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_WORK(nfs_automount_task, nfs_expire_automounts, &nfs_automount_list);
25 int nfs_mountpoint_expiry_timeout = 500 * HZ;
28 * nfs_path - reconstruct the path given an arbitrary dentry
29 * @base - arbitrary string to prepend to the path
30 * @droot - pointer to root dentry for mountpoint
31 * @dentry - pointer to dentry
32 * @buffer - result buffer
33 * @buflen - length of buffer
35 * Helper function for constructing the path from the
36 * root dentry to an arbitrary hashed dentry.
38 * This is mainly for use in figuring out the path on the
39 * server side when automounting on top of an existing partition.
41 char *nfs_path(const char *base,
42 const struct dentry *droot,
43 const struct dentry *dentry,
44 char *buffer, ssize_t buflen)
46 char *end = buffer+buflen;
51 spin_lock(&dcache_lock);
52 while (!IS_ROOT(dentry) && dentry != droot) {
53 namelen = dentry->d_name.len;
54 buflen -= namelen + 1;
58 memcpy(end, dentry->d_name.name, namelen);
60 dentry = dentry->d_parent;
62 spin_unlock(&dcache_lock);
63 namelen = strlen(base);
64 /* Strip off excess slashes in base string */
65 while (namelen > 0 && base[namelen - 1] == '/')
71 memcpy(end, base, namelen);
74 spin_unlock(&dcache_lock);
76 return ERR_PTR(-ENAMETOOLONG);
80 * nfs_follow_mountpoint - handle crossing a mountpoint on the server
81 * @dentry - dentry of mountpoint
82 * @nd - nameidata info
84 * When we encounter a mountpoint on the server, we want to set up
85 * a mountpoint on the client too, to prevent inode numbers from
86 * colliding, and to allow "df" to work properly.
87 * On NFSv4, we also want to allow for the fact that different
88 * filesystems may be migrated to different servers in a failover
89 * situation, and that different filesystems may want to use
90 * different security flavours.
92 static void * nfs_follow_mountpoint(struct dentry *dentry, struct nameidata *nd)
95 struct nfs_server *server = NFS_SERVER(dentry->d_inode);
96 struct dentry *parent;
98 struct nfs_fattr fattr;
101 dprintk("--> nfs_follow_mountpoint()\n");
103 BUG_ON(IS_ROOT(dentry));
104 dprintk("%s: enter\n", __FUNCTION__);
106 nd->dentry = dget(dentry);
108 /* Look it up again */
109 parent = dget_parent(nd->dentry);
110 err = server->nfs_client->rpc_ops->lookup(parent->d_inode,
117 if (fattr.valid & NFS_ATTR_FATTR_V4_REFERRAL)
118 mnt = nfs_do_refmount(nd->mnt, nd->dentry);
120 mnt = nfs_do_submount(nd->mnt, nd->dentry, &fh, &fattr);
126 err = do_add_mount(mnt, nd, nd->mnt->mnt_flags|MNT_SHRINKABLE, &nfs_automount_list);
136 nd->dentry = dget(mnt->mnt_root);
137 schedule_delayed_work(&nfs_automount_task, nfs_mountpoint_expiry_timeout);
139 dprintk("%s: done, returned %d\n", __FUNCTION__, err);
141 dprintk("<-- nfs_follow_mountpoint() = %d\n", err);
147 while(d_mountpoint(nd->dentry) && follow_down(&nd->mnt, &nd->dentry))
153 struct inode_operations nfs_mountpoint_inode_operations = {
154 .follow_link = nfs_follow_mountpoint,
155 .getattr = nfs_getattr,
158 struct inode_operations nfs_referral_inode_operations = {
159 .follow_link = nfs_follow_mountpoint,
162 static void nfs_expire_automounts(void *data)
164 struct list_head *list = (struct list_head *)data;
166 mark_mounts_for_expiry(list);
167 if (!list_empty(list))
168 schedule_delayed_work(&nfs_automount_task, nfs_mountpoint_expiry_timeout);
171 void nfs_release_automount_timer(void)
173 if (list_empty(&nfs_automount_list)) {
174 cancel_delayed_work(&nfs_automount_task);
175 flush_scheduled_work();
180 * Clone a mountpoint of the appropriate type
182 static struct vfsmount *nfs_do_clone_mount(struct nfs_server *server,
184 struct nfs_clone_mount *mountdata)
187 struct vfsmount *mnt = NULL;
188 switch (server->nfs_client->cl_nfsversion) {
191 mnt = vfs_kern_mount(&nfs_xdev_fs_type, 0, devname, mountdata);
194 mnt = vfs_kern_mount(&nfs4_xdev_fs_type, 0, devname, mountdata);
198 return vfs_kern_mount(&nfs_xdev_fs_type, 0, devname, mountdata);
203 * nfs_do_submount - set up mountpoint when crossing a filesystem boundary
204 * @mnt_parent - mountpoint of parent directory
205 * @dentry - parent directory
206 * @fh - filehandle for new root dentry
207 * @fattr - attributes for new root inode
210 struct vfsmount *nfs_do_submount(const struct vfsmount *mnt_parent,
211 const struct dentry *dentry, struct nfs_fh *fh,
212 struct nfs_fattr *fattr)
214 struct nfs_clone_mount mountdata = {
215 .sb = mnt_parent->mnt_sb,
220 struct vfsmount *mnt = ERR_PTR(-ENOMEM);
221 char *page = (char *) __get_free_page(GFP_USER);
224 dprintk("--> nfs_do_submount()\n");
226 dprintk("%s: submounting on %s/%s\n", __FUNCTION__,
227 dentry->d_parent->d_name.name,
228 dentry->d_name.name);
231 devname = nfs_devname(mnt_parent, dentry, page, PAGE_SIZE);
232 mnt = (struct vfsmount *)devname;
235 mnt = nfs_do_clone_mount(NFS_SB(mnt_parent->mnt_sb), devname, &mountdata);
237 free_page((unsigned long)page);
239 dprintk("%s: done\n", __FUNCTION__);
241 dprintk("<-- nfs_do_submount() = %p\n", mnt);