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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
23LIST_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
Trond Myklebust55a97592006-06-09 09:34:19 -0400108 BUG_ON(IS_ROOT(dentry));
109 dprintk("%s: enter\n", __FUNCTION__);
110 dput(nd->dentry);
111 nd->dentry = dget(dentry);
David Howells54ceac42006-08-22 20:06:13 -0400112
Trond Myklebust55a97592006-06-09 09:34:19 -0400113 /* Look it up again */
114 parent = dget_parent(nd->dentry);
David Howells8fa5c002006-08-22 20:06:12 -0400115 err = server->nfs_client->rpc_ops->lookup(parent->d_inode,
116 &nd->dentry->d_name,
117 &fh, &fattr);
Trond Myklebust55a97592006-06-09 09:34:19 -0400118 dput(parent);
119 if (err != 0)
120 goto out_err;
121
Manoj Naik6b97fd32006-06-09 09:34:29 -0400122 if (fattr.valid & NFS_ATTR_FATTR_V4_REFERRAL)
123 mnt = nfs_do_refmount(nd->mnt, nd->dentry);
124 else
125 mnt = nfs_do_submount(nd->mnt, nd->dentry, &fh, &fattr);
Trond Myklebust55a97592006-06-09 09:34:19 -0400126 err = PTR_ERR(mnt);
127 if (IS_ERR(mnt))
128 goto out_err;
129
130 mntget(mnt);
Trond Myklebust51d8fa62006-06-09 09:34:20 -0400131 err = do_add_mount(mnt, nd, nd->mnt->mnt_flags|MNT_SHRINKABLE, &nfs_automount_list);
Trond Myklebust55a97592006-06-09 09:34:19 -0400132 if (err < 0) {
133 mntput(mnt);
134 if (err == -EBUSY)
135 goto out_follow;
136 goto out_err;
137 }
138 mntput(nd->mnt);
139 dput(nd->dentry);
140 nd->mnt = mnt;
141 nd->dentry = dget(mnt->mnt_root);
Trond Myklebust51d8fa62006-06-09 09:34:20 -0400142 schedule_delayed_work(&nfs_automount_task, nfs_mountpoint_expiry_timeout);
Trond Myklebust55a97592006-06-09 09:34:19 -0400143out:
144 dprintk("%s: done, returned %d\n", __FUNCTION__, err);
David Howells54ceac42006-08-22 20:06:13 -0400145
146 dprintk("<-- nfs_follow_mountpoint() = %d\n", err);
Trond Myklebust55a97592006-06-09 09:34:19 -0400147 return ERR_PTR(err);
148out_err:
149 path_release(nd);
150 goto out;
151out_follow:
152 while(d_mountpoint(nd->dentry) && follow_down(&nd->mnt, &nd->dentry))
153 ;
154 err = 0;
155 goto out;
156}
157
Arjan van de Ven92e1d5b2007-02-12 00:55:39 -0800158const struct inode_operations nfs_mountpoint_inode_operations = {
Trond Myklebust55a97592006-06-09 09:34:19 -0400159 .follow_link = nfs_follow_mountpoint,
160 .getattr = nfs_getattr,
161};
Trond Myklebust51d8fa62006-06-09 09:34:20 -0400162
Arjan van de Ven92e1d5b2007-02-12 00:55:39 -0800163const struct inode_operations nfs_referral_inode_operations = {
Manoj Naik6b97fd32006-06-09 09:34:29 -0400164 .follow_link = nfs_follow_mountpoint,
165};
166
David Howells65f27f32006-11-22 14:55:48 +0000167static void nfs_expire_automounts(struct work_struct *work)
Trond Myklebust51d8fa62006-06-09 09:34:20 -0400168{
David Howells65f27f32006-11-22 14:55:48 +0000169 struct list_head *list = &nfs_automount_list;
Trond Myklebust51d8fa62006-06-09 09:34:20 -0400170
171 mark_mounts_for_expiry(list);
172 if (!list_empty(list))
173 schedule_delayed_work(&nfs_automount_task, nfs_mountpoint_expiry_timeout);
174}
175
176void nfs_release_automount_timer(void)
177{
178 if (list_empty(&nfs_automount_list)) {
179 cancel_delayed_work(&nfs_automount_task);
180 flush_scheduled_work();
181 }
182}
David Howellsf7b422b2006-06-09 09:34:33 -0400183
184/*
185 * Clone a mountpoint of the appropriate type
186 */
David Howells509de812006-08-22 20:06:11 -0400187static struct vfsmount *nfs_do_clone_mount(struct nfs_server *server,
188 const char *devname,
David Howellsf7b422b2006-06-09 09:34:33 -0400189 struct nfs_clone_mount *mountdata)
190{
191#ifdef CONFIG_NFS_V4
192 struct vfsmount *mnt = NULL;
David Howells8fa5c002006-08-22 20:06:12 -0400193 switch (server->nfs_client->cl_nfsversion) {
David Howellsf7b422b2006-06-09 09:34:33 -0400194 case 2:
195 case 3:
David Howells54ceac42006-08-22 20:06:13 -0400196 mnt = vfs_kern_mount(&nfs_xdev_fs_type, 0, devname, mountdata);
David Howellsf7b422b2006-06-09 09:34:33 -0400197 break;
198 case 4:
David Howells54ceac42006-08-22 20:06:13 -0400199 mnt = vfs_kern_mount(&nfs4_xdev_fs_type, 0, devname, mountdata);
David Howellsf7b422b2006-06-09 09:34:33 -0400200 }
201 return mnt;
202#else
David Howells54ceac42006-08-22 20:06:13 -0400203 return vfs_kern_mount(&nfs_xdev_fs_type, 0, devname, mountdata);
David Howellsf7b422b2006-06-09 09:34:33 -0400204#endif
205}
206
207/**
208 * nfs_do_submount - set up mountpoint when crossing a filesystem boundary
209 * @mnt_parent - mountpoint of parent directory
210 * @dentry - parent directory
211 * @fh - filehandle for new root dentry
212 * @fattr - attributes for new root inode
213 *
214 */
Adrian Bunk66f37502006-09-27 01:51:13 -0700215static struct vfsmount *nfs_do_submount(const struct vfsmount *mnt_parent,
216 const struct dentry *dentry,
217 struct nfs_fh *fh,
218 struct nfs_fattr *fattr)
David Howellsf7b422b2006-06-09 09:34:33 -0400219{
220 struct nfs_clone_mount mountdata = {
221 .sb = mnt_parent->mnt_sb,
222 .dentry = dentry,
223 .fh = fh,
224 .fattr = fattr,
225 };
226 struct vfsmount *mnt = ERR_PTR(-ENOMEM);
227 char *page = (char *) __get_free_page(GFP_USER);
228 char *devname;
229
David Howells54ceac42006-08-22 20:06:13 -0400230 dprintk("--> nfs_do_submount()\n");
231
David Howellsf7b422b2006-06-09 09:34:33 -0400232 dprintk("%s: submounting on %s/%s\n", __FUNCTION__,
233 dentry->d_parent->d_name.name,
234 dentry->d_name.name);
235 if (page == NULL)
236 goto out;
237 devname = nfs_devname(mnt_parent, dentry, page, PAGE_SIZE);
238 mnt = (struct vfsmount *)devname;
239 if (IS_ERR(devname))
240 goto free_page;
241 mnt = nfs_do_clone_mount(NFS_SB(mnt_parent->mnt_sb), devname, &mountdata);
242free_page:
243 free_page((unsigned long)page);
244out:
245 dprintk("%s: done\n", __FUNCTION__);
David Howells54ceac42006-08-22 20:06:13 -0400246
247 dprintk("<-- nfs_do_submount() = %p\n", mnt);
David Howellsf7b422b2006-06-09 09:34:33 -0400248 return mnt;
249}