1// SPDX-License-Identifier: GPL-2.0-or-later
2/* mountpoint management
3 *
4 * Copyright (C) 2002 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.com)
6 */
7
8#include <linux/kernel.h>
9#include <linux/module.h>
10#include <linux/init.h>
11#include <linux/fs.h>
12#include <linux/pagemap.h>
13#include <linux/mount.h>
14#include <linux/namei.h>
15#include <linux/gfp.h>
16#include <linux/fs_context.h>
17#include "internal.h"
18
19
20static struct dentry *afs_mntpt_lookup(struct inode *dir,
21 struct dentry *dentry,
22 unsigned int flags);
23static int afs_mntpt_open(struct inode *inode, struct file *file);
24static void afs_mntpt_expiry_timed_out(struct work_struct *work);
25
26const struct file_operations afs_mntpt_file_operations = {
27 .open = afs_mntpt_open,
28 .llseek = noop_llseek,
29};
30
31const struct inode_operations afs_mntpt_inode_operations = {
32 .lookup = afs_mntpt_lookup,
33 .readlink = afs_readlink,
34 .getattr = afs_getattr,
35};
36
37const struct inode_operations afs_autocell_inode_operations = {
38 .getattr = afs_getattr,
39};
40
41static LIST_HEAD(afs_vfsmounts);
42static DECLARE_DELAYED_WORK(afs_mntpt_expiry_timer, afs_mntpt_expiry_timed_out);
43
44static unsigned long afs_mntpt_expiry_timeout = 10 * 60;
45
46static const char afs_root_volume[] = "root.cell";
47
48/*
49 * no valid lookup procedure on this sort of dir
50 */
51static struct dentry *afs_mntpt_lookup(struct inode *dir,
52 struct dentry *dentry,
53 unsigned int flags)
54{
55 _enter("%p,%p{%pd2}", dir, dentry, dentry);
56 return ERR_PTR(error: -EREMOTE);
57}
58
59/*
60 * no valid open procedure on this sort of dir
61 */
62static int afs_mntpt_open(struct inode *inode, struct file *file)
63{
64 _enter("%p,%p{%pD2}", inode, file, file);
65 return -EREMOTE;
66}
67
68/*
69 * Set the parameters for the proposed superblock.
70 */
71static int afs_mntpt_set_params(struct fs_context *fc, struct dentry *mntpt)
72{
73 struct afs_fs_context *ctx = fc->fs_private;
74 struct afs_super_info *src_as = AFS_FS_S(sb: mntpt->d_sb);
75 struct afs_vnode *vnode = AFS_FS_I(inode: d_inode(dentry: mntpt));
76 struct afs_cell *cell;
77 const char *p;
78 int ret;
79
80 if (fc->net_ns != src_as->net_ns) {
81 put_net(net: fc->net_ns);
82 fc->net_ns = get_net(net: src_as->net_ns);
83 }
84
85 if (src_as->volume && src_as->volume->type == AFSVL_RWVOL) {
86 ctx->type = AFSVL_RWVOL;
87 ctx->force = true;
88 }
89 if (ctx->cell) {
90 afs_unuse_cell(cell: ctx->cell, reason: afs_cell_trace_unuse_mntpt);
91 ctx->cell = NULL;
92 }
93 if (test_bit(AFS_VNODE_PSEUDODIR, &vnode->flags)) {
94 /* if the directory is a pseudo directory, use the d_name */
95 unsigned size = mntpt->d_name.len;
96
97 if (size < 2)
98 return -ENOENT;
99
100 p = mntpt->d_name.name;
101 if (mntpt->d_name.name[0] == '.') {
102 size--;
103 p++;
104 ctx->type = AFSVL_RWVOL;
105 ctx->force = true;
106 }
107 if (size > AFS_MAXCELLNAME)
108 return -ENAMETOOLONG;
109
110 cell = afs_lookup_cell(net: ctx->net, name: p, namesz: size, NULL,
111 reason: AFS_LOOKUP_CELL_MOUNTPOINT,
112 trace: afs_cell_trace_use_lookup_mntpt);
113 if (IS_ERR(ptr: cell)) {
114 pr_err("kAFS: unable to lookup cell '%pd'\n", mntpt);
115 return PTR_ERR(ptr: cell);
116 }
117 ctx->cell = cell;
118
119 ctx->volname = afs_root_volume;
120 ctx->volnamesz = sizeof(afs_root_volume) - 1;
121 } else {
122 /* read the contents of the AFS special symlink */
123 DEFINE_DELAYED_CALL(cleanup);
124 const char *content;
125 loff_t size = i_size_read(inode: d_inode(dentry: mntpt));
126
127 if (src_as->cell)
128 ctx->cell = afs_use_cell(src_as->cell, afs_cell_trace_use_mntpt);
129
130 if (size < 2 || size > PAGE_SIZE - 1)
131 return -EINVAL;
132
133 content = afs_get_link(dentry: mntpt, inode: d_inode(dentry: mntpt), callback: &cleanup);
134 if (IS_ERR(ptr: content)) {
135 do_delayed_call(call: &cleanup);
136 return PTR_ERR(ptr: content);
137 }
138
139 ret = -EINVAL;
140 if (content[size - 1] == '.')
141 ret = vfs_parse_fs_qstr(fc, key: "source",
142 value: &QSTR_LEN(content, size - 1));
143 do_delayed_call(call: &cleanup);
144 if (ret < 0)
145 return ret;
146
147 /* Don't cross a backup volume mountpoint from a backup volume */
148 if (src_as->volume && src_as->volume->type == AFSVL_BACKVOL &&
149 ctx->type == AFSVL_BACKVOL)
150 return -ENODEV;
151 }
152
153 return 0;
154}
155
156/*
157 * create a vfsmount to be automounted
158 */
159static struct vfsmount *afs_mntpt_do_automount(struct dentry *mntpt)
160{
161 struct fs_context *fc;
162 struct vfsmount *mnt;
163 int ret;
164
165 BUG_ON(!d_inode(mntpt));
166
167 fc = fs_context_for_submount(fs_type: &afs_fs_type, reference: mntpt);
168 if (IS_ERR(ptr: fc))
169 return ERR_CAST(ptr: fc);
170
171 ret = afs_mntpt_set_params(fc, mntpt);
172 if (!ret)
173 mnt = fc_mount(fc);
174 else
175 mnt = ERR_PTR(error: ret);
176
177 put_fs_context(fc);
178 return mnt;
179}
180
181/*
182 * handle an automount point
183 */
184struct vfsmount *afs_d_automount(struct path *path)
185{
186 struct vfsmount *newmnt;
187
188 _enter("{%pd}", path->dentry);
189
190 newmnt = afs_mntpt_do_automount(mntpt: path->dentry);
191 if (IS_ERR(ptr: newmnt))
192 return newmnt;
193
194 mnt_set_expiry(mnt: newmnt, expiry_list: &afs_vfsmounts);
195 queue_delayed_work(wq: afs_wq, dwork: &afs_mntpt_expiry_timer,
196 delay: afs_mntpt_expiry_timeout * HZ);
197 _leave(" = %p", newmnt);
198 return newmnt;
199}
200
201/*
202 * handle mountpoint expiry timer going off
203 */
204static void afs_mntpt_expiry_timed_out(struct work_struct *work)
205{
206 _enter("");
207
208 if (!list_empty(head: &afs_vfsmounts)) {
209 mark_mounts_for_expiry(mounts: &afs_vfsmounts);
210 queue_delayed_work(wq: afs_wq, dwork: &afs_mntpt_expiry_timer,
211 delay: afs_mntpt_expiry_timeout * HZ);
212 }
213
214 _leave("");
215}
216
217/*
218 * kill the AFS mountpoint timer if it's still running
219 */
220void afs_mntpt_kill_timer(void)
221{
222 _enter("");
223
224 ASSERT(list_empty(&afs_vfsmounts));
225 cancel_delayed_work_sync(dwork: &afs_mntpt_expiry_timer);
226}
227

source code of linux/fs/afs/mntpt.c