mirror of https://gitee.com/openkylin/linux.git
291 lines
7.4 KiB
C
291 lines
7.4 KiB
C
/*
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* linux/fs/nfs/namespace.c
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*
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* Copyright (C) 2005 Trond Myklebust <Trond.Myklebust@netapp.com>
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* - Modified by David Howells <dhowells@redhat.com>
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*
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* NFS namespace
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*/
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#include <linux/module.h>
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#include <linux/dcache.h>
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#include <linux/gfp.h>
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#include <linux/mount.h>
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#include <linux/namei.h>
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#include <linux/nfs_fs.h>
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#include <linux/string.h>
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#include <linux/sunrpc/clnt.h>
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#include <linux/vfs.h>
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#include <linux/sunrpc/gss_api.h>
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#include "internal.h"
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#define NFSDBG_FACILITY NFSDBG_VFS
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static void nfs_expire_automounts(struct work_struct *work);
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static LIST_HEAD(nfs_automount_list);
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static DECLARE_DELAYED_WORK(nfs_automount_task, nfs_expire_automounts);
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int nfs_mountpoint_expiry_timeout = 500 * HZ;
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/*
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* nfs_path - reconstruct the path given an arbitrary dentry
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* @base - used to return pointer to the end of devname part of path
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* @dentry - pointer to dentry
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* @buffer - result buffer
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* @buflen - length of buffer
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* @flags - options (see below)
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*
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* Helper function for constructing the server pathname
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* by arbitrary hashed dentry.
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*
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* This is mainly for use in figuring out the path on the
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* server side when automounting on top of an existing partition
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* and in generating /proc/mounts and friends.
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*
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* Supported flags:
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* NFS_PATH_CANONICAL: ensure there is exactly one slash after
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* the original device (export) name
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* (if unset, the original name is returned verbatim)
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*/
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char *nfs_path(char **p, struct dentry *dentry, char *buffer, ssize_t buflen,
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unsigned flags)
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{
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char *end;
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int namelen;
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unsigned seq;
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const char *base;
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rename_retry:
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end = buffer+buflen;
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*--end = '\0';
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buflen--;
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seq = read_seqbegin(&rename_lock);
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rcu_read_lock();
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while (1) {
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spin_lock(&dentry->d_lock);
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if (IS_ROOT(dentry))
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break;
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namelen = dentry->d_name.len;
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buflen -= namelen + 1;
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if (buflen < 0)
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goto Elong_unlock;
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end -= namelen;
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memcpy(end, dentry->d_name.name, namelen);
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*--end = '/';
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spin_unlock(&dentry->d_lock);
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dentry = dentry->d_parent;
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}
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if (read_seqretry(&rename_lock, seq)) {
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spin_unlock(&dentry->d_lock);
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rcu_read_unlock();
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goto rename_retry;
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}
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if ((flags & NFS_PATH_CANONICAL) && *end != '/') {
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if (--buflen < 0) {
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spin_unlock(&dentry->d_lock);
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rcu_read_unlock();
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goto Elong;
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}
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*--end = '/';
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}
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*p = end;
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base = dentry->d_fsdata;
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if (!base) {
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spin_unlock(&dentry->d_lock);
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rcu_read_unlock();
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WARN_ON(1);
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return end;
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}
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namelen = strlen(base);
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if (flags & NFS_PATH_CANONICAL) {
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/* Strip off excess slashes in base string */
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while (namelen > 0 && base[namelen - 1] == '/')
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namelen--;
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}
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buflen -= namelen;
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if (buflen < 0) {
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spin_unlock(&dentry->d_lock);
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rcu_read_unlock();
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goto Elong;
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}
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end -= namelen;
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memcpy(end, base, namelen);
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spin_unlock(&dentry->d_lock);
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rcu_read_unlock();
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return end;
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Elong_unlock:
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spin_unlock(&dentry->d_lock);
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rcu_read_unlock();
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if (read_seqretry(&rename_lock, seq))
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goto rename_retry;
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Elong:
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return ERR_PTR(-ENAMETOOLONG);
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}
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EXPORT_SYMBOL_GPL(nfs_path);
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/*
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* nfs_d_automount - Handle crossing a mountpoint on the server
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* @path - The mountpoint
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*
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* When we encounter a mountpoint on the server, we want to set up
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* a mountpoint on the client too, to prevent inode numbers from
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* colliding, and to allow "df" to work properly.
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* On NFSv4, we also want to allow for the fact that different
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* filesystems may be migrated to different servers in a failover
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* situation, and that different filesystems may want to use
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* different security flavours.
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*/
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struct vfsmount *nfs_d_automount(struct path *path)
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{
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struct vfsmount *mnt;
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struct nfs_server *server = NFS_SERVER(path->dentry->d_inode);
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struct nfs_fh *fh = NULL;
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struct nfs_fattr *fattr = NULL;
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dprintk("--> nfs_d_automount()\n");
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mnt = ERR_PTR(-ESTALE);
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if (IS_ROOT(path->dentry))
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goto out_nofree;
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mnt = ERR_PTR(-ENOMEM);
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fh = nfs_alloc_fhandle();
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fattr = nfs_alloc_fattr();
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if (fh == NULL || fattr == NULL)
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goto out;
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dprintk("%s: enter\n", __func__);
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mnt = server->nfs_client->rpc_ops->submount(server, path->dentry, fh, fattr);
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if (IS_ERR(mnt))
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goto out;
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dprintk("%s: done, success\n", __func__);
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mntget(mnt); /* prevent immediate expiration */
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mnt_set_expiry(mnt, &nfs_automount_list);
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schedule_delayed_work(&nfs_automount_task, nfs_mountpoint_expiry_timeout);
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out:
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nfs_free_fattr(fattr);
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nfs_free_fhandle(fh);
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out_nofree:
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if (IS_ERR(mnt))
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dprintk("<-- %s(): error %ld\n", __func__, PTR_ERR(mnt));
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else
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dprintk("<-- %s() = %p\n", __func__, mnt);
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return mnt;
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}
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static int
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nfs_namespace_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
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{
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if (NFS_FH(dentry->d_inode)->size != 0)
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return nfs_getattr(mnt, dentry, stat);
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generic_fillattr(dentry->d_inode, stat);
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return 0;
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}
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static int
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nfs_namespace_setattr(struct dentry *dentry, struct iattr *attr)
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{
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if (NFS_FH(dentry->d_inode)->size != 0)
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return nfs_setattr(dentry, attr);
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return -EACCES;
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}
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const struct inode_operations nfs_mountpoint_inode_operations = {
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.getattr = nfs_getattr,
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.setattr = nfs_setattr,
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};
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const struct inode_operations nfs_referral_inode_operations = {
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.getattr = nfs_namespace_getattr,
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.setattr = nfs_namespace_setattr,
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};
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static void nfs_expire_automounts(struct work_struct *work)
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{
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struct list_head *list = &nfs_automount_list;
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mark_mounts_for_expiry(list);
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if (!list_empty(list))
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schedule_delayed_work(&nfs_automount_task, nfs_mountpoint_expiry_timeout);
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}
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void nfs_release_automount_timer(void)
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{
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if (list_empty(&nfs_automount_list))
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cancel_delayed_work(&nfs_automount_task);
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}
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/*
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* Clone a mountpoint of the appropriate type
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*/
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static struct vfsmount *nfs_do_clone_mount(struct nfs_server *server,
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const char *devname,
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struct nfs_clone_mount *mountdata)
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{
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return vfs_kern_mount(&nfs_xdev_fs_type, 0, devname, mountdata);
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}
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/**
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* nfs_do_submount - set up mountpoint when crossing a filesystem boundary
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* @dentry - parent directory
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* @fh - filehandle for new root dentry
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* @fattr - attributes for new root inode
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* @authflavor - security flavor to use when performing the mount
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*
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*/
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struct vfsmount *nfs_do_submount(struct dentry *dentry, struct nfs_fh *fh,
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struct nfs_fattr *fattr, rpc_authflavor_t authflavor)
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{
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struct nfs_clone_mount mountdata = {
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.sb = dentry->d_sb,
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.dentry = dentry,
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.fh = fh,
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.fattr = fattr,
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.authflavor = authflavor,
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};
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struct vfsmount *mnt = ERR_PTR(-ENOMEM);
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char *page = (char *) __get_free_page(GFP_USER);
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char *devname;
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dprintk("--> nfs_do_submount()\n");
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dprintk("%s: submounting on %s/%s\n", __func__,
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dentry->d_parent->d_name.name,
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dentry->d_name.name);
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if (page == NULL)
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goto out;
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devname = nfs_devname(dentry, page, PAGE_SIZE);
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mnt = (struct vfsmount *)devname;
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if (IS_ERR(devname))
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goto free_page;
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mnt = nfs_do_clone_mount(NFS_SB(dentry->d_sb), devname, &mountdata);
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free_page:
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free_page((unsigned long)page);
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out:
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dprintk("%s: done\n", __func__);
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dprintk("<-- nfs_do_submount() = %p\n", mnt);
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return mnt;
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}
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EXPORT_SYMBOL_GPL(nfs_do_submount);
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struct vfsmount *nfs_submount(struct nfs_server *server, struct dentry *dentry,
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struct nfs_fh *fh, struct nfs_fattr *fattr)
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{
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int err;
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struct dentry *parent = dget_parent(dentry);
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/* Look it up again to get its attributes */
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err = server->nfs_client->rpc_ops->lookup(parent->d_inode, &dentry->d_name, fh, fattr, NULL);
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dput(parent);
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if (err != 0)
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return ERR_PTR(err);
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return nfs_do_submount(dentry, fh, fattr, server->client->cl_auth->au_flavor);
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}
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EXPORT_SYMBOL_GPL(nfs_submount);
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