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)
52 char *end = buffer+buflen;
57 spin_lock(&dcache_lock);
58 while (!IS_ROOT(dentry) && dentry != droot) {
59 namelen = dentry->d_name.len;
60 buflen -= namelen + 1;
64 memcpy(end, dentry->d_name.name, namelen);
66 dentry = dentry->d_parent;
68 spin_unlock(&dcache_lock);
74 namelen = strlen(base);
75 /* Strip off excess slashes in base string */
76 while (namelen > 0 && base[namelen - 1] == '/')
82 memcpy(end, base, namelen);
85 spin_unlock(&dcache_lock);
87 return ERR_PTR(-ENAMETOOLONG);
91 * nfs_follow_mountpoint - handle crossing a mountpoint on the server
92 * @dentry - dentry of mountpoint
93 * @nd - nameidata info
95 * When we encounter a mountpoint on the server, we want to set up
96 * a mountpoint on the client too, to prevent inode numbers from
97 * colliding, and to allow "df" to work properly.
98 * On NFSv4, we also want to allow for the fact that different
99 * filesystems may be migrated to different servers in a failover
100 * situation, and that different filesystems may want to use
101 * different security flavours.
103 static void * nfs_follow_mountpoint(struct dentry *dentry, struct nameidata *nd)
105 struct vfsmount *mnt;
106 struct nfs_server *server = NFS_SERVER(dentry->d_inode);
107 struct dentry *parent;
109 struct nfs_fattr fattr;
112 dprintk("--> nfs_follow_mountpoint()\n");
118 dprintk("%s: enter\n", __func__);
119 dput(nd->path.dentry);
120 nd->path.dentry = dget(dentry);
122 /* Look it up again */
123 parent = dget_parent(nd->path.dentry);
124 err = server->nfs_client->rpc_ops->lookup(parent->d_inode,
125 &nd->path.dentry->d_name,
131 if (fattr.valid & NFS_ATTR_FATTR_V4_REFERRAL)
132 mnt = nfs_do_refmount(nd->path.mnt, nd->path.dentry);
134 mnt = nfs_do_submount(nd->path.mnt, nd->path.dentry, &fh,
141 err = do_add_mount(mnt, &nd->path, nd->path.mnt->mnt_flags|MNT_SHRINKABLE,
142 &nfs_automount_list);
151 nd->path.dentry = dget(mnt->mnt_root);
152 schedule_delayed_work(&nfs_automount_task, nfs_mountpoint_expiry_timeout);
154 dprintk("%s: done, returned %d\n", __func__, err);
156 dprintk("<-- nfs_follow_mountpoint() = %d\n", err);
162 while (d_mountpoint(nd->path.dentry) &&
163 follow_down(&nd->path))
169 const struct inode_operations nfs_mountpoint_inode_operations = {
170 .follow_link = nfs_follow_mountpoint,
171 .getattr = nfs_getattr,
174 const struct inode_operations nfs_referral_inode_operations = {
175 .follow_link = nfs_follow_mountpoint,
178 static void nfs_expire_automounts(struct work_struct *work)
180 struct list_head *list = &nfs_automount_list;
182 mark_mounts_for_expiry(list);
183 if (!list_empty(list))
184 schedule_delayed_work(&nfs_automount_task, nfs_mountpoint_expiry_timeout);
187 void nfs_release_automount_timer(void)
189 if (list_empty(&nfs_automount_list))
190 cancel_delayed_work(&nfs_automount_task);
194 * Clone a mountpoint of the appropriate type
196 static struct vfsmount *nfs_do_clone_mount(struct nfs_server *server,
198 struct nfs_clone_mount *mountdata)
201 struct vfsmount *mnt = ERR_PTR(-EINVAL);
202 switch (server->nfs_client->rpc_ops->version) {
205 mnt = vfs_kern_mount(&nfs_xdev_fs_type, 0, devname, mountdata);
208 mnt = vfs_kern_mount(&nfs4_xdev_fs_type, 0, devname, mountdata);
212 return vfs_kern_mount(&nfs_xdev_fs_type, 0, devname, mountdata);
217 * nfs_do_submount - set up mountpoint when crossing a filesystem boundary
218 * @mnt_parent - mountpoint of parent directory
219 * @dentry - parent directory
220 * @fh - filehandle for new root dentry
221 * @fattr - attributes for new root inode
224 static struct vfsmount *nfs_do_submount(const struct vfsmount *mnt_parent,
225 const struct dentry *dentry,
227 struct nfs_fattr *fattr)
229 struct nfs_clone_mount mountdata = {
230 .sb = mnt_parent->mnt_sb,
235 struct vfsmount *mnt = ERR_PTR(-ENOMEM);
236 char *page = (char *) __get_free_page(GFP_USER);
239 dprintk("--> nfs_do_submount()\n");
241 dprintk("%s: submounting on %s/%s\n", __func__,
242 dentry->d_parent->d_name.name,
243 dentry->d_name.name);
246 devname = nfs_devname(mnt_parent, dentry, page, PAGE_SIZE);
247 mnt = (struct vfsmount *)devname;
250 mnt = nfs_do_clone_mount(NFS_SB(mnt_parent->mnt_sb), devname, &mountdata);
252 free_page((unsigned long)page);
254 dprintk("%s: done\n", __func__);
256 dprintk("<-- nfs_do_submount() = %p\n", mnt);