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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>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090011#include <linux/gfp.h>
Trond Myklebust55a97592006-06-09 09:34:19 -040012#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>
David Howellsf7b422b2006-06-09 09:34:33 -040018#include "internal.h"
Trond Myklebust55a97592006-06-09 09:34:19 -040019
20#define NFSDBG_FACILITY NFSDBG_VFS
21
David Howells65f27f32006-11-22 14:55:48 +000022static void nfs_expire_automounts(struct work_struct *work);
David Howellsf7b422b2006-06-09 09:34:33 -040023
Adrian Bunka3dab292008-04-14 21:41:32 +030024static LIST_HEAD(nfs_automount_list);
David Howells65f27f32006-11-22 14:55:48 +000025static DECLARE_DELAYED_WORK(nfs_automount_task, nfs_expire_automounts);
Trond Myklebust51d8fa62006-06-09 09:34:20 -040026int nfs_mountpoint_expiry_timeout = 500 * HZ;
27
Adrian Bunk66f37502006-09-27 01:51:13 -070028static struct vfsmount *nfs_do_submount(const struct vfsmount *mnt_parent,
29 const struct dentry *dentry,
30 struct nfs_fh *fh,
31 struct nfs_fattr *fattr);
32
Trond Myklebust55a97592006-06-09 09:34:19 -040033/*
David Howellsf7b422b2006-06-09 09:34:33 -040034 * nfs_path - reconstruct the path given an arbitrary dentry
35 * @base - arbitrary string to prepend to the path
David Howells54ceac42006-08-22 20:06:13 -040036 * @droot - pointer to root dentry for mountpoint
David Howellsf7b422b2006-06-09 09:34:33 -040037 * @dentry - pointer to dentry
38 * @buffer - result buffer
39 * @buflen - length of buffer
40 *
41 * Helper function for constructing the path from the
42 * root dentry to an arbitrary hashed dentry.
43 *
44 * This is mainly for use in figuring out the path on the
45 * server side when automounting on top of an existing partition.
46 */
David Howells54ceac42006-08-22 20:06:13 -040047char *nfs_path(const char *base,
48 const struct dentry *droot,
49 const struct dentry *dentry,
David Howellsf7b422b2006-06-09 09:34:33 -040050 char *buffer, ssize_t buflen)
51{
52 char *end = buffer+buflen;
53 int namelen;
54
55 *--end = '\0';
56 buflen--;
57 spin_lock(&dcache_lock);
David Howells54ceac42006-08-22 20:06:13 -040058 while (!IS_ROOT(dentry) && dentry != droot) {
David Howellsf7b422b2006-06-09 09:34:33 -040059 namelen = dentry->d_name.len;
60 buflen -= namelen + 1;
61 if (buflen < 0)
Josh Triplettce510192006-07-24 16:30:00 -070062 goto Elong_unlock;
David Howellsf7b422b2006-06-09 09:34:33 -040063 end -= namelen;
64 memcpy(end, dentry->d_name.name, namelen);
65 *--end = '/';
66 dentry = dentry->d_parent;
67 }
68 spin_unlock(&dcache_lock);
Trond Myklebust0b75b352009-06-22 15:09:14 -040069 if (*end != '/') {
70 if (--buflen < 0)
71 goto Elong;
72 *--end = '/';
73 }
David Howellsf7b422b2006-06-09 09:34:33 -040074 namelen = strlen(base);
75 /* Strip off excess slashes in base string */
76 while (namelen > 0 && base[namelen - 1] == '/')
77 namelen--;
78 buflen -= namelen;
79 if (buflen < 0)
80 goto Elong;
81 end -= namelen;
82 memcpy(end, base, namelen);
83 return end;
Josh Triplettce510192006-07-24 16:30:00 -070084Elong_unlock:
85 spin_unlock(&dcache_lock);
David Howellsf7b422b2006-06-09 09:34:33 -040086Elong:
87 return ERR_PTR(-ENAMETOOLONG);
88}
89
90/*
Trond Myklebust55a97592006-06-09 09:34:19 -040091 * nfs_follow_mountpoint - handle crossing a mountpoint on the server
92 * @dentry - dentry of mountpoint
93 * @nd - nameidata info
94 *
95 * When we encounter a mountpoint on the server, we want to set up
96 * a mountpoint on the client too, to prevent inode numbers from
97 * colliding, and to allow "df" to work properly.
98 * On NFSv4, we also want to allow for the fact that different
99 * filesystems may be migrated to different servers in a failover
100 * situation, and that different filesystems may want to use
101 * different security flavours.
102 */
103static void * nfs_follow_mountpoint(struct dentry *dentry, struct nameidata *nd)
104{
105 struct vfsmount *mnt;
106 struct nfs_server *server = NFS_SERVER(dentry->d_inode);
107 struct dentry *parent;
Trond Myklebusta4d7f162010-04-16 16:22:46 -0400108 struct nfs_fh *fh = NULL;
109 struct nfs_fattr *fattr = NULL;
Trond Myklebust55a97592006-06-09 09:34:19 -0400110 int err;
111
David Howells54ceac42006-08-22 20:06:13 -0400112 dprintk("--> nfs_follow_mountpoint()\n");
113
Denis V. Lunev44d57592008-08-11 12:02:34 +0400114 err = -ESTALE;
115 if (IS_ROOT(dentry))
116 goto out_err;
117
Trond Myklebusta4d7f162010-04-16 16:22:46 -0400118 err = -ENOMEM;
119 fh = nfs_alloc_fhandle();
120 fattr = nfs_alloc_fattr();
121 if (fh == NULL || fattr == NULL)
122 goto out_err;
123
Harvey Harrison3110ff82008-05-02 13:42:44 -0700124 dprintk("%s: enter\n", __func__);
Jan Blunck4ac91372008-02-14 19:34:32 -0800125 dput(nd->path.dentry);
126 nd->path.dentry = dget(dentry);
David Howells54ceac42006-08-22 20:06:13 -0400127
Trond Myklebust55a97592006-06-09 09:34:19 -0400128 /* Look it up again */
Jan Blunck4ac91372008-02-14 19:34:32 -0800129 parent = dget_parent(nd->path.dentry);
David Howells8fa5c002006-08-22 20:06:12 -0400130 err = server->nfs_client->rpc_ops->lookup(parent->d_inode,
Jan Blunck4ac91372008-02-14 19:34:32 -0800131 &nd->path.dentry->d_name,
Trond Myklebusta4d7f162010-04-16 16:22:46 -0400132 fh, fattr);
Trond Myklebust55a97592006-06-09 09:34:19 -0400133 dput(parent);
134 if (err != 0)
135 goto out_err;
136
Trond Myklebusta4d7f162010-04-16 16:22:46 -0400137 if (fattr->valid & NFS_ATTR_FATTR_V4_REFERRAL)
Jan Blunck4ac91372008-02-14 19:34:32 -0800138 mnt = nfs_do_refmount(nd->path.mnt, nd->path.dentry);
Manoj Naik6b97fd32006-06-09 09:34:29 -0400139 else
Trond Myklebusta4d7f162010-04-16 16:22:46 -0400140 mnt = nfs_do_submount(nd->path.mnt, nd->path.dentry, fh,
141 fattr);
Trond Myklebust55a97592006-06-09 09:34:19 -0400142 err = PTR_ERR(mnt);
143 if (IS_ERR(mnt))
144 goto out_err;
145
146 mntget(mnt);
Al Viro8d66bf52008-08-01 09:05:54 -0400147 err = do_add_mount(mnt, &nd->path, nd->path.mnt->mnt_flags|MNT_SHRINKABLE,
Jan Blunck4ac91372008-02-14 19:34:32 -0800148 &nfs_automount_list);
Trond Myklebust55a97592006-06-09 09:34:19 -0400149 if (err < 0) {
150 mntput(mnt);
151 if (err == -EBUSY)
152 goto out_follow;
153 goto out_err;
154 }
Jan Blunck31f31db12008-05-02 13:42:45 -0700155 path_put(&nd->path);
Jan Blunck4ac91372008-02-14 19:34:32 -0800156 nd->path.mnt = mnt;
157 nd->path.dentry = dget(mnt->mnt_root);
Trond Myklebust51d8fa62006-06-09 09:34:20 -0400158 schedule_delayed_work(&nfs_automount_task, nfs_mountpoint_expiry_timeout);
Trond Myklebust55a97592006-06-09 09:34:19 -0400159out:
Trond Myklebusta4d7f162010-04-16 16:22:46 -0400160 nfs_free_fattr(fattr);
161 nfs_free_fhandle(fh);
Harvey Harrison3110ff82008-05-02 13:42:44 -0700162 dprintk("%s: done, returned %d\n", __func__, err);
David Howells54ceac42006-08-22 20:06:13 -0400163
164 dprintk("<-- nfs_follow_mountpoint() = %d\n", err);
Trond Myklebust55a97592006-06-09 09:34:19 -0400165 return ERR_PTR(err);
166out_err:
Jan Blunck1d957f92008-02-14 19:34:35 -0800167 path_put(&nd->path);
Trond Myklebust55a97592006-06-09 09:34:19 -0400168 goto out;
169out_follow:
Jan Blunck4ac91372008-02-14 19:34:32 -0800170 while (d_mountpoint(nd->path.dentry) &&
Al Viro9393bd02009-04-18 13:58:15 -0400171 follow_down(&nd->path))
Trond Myklebust55a97592006-06-09 09:34:19 -0400172 ;
173 err = 0;
174 goto out;
175}
176
Arjan van de Ven92e1d5b2007-02-12 00:55:39 -0800177const struct inode_operations nfs_mountpoint_inode_operations = {
Trond Myklebust55a97592006-06-09 09:34:19 -0400178 .follow_link = nfs_follow_mountpoint,
179 .getattr = nfs_getattr,
180};
Trond Myklebust51d8fa62006-06-09 09:34:20 -0400181
Arjan van de Ven92e1d5b2007-02-12 00:55:39 -0800182const struct inode_operations nfs_referral_inode_operations = {
Manoj Naik6b97fd32006-06-09 09:34:29 -0400183 .follow_link = nfs_follow_mountpoint,
184};
185
David Howells65f27f32006-11-22 14:55:48 +0000186static void nfs_expire_automounts(struct work_struct *work)
Trond Myklebust51d8fa62006-06-09 09:34:20 -0400187{
David Howells65f27f32006-11-22 14:55:48 +0000188 struct list_head *list = &nfs_automount_list;
Trond Myklebust51d8fa62006-06-09 09:34:20 -0400189
190 mark_mounts_for_expiry(list);
191 if (!list_empty(list))
192 schedule_delayed_work(&nfs_automount_task, nfs_mountpoint_expiry_timeout);
193}
194
195void nfs_release_automount_timer(void)
196{
Trond Myklebust3d39c692007-08-07 15:28:33 -0400197 if (list_empty(&nfs_automount_list))
Trond Myklebust560aef72007-08-27 09:14:56 -0400198 cancel_delayed_work(&nfs_automount_task);
Trond Myklebust51d8fa62006-06-09 09:34:20 -0400199}
David Howellsf7b422b2006-06-09 09:34:33 -0400200
201/*
202 * Clone a mountpoint of the appropriate type
203 */
David Howells509de812006-08-22 20:06:11 -0400204static struct vfsmount *nfs_do_clone_mount(struct nfs_server *server,
205 const char *devname,
David Howellsf7b422b2006-06-09 09:34:33 -0400206 struct nfs_clone_mount *mountdata)
207{
208#ifdef CONFIG_NFS_V4
Denis V. Lunevfd08d7e2008-07-31 09:38:55 +0400209 struct vfsmount *mnt = ERR_PTR(-EINVAL);
Trond Myklebust40c553192007-12-14 14:56:07 -0500210 switch (server->nfs_client->rpc_ops->version) {
David Howellsf7b422b2006-06-09 09:34:33 -0400211 case 2:
212 case 3:
David Howells54ceac42006-08-22 20:06:13 -0400213 mnt = vfs_kern_mount(&nfs_xdev_fs_type, 0, devname, mountdata);
David Howellsf7b422b2006-06-09 09:34:33 -0400214 break;
215 case 4:
David Howells54ceac42006-08-22 20:06:13 -0400216 mnt = vfs_kern_mount(&nfs4_xdev_fs_type, 0, devname, mountdata);
David Howellsf7b422b2006-06-09 09:34:33 -0400217 }
218 return mnt;
219#else
David Howells54ceac42006-08-22 20:06:13 -0400220 return vfs_kern_mount(&nfs_xdev_fs_type, 0, devname, mountdata);
David Howellsf7b422b2006-06-09 09:34:33 -0400221#endif
222}
223
224/**
225 * nfs_do_submount - set up mountpoint when crossing a filesystem boundary
226 * @mnt_parent - mountpoint of parent directory
227 * @dentry - parent directory
228 * @fh - filehandle for new root dentry
229 * @fattr - attributes for new root inode
230 *
231 */
Adrian Bunk66f37502006-09-27 01:51:13 -0700232static struct vfsmount *nfs_do_submount(const struct vfsmount *mnt_parent,
233 const struct dentry *dentry,
234 struct nfs_fh *fh,
235 struct nfs_fattr *fattr)
David Howellsf7b422b2006-06-09 09:34:33 -0400236{
237 struct nfs_clone_mount mountdata = {
238 .sb = mnt_parent->mnt_sb,
239 .dentry = dentry,
240 .fh = fh,
241 .fattr = fattr,
242 };
243 struct vfsmount *mnt = ERR_PTR(-ENOMEM);
244 char *page = (char *) __get_free_page(GFP_USER);
245 char *devname;
246
David Howells54ceac42006-08-22 20:06:13 -0400247 dprintk("--> nfs_do_submount()\n");
248
Harvey Harrison3110ff82008-05-02 13:42:44 -0700249 dprintk("%s: submounting on %s/%s\n", __func__,
David Howellsf7b422b2006-06-09 09:34:33 -0400250 dentry->d_parent->d_name.name,
251 dentry->d_name.name);
252 if (page == NULL)
253 goto out;
254 devname = nfs_devname(mnt_parent, dentry, page, PAGE_SIZE);
255 mnt = (struct vfsmount *)devname;
256 if (IS_ERR(devname))
257 goto free_page;
258 mnt = nfs_do_clone_mount(NFS_SB(mnt_parent->mnt_sb), devname, &mountdata);
259free_page:
260 free_page((unsigned long)page);
261out:
Harvey Harrison3110ff82008-05-02 13:42:44 -0700262 dprintk("%s: done\n", __func__);
David Howells54ceac42006-08-22 20:06:13 -0400263
264 dprintk("<-- nfs_do_submount() = %p\n", mnt);
David Howellsf7b422b2006-06-09 09:34:33 -0400265 return mnt;
266}