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
);