2 * linux/fs/nfs/namespace.c
4 * Copyright (C) 2005 Trond Myklebust <Trond.Myklebust@netapp.com>
5 * - Modified by David Howells <dhowells@redhat.com>
10 #include <linux/dcache.h>
11 #include <linux/gfp.h>
12 #include <linux/mount.h>
13 #include <linux/namei.h>
14 #include <linux/nfs_fs.h>
15 #include <linux/string.h>
16 #include <linux/sunrpc/clnt.h>
17 #include <linux/vfs.h>
20 #define NFSDBG_FACILITY NFSDBG_VFS
22 static void nfs_expire_automounts(struct work_struct *work);
24 static LIST_HEAD(nfs_automount_list);
25 static DECLARE_DELAYED_WORK(nfs_automount_task, nfs_expire_automounts);
26 int nfs_mountpoint_expiry_timeout = 500 * HZ;
28 static struct vfsmount *nfs_do_submount(const struct vfsmount *mnt_parent,
29 const struct dentry *dentry,
31 struct nfs_fattr *fattr);
34 * nfs_path - reconstruct the path given an arbitrary dentry
35 * @base - arbitrary string to prepend to the path
36 * @droot - pointer to root dentry for mountpoint
37 * @dentry - pointer to dentry
38 * @buffer - result buffer
39 * @buflen - length of buffer
41 * Helper function for constructing the path from the
42 * root dentry to an arbitrary hashed dentry.
44 * This is mainly for use in figuring out the path on the
45 * server side when automounting on top of an existing partition.
47 char *nfs_path(const char *base,
48 const struct dentry *droot,
49 const struct dentry *dentry,
50 char *buffer, ssize_t buflen)
61 seq = read_seqbegin(&rename_lock);
63 while (!IS_ROOT(dentry) && dentry != droot) {
64 namelen = dentry->d_name.len;
65 buflen -= namelen + 1;
69 memcpy(end, dentry->d_name.name, namelen);
71 dentry = dentry->d_parent;
74 if (read_seqretry(&rename_lock, seq))
81 namelen = strlen(base);
82 /* Strip off excess slashes in base string */
83 while (namelen > 0 && base[namelen - 1] == '/')
89 memcpy(end, base, namelen);
93 if (read_seqretry(&rename_lock, seq))
96 return ERR_PTR(-ENAMETOOLONG);
100 * nfs_follow_mountpoint - handle crossing a mountpoint on the server
101 * @dentry - dentry of mountpoint
102 * @nd - nameidata info
104 * When we encounter a mountpoint on the server, we want to set up
105 * a mountpoint on the client too, to prevent inode numbers from
106 * colliding, and to allow "df" to work properly.
107 * On NFSv4, we also want to allow for the fact that different
108 * filesystems may be migrated to different servers in a failover
109 * situation, and that different filesystems may want to use
110 * different security flavours.
112 static void * nfs_follow_mountpoint(struct dentry *dentry, struct nameidata *nd)
114 struct vfsmount *mnt;
115 struct nfs_server *server = NFS_SERVER(dentry->d_inode);
116 struct dentry *parent;
117 struct nfs_fh *fh = NULL;
118 struct nfs_fattr *fattr = NULL;
121 dprintk("--> nfs_follow_mountpoint()\n");
128 fh = nfs_alloc_fhandle();
129 fattr = nfs_alloc_fattr();
130 if (fh == NULL || fattr == NULL)
133 dprintk("%s: enter\n", __func__);
134 dput(nd->path.dentry);
135 nd->path.dentry = dget(dentry);
137 /* Look it up again */
138 parent = dget_parent(nd->path.dentry);
139 err = server->nfs_client->rpc_ops->lookup(parent->d_inode,
140 &nd->path.dentry->d_name,
146 if (fattr->valid & NFS_ATTR_FATTR_V4_REFERRAL)
147 mnt = nfs_do_refmount(nd->path.mnt, nd->path.dentry);
149 mnt = nfs_do_submount(nd->path.mnt, nd->path.dentry, fh,
156 err = do_add_mount(mnt, &nd->path, nd->path.mnt->mnt_flags|MNT_SHRINKABLE,
157 &nfs_automount_list);
166 nd->path.dentry = dget(mnt->mnt_root);
167 schedule_delayed_work(&nfs_automount_task, nfs_mountpoint_expiry_timeout);
169 nfs_free_fattr(fattr);
170 nfs_free_fhandle(fh);
171 dprintk("%s: done, returned %d\n", __func__, err);
173 dprintk("<-- nfs_follow_mountpoint() = %d\n", err);
179 while (d_mountpoint(nd->path.dentry) &&
180 follow_down(&nd->path))
186 const struct inode_operations nfs_mountpoint_inode_operations = {
187 .follow_link = nfs_follow_mountpoint,
188 .getattr = nfs_getattr,
191 const struct inode_operations nfs_referral_inode_operations = {
192 .follow_link = nfs_follow_mountpoint,
195 static void nfs_expire_automounts(struct work_struct *work)
197 struct list_head *list = &nfs_automount_list;
199 mark_mounts_for_expiry(list);
200 if (!list_empty(list))
201 schedule_delayed_work(&nfs_automount_task, nfs_mountpoint_expiry_timeout);
204 void nfs_release_automount_timer(void)
206 if (list_empty(&nfs_automount_list))
207 cancel_delayed_work(&nfs_automount_task);
211 * Clone a mountpoint of the appropriate type
213 static struct vfsmount *nfs_do_clone_mount(struct nfs_server *server,
215 struct nfs_clone_mount *mountdata)
218 struct vfsmount *mnt = ERR_PTR(-EINVAL);
219 switch (server->nfs_client->rpc_ops->version) {
222 mnt = vfs_kern_mount(&nfs_xdev_fs_type, 0, devname, mountdata);
225 mnt = vfs_kern_mount(&nfs4_xdev_fs_type, 0, devname, mountdata);
229 return vfs_kern_mount(&nfs_xdev_fs_type, 0, devname, mountdata);
234 * nfs_do_submount - set up mountpoint when crossing a filesystem boundary
235 * @mnt_parent - mountpoint of parent directory
236 * @dentry - parent directory
237 * @fh - filehandle for new root dentry
238 * @fattr - attributes for new root inode
241 static struct vfsmount *nfs_do_submount(const struct vfsmount *mnt_parent,
242 const struct dentry *dentry,
244 struct nfs_fattr *fattr)
246 struct nfs_clone_mount mountdata = {
247 .sb = mnt_parent->mnt_sb,
252 struct vfsmount *mnt = ERR_PTR(-ENOMEM);
253 char *page = (char *) __get_free_page(GFP_USER);
256 dprintk("--> nfs_do_submount()\n");
258 dprintk("%s: submounting on %s/%s\n", __func__,
259 dentry->d_parent->d_name.name,
260 dentry->d_name.name);
263 devname = nfs_devname(mnt_parent, dentry, page, PAGE_SIZE);
264 mnt = (struct vfsmount *)devname;
267 mnt = nfs_do_clone_mount(NFS_SB(mnt_parent->mnt_sb), devname, &mountdata);
269 free_page((unsigned long)page);
271 dprintk("%s: done\n", __func__);
273 dprintk("<-- nfs_do_submount() = %p\n", mnt);