aboutsummaryrefslogtreecommitdiff
path: root/fs/afs/mntpt.c
blob: 97f50e9fd9eb017384e5790a33519662d3cca978 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
// SPDX-License-Identifier: GPL-2.0-or-later
/* mountpoint management
 *
 * Copyright (C) 2002 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/fs.h>
#include <linux/pagemap.h>
#include <linux/mount.h>
#include <linux/namei.h>
#include <linux/gfp.h>
#include <linux/fs_context.h>
#include "internal.h"


static struct dentry *afs_mntpt_lookup(struct inode *dir,
				       struct dentry *dentry,
				       unsigned int flags);
static int afs_mntpt_open(struct inode *inode, struct file *file);
static void afs_mntpt_expiry_timed_out(struct work_struct *work);

const struct file_operations afs_mntpt_file_operations = {
	.open		= afs_mntpt_open,
	.llseek		= noop_llseek,
};

const struct inode_operations afs_mntpt_inode_operations = {
	.lookup		= afs_mntpt_lookup,
	.readlink	= page_readlink,
	.getattr	= afs_getattr,
};

const struct inode_operations afs_autocell_inode_operations = {
	.getattr	= afs_getattr,
};

static LIST_HEAD(afs_vfsmounts);
static DECLARE_DELAYED_WORK(afs_mntpt_expiry_timer, afs_mntpt_expiry_timed_out);

static unsigned long afs_mntpt_expiry_timeout = 10 * 60;

static const char afs_root_volume[] = "root.cell";

/*
 * no valid lookup procedure on this sort of dir
 */
static struct dentry *afs_mntpt_lookup(struct inode *dir,
				       struct dentry *dentry,
				       unsigned int flags)
{
	_enter("%p,%p{%pd2}", dir, dentry, dentry);
	return ERR_PTR(-EREMOTE);
}

/*
 * no valid open procedure on this sort of dir
 */
static int afs_mntpt_open(struct inode *inode, struct file *file)
{
	_enter("%p,%p{%pD2}", inode, file, file);
	return -EREMOTE;
}

/*
 * Set the parameters for the proposed superblock.
 */
static int afs_mntpt_set_params(struct fs_context *fc, struct dentry *mntpt)
{
	struct afs_fs_context *ctx = fc->fs_private;
	struct afs_super_info *src_as = AFS_FS_S(mntpt->d_sb);
	struct afs_vnode *vnode = AFS_FS_I(d_inode(mntpt));
	struct afs_cell *cell;
	const char *p;
	int ret;

	if (fc->net_ns != src_as->net_ns) {
		put_net(fc->net_ns);
		fc->net_ns = get_net(src_as->net_ns);
	}

	if (src_as->volume && src_as->volume->type == AFSVL_RWVOL) {
		ctx->type = AFSVL_RWVOL;
		ctx->force = true;
	}
	if (ctx->cell) {
		afs_unuse_cell(ctx->net, ctx->cell, afs_cell_trace_unuse_mntpt);
		ctx->cell = NULL;
	}
	if (test_bit(AFS_VNODE_PSEUDODIR, &vnode->flags)) {
		/* if the directory is a pseudo directory, use the d_name */
		unsigned size = mntpt->d_name.len;

		if (size < 2)
			return -ENOENT;

		p = mntpt->d_name.name;
		if (mntpt->d_name.name[0] == '.') {
			size--;
			p++;
			ctx->type = AFSVL_RWVOL;
			ctx->force = true;
		}
		if (size > AFS_MAXCELLNAME)
			return -ENAMETOOLONG;

		cell = afs_lookup_cell(ctx->net, p, size, NULL, false);
		if (IS_ERR(cell)) {
			pr_err("kAFS: unable to lookup cell '%pd'\n", mntpt);
			return PTR_ERR(cell);
		}
		ctx->cell = cell;

		ctx->volname = afs_root_volume;
		ctx->volnamesz = sizeof(afs_root_volume) - 1;
	} else {
		/* read the contents of the AFS special symlink */
		struct page *page;
		loff_t size = i_size_read(d_inode(mntpt));
		char *buf;

		if (src_as->cell)
			ctx->cell = afs_use_cell(src_as->cell, afs_cell_trace_use_mntpt);

		if (size < 2 || size > PAGE_SIZE - 1)
			return -EINVAL;

		page = read_mapping_page(d_inode(mntpt)->i_mapping, 0, NULL);
		if (IS_ERR(page))
			return PTR_ERR(page);

		buf = kmap(page);
		ret = -EINVAL;
		if (buf[size - 1] == '.')
			ret = vfs_parse_fs_string(fc, "source", buf, size - 1);
		kunmap(page);
		put_page(page);
		if (ret < 0)
			return ret;
	}

	return 0;
}

/*
 * create a vfsmount to be automounted
 */
static struct vfsmount *afs_mntpt_do_automount(struct dentry *mntpt)
{
	struct fs_context *fc;
	struct vfsmount *mnt;
	int ret;

	BUG_ON(!d_inode(mntpt));

	fc = fs_context_for_submount(&afs_fs_type, mntpt);
	if (IS_ERR(fc))
		return ERR_CAST(fc);

	ret = afs_mntpt_set_params(fc, mntpt);
	if (!ret)
		mnt = fc_mount(fc);
	else
		mnt = ERR_PTR(ret);

	put_fs_context(fc);
	return mnt;
}

/*
 * handle an automount point
 */
struct vfsmount *afs_d_automount(struct path *path)
{
	struct vfsmount *newmnt;

	_enter("{%pd}", path->dentry);

	newmnt = afs_mntpt_do_automount(path->dentry);
	if (IS_ERR(newmnt))
		return newmnt;

	mntget(newmnt); /* prevent immediate expiration */
	mnt_set_expiry(newmnt, &afs_vfsmounts);
	queue_delayed_work(afs_wq, &afs_mntpt_expiry_timer,
			   afs_mntpt_expiry_timeout * HZ);
	_leave(" = %p", newmnt);
	return newmnt;
}

/*
 * handle mountpoint expiry timer going off
 */
static void afs_mntpt_expiry_timed_out(struct work_struct *work)
{
	_enter("");

	if (!list_empty(&afs_vfsmounts)) {
		mark_mounts_for_expiry(&afs_vfsmounts);
		queue_delayed_work(afs_wq, &afs_mntpt_expiry_timer,
				   afs_mntpt_expiry_timeout * HZ);
	}

	_leave("");
}

/*
 * kill the AFS mountpoint timer if it's still running
 */
void afs_mntpt_kill_timer(void)
{
	_enter("");

	ASSERT(list_empty(&afs_vfsmounts));
	cancel_delayed_work_sync(&afs_mntpt_expiry_timer);
}