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/config.h>
12 #include <linux/dcache.h>
13 #include <linux/mount.h>
14 #include <linux/namei.h>
15 #include <linux/nfs_fs.h>
16 #include <linux/string.h>
17 #include <linux/sunrpc/clnt.h>
18 #include <linux/vfs.h>
21 #define NFSDBG_FACILITY NFSDBG_VFS
23 static void nfs_expire_automounts(void *list);
25 LIST_HEAD(nfs_automount_list);
26 static DECLARE_WORK(nfs_automount_task, nfs_expire_automounts, &nfs_automount_list);
27 int nfs_mountpoint_expiry_timeout = 500 * HZ;
30 * nfs_path - reconstruct the path given an arbitrary dentry
31 * @base - arbitrary string to prepend to the path
32 * @droot - pointer to root dentry for mountpoint
33 * @dentry - pointer to dentry
34 * @buffer - result buffer
35 * @buflen - length of buffer
37 * Helper function for constructing the path from the
38 * root dentry to an arbitrary hashed dentry.
40 * This is mainly for use in figuring out the path on the
41 * server side when automounting on top of an existing partition.
43 char *nfs_path(const char *base,
44 const struct dentry *droot,
45 const struct dentry *dentry,
46 char *buffer, ssize_t buflen)
48 char *end = buffer+buflen;
53 spin_lock(&dcache_lock);
54 while (!IS_ROOT(dentry) && dentry != droot) {
55 namelen = dentry->d_name.len;
56 buflen -= namelen + 1;
60 memcpy(end, dentry->d_name.name, namelen);
62 dentry = dentry->d_parent;
64 spin_unlock(&dcache_lock);
65 namelen = strlen(base);
66 /* Strip off excess slashes in base string */
67 while (namelen > 0 && base[namelen - 1] == '/')
73 memcpy(end, base, namelen);
76 spin_unlock(&dcache_lock);
78 return ERR_PTR(-ENAMETOOLONG);
82 * nfs_follow_mountpoint - handle crossing a mountpoint on the server
83 * @dentry - dentry of mountpoint
84 * @nd - nameidata info
86 * When we encounter a mountpoint on the server, we want to set up
87 * a mountpoint on the client too, to prevent inode numbers from
88 * colliding, and to allow "df" to work properly.
89 * On NFSv4, we also want to allow for the fact that different
90 * filesystems may be migrated to different servers in a failover
91 * situation, and that different filesystems may want to use
92 * different security flavours.
94 static void * nfs_follow_mountpoint(struct dentry *dentry, struct nameidata *nd)
97 struct nfs_server *server = NFS_SERVER(dentry->d_inode);
98 struct dentry *parent;
100 struct nfs_fattr fattr;
103 dprintk("--> nfs_follow_mountpoint()\n");
105 BUG_ON(IS_ROOT(dentry));
106 dprintk("%s: enter\n", __FUNCTION__);
108 nd->dentry = dget(dentry);
110 /* Look it up again */
111 parent = dget_parent(nd->dentry);
112 err = server->nfs_client->rpc_ops->lookup(parent->d_inode,
119 if (fattr.valid & NFS_ATTR_FATTR_V4_REFERRAL)
120 mnt = nfs_do_refmount(nd->mnt, nd->dentry);
122 mnt = nfs_do_submount(nd->mnt, nd->dentry, &fh, &fattr);
128 err = do_add_mount(mnt, nd, nd->mnt->mnt_flags|MNT_SHRINKABLE, &nfs_automount_list);
138 nd->dentry = dget(mnt->mnt_root);
139 schedule_delayed_work(&nfs_automount_task, nfs_mountpoint_expiry_timeout);
141 dprintk("%s: done, returned %d\n", __FUNCTION__, err);
143 dprintk("<-- nfs_follow_mountpoint() = %d\n", err);
149 while(d_mountpoint(nd->dentry) && follow_down(&nd->mnt, &nd->dentry))
155 struct inode_operations nfs_mountpoint_inode_operations = {
156 .follow_link = nfs_follow_mountpoint,
157 .getattr = nfs_getattr,
160 struct inode_operations nfs_referral_inode_operations = {
161 .follow_link = nfs_follow_mountpoint,
164 static void nfs_expire_automounts(void *data)
166 struct list_head *list = (struct list_head *)data;
168 mark_mounts_for_expiry(list);
169 if (!list_empty(list))
170 schedule_delayed_work(&nfs_automount_task, nfs_mountpoint_expiry_timeout);
173 void nfs_release_automount_timer(void)
175 if (list_empty(&nfs_automount_list)) {
176 cancel_delayed_work(&nfs_automount_task);
177 flush_scheduled_work();
182 * Clone a mountpoint of the appropriate type
184 static struct vfsmount *nfs_do_clone_mount(struct nfs_server *server,
186 struct nfs_clone_mount *mountdata)
189 struct vfsmount *mnt = NULL;
190 switch (server->nfs_client->cl_nfsversion) {
193 mnt = vfs_kern_mount(&nfs_xdev_fs_type, 0, devname, mountdata);
196 mnt = vfs_kern_mount(&nfs4_xdev_fs_type, 0, devname, mountdata);
200 return vfs_kern_mount(&nfs_xdev_fs_type, 0, devname, mountdata);
205 * nfs_do_submount - set up mountpoint when crossing a filesystem boundary
206 * @mnt_parent - mountpoint of parent directory
207 * @dentry - parent directory
208 * @fh - filehandle for new root dentry
209 * @fattr - attributes for new root inode
212 struct vfsmount *nfs_do_submount(const struct vfsmount *mnt_parent,
213 const struct dentry *dentry, struct nfs_fh *fh,
214 struct nfs_fattr *fattr)
216 struct nfs_clone_mount mountdata = {
217 .sb = mnt_parent->mnt_sb,
222 struct vfsmount *mnt = ERR_PTR(-ENOMEM);
223 char *page = (char *) __get_free_page(GFP_USER);
226 dprintk("--> nfs_do_submount()\n");
228 dprintk("%s: submounting on %s/%s\n", __FUNCTION__,
229 dentry->d_parent->d_name.name,
230 dentry->d_name.name);
233 devname = nfs_devname(mnt_parent, dentry, page, PAGE_SIZE);
234 mnt = (struct vfsmount *)devname;
237 mnt = nfs_do_clone_mount(NFS_SB(mnt_parent->mnt_sb), devname, &mountdata);
239 free_page((unsigned long)page);
241 dprintk("%s: done\n", __FUNCTION__);
243 dprintk("<-- nfs_do_submount() = %p\n", mnt);