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_follow_mountpoint - handle crossing a mountpoint on the server
101 * @dentry - dentry of mountpoint
102 * @nd - nameidata info
104 * When we encounter a mountpoint on the server, we want to set up
105 * a mountpoint on the client too, to prevent inode numbers from
106 * colliding, and to allow "df" to work properly.
107 * On NFSv4, we also want to allow for the fact that different
108 * filesystems may be migrated to different servers in a failover
109 * situation, and that different filesystems may want to use
110 * different security flavours.
112 static void * nfs_follow_mountpoint(struct dentry
*dentry
, struct nameidata
*nd
)
114 struct vfsmount
*mnt
;
115 struct nfs_server
*server
= NFS_SERVER(dentry
->d_inode
);
116 struct dentry
*parent
;
117 struct nfs_fh
*fh
= NULL
;
118 struct nfs_fattr
*fattr
= NULL
;
121 dprintk("--> nfs_follow_mountpoint()\n");
128 fh
= nfs_alloc_fhandle();
129 fattr
= nfs_alloc_fattr();
130 if (fh
== NULL
|| fattr
== NULL
)
133 dprintk("%s: enter\n", __func__
);
134 dput(nd
->path
.dentry
);
135 nd
->path
.dentry
= dget(dentry
);
137 /* Look it up again */
138 parent
= dget_parent(nd
->path
.dentry
);
139 err
= server
->nfs_client
->rpc_ops
->lookup(parent
->d_inode
,
140 &nd
->path
.dentry
->d_name
,
146 if (fattr
->valid
& NFS_ATTR_FATTR_V4_REFERRAL
)
147 mnt
= nfs_do_refmount(nd
->path
.mnt
, nd
->path
.dentry
);
149 mnt
= nfs_do_submount(nd
->path
.mnt
, nd
->path
.dentry
, fh
,
156 err
= do_add_mount(mnt
, &nd
->path
, nd
->path
.mnt
->mnt_flags
|MNT_SHRINKABLE
,
157 &nfs_automount_list
);
166 nd
->path
.dentry
= dget(mnt
->mnt_root
);
167 schedule_delayed_work(&nfs_automount_task
, nfs_mountpoint_expiry_timeout
);
169 nfs_free_fattr(fattr
);
170 nfs_free_fhandle(fh
);
171 dprintk("%s: done, returned %d\n", __func__
, err
);
173 dprintk("<-- nfs_follow_mountpoint() = %d\n", err
);
179 while (d_mountpoint(nd
->path
.dentry
) &&
180 follow_down(&nd
->path
))
186 const struct inode_operations nfs_mountpoint_inode_operations
= {
187 .follow_link
= nfs_follow_mountpoint
,
188 .getattr
= nfs_getattr
,
191 const struct inode_operations nfs_referral_inode_operations
= {
192 .follow_link
= nfs_follow_mountpoint
,
195 static void nfs_expire_automounts(struct work_struct
*work
)
197 struct list_head
*list
= &nfs_automount_list
;
199 mark_mounts_for_expiry(list
);
200 if (!list_empty(list
))
201 schedule_delayed_work(&nfs_automount_task
, nfs_mountpoint_expiry_timeout
);
204 void nfs_release_automount_timer(void)
206 if (list_empty(&nfs_automount_list
))
207 cancel_delayed_work(&nfs_automount_task
);
211 * Clone a mountpoint of the appropriate type
213 static struct vfsmount
*nfs_do_clone_mount(struct nfs_server
*server
,
215 struct nfs_clone_mount
*mountdata
)
218 struct vfsmount
*mnt
= ERR_PTR(-EINVAL
);
219 switch (server
->nfs_client
->rpc_ops
->version
) {
222 mnt
= vfs_kern_mount(&nfs_xdev_fs_type
, 0, devname
, mountdata
);
225 mnt
= vfs_kern_mount(&nfs4_xdev_fs_type
, 0, devname
, mountdata
);
229 return vfs_kern_mount(&nfs_xdev_fs_type
, 0, devname
, mountdata
);
234 * nfs_do_submount - set up mountpoint when crossing a filesystem boundary
235 * @mnt_parent - mountpoint of parent directory
236 * @dentry - parent directory
237 * @fh - filehandle for new root dentry
238 * @fattr - attributes for new root inode
241 static struct vfsmount
*nfs_do_submount(const struct vfsmount
*mnt_parent
,
242 const struct dentry
*dentry
,
244 struct nfs_fattr
*fattr
)
246 struct nfs_clone_mount mountdata
= {
247 .sb
= mnt_parent
->mnt_sb
,
252 struct vfsmount
*mnt
= ERR_PTR(-ENOMEM
);
253 char *page
= (char *) __get_free_page(GFP_USER
);
256 dprintk("--> nfs_do_submount()\n");
258 dprintk("%s: submounting on %s/%s\n", __func__
,
259 dentry
->d_parent
->d_name
.name
,
260 dentry
->d_name
.name
);
263 devname
= nfs_devname(mnt_parent
, dentry
, page
, PAGE_SIZE
);
264 mnt
= (struct vfsmount
*)devname
;
267 mnt
= nfs_do_clone_mount(NFS_SB(mnt_parent
->mnt_sb
), devname
, &mountdata
);
269 free_page((unsigned long)page
);
271 dprintk("%s: done\n", __func__
);
273 dprintk("<-- nfs_do_submount() = %p\n", mnt
);