source: src/linux/universal/linux-4.9/fs/nfs/namespace.c @ 31662

Last change on this file since 31662 was 31662, checked in by brainslayer, 4 months ago

use new squashfs in all kernels

File size: 7.3 KB
Line 
1/*
2 * linux/fs/nfs/namespace.c
3 *
4 * Copyright (C) 2005 Trond Myklebust <Trond.Myklebust@netapp.com>
5 * - Modified by David Howells <dhowells@redhat.com>
6 *
7 * NFS namespace
8 */
9
10#include <linux/module.h>
11#include <linux/dcache.h>
12#include <linux/gfp.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>
19#include <linux/sunrpc/gss_api.h>
20#include "internal.h"
21
22#define NFSDBG_FACILITY         NFSDBG_VFS
23
24static void nfs_expire_automounts(struct work_struct *work);
25
26static LIST_HEAD(nfs_automount_list);
27static DECLARE_DELAYED_WORK(nfs_automount_task, nfs_expire_automounts);
28int nfs_mountpoint_expiry_timeout = 500 * HZ;
29
30/*
31 * nfs_path - reconstruct the path given an arbitrary dentry
32 * @base - used to return pointer to the end of devname part of path
33 * @dentry - pointer to dentry
34 * @buffer - result buffer
35 * @buflen - length of buffer
36 * @flags - options (see below)
37 *
38 * Helper function for constructing the server pathname
39 * by arbitrary hashed dentry.
40 *
41 * This is mainly for use in figuring out the path on the
42 * server side when automounting on top of an existing partition
43 * and in generating /proc/mounts and friends.
44 *
45 * Supported flags:
46 * NFS_PATH_CANONICAL: ensure there is exactly one slash after
47 *                     the original device (export) name
48 *                     (if unset, the original name is returned verbatim)
49 */
50char *nfs_path(char **p, struct dentry *dentry, char *buffer, ssize_t buflen,
51               unsigned flags)
52{
53        char *end;
54        int namelen;
55        unsigned seq;
56        const char *base;
57
58rename_retry:
59        end = buffer+buflen;
60        *--end = '\0';
61        buflen--;
62
63        seq = read_seqbegin(&rename_lock);
64        rcu_read_lock();
65        while (1) {
66                spin_lock(&dentry->d_lock);
67                if (IS_ROOT(dentry))
68                        break;
69                namelen = dentry->d_name.len;
70                buflen -= namelen + 1;
71                if (buflen < 0)
72                        goto Elong_unlock;
73                end -= namelen;
74                memcpy(end, dentry->d_name.name, namelen);
75                *--end = '/';
76                spin_unlock(&dentry->d_lock);
77                dentry = dentry->d_parent;
78        }
79        if (read_seqretry(&rename_lock, seq)) {
80                spin_unlock(&dentry->d_lock);
81                rcu_read_unlock();
82                goto rename_retry;
83        }
84        if ((flags & NFS_PATH_CANONICAL) && *end != '/') {
85                if (--buflen < 0) {
86                        spin_unlock(&dentry->d_lock);
87                        rcu_read_unlock();
88                        goto Elong;
89                }
90                *--end = '/';
91        }
92        *p = end;
93        base = dentry->d_fsdata;
94        if (!base) {
95                spin_unlock(&dentry->d_lock);
96                rcu_read_unlock();
97                WARN_ON(1);
98                return end;
99        }
100        namelen = strlen(base);
101        if (*end == '/') {
102                /* Strip off excess slashes in base string */
103                while (namelen > 0 && base[namelen - 1] == '/')
104                        namelen--;
105        }
106        buflen -= namelen;
107        if (buflen < 0) {
108                spin_unlock(&dentry->d_lock);
109                rcu_read_unlock();
110                goto Elong;
111        }
112        end -= namelen;
113        memcpy(end, base, namelen);
114        spin_unlock(&dentry->d_lock);
115        rcu_read_unlock();
116        return end;
117Elong_unlock:
118        spin_unlock(&dentry->d_lock);
119        rcu_read_unlock();
120        if (read_seqretry(&rename_lock, seq))
121                goto rename_retry;
122Elong:
123        return ERR_PTR(-ENAMETOOLONG);
124}
125EXPORT_SYMBOL_GPL(nfs_path);
126
127/*
128 * nfs_d_automount - Handle crossing a mountpoint on the server
129 * @path - The mountpoint
130 *
131 * When we encounter a mountpoint on the server, we want to set up
132 * a mountpoint on the client too, to prevent inode numbers from
133 * colliding, and to allow "df" to work properly.
134 * On NFSv4, we also want to allow for the fact that different
135 * filesystems may be migrated to different servers in a failover
136 * situation, and that different filesystems may want to use
137 * different security flavours.
138 */
139struct vfsmount *nfs_d_automount(struct path *path)
140{
141        struct vfsmount *mnt;
142        struct nfs_server *server = NFS_SERVER(d_inode(path->dentry));
143        struct nfs_fh *fh = NULL;
144        struct nfs_fattr *fattr = NULL;
145
146        dprintk("--> nfs_d_automount()\n");
147
148        mnt = ERR_PTR(-ESTALE);
149        if (IS_ROOT(path->dentry))
150                goto out_nofree;
151
152        mnt = ERR_PTR(-ENOMEM);
153        fh = nfs_alloc_fhandle();
154        fattr = nfs_alloc_fattr();
155        if (fh == NULL || fattr == NULL)
156                goto out;
157
158        dprintk("%s: enter\n", __func__);
159
160        mnt = server->nfs_client->rpc_ops->submount(server, path->dentry, fh, fattr);
161        if (IS_ERR(mnt))
162                goto out;
163
164        dprintk("%s: done, success\n", __func__);
165        mntget(mnt); /* prevent immediate expiration */
166        mnt_set_expiry(mnt, &nfs_automount_list);
167        schedule_delayed_work(&nfs_automount_task, nfs_mountpoint_expiry_timeout);
168
169out:
170        nfs_free_fattr(fattr);
171        nfs_free_fhandle(fh);
172out_nofree:
173        if (IS_ERR(mnt))
174                dprintk("<-- %s(): error %ld\n", __func__, PTR_ERR(mnt));
175        else
176                dprintk("<-- %s() = %p\n", __func__, mnt);
177        return mnt;
178}
179
180static int
181nfs_namespace_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
182{
183        if (NFS_FH(d_inode(dentry))->size != 0)
184                return nfs_getattr(mnt, dentry, stat);
185        generic_fillattr(d_inode(dentry), stat);
186        return 0;
187}
188
189static int
190nfs_namespace_setattr(struct dentry *dentry, struct iattr *attr)
191{
192        if (NFS_FH(d_inode(dentry))->size != 0)
193                return nfs_setattr(dentry, attr);
194        return -EACCES;
195}
196
197const struct inode_operations nfs_mountpoint_inode_operations = {
198        .getattr        = nfs_getattr,
199        .setattr        = nfs_setattr,
200};
201
202const struct inode_operations nfs_referral_inode_operations = {
203        .getattr        = nfs_namespace_getattr,
204        .setattr        = nfs_namespace_setattr,
205};
206
207static void nfs_expire_automounts(struct work_struct *work)
208{
209        struct list_head *list = &nfs_automount_list;
210
211        mark_mounts_for_expiry(list);
212        if (!list_empty(list))
213                schedule_delayed_work(&nfs_automount_task, nfs_mountpoint_expiry_timeout);
214}
215
216void nfs_release_automount_timer(void)
217{
218        if (list_empty(&nfs_automount_list))
219                cancel_delayed_work(&nfs_automount_task);
220}
221
222/*
223 * Clone a mountpoint of the appropriate type
224 */
225static struct vfsmount *nfs_do_clone_mount(struct nfs_server *server,
226                                           const char *devname,
227                                           struct nfs_clone_mount *mountdata)
228{
229        return vfs_submount(mountdata->dentry, &nfs_xdev_fs_type, devname, mountdata);
230}
231
232/**
233 * nfs_do_submount - set up mountpoint when crossing a filesystem boundary
234 * @dentry - parent directory
235 * @fh - filehandle for new root dentry
236 * @fattr - attributes for new root inode
237 * @authflavor - security flavor to use when performing the mount
238 *
239 */
240struct vfsmount *nfs_do_submount(struct dentry *dentry, struct nfs_fh *fh,
241                                 struct nfs_fattr *fattr, rpc_authflavor_t authflavor)
242{
243        struct nfs_clone_mount mountdata = {
244                .sb = dentry->d_sb,
245                .dentry = dentry,
246                .fh = fh,
247                .fattr = fattr,
248                .authflavor = authflavor,
249        };
250        struct vfsmount *mnt = ERR_PTR(-ENOMEM);
251        char *page = (char *) __get_free_page(GFP_USER);
252        char *devname;
253
254        dprintk("--> nfs_do_submount()\n");
255
256        dprintk("%s: submounting on %pd2\n", __func__,
257                        dentry);
258        if (page == NULL)
259                goto out;
260        devname = nfs_devname(dentry, page, PAGE_SIZE);
261        mnt = (struct vfsmount *)devname;
262        if (IS_ERR(devname))
263                goto free_page;
264        mnt = nfs_do_clone_mount(NFS_SB(dentry->d_sb), devname, &mountdata);
265free_page:
266        free_page((unsigned long)page);
267out:
268        dprintk("%s: done\n", __func__);
269
270        dprintk("<-- nfs_do_submount() = %p\n", mnt);
271        return mnt;
272}
273EXPORT_SYMBOL_GPL(nfs_do_submount);
274
275struct vfsmount *nfs_submount(struct nfs_server *server, struct dentry *dentry,
276                              struct nfs_fh *fh, struct nfs_fattr *fattr)
277{
278        int err;
279        struct dentry *parent = dget_parent(dentry);
280
281        /* Look it up again to get its attributes */
282        err = server->nfs_client->rpc_ops->lookup(d_inode(parent), &dentry->d_name, fh, fattr, NULL);
283        dput(parent);
284        if (err != 0)
285                return ERR_PTR(err);
286
287        return nfs_do_submount(dentry, fh, fattr, server->client->cl_auth->au_flavor);
288}
289EXPORT_SYMBOL_GPL(nfs_submount);
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