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/mount.h>
12 #include <linux/namei.h>
13 #include <linux/nfs_fs.h>
14 #include <linux/string.h>
15 #include <linux/sunrpc/clnt.h>
16 #include <linux/vfs.h>
19 #define NFSDBG_FACILITY NFSDBG_VFS
21 static void nfs_expire_automounts(void *list);
23 LIST_HEAD(nfs_automount_list);
24 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);
69 namelen = strlen(base);
70 /* Strip off excess slashes in base string */
71 while (namelen > 0 && base[namelen - 1] == '/')
77 memcpy(end, base, namelen);
80 spin_unlock(&dcache_lock);
82 return ERR_PTR(-ENAMETOOLONG);
86 * nfs_follow_mountpoint - handle crossing a mountpoint on the server
87 * @dentry - dentry of mountpoint
88 * @nd - nameidata info
90 * When we encounter a mountpoint on the server, we want to set up
91 * a mountpoint on the client too, to prevent inode numbers from
92 * colliding, and to allow "df" to work properly.
93 * On NFSv4, we also want to allow for the fact that different
94 * filesystems may be migrated to different servers in a failover
95 * situation, and that different filesystems may want to use
96 * different security flavours.
98 static void * nfs_follow_mountpoint(struct dentry *dentry, struct nameidata *nd)
100 struct vfsmount *mnt;
101 struct nfs_server *server = NFS_SERVER(dentry->d_inode);
102 struct dentry *parent;
104 struct nfs_fattr fattr;
107 dprintk("--> nfs_follow_mountpoint()\n");
109 BUG_ON(IS_ROOT(dentry));
110 dprintk("%s: enter\n", __FUNCTION__);
112 nd->dentry = dget(dentry);
114 /* Look it up again */
115 parent = dget_parent(nd->dentry);
116 err = server->nfs_client->rpc_ops->lookup(parent->d_inode,
123 if (fattr.valid & NFS_ATTR_FATTR_V4_REFERRAL)
124 mnt = nfs_do_refmount(nd->mnt, nd->dentry);
126 mnt = nfs_do_submount(nd->mnt, nd->dentry, &fh, &fattr);
132 err = do_add_mount(mnt, nd, nd->mnt->mnt_flags|MNT_SHRINKABLE, &nfs_automount_list);
142 nd->dentry = dget(mnt->mnt_root);
143 schedule_delayed_work(&nfs_automount_task, nfs_mountpoint_expiry_timeout);
145 dprintk("%s: done, returned %d\n", __FUNCTION__, err);
147 dprintk("<-- nfs_follow_mountpoint() = %d\n", err);
153 while(d_mountpoint(nd->dentry) && follow_down(&nd->mnt, &nd->dentry))
159 struct inode_operations nfs_mountpoint_inode_operations = {
160 .follow_link = nfs_follow_mountpoint,
161 .getattr = nfs_getattr,
164 struct inode_operations nfs_referral_inode_operations = {
165 .follow_link = nfs_follow_mountpoint,
168 static void nfs_expire_automounts(void *data)
170 struct list_head *list = (struct list_head *)data;
172 mark_mounts_for_expiry(list);
173 if (!list_empty(list))
174 schedule_delayed_work(&nfs_automount_task, nfs_mountpoint_expiry_timeout);
177 void nfs_release_automount_timer(void)
179 if (list_empty(&nfs_automount_list)) {
180 cancel_delayed_work(&nfs_automount_task);
181 flush_scheduled_work();
186 * Clone a mountpoint of the appropriate type
188 static struct vfsmount *nfs_do_clone_mount(struct nfs_server *server,
190 struct nfs_clone_mount *mountdata)
193 struct vfsmount *mnt = NULL;
194 switch (server->nfs_client->cl_nfsversion) {
197 mnt = vfs_kern_mount(&nfs_xdev_fs_type, 0, devname, mountdata);
200 mnt = vfs_kern_mount(&nfs4_xdev_fs_type, 0, devname, mountdata);
204 return vfs_kern_mount(&nfs_xdev_fs_type, 0, devname, mountdata);
209 * nfs_do_submount - set up mountpoint when crossing a filesystem boundary
210 * @mnt_parent - mountpoint of parent directory
211 * @dentry - parent directory
212 * @fh - filehandle for new root dentry
213 * @fattr - attributes for new root inode
216 static struct vfsmount *nfs_do_submount(const struct vfsmount *mnt_parent,
217 const struct dentry *dentry,
219 struct nfs_fattr *fattr)
221 struct nfs_clone_mount mountdata = {
222 .sb = mnt_parent->mnt_sb,
227 struct vfsmount *mnt = ERR_PTR(-ENOMEM);
228 char *page = (char *) __get_free_page(GFP_USER);
231 dprintk("--> nfs_do_submount()\n");
233 dprintk("%s: submounting on %s/%s\n", __FUNCTION__,
234 dentry->d_parent->d_name.name,
235 dentry->d_name.name);
238 devname = nfs_devname(mnt_parent, dentry, page, PAGE_SIZE);
239 mnt = (struct vfsmount *)devname;
242 mnt = nfs_do_clone_mount(NFS_SB(mnt_parent->mnt_sb), devname, &mountdata);
244 free_page((unsigned long)page);
246 dprintk("%s: done\n", __FUNCTION__);
248 dprintk("<-- nfs_do_submount() = %p\n", mnt);