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Trond Myklebust55a97592006-06-09 09:34:19 -04001/*
2 * linux/fs/nfs/namespace.c
3 *
4 * Copyright (C) 2005 Trond Myklebust <Trond.Myklebust@netapp.com>
David Howells54ceac42006-08-22 20:06:13 -04005 * - Modified by David Howells <dhowells@redhat.com>
Trond Myklebust55a97592006-06-09 09:34:19 -04006 *
7 * NFS namespace
8 */
9
Trond Myklebust55a97592006-06-09 09:34:19 -040010#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>
David Howellsf7b422b2006-06-09 09:34:33 -040017#include "internal.h"
Trond Myklebust55a97592006-06-09 09:34:19 -040018
19#define NFSDBG_FACILITY NFSDBG_VFS
20
David Howells65f27f32006-11-22 14:55:48 +000021static void nfs_expire_automounts(struct work_struct *work);
David Howellsf7b422b2006-06-09 09:34:33 -040022
Adrian Bunka3dab292008-04-14 21:41:32 +030023static LIST_HEAD(nfs_automount_list);
David Howells65f27f32006-11-22 14:55:48 +000024static DECLARE_DELAYED_WORK(nfs_automount_task, nfs_expire_automounts);
Trond Myklebust51d8fa62006-06-09 09:34:20 -040025int nfs_mountpoint_expiry_timeout = 500 * HZ;
26
Adrian Bunk66f37502006-09-27 01:51:13 -070027static struct vfsmount *nfs_do_submount(const struct vfsmount *mnt_parent,
28 const struct dentry *dentry,
29 struct nfs_fh *fh,
30 struct nfs_fattr *fattr);
31
Trond Myklebust55a97592006-06-09 09:34:19 -040032/*
David Howellsf7b422b2006-06-09 09:34:33 -040033 * nfs_path - reconstruct the path given an arbitrary dentry
34 * @base - arbitrary string to prepend to the path
David Howells54ceac42006-08-22 20:06:13 -040035 * @droot - pointer to root dentry for mountpoint
David Howellsf7b422b2006-06-09 09:34:33 -040036 * @dentry - pointer to dentry
37 * @buffer - result buffer
38 * @buflen - length of buffer
39 *
40 * Helper function for constructing the path from the
41 * root dentry to an arbitrary hashed dentry.
42 *
43 * This is mainly for use in figuring out the path on the
44 * server side when automounting on top of an existing partition.
45 */
David Howells54ceac42006-08-22 20:06:13 -040046char *nfs_path(const char *base,
47 const struct dentry *droot,
48 const struct dentry *dentry,
David Howellsf7b422b2006-06-09 09:34:33 -040049 char *buffer, ssize_t buflen)
50{
51 char *end = buffer+buflen;
52 int namelen;
53
54 *--end = '\0';
55 buflen--;
56 spin_lock(&dcache_lock);
David Howells54ceac42006-08-22 20:06:13 -040057 while (!IS_ROOT(dentry) && dentry != droot) {
David Howellsf7b422b2006-06-09 09:34:33 -040058 namelen = dentry->d_name.len;
59 buflen -= namelen + 1;
60 if (buflen < 0)
Josh Triplettce510192006-07-24 16:30:00 -070061 goto Elong_unlock;
David Howellsf7b422b2006-06-09 09:34:33 -040062 end -= namelen;
63 memcpy(end, dentry->d_name.name, namelen);
64 *--end = '/';
65 dentry = dentry->d_parent;
66 }
67 spin_unlock(&dcache_lock);
68 namelen = strlen(base);
69 /* Strip off excess slashes in base string */
70 while (namelen > 0 && base[namelen - 1] == '/')
71 namelen--;
72 buflen -= namelen;
73 if (buflen < 0)
74 goto Elong;
75 end -= namelen;
76 memcpy(end, base, namelen);
77 return end;
Josh Triplettce510192006-07-24 16:30:00 -070078Elong_unlock:
79 spin_unlock(&dcache_lock);
David Howellsf7b422b2006-06-09 09:34:33 -040080Elong:
81 return ERR_PTR(-ENAMETOOLONG);
82}
83
84/*
Trond Myklebust55a97592006-06-09 09:34:19 -040085 * nfs_follow_mountpoint - handle crossing a mountpoint on the server
86 * @dentry - dentry of mountpoint
87 * @nd - nameidata info
88 *
89 * When we encounter a mountpoint on the server, we want to set up
90 * a mountpoint on the client too, to prevent inode numbers from
91 * colliding, and to allow "df" to work properly.
92 * On NFSv4, we also want to allow for the fact that different
93 * filesystems may be migrated to different servers in a failover
94 * situation, and that different filesystems may want to use
95 * different security flavours.
96 */
97static void * nfs_follow_mountpoint(struct dentry *dentry, struct nameidata *nd)
98{
99 struct vfsmount *mnt;
100 struct nfs_server *server = NFS_SERVER(dentry->d_inode);
101 struct dentry *parent;
102 struct nfs_fh fh;
103 struct nfs_fattr fattr;
104 int err;
105
David Howells54ceac42006-08-22 20:06:13 -0400106 dprintk("--> nfs_follow_mountpoint()\n");
107
Denis V. Lunev44d57592008-08-11 12:02:34 +0400108 err = -ESTALE;
109 if (IS_ROOT(dentry))
110 goto out_err;
111
Harvey Harrison3110ff82008-05-02 13:42:44 -0700112 dprintk("%s: enter\n", __func__);
Jan Blunck4ac91372008-02-14 19:34:32 -0800113 dput(nd->path.dentry);
114 nd->path.dentry = dget(dentry);
David Howells54ceac42006-08-22 20:06:13 -0400115
Trond Myklebust55a97592006-06-09 09:34:19 -0400116 /* Look it up again */
Jan Blunck4ac91372008-02-14 19:34:32 -0800117 parent = dget_parent(nd->path.dentry);
David Howells8fa5c002006-08-22 20:06:12 -0400118 err = server->nfs_client->rpc_ops->lookup(parent->d_inode,
Jan Blunck4ac91372008-02-14 19:34:32 -0800119 &nd->path.dentry->d_name,
David Howells8fa5c002006-08-22 20:06:12 -0400120 &fh, &fattr);
Trond Myklebust55a97592006-06-09 09:34:19 -0400121 dput(parent);
122 if (err != 0)
123 goto out_err;
124
Manoj Naik6b97fd32006-06-09 09:34:29 -0400125 if (fattr.valid & NFS_ATTR_FATTR_V4_REFERRAL)
Jan Blunck4ac91372008-02-14 19:34:32 -0800126 mnt = nfs_do_refmount(nd->path.mnt, nd->path.dentry);
Manoj Naik6b97fd32006-06-09 09:34:29 -0400127 else
Jan Blunck4ac91372008-02-14 19:34:32 -0800128 mnt = nfs_do_submount(nd->path.mnt, nd->path.dentry, &fh,
129 &fattr);
Trond Myklebust55a97592006-06-09 09:34:19 -0400130 err = PTR_ERR(mnt);
131 if (IS_ERR(mnt))
132 goto out_err;
133
134 mntget(mnt);
Al Viro8d66bf52008-08-01 09:05:54 -0400135 err = do_add_mount(mnt, &nd->path, nd->path.mnt->mnt_flags|MNT_SHRINKABLE,
Jan Blunck4ac91372008-02-14 19:34:32 -0800136 &nfs_automount_list);
Trond Myklebust55a97592006-06-09 09:34:19 -0400137 if (err < 0) {
138 mntput(mnt);
139 if (err == -EBUSY)
140 goto out_follow;
141 goto out_err;
142 }
Jan Blunck31f31db12008-05-02 13:42:45 -0700143 path_put(&nd->path);
Jan Blunck4ac91372008-02-14 19:34:32 -0800144 nd->path.mnt = mnt;
145 nd->path.dentry = dget(mnt->mnt_root);
Trond Myklebust51d8fa62006-06-09 09:34:20 -0400146 schedule_delayed_work(&nfs_automount_task, nfs_mountpoint_expiry_timeout);
Trond Myklebust55a97592006-06-09 09:34:19 -0400147out:
Harvey Harrison3110ff82008-05-02 13:42:44 -0700148 dprintk("%s: done, returned %d\n", __func__, err);
David Howells54ceac42006-08-22 20:06:13 -0400149
150 dprintk("<-- nfs_follow_mountpoint() = %d\n", err);
Trond Myklebust55a97592006-06-09 09:34:19 -0400151 return ERR_PTR(err);
152out_err:
Jan Blunck1d957f92008-02-14 19:34:35 -0800153 path_put(&nd->path);
Trond Myklebust55a97592006-06-09 09:34:19 -0400154 goto out;
155out_follow:
Jan Blunck4ac91372008-02-14 19:34:32 -0800156 while (d_mountpoint(nd->path.dentry) &&
157 follow_down(&nd->path.mnt, &nd->path.dentry))
Trond Myklebust55a97592006-06-09 09:34:19 -0400158 ;
159 err = 0;
160 goto out;
161}
162
Arjan van de Ven92e1d5b2007-02-12 00:55:39 -0800163const struct inode_operations nfs_mountpoint_inode_operations = {
Trond Myklebust55a97592006-06-09 09:34:19 -0400164 .follow_link = nfs_follow_mountpoint,
165 .getattr = nfs_getattr,
166};
Trond Myklebust51d8fa62006-06-09 09:34:20 -0400167
Arjan van de Ven92e1d5b2007-02-12 00:55:39 -0800168const struct inode_operations nfs_referral_inode_operations = {
Manoj Naik6b97fd32006-06-09 09:34:29 -0400169 .follow_link = nfs_follow_mountpoint,
170};
171
David Howells65f27f32006-11-22 14:55:48 +0000172static void nfs_expire_automounts(struct work_struct *work)
Trond Myklebust51d8fa62006-06-09 09:34:20 -0400173{
David Howells65f27f32006-11-22 14:55:48 +0000174 struct list_head *list = &nfs_automount_list;
Trond Myklebust51d8fa62006-06-09 09:34:20 -0400175
176 mark_mounts_for_expiry(list);
177 if (!list_empty(list))
178 schedule_delayed_work(&nfs_automount_task, nfs_mountpoint_expiry_timeout);
179}
180
181void nfs_release_automount_timer(void)
182{
Trond Myklebust3d39c692007-08-07 15:28:33 -0400183 if (list_empty(&nfs_automount_list))
Trond Myklebust560aef72007-08-27 09:14:56 -0400184 cancel_delayed_work(&nfs_automount_task);
Trond Myklebust51d8fa62006-06-09 09:34:20 -0400185}
David Howellsf7b422b2006-06-09 09:34:33 -0400186
187/*
188 * Clone a mountpoint of the appropriate type
189 */
David Howells509de812006-08-22 20:06:11 -0400190static struct vfsmount *nfs_do_clone_mount(struct nfs_server *server,
191 const char *devname,
David Howellsf7b422b2006-06-09 09:34:33 -0400192 struct nfs_clone_mount *mountdata)
193{
194#ifdef CONFIG_NFS_V4
Denis V. Lunevfd08d7e2008-07-31 09:38:55 +0400195 struct vfsmount *mnt = ERR_PTR(-EINVAL);
Trond Myklebust40c553192007-12-14 14:56:07 -0500196 switch (server->nfs_client->rpc_ops->version) {
David Howellsf7b422b2006-06-09 09:34:33 -0400197 case 2:
198 case 3:
David Howells54ceac42006-08-22 20:06:13 -0400199 mnt = vfs_kern_mount(&nfs_xdev_fs_type, 0, devname, mountdata);
David Howellsf7b422b2006-06-09 09:34:33 -0400200 break;
201 case 4:
David Howells54ceac42006-08-22 20:06:13 -0400202 mnt = vfs_kern_mount(&nfs4_xdev_fs_type, 0, devname, mountdata);
David Howellsf7b422b2006-06-09 09:34:33 -0400203 }
204 return mnt;
205#else
David Howells54ceac42006-08-22 20:06:13 -0400206 return vfs_kern_mount(&nfs_xdev_fs_type, 0, devname, mountdata);
David Howellsf7b422b2006-06-09 09:34:33 -0400207#endif
208}
209
210/**
211 * nfs_do_submount - set up mountpoint when crossing a filesystem boundary
212 * @mnt_parent - mountpoint of parent directory
213 * @dentry - parent directory
214 * @fh - filehandle for new root dentry
215 * @fattr - attributes for new root inode
216 *
217 */
Adrian Bunk66f37502006-09-27 01:51:13 -0700218static struct vfsmount *nfs_do_submount(const struct vfsmount *mnt_parent,
219 const struct dentry *dentry,
220 struct nfs_fh *fh,
221 struct nfs_fattr *fattr)
David Howellsf7b422b2006-06-09 09:34:33 -0400222{
223 struct nfs_clone_mount mountdata = {
224 .sb = mnt_parent->mnt_sb,
225 .dentry = dentry,
226 .fh = fh,
227 .fattr = fattr,
228 };
229 struct vfsmount *mnt = ERR_PTR(-ENOMEM);
230 char *page = (char *) __get_free_page(GFP_USER);
231 char *devname;
232
David Howells54ceac42006-08-22 20:06:13 -0400233 dprintk("--> nfs_do_submount()\n");
234
Harvey Harrison3110ff82008-05-02 13:42:44 -0700235 dprintk("%s: submounting on %s/%s\n", __func__,
David Howellsf7b422b2006-06-09 09:34:33 -0400236 dentry->d_parent->d_name.name,
237 dentry->d_name.name);
238 if (page == NULL)
239 goto out;
240 devname = nfs_devname(mnt_parent, dentry, page, PAGE_SIZE);
241 mnt = (struct vfsmount *)devname;
242 if (IS_ERR(devname))
243 goto free_page;
244 mnt = nfs_do_clone_mount(NFS_SB(mnt_parent->mnt_sb), devname, &mountdata);
245free_page:
246 free_page((unsigned long)page);
247out:
Harvey Harrison3110ff82008-05-02 13:42:44 -0700248 dprintk("%s: done\n", __func__);
David Howells54ceac42006-08-22 20:06:13 -0400249
250 dprintk("<-- nfs_do_submount() = %p\n", mnt);
David Howellsf7b422b2006-06-09 09:34:33 -0400251 return mnt;
252}