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 = page_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(ctx->net, ctx->cell, 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(ctx->net, p, size, NULL, false);
111 if (IS_ERR(ptr: cell)) {
112 pr_err("kAFS: unable to lookup cell '%pd'\n", mntpt);
113 return PTR_ERR(ptr: cell);
114 }
115 ctx->cell = cell;
116
117 ctx->volname = afs_root_volume;
118 ctx->volnamesz = sizeof(afs_root_volume) - 1;
119 } else {
120 /* read the contents of the AFS special symlink */
121 struct page *page;
122 loff_t size = i_size_read(inode: d_inode(dentry: mntpt));
123 char *buf;
124
125 if (src_as->cell)
126 ctx->cell = afs_use_cell(src_as->cell, afs_cell_trace_use_mntpt);
127
128 if (size < 2 || size > PAGE_SIZE - 1)
129 return -EINVAL;
130
131 page = read_mapping_page(mapping: d_inode(dentry: mntpt)->i_mapping, index: 0, NULL);
132 if (IS_ERR(ptr: page))
133 return PTR_ERR(ptr: page);
134
135 buf = kmap(page);
136 ret = -EINVAL;
137 if (buf[size - 1] == '.')
138 ret = vfs_parse_fs_string(fc, key: "source", value: buf, v_size: size - 1);
139 kunmap(page);
140 put_page(page);
141 if (ret < 0)
142 return ret;
143 }
144
145 return 0;
146}
147
148/*
149 * create a vfsmount to be automounted
150 */
151static struct vfsmount *afs_mntpt_do_automount(struct dentry *mntpt)
152{
153 struct fs_context *fc;
154 struct vfsmount *mnt;
155 int ret;
156
157 BUG_ON(!d_inode(mntpt));
158
159 fc = fs_context_for_submount(fs_type: &afs_fs_type, reference: mntpt);
160 if (IS_ERR(ptr: fc))
161 return ERR_CAST(ptr: fc);
162
163 ret = afs_mntpt_set_params(fc, mntpt);
164 if (!ret)
165 mnt = fc_mount(fc);
166 else
167 mnt = ERR_PTR(error: ret);
168
169 put_fs_context(fc);
170 return mnt;
171}
172
173/*
174 * handle an automount point
175 */
176struct vfsmount *afs_d_automount(struct path *path)
177{
178 struct vfsmount *newmnt;
179
180 _enter("{%pd}", path->dentry);
181
182 newmnt = afs_mntpt_do_automount(mntpt: path->dentry);
183 if (IS_ERR(ptr: newmnt))
184 return newmnt;
185
186 mntget(mnt: newmnt); /* prevent immediate expiration */
187 mnt_set_expiry(mnt: newmnt, expiry_list: &afs_vfsmounts);
188 queue_delayed_work(wq: afs_wq, dwork: &afs_mntpt_expiry_timer,
189 delay: afs_mntpt_expiry_timeout * HZ);
190 _leave(" = %p", newmnt);
191 return newmnt;
192}
193
194/*
195 * handle mountpoint expiry timer going off
196 */
197static void afs_mntpt_expiry_timed_out(struct work_struct *work)
198{
199 _enter("");
200
201 if (!list_empty(head: &afs_vfsmounts)) {
202 mark_mounts_for_expiry(mounts: &afs_vfsmounts);
203 queue_delayed_work(wq: afs_wq, dwork: &afs_mntpt_expiry_timer,
204 delay: afs_mntpt_expiry_timeout * HZ);
205 }
206
207 _leave("");
208}
209
210/*
211 * kill the AFS mountpoint timer if it's still running
212 */
213void afs_mntpt_kill_timer(void)
214{
215 _enter("");
216
217 ASSERT(list_empty(&afs_vfsmounts));
218 cancel_delayed_work_sync(dwork: &afs_mntpt_expiry_timer);
219}
220

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