xref: /openbmc/linux/fs/pstore/inode.c (revision 54525552) 
1 /*
2  * Persistent Storage - ramfs parts.
3  *
4  * Copyright (C) 2010 Intel Corporation <tony.luck@intel.com>
5  *
6  *  This program is free software; you can redistribute it and/or modify
7  *  it under the terms of the GNU General Public License version 2 as
8  *  published by the Free Software Foundation.
9  *
10  *  This program is distributed in the hope that it will be useful,
11  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
12  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
13  *  GNU General Public License for more details.
14  *
15  *  You should have received a copy of the GNU General Public License
16  *  along with this program; if not, write to the Free Software
17  *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
18  */
19 
20 #include <linux/module.h>
21 #include <linux/fs.h>
22 #include <linux/fsnotify.h>
23 #include <linux/pagemap.h>
24 #include <linux/highmem.h>
25 #include <linux/time.h>
26 #include <linux/init.h>
27 #include <linux/string.h>
28 #include <linux/mount.h>
29 #include <linux/ramfs.h>
30 #include <linux/parser.h>
31 #include <linux/sched.h>
32 #include <linux/magic.h>
33 #include <linux/pstore.h>
34 #include <linux/slab.h>
35 #include <linux/uaccess.h>
36 
37 #include "internal.h"
38 
39 #define	PSTORE_NAMELEN	64
40 
41 struct pstore_private {
42 	u64	id;
43 	int	(*erase)(u64);
44 	ssize_t	size;
45 	char	data[];
46 };
47 
48 static int pstore_file_open(struct inode *inode, struct file *file)
49 {
50 	file->private_data = inode->i_private;
51 	return 0;
52 }
53 
54 static ssize_t pstore_file_read(struct file *file, char __user *userbuf,
55 						size_t count, loff_t *ppos)
56 {
57 	struct pstore_private *ps = file->private_data;
58 
59 	return simple_read_from_buffer(userbuf, count, ppos, ps->data, ps->size);
60 }
61 
62 static const struct file_operations pstore_file_operations = {
63 	.open	= pstore_file_open,
64 	.read	= pstore_file_read,
65 	.llseek	= default_llseek,
66 };
67 
68 /*
69  * When a file is unlinked from our file system we call the
70  * platform driver to erase the record from persistent store.
71  */
72 static int pstore_unlink(struct inode *dir, struct dentry *dentry)
73 {
74 	struct pstore_private *p = dentry->d_inode->i_private;
75 
76 	p->erase(p->id);
77 
78 	return simple_unlink(dir, dentry);
79 }
80 
81 static void pstore_evict_inode(struct inode *inode)
82 {
83 	end_writeback(inode);
84 	kfree(inode->i_private);
85 }
86 
87 static const struct inode_operations pstore_dir_inode_operations = {
88 	.lookup		= simple_lookup,
89 	.unlink		= pstore_unlink,
90 };
91 
92 static struct inode *pstore_get_inode(struct super_block *sb,
93 					const struct inode *dir, int mode, dev_t dev)
94 {
95 	struct inode *inode = new_inode(sb);
96 
97 	if (inode) {
98 		inode->i_ino = get_next_ino();
99 		inode->i_uid = inode->i_gid = 0;
100 		inode->i_mode = mode;
101 		inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
102 		switch (mode & S_IFMT) {
103 		case S_IFREG:
104 			inode->i_fop = &pstore_file_operations;
105 			break;
106 		case S_IFDIR:
107 			inode->i_op = &pstore_dir_inode_operations;
108 			inode->i_fop = &simple_dir_operations;
109 			inc_nlink(inode);
110 			break;
111 		}
112 	}
113 	return inode;
114 }
115 
116 enum {
117 	Opt_kmsg_bytes, Opt_err
118 };
119 
120 static const match_table_t tokens = {
121 	{Opt_kmsg_bytes, "kmsg_bytes=%u"},
122 	{Opt_err, NULL}
123 };
124 
125 static void parse_options(char *options)
126 {
127 	char		*p;
128 	substring_t	args[MAX_OPT_ARGS];
129 	int		option;
130 
131 	if (!options)
132 		return;
133 
134 	while ((p = strsep(&options, ",")) != NULL) {
135 		int token;
136 
137 		if (!*p)
138 			continue;
139 
140 		token = match_token(p, tokens, args);
141 		switch (token) {
142 		case Opt_kmsg_bytes:
143 			if (!match_int(&args[0], &option))
144 				pstore_set_kmsg_bytes(option);
145 			break;
146 		}
147 	}
148 }
149 
150 static int pstore_remount(struct super_block *sb, int *flags, char *data)
151 {
152 	parse_options(data);
153 
154 	return 0;
155 }
156 
157 static const struct super_operations pstore_ops = {
158 	.statfs		= simple_statfs,
159 	.drop_inode	= generic_delete_inode,
160 	.evict_inode	= pstore_evict_inode,
161 	.remount_fs	= pstore_remount,
162 	.show_options	= generic_show_options,
163 };
164 
165 static struct super_block *pstore_sb;
166 
167 int pstore_is_mounted(void)
168 {
169 	return pstore_sb != NULL;
170 }
171 
172 /*
173  * Make a regular file in the root directory of our file system.
174  * Load it up with "size" bytes of data from "buf".
175  * Set the mtime & ctime to the date that this record was originally stored.
176  */
177 int pstore_mkfile(enum pstore_type_id type, char *psname, u64 id,
178 			      char *data, size_t size,
179 			      struct timespec time, int (*erase)(u64))
180 {
181 	struct dentry		*root = pstore_sb->s_root;
182 	struct dentry		*dentry;
183 	struct inode		*inode;
184 	int			rc;
185 	char			name[PSTORE_NAMELEN];
186 	struct pstore_private	*private;
187 
188 	rc = -ENOMEM;
189 	inode = pstore_get_inode(pstore_sb, root->d_inode, S_IFREG | 0444, 0);
190 	if (!inode)
191 		goto fail;
192 	private = kmalloc(sizeof *private + size, GFP_KERNEL);
193 	if (!private)
194 		goto fail_alloc;
195 	private->id = id;
196 	private->erase = erase;
197 
198 	switch (type) {
199 	case PSTORE_TYPE_DMESG:
200 		sprintf(name, "dmesg-%s-%lld", psname, id);
201 		break;
202 	case PSTORE_TYPE_MCE:
203 		sprintf(name, "mce-%s-%lld", psname, id);
204 		break;
205 	case PSTORE_TYPE_UNKNOWN:
206 		sprintf(name, "unknown-%s-%lld", psname, id);
207 		break;
208 	default:
209 		sprintf(name, "type%d-%s-%lld", type, psname, id);
210 		break;
211 	}
212 
213 	mutex_lock(&root->d_inode->i_mutex);
214 
215 	rc = -ENOSPC;
216 	dentry = d_alloc_name(root, name);
217 	if (IS_ERR(dentry))
218 		goto fail_lockedalloc;
219 
220 	memcpy(private->data, data, size);
221 	inode->i_size = private->size = size;
222 
223 	inode->i_private = private;
224 
225 	if (time.tv_sec)
226 		inode->i_mtime = inode->i_ctime = time;
227 
228 	d_add(dentry, inode);
229 
230 	mutex_unlock(&root->d_inode->i_mutex);
231 
232 	return 0;
233 
234 fail_lockedalloc:
235 	mutex_unlock(&root->d_inode->i_mutex);
236 	kfree(private);
237 fail_alloc:
238 	iput(inode);
239 
240 fail:
241 	return rc;
242 }
243 
244 int pstore_fill_super(struct super_block *sb, void *data, int silent)
245 {
246 	struct inode *inode = NULL;
247 	struct dentry *root;
248 	int err;
249 
250 	save_mount_options(sb, data);
251 
252 	pstore_sb = sb;
253 
254 	sb->s_maxbytes		= MAX_LFS_FILESIZE;
255 	sb->s_blocksize		= PAGE_CACHE_SIZE;
256 	sb->s_blocksize_bits	= PAGE_CACHE_SHIFT;
257 	sb->s_magic		= PSTOREFS_MAGIC;
258 	sb->s_op		= &pstore_ops;
259 	sb->s_time_gran		= 1;
260 
261 	parse_options(data);
262 
263 	inode = pstore_get_inode(sb, NULL, S_IFDIR | 0755, 0);
264 	if (!inode) {
265 		err = -ENOMEM;
266 		goto fail;
267 	}
268 	/* override ramfs "dir" options so we catch unlink(2) */
269 	inode->i_op = &pstore_dir_inode_operations;
270 
271 	root = d_alloc_root(inode);
272 	sb->s_root = root;
273 	if (!root) {
274 		err = -ENOMEM;
275 		goto fail;
276 	}
277 
278 	pstore_get_records();
279 
280 	return 0;
281 fail:
282 	iput(inode);
283 	return err;
284 }
285 
286 static struct dentry *pstore_mount(struct file_system_type *fs_type,
287 	int flags, const char *dev_name, void *data)
288 {
289 	return mount_single(fs_type, flags, data, pstore_fill_super);
290 }
291 
292 static void pstore_kill_sb(struct super_block *sb)
293 {
294 	kill_litter_super(sb);
295 	pstore_sb = NULL;
296 }
297 
298 static struct file_system_type pstore_fs_type = {
299 	.name		= "pstore",
300 	.mount		= pstore_mount,
301 	.kill_sb	= pstore_kill_sb,
302 };
303 
304 static int __init init_pstore_fs(void)
305 {
306 	return register_filesystem(&pstore_fs_type);
307 }
308 module_init(init_pstore_fs)
309 
310 MODULE_AUTHOR("Tony Luck <tony.luck@intel.com>");
311 MODULE_LICENSE("GPL");
312