/*
* linux/fs/nfs/namespace.c
*
* Copyright (C) 2005 Trond Myklebust <Trond.Myklebust@netapp.com>
*
* NFS namespace
*/
#include <linux/config.h>
#include <linux/dcache.h>
#include <linux/mount.h>
#include <linux/namei.h>
#include <linux/nfs_fs.h>
#include <linux/string.h>
#include <linux/sunrpc/clnt.h>
#include <linux/vfs.h>
#include "internal.h"
#define NFSDBG_FACILITY NFSDBG_VFS
static void nfs_expire_automounts(void *list);
LIST_HEAD(nfs_automount_list);
static DECLARE_WORK(nfs_automount_task, nfs_expire_automounts, &nfs_automount_list);
int nfs_mountpoint_expiry_timeout = 500 * HZ;
/*
* nfs_path - reconstruct the path given an arbitrary dentry
* @base - arbitrary string to prepend to the path
* @dentry - pointer to dentry
* @buffer - result buffer
* @buflen - length of buffer
*
* Helper function for constructing the path from the
* root dentry to an arbitrary hashed dentry.
*
* This is mainly for use in figuring out the path on the
* server side when automounting on top of an existing partition.
*/
char *nfs_path(const char *base, const struct dentry *dentry,
char *buffer, ssize_t buflen)
{
char *end = buffer+buflen;
int namelen;
*--end = '\0';
buflen--;
spin_lock(&dcache_lock);
while (!IS_ROOT(dentry)) {
namelen = dentry->d_name.len;
buflen -= namelen + 1;
if (buflen < 0)
goto Elong_unlock;
end -= namelen;
memcpy(end, dentry->d_name.name, namelen);
*--end = '/';
dentry = dentry->d_parent;
}
spin_unlock(&dcache_lock);
namelen = strlen(base);
/* Strip off excess slashes in base string */
while (namelen > 0 && base[namelen - 1] == '/')
namelen--;
buflen -= namelen;
if (buflen < 0)
goto Elong;
end -= namelen;
memcpy(end, base, namelen);
return end;
Elong_unlock:
spin_unlock(&dcache_lock);
Elong:
return ERR_PTR(-ENAMETOOLONG);
}
/*
* nfs_follow_mountpoint - handle crossing a mountpoint on the server
* @dentry - dentry of mountpoint
* @nd - nameidata info
*
* When we encounter a mountpoint on the server, we want to set up
* a mountpoint on the client too, to prevent inode numbers from
* colliding, and to allow "df" to work properly.
* On NFSv4, we also want to allow for the fact that different
* filesystems may be migrated to different servers in a failover
* situation, and that different filesystems may want to use
* different security flavours.
*/
static void * nfs_follow_mountpoint(struct dentry *dentry, struct nameidata *nd)
{
struct vfsmount *mnt;
struct nfs_server *server = NFS_SERVER(dentry->d_inode);
struct dentry *parent;
struct nfs_fh fh;
struct nfs_fattr fattr;
int err;
BUG_ON(IS_ROOT(dentry));
dprintk("%s: enter\n", __FUNCTION__);
dput(nd->dentry);
nd->dentry = dget(dentry);
if (d_mountpoint(nd->dentry))
goto out_follow;
/* Look it up again */
parent = dget_parent(nd->dentry);
err = server->nfs_client->rpc_ops->lookup(parent->d_inode,
&nd->dentry->d_name,
&fh, &fattr);
dput(parent);
if (err != 0)
goto out_err;
if (fattr.valid & NFS_ATTR_FATTR_V4_REFERRAL)
mnt = nfs_do_refmount(nd->mnt, nd->dentry);
else
mnt = nfs_do_submount(nd->mnt, nd->dentry, &fh, &fattr);
err = PTR_ERR(mnt);
if (IS_ERR(mnt))
goto out_err;
mntget(mnt);
err = do_add_mount(mnt, nd, nd->mnt->mnt_flags|MNT_SHRINKABLE, &nfs_automount_list);
if (err < 0) {
mntput(mnt);
if (err == -EBUSY)
goto out_follow;
goto out_err;
}
mntput(nd->mnt);
dput(nd->dentry);
nd->mnt = mnt;
nd->dentry = dget(mnt->mnt_root);
schedule_delayed_work(&nfs_automount_task, nfs_mountpoint_expiry_timeout);
out:
dprintk("%s: done, returned %d\n", __FUNCTION__, err);
return ERR_PTR(err);
out_err:
path_release(nd);
goto out;
out_follow:
while(d_mountpoint(nd->dentry) && follow_down(&nd->mnt, &nd->dentry))
;
err = 0;
goto out;
}
struct inode_operations nfs_mountpoint_inode_operations = {
.follow_link = nfs_follow_mountpoint,
.getattr = nfs_getattr,
};
struct inode_operations nfs_referral_inode_operations = {
.follow_link = nfs_follow_mountpoint,
};
static void nfs_expire_automounts(void *data)
{
struct list_head *list = (struct list_head *)data;
mark_mounts_for_expiry(list);
if (!list_empty(list))
schedule_delayed_work(&nfs_automount_task, nfs_mountpoint_expiry_timeout);
}
void nfs_release_automount_timer(void)
{
if (list_empty(&nfs_automount_list)) {
cancel_delayed_work(&nfs_automount_task);
flush_scheduled_work();
}
}
/*
* Clone a mountpoint of the appropriate type
*/
static struct vfsmount *nfs_do_clone_mount(struct nfs_server *server,
const char *devname,
struct nfs_clone_mount *mountdata)
{
#ifdef CONFIG_NFS_V4
struct vfsmount *mnt = NULL;
switch (server->nfs_client->cl_nfsversion) {
case 2:
case 3:
mnt = vfs_kern_mount(&clone_nfs_fs_type, 0, devname, mountdata);
break;
case 4:
mnt = vfs_kern_mount(&clone_nfs4_fs_type, 0, devname, mountdata);
}
return mnt;
#else
return vfs_kern_mount(&clone_nfs_fs_type, 0, devname, mountdata);
#endif
}
/**
* nfs_do_submount - set up mountpoint when crossing a filesystem boundary
* @mnt_parent - mountpoint of parent directory
* @dentry - parent directory
* @fh - filehandle for new root dentry
* @fattr - attributes for new root inode
*
*/
struct vfsmount *nfs_do_submount(const struct vfsmount *mnt_parent,
const struct dentry *dentry, struct nfs_fh *fh,
struct nfs_fattr *fattr)
{
struct nfs_clone_mount mountdata = {
.sb = mnt_parent->mnt_sb,
.dentry = dentry,
.fh = fh,
.fattr = fattr,
};
struct vfsmount *mnt = ERR_PTR(-ENOMEM);
char *page = (char *) __get_free_page(GFP_USER);
char *devname;
dprintk("%s: submounting on %s/%s\n", __FUNCTION__,
dentry->d_parent->d_name.name,
dentry->d_name.name);
if (page == NULL)
goto out;
devname = nfs_devname(mnt_parent, dentry, page, PAGE_SIZE);
mnt = (struct vfsmount *)devname;
if (IS_ERR(devname))
goto free_page;
mnt = nfs_do_clone_mount(NFS_SB(mnt_parent->mnt_sb), devname, &mountdata);
free_page:
free_page((unsigned long)page);
out:
dprintk("%s: done\n", __FUNCTION__);
return mnt;
}
