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_d_automount - Handle crossing a mountpoint on the server
101 * @path - The mountpoint
103 * When we encounter a mountpoint on the server, we want to set up
104 * a mountpoint on the client too, to prevent inode numbers from
105 * colliding, and to allow "df" to work properly.
106 * On NFSv4, we also want to allow for the fact that different
107 * filesystems may be migrated to different servers in a failover
108 * situation, and that different filesystems may want to use
109 * different security flavours.
111 struct vfsmount *nfs_d_automount(struct path *path)
113 struct vfsmount *mnt;
114 struct nfs_server *server = NFS_SERVER(path->dentry->d_inode);
115 struct dentry *parent;
116 struct nfs_fh *fh = NULL;
117 struct nfs_fattr *fattr = NULL;
120 dprintk("--> nfs_d_automount()\n");
122 mnt = ERR_PTR(-ESTALE);
123 if (IS_ROOT(path->dentry))
126 mnt = ERR_PTR(-ENOMEM);
127 fh = nfs_alloc_fhandle();
128 fattr = nfs_alloc_fattr();
129 if (fh == NULL || fattr == NULL)
132 dprintk("%s: enter\n", __func__);
134 /* Look it up again to get its attributes */
135 parent = dget_parent(path->dentry);
136 err = server->nfs_client->rpc_ops->lookup(parent->d_inode,
137 &path->dentry->d_name,
145 if (fattr->valid & NFS_ATTR_FATTR_V4_REFERRAL)
146 mnt = nfs_do_refmount(path->mnt, path->dentry);
148 mnt = nfs_do_submount(path->mnt, path->dentry, fh, fattr);
153 err = do_add_mount(mnt, path, path->mnt->mnt_flags | MNT_SHRINKABLE,
154 &nfs_automount_list);
157 dprintk("%s: done, success\n", __func__);
158 schedule_delayed_work(&nfs_automount_task, nfs_mountpoint_expiry_timeout);
161 /* someone else made a mount here whilst we were busy */
163 dprintk("%s: done, collision\n", __func__);
168 dprintk("%s: done, error %d\n", __func__, err);
174 nfs_free_fattr(fattr);
175 nfs_free_fhandle(fh);
177 dprintk("<-- nfs_follow_mountpoint() = %p\n", mnt);
181 const struct inode_operations nfs_mountpoint_inode_operations = {
182 .getattr = nfs_getattr,
185 const struct inode_operations nfs_referral_inode_operations = {
188 static void nfs_expire_automounts(struct work_struct *work)
190 struct list_head *list = &nfs_automount_list;
192 mark_mounts_for_expiry(list);
193 if (!list_empty(list))
194 schedule_delayed_work(&nfs_automount_task, nfs_mountpoint_expiry_timeout);
197 void nfs_release_automount_timer(void)
199 if (list_empty(&nfs_automount_list))
200 cancel_delayed_work(&nfs_automount_task);
204 * Clone a mountpoint of the appropriate type
206 static struct vfsmount *nfs_do_clone_mount(struct nfs_server *server,
208 struct nfs_clone_mount *mountdata)
211 struct vfsmount *mnt = ERR_PTR(-EINVAL);
212 switch (server->nfs_client->rpc_ops->version) {
215 mnt = vfs_kern_mount(&nfs_xdev_fs_type, 0, devname, mountdata);
218 mnt = vfs_kern_mount(&nfs4_xdev_fs_type, 0, devname, mountdata);
222 return vfs_kern_mount(&nfs_xdev_fs_type, 0, devname, mountdata);
227 * nfs_do_submount - set up mountpoint when crossing a filesystem boundary
228 * @mnt_parent - mountpoint of parent directory
229 * @dentry - parent directory
230 * @fh - filehandle for new root dentry
231 * @fattr - attributes for new root inode
234 static struct vfsmount *nfs_do_submount(const struct vfsmount *mnt_parent,
235 const struct dentry *dentry,
237 struct nfs_fattr *fattr)
239 struct nfs_clone_mount mountdata = {
240 .sb = mnt_parent->mnt_sb,
245 struct vfsmount *mnt = ERR_PTR(-ENOMEM);
246 char *page = (char *) __get_free_page(GFP_USER);
249 dprintk("--> nfs_do_submount()\n");
251 dprintk("%s: submounting on %s/%s\n", __func__,
252 dentry->d_parent->d_name.name,
253 dentry->d_name.name);
256 devname = nfs_devname(mnt_parent, dentry, page, PAGE_SIZE);
257 mnt = (struct vfsmount *)devname;
260 mnt = nfs_do_clone_mount(NFS_SB(mnt_parent->mnt_sb), devname, &mountdata);
262 free_page((unsigned long)page);
264 dprintk("%s: done\n", __func__);
266 dprintk("<-- nfs_do_submount() = %p\n", mnt);