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10#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>
17#include "internal.h"
18
19#define NFSDBG_FACILITY NFSDBG_VFS
20
21static void nfs_expire_automounts(struct work_struct *work);
22
23static LIST_HEAD(nfs_automount_list);
24static DECLARE_DELAYED_WORK(nfs_automount_task, nfs_expire_automounts);
25int nfs_mountpoint_expiry_timeout = 500 * HZ;
26
27static 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);
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45
46char *nfs_path(const char *base,
47 const struct dentry *droot,
48 const struct dentry *dentry,
49 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);
57 while (!IS_ROOT(dentry) && dentry != droot) {
58 namelen = dentry->d_name.len;
59 buflen -= namelen + 1;
60 if (buflen < 0)
61 goto Elong_unlock;
62 end -= namelen;
63 memcpy(end, dentry->d_name.name, namelen);
64 *--end = '/';
65 dentry = dentry->d_parent;
66 }
67 spin_unlock(&dcache_lock);
68 if (*end != '/') {
69 if (--buflen < 0)
70 goto Elong;
71 *--end = '/';
72 }
73 namelen = strlen(base);
74
75 while (namelen > 0 && base[namelen - 1] == '/')
76 namelen--;
77 buflen -= namelen;
78 if (buflen < 0)
79 goto Elong;
80 end -= namelen;
81 memcpy(end, base, namelen);
82 return end;
83Elong_unlock:
84 spin_unlock(&dcache_lock);
85Elong:
86 return ERR_PTR(-ENAMETOOLONG);
87}
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101
102static void * nfs_follow_mountpoint(struct dentry *dentry, struct nameidata *nd)
103{
104 struct vfsmount *mnt;
105 struct nfs_server *server = NFS_SERVER(dentry->d_inode);
106 struct dentry *parent;
107 struct nfs_fh fh;
108 struct nfs_fattr fattr;
109 int err;
110
111 dprintk("--> nfs_follow_mountpoint()\n");
112
113 err = -ESTALE;
114 if (IS_ROOT(dentry))
115 goto out_err;
116
117 dprintk("%s: enter\n", __func__);
118 dput(nd->path.dentry);
119 nd->path.dentry = dget(dentry);
120
121
122 parent = dget_parent(nd->path.dentry);
123 err = server->nfs_client->rpc_ops->lookup(parent->d_inode,
124 &nd->path.dentry->d_name,
125 &fh, &fattr);
126 dput(parent);
127 if (err != 0)
128 goto out_err;
129
130 if (fattr.valid & NFS_ATTR_FATTR_V4_REFERRAL)
131 mnt = nfs_do_refmount(nd->path.mnt, nd->path.dentry);
132 else
133 mnt = nfs_do_submount(nd->path.mnt, nd->path.dentry, &fh,
134 &fattr);
135 err = PTR_ERR(mnt);
136 if (IS_ERR(mnt))
137 goto out_err;
138
139 mntget(mnt);
140 err = do_add_mount(mnt, &nd->path, nd->path.mnt->mnt_flags|MNT_SHRINKABLE,
141 &nfs_automount_list);
142 if (err < 0) {
143 mntput(mnt);
144 if (err == -EBUSY)
145 goto out_follow;
146 goto out_err;
147 }
148 path_put(&nd->path);
149 nd->path.mnt = mnt;
150 nd->path.dentry = dget(mnt->mnt_root);
151 schedule_delayed_work(&nfs_automount_task, nfs_mountpoint_expiry_timeout);
152out:
153 dprintk("%s: done, returned %d\n", __func__, err);
154
155 dprintk("<-- nfs_follow_mountpoint() = %d\n", err);
156 return ERR_PTR(err);
157out_err:
158 path_put(&nd->path);
159 goto out;
160out_follow:
161 while (d_mountpoint(nd->path.dentry) &&
162 follow_down(&nd->path))
163 ;
164 err = 0;
165 goto out;
166}
167
168const struct inode_operations nfs_mountpoint_inode_operations = {
169 .follow_link = nfs_follow_mountpoint,
170 .getattr = nfs_getattr,
171};
172
173const struct inode_operations nfs_referral_inode_operations = {
174 .follow_link = nfs_follow_mountpoint,
175};
176
177static void nfs_expire_automounts(struct work_struct *work)
178{
179 struct list_head *list = &nfs_automount_list;
180
181 mark_mounts_for_expiry(list);
182 if (!list_empty(list))
183 schedule_delayed_work(&nfs_automount_task, nfs_mountpoint_expiry_timeout);
184}
185
186void nfs_release_automount_timer(void)
187{
188 if (list_empty(&nfs_automount_list))
189 cancel_delayed_work(&nfs_automount_task);
190}
191
192
193
194
195static struct vfsmount *nfs_do_clone_mount(struct nfs_server *server,
196 const char *devname,
197 struct nfs_clone_mount *mountdata)
198{
199#ifdef CONFIG_NFS_V4
200 struct vfsmount *mnt = ERR_PTR(-EINVAL);
201 switch (server->nfs_client->rpc_ops->version) {
202 case 2:
203 case 3:
204 mnt = vfs_kern_mount(&nfs_xdev_fs_type, 0, devname, mountdata);
205 break;
206 case 4:
207 mnt = vfs_kern_mount(&nfs4_xdev_fs_type, 0, devname, mountdata);
208 }
209 return mnt;
210#else
211 return vfs_kern_mount(&nfs_xdev_fs_type, 0, devname, mountdata);
212#endif
213}
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223static struct vfsmount *nfs_do_submount(const struct vfsmount *mnt_parent,
224 const struct dentry *dentry,
225 struct nfs_fh *fh,
226 struct nfs_fattr *fattr)
227{
228 struct nfs_clone_mount mountdata = {
229 .sb = mnt_parent->mnt_sb,
230 .dentry = dentry,
231 .fh = fh,
232 .fattr = fattr,
233 };
234 struct vfsmount *mnt = ERR_PTR(-ENOMEM);
235 char *page = (char *) __get_free_page(GFP_USER);
236 char *devname;
237
238 dprintk("--> nfs_do_submount()\n");
239
240 dprintk("%s: submounting on %s/%s\n", __func__,
241 dentry->d_parent->d_name.name,
242 dentry->d_name.name);
243 if (page == NULL)
244 goto out;
245 devname = nfs_devname(mnt_parent, dentry, page, PAGE_SIZE);
246 mnt = (struct vfsmount *)devname;
247 if (IS_ERR(devname))
248 goto free_page;
249 mnt = nfs_do_clone_mount(NFS_SB(mnt_parent->mnt_sb), devname, &mountdata);
250free_page:
251 free_page((unsigned long)page);
252out:
253 dprintk("%s: done\n", __func__);
254
255 dprintk("<-- nfs_do_submount() = %p\n", mnt);
256 return mnt;
257}
258