Commit | Line | Data |
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55a97593 TM |
1 | /* |
2 | * linux/fs/nfs/namespace.c | |
3 | * | |
4 | * Copyright (C) 2005 Trond Myklebust <Trond.Myklebust@netapp.com> | |
5 | * | |
6 | * NFS namespace | |
7 | */ | |
8 | ||
9 | #include <linux/config.h> | |
10 | ||
11 | #include <linux/dcache.h> | |
12 | #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> | |
f7b422b1 | 18 | #include "internal.h" |
55a97593 TM |
19 | |
20 | #define NFSDBG_FACILITY NFSDBG_VFS | |
21 | ||
51d8fa6a | 22 | static void nfs_expire_automounts(void *list); |
f7b422b1 DH |
23 | |
24 | LIST_HEAD(nfs_automount_list); | |
51d8fa6a TM |
25 | static DECLARE_WORK(nfs_automount_task, nfs_expire_automounts, &nfs_automount_list); |
26 | int nfs_mountpoint_expiry_timeout = 500 * HZ; | |
27 | ||
f7b422b1 DH |
28 | /* |
29 | * nfs_path - reconstruct the path given an arbitrary dentry | |
30 | * @base - arbitrary string to prepend to the path | |
31 | * @dentry - pointer to dentry | |
32 | * @buffer - result buffer | |
33 | * @buflen - length of buffer | |
34 | * | |
35 | * Helper function for constructing the path from the | |
36 | * root dentry to an arbitrary hashed dentry. | |
37 | * | |
38 | * This is mainly for use in figuring out the path on the | |
39 | * server side when automounting on top of an existing partition. | |
40 | */ | |
41 | char *nfs_path(const char *base, const struct dentry *dentry, | |
42 | char *buffer, ssize_t buflen) | |
43 | { | |
44 | char *end = buffer+buflen; | |
45 | int namelen; | |
46 | ||
47 | *--end = '\0'; | |
48 | buflen--; | |
49 | spin_lock(&dcache_lock); | |
50 | while (!IS_ROOT(dentry)) { | |
51 | namelen = dentry->d_name.len; | |
52 | buflen -= namelen + 1; | |
53 | if (buflen < 0) | |
ce510193 | 54 | goto Elong_unlock; |
f7b422b1 DH |
55 | end -= namelen; |
56 | memcpy(end, dentry->d_name.name, namelen); | |
57 | *--end = '/'; | |
58 | dentry = dentry->d_parent; | |
59 | } | |
60 | spin_unlock(&dcache_lock); | |
61 | namelen = strlen(base); | |
62 | /* Strip off excess slashes in base string */ | |
63 | while (namelen > 0 && base[namelen - 1] == '/') | |
64 | namelen--; | |
65 | buflen -= namelen; | |
66 | if (buflen < 0) | |
67 | goto Elong; | |
68 | end -= namelen; | |
69 | memcpy(end, base, namelen); | |
70 | return end; | |
ce510193 JT |
71 | Elong_unlock: |
72 | spin_unlock(&dcache_lock); | |
f7b422b1 DH |
73 | Elong: |
74 | return ERR_PTR(-ENAMETOOLONG); | |
75 | } | |
76 | ||
55a97593 TM |
77 | /* |
78 | * nfs_follow_mountpoint - handle crossing a mountpoint on the server | |
79 | * @dentry - dentry of mountpoint | |
80 | * @nd - nameidata info | |
81 | * | |
82 | * When we encounter a mountpoint on the server, we want to set up | |
83 | * a mountpoint on the client too, to prevent inode numbers from | |
84 | * colliding, and to allow "df" to work properly. | |
85 | * On NFSv4, we also want to allow for the fact that different | |
86 | * filesystems may be migrated to different servers in a failover | |
87 | * situation, and that different filesystems may want to use | |
88 | * different security flavours. | |
89 | */ | |
90 | static void * nfs_follow_mountpoint(struct dentry *dentry, struct nameidata *nd) | |
91 | { | |
92 | struct vfsmount *mnt; | |
93 | struct nfs_server *server = NFS_SERVER(dentry->d_inode); | |
94 | struct dentry *parent; | |
95 | struct nfs_fh fh; | |
96 | struct nfs_fattr fattr; | |
97 | int err; | |
98 | ||
99 | BUG_ON(IS_ROOT(dentry)); | |
100 | dprintk("%s: enter\n", __FUNCTION__); | |
101 | dput(nd->dentry); | |
102 | nd->dentry = dget(dentry); | |
103 | if (d_mountpoint(nd->dentry)) | |
104 | goto out_follow; | |
105 | /* Look it up again */ | |
106 | parent = dget_parent(nd->dentry); | |
107 | err = server->rpc_ops->lookup(parent->d_inode, &nd->dentry->d_name, &fh, &fattr); | |
108 | dput(parent); | |
109 | if (err != 0) | |
110 | goto out_err; | |
111 | ||
6b97fd3d MN |
112 | if (fattr.valid & NFS_ATTR_FATTR_V4_REFERRAL) |
113 | mnt = nfs_do_refmount(nd->mnt, nd->dentry); | |
114 | else | |
115 | mnt = nfs_do_submount(nd->mnt, nd->dentry, &fh, &fattr); | |
55a97593 TM |
116 | err = PTR_ERR(mnt); |
117 | if (IS_ERR(mnt)) | |
118 | goto out_err; | |
119 | ||
120 | mntget(mnt); | |
51d8fa6a | 121 | err = do_add_mount(mnt, nd, nd->mnt->mnt_flags|MNT_SHRINKABLE, &nfs_automount_list); |
55a97593 TM |
122 | if (err < 0) { |
123 | mntput(mnt); | |
124 | if (err == -EBUSY) | |
125 | goto out_follow; | |
126 | goto out_err; | |
127 | } | |
128 | mntput(nd->mnt); | |
129 | dput(nd->dentry); | |
130 | nd->mnt = mnt; | |
131 | nd->dentry = dget(mnt->mnt_root); | |
51d8fa6a | 132 | schedule_delayed_work(&nfs_automount_task, nfs_mountpoint_expiry_timeout); |
55a97593 TM |
133 | out: |
134 | dprintk("%s: done, returned %d\n", __FUNCTION__, err); | |
135 | return ERR_PTR(err); | |
136 | out_err: | |
137 | path_release(nd); | |
138 | goto out; | |
139 | out_follow: | |
140 | while(d_mountpoint(nd->dentry) && follow_down(&nd->mnt, &nd->dentry)) | |
141 | ; | |
142 | err = 0; | |
143 | goto out; | |
144 | } | |
145 | ||
146 | struct inode_operations nfs_mountpoint_inode_operations = { | |
147 | .follow_link = nfs_follow_mountpoint, | |
148 | .getattr = nfs_getattr, | |
149 | }; | |
51d8fa6a | 150 | |
6b97fd3d MN |
151 | struct inode_operations nfs_referral_inode_operations = { |
152 | .follow_link = nfs_follow_mountpoint, | |
153 | }; | |
154 | ||
51d8fa6a TM |
155 | static void nfs_expire_automounts(void *data) |
156 | { | |
157 | struct list_head *list = (struct list_head *)data; | |
158 | ||
159 | mark_mounts_for_expiry(list); | |
160 | if (!list_empty(list)) | |
161 | schedule_delayed_work(&nfs_automount_task, nfs_mountpoint_expiry_timeout); | |
162 | } | |
163 | ||
164 | void nfs_release_automount_timer(void) | |
165 | { | |
166 | if (list_empty(&nfs_automount_list)) { | |
167 | cancel_delayed_work(&nfs_automount_task); | |
168 | flush_scheduled_work(); | |
169 | } | |
170 | } | |
f7b422b1 DH |
171 | |
172 | /* | |
173 | * Clone a mountpoint of the appropriate type | |
174 | */ | |
175 | static struct vfsmount *nfs_do_clone_mount(struct nfs_server *server, char *devname, | |
176 | struct nfs_clone_mount *mountdata) | |
177 | { | |
178 | #ifdef CONFIG_NFS_V4 | |
179 | struct vfsmount *mnt = NULL; | |
180 | switch (server->rpc_ops->version) { | |
181 | case 2: | |
182 | case 3: | |
183 | mnt = vfs_kern_mount(&clone_nfs_fs_type, 0, devname, mountdata); | |
184 | break; | |
185 | case 4: | |
186 | mnt = vfs_kern_mount(&clone_nfs4_fs_type, 0, devname, mountdata); | |
187 | } | |
188 | return mnt; | |
189 | #else | |
190 | return vfs_kern_mount(&clone_nfs_fs_type, 0, devname, mountdata); | |
191 | #endif | |
192 | } | |
193 | ||
194 | /** | |
195 | * nfs_do_submount - set up mountpoint when crossing a filesystem boundary | |
196 | * @mnt_parent - mountpoint of parent directory | |
197 | * @dentry - parent directory | |
198 | * @fh - filehandle for new root dentry | |
199 | * @fattr - attributes for new root inode | |
200 | * | |
201 | */ | |
202 | struct vfsmount *nfs_do_submount(const struct vfsmount *mnt_parent, | |
203 | const struct dentry *dentry, struct nfs_fh *fh, | |
204 | struct nfs_fattr *fattr) | |
205 | { | |
206 | struct nfs_clone_mount mountdata = { | |
207 | .sb = mnt_parent->mnt_sb, | |
208 | .dentry = dentry, | |
209 | .fh = fh, | |
210 | .fattr = fattr, | |
211 | }; | |
212 | struct vfsmount *mnt = ERR_PTR(-ENOMEM); | |
213 | char *page = (char *) __get_free_page(GFP_USER); | |
214 | char *devname; | |
215 | ||
216 | dprintk("%s: submounting on %s/%s\n", __FUNCTION__, | |
217 | dentry->d_parent->d_name.name, | |
218 | dentry->d_name.name); | |
219 | if (page == NULL) | |
220 | goto out; | |
221 | devname = nfs_devname(mnt_parent, dentry, page, PAGE_SIZE); | |
222 | mnt = (struct vfsmount *)devname; | |
223 | if (IS_ERR(devname)) | |
224 | goto free_page; | |
225 | mnt = nfs_do_clone_mount(NFS_SB(mnt_parent->mnt_sb), devname, &mountdata); | |
226 | free_page: | |
227 | free_page((unsigned long)page); | |
228 | out: | |
229 | dprintk("%s: done\n", __FUNCTION__); | |
230 | return mnt; | |
231 | } |