linux/fs/nfs/namespace.c

290 lines
7.3 KiB
C

/*
* linux/fs/nfs/namespace.c
*
* Copyright (C) 2005 Trond Myklebust <Trond.Myklebust@netapp.com>
* - Modified by David Howells <dhowells@redhat.com>
*
* NFS namespace
*/
#include <linux/module.h>
#include <linux/dcache.h>
#include <linux/gfp.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 <linux/sunrpc/gss_api.h>
#include "internal.h"
#define NFSDBG_FACILITY NFSDBG_VFS
static void nfs_expire_automounts(struct work_struct *work);
static LIST_HEAD(nfs_automount_list);
static DECLARE_DELAYED_WORK(nfs_automount_task, nfs_expire_automounts);
int nfs_mountpoint_expiry_timeout = 500 * HZ;
/*
* nfs_path - reconstruct the path given an arbitrary dentry
* @base - used to return pointer to the end of devname part of path
* @dentry - pointer to dentry
* @buffer - result buffer
* @buflen - length of buffer
* @flags - options (see below)
*
* Helper function for constructing the server pathname
* by 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
* and in generating /proc/mounts and friends.
*
* Supported flags:
* NFS_PATH_CANONICAL: ensure there is exactly one slash after
* the original device (export) name
* (if unset, the original name is returned verbatim)
*/
char *nfs_path(char **p, struct dentry *dentry, char *buffer, ssize_t buflen,
unsigned flags)
{
char *end;
int namelen;
unsigned seq;
const char *base;
rename_retry:
end = buffer+buflen;
*--end = '\0';
buflen--;
seq = read_seqbegin(&rename_lock);
rcu_read_lock();
while (1) {
spin_lock(&dentry->d_lock);
if (IS_ROOT(dentry))
break;
namelen = dentry->d_name.len;
buflen -= namelen + 1;
if (buflen < 0)
goto Elong_unlock;
end -= namelen;
memcpy(end, dentry->d_name.name, namelen);
*--end = '/';
spin_unlock(&dentry->d_lock);
dentry = dentry->d_parent;
}
if (read_seqretry(&rename_lock, seq)) {
spin_unlock(&dentry->d_lock);
rcu_read_unlock();
goto rename_retry;
}
if ((flags & NFS_PATH_CANONICAL) && *end != '/') {
if (--buflen < 0) {
spin_unlock(&dentry->d_lock);
rcu_read_unlock();
goto Elong;
}
*--end = '/';
}
*p = end;
base = dentry->d_fsdata;
if (!base) {
spin_unlock(&dentry->d_lock);
rcu_read_unlock();
WARN_ON(1);
return end;
}
namelen = strlen(base);
if (flags & NFS_PATH_CANONICAL) {
/* Strip off excess slashes in base string */
while (namelen > 0 && base[namelen - 1] == '/')
namelen--;
}
buflen -= namelen;
if (buflen < 0) {
spin_unlock(&dentry->d_lock);
rcu_read_unlock();
goto Elong;
}
end -= namelen;
memcpy(end, base, namelen);
spin_unlock(&dentry->d_lock);
rcu_read_unlock();
return end;
Elong_unlock:
spin_unlock(&dentry->d_lock);
rcu_read_unlock();
if (read_seqretry(&rename_lock, seq))
goto rename_retry;
Elong:
return ERR_PTR(-ENAMETOOLONG);
}
EXPORT_SYMBOL_GPL(nfs_path);
/*
* nfs_d_automount - Handle crossing a mountpoint on the server
* @path - The mountpoint
*
* 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.
*/
struct vfsmount *nfs_d_automount(struct path *path)
{
struct vfsmount *mnt;
struct nfs_server *server = NFS_SERVER(path->dentry->d_inode);
struct nfs_fh *fh = NULL;
struct nfs_fattr *fattr = NULL;
dprintk("--> nfs_d_automount()\n");
mnt = ERR_PTR(-ESTALE);
if (IS_ROOT(path->dentry))
goto out_nofree;
mnt = ERR_PTR(-ENOMEM);
fh = nfs_alloc_fhandle();
fattr = nfs_alloc_fattr();
if (fh == NULL || fattr == NULL)
goto out;
dprintk("%s: enter\n", __func__);
mnt = server->nfs_client->rpc_ops->submount(server, path->dentry, fh, fattr);
if (IS_ERR(mnt))
goto out;
dprintk("%s: done, success\n", __func__);
mntget(mnt); /* prevent immediate expiration */
mnt_set_expiry(mnt, &nfs_automount_list);
schedule_delayed_work(&nfs_automount_task, nfs_mountpoint_expiry_timeout);
out:
nfs_free_fattr(fattr);
nfs_free_fhandle(fh);
out_nofree:
if (IS_ERR(mnt))
dprintk("<-- %s(): error %ld\n", __func__, PTR_ERR(mnt));
else
dprintk("<-- %s() = %p\n", __func__, mnt);
return mnt;
}
static int
nfs_namespace_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
{
if (NFS_FH(dentry->d_inode)->size != 0)
return nfs_getattr(mnt, dentry, stat);
generic_fillattr(dentry->d_inode, stat);
return 0;
}
static int
nfs_namespace_setattr(struct dentry *dentry, struct iattr *attr)
{
if (NFS_FH(dentry->d_inode)->size != 0)
return nfs_setattr(dentry, attr);
return -EACCES;
}
const struct inode_operations nfs_mountpoint_inode_operations = {
.getattr = nfs_getattr,
.setattr = nfs_setattr,
};
const struct inode_operations nfs_referral_inode_operations = {
.getattr = nfs_namespace_getattr,
.setattr = nfs_namespace_setattr,
};
static void nfs_expire_automounts(struct work_struct *work)
{
struct list_head *list = &nfs_automount_list;
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);
}
/*
* 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)
{
return vfs_kern_mount(&nfs_xdev_fs_type, 0, devname, mountdata);
}
/**
* nfs_do_submount - set up mountpoint when crossing a filesystem boundary
* @dentry - parent directory
* @fh - filehandle for new root dentry
* @fattr - attributes for new root inode
* @authflavor - security flavor to use when performing the mount
*
*/
struct vfsmount *nfs_do_submount(struct dentry *dentry, struct nfs_fh *fh,
struct nfs_fattr *fattr, rpc_authflavor_t authflavor)
{
struct nfs_clone_mount mountdata = {
.sb = dentry->d_sb,
.dentry = dentry,
.fh = fh,
.fattr = fattr,
.authflavor = authflavor,
};
struct vfsmount *mnt = ERR_PTR(-ENOMEM);
char *page = (char *) __get_free_page(GFP_USER);
char *devname;
dprintk("--> nfs_do_submount()\n");
dprintk("%s: submounting on %pd2\n", __func__,
dentry);
if (page == NULL)
goto out;
devname = nfs_devname(dentry, page, PAGE_SIZE);
mnt = (struct vfsmount *)devname;
if (IS_ERR(devname))
goto free_page;
mnt = nfs_do_clone_mount(NFS_SB(dentry->d_sb), devname, &mountdata);
free_page:
free_page((unsigned long)page);
out:
dprintk("%s: done\n", __func__);
dprintk("<-- nfs_do_submount() = %p\n", mnt);
return mnt;
}
EXPORT_SYMBOL_GPL(nfs_do_submount);
struct vfsmount *nfs_submount(struct nfs_server *server, struct dentry *dentry,
struct nfs_fh *fh, struct nfs_fattr *fattr)
{
int err;
struct dentry *parent = dget_parent(dentry);
/* Look it up again to get its attributes */
err = server->nfs_client->rpc_ops->lookup(parent->d_inode, &dentry->d_name, fh, fattr, NULL);
dput(parent);
if (err != 0)
return ERR_PTR(err);
return nfs_do_submount(dentry, fh, fattr, server->client->cl_auth->au_flavor);
}
EXPORT_SYMBOL_GPL(nfs_submount);