].mode & S_IFMT) {
            default:
                BUG();
            case S_IFREG:
                err = __rpc_create(dir, dentry,
                        files[i].mode,
                        files[i].i_fop,
                        private);
                break;
            case S_IFDIR:
                err = __rpc_mkdir(dir, dentry,
                        files[i].mode,
                        NULL,
                        private);
        }
        if (err != 0)
            goto out_bad;
    }
    mutex_unlock(&dir->i_mutex);
    return 0;
out_bad:
    __rpc_depopulate(parent, files, start, eof);
    mutex_unlock(&dir->i_mutex);
    printk(KERN_WARNING "%s: %s failed to populate directory %s\n",
            __FILE__, __func__, parent->d_name.name);
    return err;
}

static struct dentry *rpc_mkdir_populate(struct dentry *parent,
        struct qstr *name, umode_t mode, void *private,
        int (*populate)(struct dentry *, void *), void *args_populate)
{
    struct dentry *dentry;
    struct inode *dir = parent->d_inode;
    int error;

    mutex_lock_nested(&dir->i_mutex, I_MUTEX_PARENT);
    dentry = __rpc_lookup_create_exclusive(parent, name);
    if (IS_ERR(dentry))
        goto out;
    error = __rpc_mkdir(dir, dentry, mode, NULL, private);
    if (error != 0)
        goto out_err;
    if (populate != NULL) {
        error = populate(dentry, args_populate);
        if (error)
            goto err_rmdir;
    }
out:
    mutex_unlock(&dir->i_mutex);
    return dentry;
err_rmdir:
    __rpc_rmdir(dir, dentry);
out_err:
    dentry = ERR_PTR(error);
    goto out;
}

static int rpc_rmdir_depopulate(struct dentry *dentry,
        void (*depopulate)(struct dentry *))
{
    struct dentry *parent;
    struct inode *dir;
    int error;

    parent = dget_parent(dentry);
    dir = parent->d_inode;
    mutex_lock_nested(&dir->i_mutex, I_MUTEX_PARENT);
    if (depopulate != NULL)
        depopulate(dentry);
    error = __rpc_rmdir(dir, dentry);
    mutex_unlock(&dir->i_mutex);
    dput(parent);
    return error;
}

struct dentry *rpc_mkpipe_dentry(struct dentry *parent, const char *name,
                 void *private, struct rpc_pipe *pipe)
{
    struct dentry *dentry;
    struct inode *dir = parent->d_inode;
    umode_t umode = S_IFIFO | S_IRUSR | S_IWUSR;
    struct qstr q;
    int err;

    if (pipe->ops->upcall == NULL)
        umode &= ~S_IRUGO;
    if (pipe->ops->downcall == NULL)
        umode &= ~S_IWUGO;

    q.name = name;
    q.len = strlen(name);
    q.hash = full_name_hash(q.name, q.len),

    mutex_lock_nested(&dir->i_mutex, I_MUTEX_PARENT);
    dentry = __rpc_lookup_create_exclusive(parent, &q);
    if (IS_ERR(dentry))
        goto out;
    err = __rpc_mkpipe_dentry(dir, dentry, umode, &rpc_pipe_fops,
                  private, pipe);
    if (err)
        goto out_err;
out:
    mutex_unlock(&dir->i_mutex);
    return dentry;
out_err:
    dentry = ERR_PTR(err);
    printk(KERN_WARNING "%s: %s() failed to create pipe %s/%s (errno = %d)\n",
            __FILE__, __func__, parent->d_name.name, name,
            err);
    goto out;
}
EXPORT_SYMBOL_GPL(rpc_mkpipe_dentry);

int
rpc_unlink(struct dentry *dentry)
{
    struct dentry *parent;
    struct inode *dir;
    int error = 0;

    parent = dget_parent(dentry);
    dir = parent->d_inode;
    mutex_lock_nested(&dir->i_mutex, I_MUTEX_PARENT);
    error = __rpc_rmpipe(dir, dentry);
    mutex_unlock(&dir->i_mutex);
    dput(parent);
    return error;
}
EXPORT_SYMBOL_GPL(rpc_unlink);

enum {
    RPCAUTH_info,
    RPCAUTH_EOF
};

static const struct rpc_filelist authfiles[] = {
    [RPCAUTH_info] = {
        .name = "info",
        .i_fop = &rpc_info_operations,
        .mode = S_IFREG | S_IRUSR,
    },
};

static int rpc_clntdir_populate(struct dentry *dentry, void *private)
{
    return rpc_populate(dentry,
                authfiles, RPCAUTH_info, RPCAUTH_EOF,
                private);
}

static void rpc_clntdir_depopulate(struct dentry *dentry)
{
    rpc_depopulate(dentry, authfiles, RPCAUTH_info, RPCAUTH_EOF);
}

struct dentry *rpc_create_client_dir(struct dentry *dentry,
                   struct qstr *name,
                   struct rpc_clnt *rpc_client)
{
    return rpc_mkdir_populate(dentry, name, S_IRUGO | S_IXUGO, NULL,
            rpc_clntdir_populate, rpc_client);
}

int rpc_remove_client_dir(struct dentry *dentry)
{
    return rpc_rmdir_depopulate(dentry, rpc_clntdir_depopulate);
}

static const struct rpc_filelist cache_pipefs_files[3] = {
    [0] = {
        .name = "channel",
        .i_fop = &cache_file_operations_pipefs,
        .mode = S_IFREG|S_IRUSR|S_IWUSR,
    },
    [1] = {
        .name = "content",
        .i_fop = &content_file_operations_pipefs,
        .mode = S_IFREG|S_IRUSR,
    },
    [2] = {
        .name = "flush",
        .i_fop = &cache_flush_operations_pipefs,
        .mode = S_IFREG|S_IRUSR|S_IWUSR,
    },
};

static int rpc_cachedir_populate(struct dentry *dentry, void *private)
{
    return rpc_populate(dentry,
                cache_pipefs_files, 0, 3,
                private);
}

static void rpc_cachedir_depopulate(struct dentry *dentry)
{
    rpc_depopulate(dentry, cache_pipefs_files, 0, 3);
}

struct dentry *rpc_create_cache_dir(struct dentry *parent, struct qstr *name,
                    umode_t umode, struct cache_detail *cd)
{
    return rpc_mkdir_populate(parent, name, umode, NULL,
            rpc_cachedir_populate, cd);
}

void rpc_remove_cache_dir(struct dentry *dentry)
{
    rpc_rmdir_depopulate(dentry, rpc_cachedir_depopulate);
}

/*
 * populate the filesystem
 */
static const struct super_operations s_ops = {
    .alloc_inode    = rpc_alloc_inode,
    .destroy_inode  = rpc_destroy_inode,
    .statfs     = simple_statfs,
};

#define RPCAUTH_GSSMAGIC 0x67596969

/*
 * We have a single directory with 1 node in it.
 */
enum {
    RPCAUTH_lockd,
    RPCAUTH_mount,
    RPCAUTH_nfs,
    RPCAUTH_portmap,
    RPCAUTH_statd,
    RPCAUTH_nfsd4_cb,
    RPCAUTH_cache,
    RPCAUTH_nfsd,
    RPCAUTH_RootEOF
};

static const struct rpc_filelist files[] = {
    [RPCAUTH_lockd] = {
        .name = "lockd",
        .mode = S_IFDIR | S_IRUGO | S_IXUGO,
    },
    [RPCAUTH_mount] = {
        .name = "mount",
        .mode = S_IFDIR | S_IRUGO | S_IXUGO,
    },
    [RPCAUTH_nfs] = {
        .name = "nfs",
        .mode = S_IFDIR | S_IRUGO | S_IXUGO,
    },
    [RPCAUTH_portmap] = {
        .name = "portmap",
        .mode = S_IFDIR | S_IRUGO | S_IXUGO,
    },
    [RPCAUTH_statd] = {
        .name = "statd",
        .mode = S_IFDIR | S_IRUGO | S_IXUGO,
    },
    [RPCAUTH_nfsd4_cb] = {
        .name = "nfsd4_cb",
        .mode = S_IFDIR | S_IRUGO | S_IXUGO,
    },
    [RPCAUTH_cache] = {
        .name = "cache",
        .mode = S_IFDIR | S_IRUGO | S_IXUGO,
    },
    [RPCAUTH_nfsd] = {
        .name = "nfsd",
        .mode = S_IFDIR | S_IRUGO | S_IXUGO,
    },
};

/*
 * This call can be used only in RPC pipefs mount notification hooks.
 */
struct dentry *rpc_d_lookup_sb(const struct super_block *sb,
                   const unsigned char *dir_name)
{
    struct qstr dir = QSTR_INIT(dir_name, strlen(dir_name));

    dir.hash = full_name_hash(dir.name, dir.len);
    return d_lookup(sb->s_root, &dir);
}
EXPORT_SYMBOL_GPL(rpc_d_lookup_sb);

void rpc_pipefs_init_net(struct net *net)
{
    struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);

    mutex_init(&sn->pipefs_sb_lock);
}

/*
 * This call will be used for per network namespace operations calls.
 * Note: Function will be returned with pipefs_sb_lock taken if superblock was
 * found. This lock have to be released by rpc_put_sb_net() when all operations
 * will be completed.
 */
struct super_block *rpc_get_sb_net(const struct net *net)
{
    struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);

    mutex_lock(&sn->pipefs_sb_lock);
    if (sn->pipefs_sb)
        return sn->pipefs_sb;
    mutex_unlock(&sn->pipefs_sb_lock);
    return NULL;
}
EXPORT_SYMBOL_GPL(rpc_get_sb_net);

void rpc_put_sb_net(const struct net *net)
{
    struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);

    BUG_ON(sn->pipefs_sb == NULL);
    mutex_unlock(&sn->pipefs_sb_lock);
}
EXPORT_SYMBOL_GPL(rpc_put_sb_net);

static int
rpc_fill_super(struct super_block *sb, void *data, int silent)
{
    struct inode *inode;
    struct dentry *root;
    struct net *net = data;
    struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);
    int err;

    sb->s_blocksize = PAGE_CACHE_SIZE;
    sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
    sb->s_magic = RPCAUTH_GSSMAGIC;
    sb->s_op = &s_ops;
    sb->s_time_gran = 1;

    inode = rpc_get_inode(sb, S_IFDIR | S_IRUGO | S_IXUGO);
    sb->s_root = root = d_make_root(inode);
    if (!root)
        return -ENOMEM;
    if (rpc_populate(root, files, RPCAUTH_lockd, RPCAUTH_RootEOF, NULL))
        return -ENOMEM;
    dprintk("RPC:       sending pipefs MOUNT notification for net %p%s\n",
        net, NET_NAME(net));
    sn->pipefs_sb = sb;
    err = blocking_notifier_call_chain(&rpc_pipefs_notifier_list,
                       RPC_PIPEFS_MOUNT,
                       sb);
    if (err)
        goto err_depopulate;
    sb->s_fs_info = get_net(net);
    return 0;

err_depopulate:
    blocking_notifier_call_chain(&rpc_pipefs_notifier_list,
                       RPC_PIPEFS_UMOUNT,
                       sb);
    sn->pipefs_sb = NULL;
    __rpc_depopulate(root, files, RPCAUTH_lockd, RPCAUTH_RootEOF);
    return err;
}

static struct dentry *
rpc_mount(struct file_system_type *fs_type,
        int flags, const char *dev_name, void *data)
{
    return mount_ns(fs_type, flags, current->nsproxy->net_ns, rpc_fill_super);
}

static void rpc_kill_sb(struct super_block *sb)
{
    struct net *net = sb->s_fs_info;
    struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);

    mutex_lock(&sn->pipefs_sb_lock);
    sn->pipefs_sb = NULL;
    mutex_unlock(&sn->pipefs_sb_lock);
    put_net(net);
    dprintk("RPC:       sending pipefs UMOUNT notification for net %p%s\n",
        net, NET_NAME(net));
    blocking_notifier_call_chain(&rpc_pipefs_notifier_list,
                       RPC_PIPEFS_UMOUNT,
                       sb);
    kill_litter_super(sb);
}

static struct file_system_type rpc_pipe_fs_type = {
    .owner      = THIS_MODULE,
    .name       = "rpc_pipefs",
    .mount      = rpc_mount,
    .kill_sb    = rpc_kill_sb,
};

static void
init_once(void *foo)
{
    struct rpc_inode *rpci = (struct rpc_inode *) foo;

    inode_init_once(&rpci->vfs_inode);
    rpci->private = NULL;
    rpci->pipe = NULL;
    init_waitqueue_head(&rpci->waitq);
}

int register_rpc_pipefs(void)
{
    int err;

    rpc_inode_cachep = kmem_cache_create("rpc_inode_cache",
                sizeof(struct rpc_inode),
                0, (SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT|
                        SLAB_MEM_SPREAD),
                init_once);
    if (!rpc_inode_cachep)
        return -ENOMEM;
    err = rpc_clients_notifier_register();
    if (err)
        goto err_notifier;
    err = register_filesystem(&rpc_pipe_fs_type);
    if (err)
        goto err_register;
    return 0;

err_register:
    rpc_clients_notifier_unregister();
err_notifier:
    kmem_cache_destroy(rpc_inode_cachep);
    return err;
}

void unregister_rpc_pipefs(void)
{
    rpc_clients_notifier_unregister();
    kmem_cache_destroy(rpc_inode_cachep);
    unregister_filesystem(&rpc_pipe_fs_type);
}

/* Make 'mount -t rpc_pipefs ...' autoload this module. */
MODULE_ALIAS("rpc_pipefs");