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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
10#include <linux/config.h>
11
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>
David Howellsf7b422b2006-06-09 09:34:33 -040019#include "internal.h"
Trond Myklebust55a97592006-06-09 09:34:19 -040020
21#define NFSDBG_FACILITY NFSDBG_VFS
22
Trond Myklebust51d8fa62006-06-09 09:34:20 -040023static void nfs_expire_automounts(void *list);
David Howellsf7b422b2006-06-09 09:34:33 -040024
25LIST_HEAD(nfs_automount_list);
Trond Myklebust51d8fa62006-06-09 09:34:20 -040026static DECLARE_WORK(nfs_automount_task, nfs_expire_automounts, &nfs_automount_list);
27int nfs_mountpoint_expiry_timeout = 500 * HZ;
28
Trond Myklebust55a97592006-06-09 09:34:19 -040029/*
David Howellsf7b422b2006-06-09 09:34:33 -040030 * nfs_path - reconstruct the path given an arbitrary dentry
31 * @base - arbitrary string to prepend to the path
David Howells54ceac42006-08-22 20:06:13 -040032 * @droot - pointer to root dentry for mountpoint
David Howellsf7b422b2006-06-09 09:34:33 -040033 * @dentry - pointer to dentry
34 * @buffer - result buffer
35 * @buflen - length of buffer
36 *
37 * Helper function for constructing the path from the
38 * root dentry to an arbitrary hashed dentry.
39 *
40 * This is mainly for use in figuring out the path on the
41 * server side when automounting on top of an existing partition.
42 */
David Howells54ceac42006-08-22 20:06:13 -040043char *nfs_path(const char *base,
44 const struct dentry *droot,
45 const struct dentry *dentry,
David Howellsf7b422b2006-06-09 09:34:33 -040046 char *buffer, ssize_t buflen)
47{
48 char *end = buffer+buflen;
49 int namelen;
50
51 *--end = '\0';
52 buflen--;
53 spin_lock(&dcache_lock);
David Howells54ceac42006-08-22 20:06:13 -040054 while (!IS_ROOT(dentry) && dentry != droot) {
David Howellsf7b422b2006-06-09 09:34:33 -040055 namelen = dentry->d_name.len;
56 buflen -= namelen + 1;
57 if (buflen < 0)
Josh Triplettce510192006-07-24 16:30:00 -070058 goto Elong_unlock;
David Howellsf7b422b2006-06-09 09:34:33 -040059 end -= namelen;
60 memcpy(end, dentry->d_name.name, namelen);
61 *--end = '/';
62 dentry = dentry->d_parent;
63 }
64 spin_unlock(&dcache_lock);
65 namelen = strlen(base);
66 /* Strip off excess slashes in base string */
67 while (namelen > 0 && base[namelen - 1] == '/')
68 namelen--;
69 buflen -= namelen;
70 if (buflen < 0)
71 goto Elong;
72 end -= namelen;
73 memcpy(end, base, namelen);
74 return end;
Josh Triplettce510192006-07-24 16:30:00 -070075Elong_unlock:
76 spin_unlock(&dcache_lock);
David Howellsf7b422b2006-06-09 09:34:33 -040077Elong:
78 return ERR_PTR(-ENAMETOOLONG);
79}
80
81/*
Trond Myklebust55a97592006-06-09 09:34:19 -040082 * nfs_follow_mountpoint - handle crossing a mountpoint on the server
83 * @dentry - dentry of mountpoint
84 * @nd - nameidata info
85 *
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.
93 */
94static void * nfs_follow_mountpoint(struct dentry *dentry, struct nameidata *nd)
95{
96 struct vfsmount *mnt;
97 struct nfs_server *server = NFS_SERVER(dentry->d_inode);
98 struct dentry *parent;
99 struct nfs_fh fh;
100 struct nfs_fattr fattr;
101 int err;
102
David Howells54ceac42006-08-22 20:06:13 -0400103 dprintk("--> nfs_follow_mountpoint()\n");
104
Trond Myklebust55a97592006-06-09 09:34:19 -0400105 BUG_ON(IS_ROOT(dentry));
106 dprintk("%s: enter\n", __FUNCTION__);
107 dput(nd->dentry);
108 nd->dentry = dget(dentry);
David Howells54ceac42006-08-22 20:06:13 -0400109
Trond Myklebust55a97592006-06-09 09:34:19 -0400110 /* Look it up again */
111 parent = dget_parent(nd->dentry);
David Howells8fa5c002006-08-22 20:06:12 -0400112 err = server->nfs_client->rpc_ops->lookup(parent->d_inode,
113 &nd->dentry->d_name,
114 &fh, &fattr);
Trond Myklebust55a97592006-06-09 09:34:19 -0400115 dput(parent);
116 if (err != 0)
117 goto out_err;
118
Manoj Naik6b97fd32006-06-09 09:34:29 -0400119 if (fattr.valid & NFS_ATTR_FATTR_V4_REFERRAL)
120 mnt = nfs_do_refmount(nd->mnt, nd->dentry);
121 else
122 mnt = nfs_do_submount(nd->mnt, nd->dentry, &fh, &fattr);
Trond Myklebust55a97592006-06-09 09:34:19 -0400123 err = PTR_ERR(mnt);
124 if (IS_ERR(mnt))
125 goto out_err;
126
127 mntget(mnt);
Trond Myklebust51d8fa62006-06-09 09:34:20 -0400128 err = do_add_mount(mnt, nd, nd->mnt->mnt_flags|MNT_SHRINKABLE, &nfs_automount_list);
Trond Myklebust55a97592006-06-09 09:34:19 -0400129 if (err < 0) {
130 mntput(mnt);
131 if (err == -EBUSY)
132 goto out_follow;
133 goto out_err;
134 }
135 mntput(nd->mnt);
136 dput(nd->dentry);
137 nd->mnt = mnt;
138 nd->dentry = dget(mnt->mnt_root);
Trond Myklebust51d8fa62006-06-09 09:34:20 -0400139 schedule_delayed_work(&nfs_automount_task, nfs_mountpoint_expiry_timeout);
Trond Myklebust55a97592006-06-09 09:34:19 -0400140out:
141 dprintk("%s: done, returned %d\n", __FUNCTION__, err);
David Howells54ceac42006-08-22 20:06:13 -0400142
143 dprintk("<-- nfs_follow_mountpoint() = %d\n", err);
Trond Myklebust55a97592006-06-09 09:34:19 -0400144 return ERR_PTR(err);
145out_err:
146 path_release(nd);
147 goto out;
148out_follow:
149 while(d_mountpoint(nd->dentry) && follow_down(&nd->mnt, &nd->dentry))
150 ;
151 err = 0;
152 goto out;
153}
154
155struct inode_operations nfs_mountpoint_inode_operations = {
156 .follow_link = nfs_follow_mountpoint,
157 .getattr = nfs_getattr,
158};
Trond Myklebust51d8fa62006-06-09 09:34:20 -0400159
Manoj Naik6b97fd32006-06-09 09:34:29 -0400160struct inode_operations nfs_referral_inode_operations = {
161 .follow_link = nfs_follow_mountpoint,
162};
163
Trond Myklebust51d8fa62006-06-09 09:34:20 -0400164static void nfs_expire_automounts(void *data)
165{
166 struct list_head *list = (struct list_head *)data;
167
168 mark_mounts_for_expiry(list);
169 if (!list_empty(list))
170 schedule_delayed_work(&nfs_automount_task, nfs_mountpoint_expiry_timeout);
171}
172
173void nfs_release_automount_timer(void)
174{
175 if (list_empty(&nfs_automount_list)) {
176 cancel_delayed_work(&nfs_automount_task);
177 flush_scheduled_work();
178 }
179}
David Howellsf7b422b2006-06-09 09:34:33 -0400180
181/*
182 * Clone a mountpoint of the appropriate type
183 */
David Howells509de812006-08-22 20:06:11 -0400184static struct vfsmount *nfs_do_clone_mount(struct nfs_server *server,
185 const char *devname,
David Howellsf7b422b2006-06-09 09:34:33 -0400186 struct nfs_clone_mount *mountdata)
187{
188#ifdef CONFIG_NFS_V4
189 struct vfsmount *mnt = NULL;
David Howells8fa5c002006-08-22 20:06:12 -0400190 switch (server->nfs_client->cl_nfsversion) {
David Howellsf7b422b2006-06-09 09:34:33 -0400191 case 2:
192 case 3:
David Howells54ceac42006-08-22 20:06:13 -0400193 mnt = vfs_kern_mount(&nfs_xdev_fs_type, 0, devname, mountdata);
David Howellsf7b422b2006-06-09 09:34:33 -0400194 break;
195 case 4:
David Howells54ceac42006-08-22 20:06:13 -0400196 mnt = vfs_kern_mount(&nfs4_xdev_fs_type, 0, devname, mountdata);
David Howellsf7b422b2006-06-09 09:34:33 -0400197 }
198 return mnt;
199#else
David Howells54ceac42006-08-22 20:06:13 -0400200 return vfs_kern_mount(&nfs_xdev_fs_type, 0, devname, mountdata);
David Howellsf7b422b2006-06-09 09:34:33 -0400201#endif
202}
203
204/**
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
210 *
211 */
212struct vfsmount *nfs_do_submount(const struct vfsmount *mnt_parent,
213 const struct dentry *dentry, struct nfs_fh *fh,
214 struct nfs_fattr *fattr)
215{
216 struct nfs_clone_mount mountdata = {
217 .sb = mnt_parent->mnt_sb,
218 .dentry = dentry,
219 .fh = fh,
220 .fattr = fattr,
221 };
222 struct vfsmount *mnt = ERR_PTR(-ENOMEM);
223 char *page = (char *) __get_free_page(GFP_USER);
224 char *devname;
225
David Howells54ceac42006-08-22 20:06:13 -0400226 dprintk("--> nfs_do_submount()\n");
227
David Howellsf7b422b2006-06-09 09:34:33 -0400228 dprintk("%s: submounting on %s/%s\n", __FUNCTION__,
229 dentry->d_parent->d_name.name,
230 dentry->d_name.name);
231 if (page == NULL)
232 goto out;
233 devname = nfs_devname(mnt_parent, dentry, page, PAGE_SIZE);
234 mnt = (struct vfsmount *)devname;
235 if (IS_ERR(devname))
236 goto free_page;
237 mnt = nfs_do_clone_mount(NFS_SB(mnt_parent->mnt_sb), devname, &mountdata);
238free_page:
239 free_page((unsigned long)page);
240out:
241 dprintk("%s: done\n", __FUNCTION__);
David Howells54ceac42006-08-22 20:06:13 -0400242
243 dprintk("<-- nfs_do_submount() = %p\n", mnt);
David Howellsf7b422b2006-06-09 09:34:33 -0400244 return mnt;
245}