xref: /openbmc/linux/fs/pstore/inode.c (revision edfd52e6) 
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/list.h>
28 #include <linux/string.h>
29 #include <linux/mount.h>
30 #include <linux/ramfs.h>
31 #include <linux/parser.h>
32 #include <linux/sched.h>
33 #include <linux/magic.h>
34 #include <linux/pstore.h>
35 #include <linux/slab.h>
36 #include <linux/spinlock.h>
37 #include <linux/uaccess.h>
38 
39 #include "internal.h"
40 
41 #define	PSTORE_NAMELEN	64
42 
43 static DEFINE_SPINLOCK(allpstore_lock);
44 static LIST_HEAD(allpstore);
45 
46 struct pstore_private {
47 	struct list_head list;
48 	struct pstore_info *psi;
49 	enum pstore_type_id type;
50 	u64	id;
51 	ssize_t	size;
52 	char	data[];
53 };
54 
55 static int pstore_file_open(struct inode *inode, struct file *file)
56 {
57 	file->private_data = inode->i_private;
58 	return 0;
59 }
60 
61 static ssize_t pstore_file_read(struct file *file, char __user *userbuf,
62 						size_t count, loff_t *ppos)
63 {
64 	struct pstore_private *ps = file->private_data;
65 
66 	return simple_read_from_buffer(userbuf, count, ppos, ps->data, ps->size);
67 }
68 
69 static const struct file_operations pstore_file_operations = {
70 	.open	= pstore_file_open,
71 	.read	= pstore_file_read,
72 	.llseek	= default_llseek,
73 };
74 
75 /*
76  * When a file is unlinked from our file system we call the
77  * platform driver to erase the record from persistent store.
78  */
79 static int pstore_unlink(struct inode *dir, struct dentry *dentry)
80 {
81 	struct pstore_private *p = dentry->d_inode->i_private;
82 
83 	p->psi->erase(p->type, p->id, p->psi);
84 
85 	return simple_unlink(dir, dentry);
86 }
87 
88 static void pstore_evict_inode(struct inode *inode)
89 {
90 	struct pstore_private	*p = inode->i_private;
91 	unsigned long		flags;
92 
93 	end_writeback(inode);
94 	if (p) {
95 		spin_lock_irqsave(&allpstore_lock, flags);
96 		list_del(&p->list);
97 		spin_unlock_irqrestore(&allpstore_lock, flags);
98 		kfree(p);
99 	}
100 }
101 
102 static const struct inode_operations pstore_dir_inode_operations = {
103 	.lookup		= simple_lookup,
104 	.unlink		= pstore_unlink,
105 };
106 
107 static struct inode *pstore_get_inode(struct super_block *sb,
108 					const struct inode *dir, int mode, dev_t dev)
109 {
110 	struct inode *inode = new_inode(sb);
111 
112 	if (inode) {
113 		inode->i_ino = get_next_ino();
114 		inode->i_uid = inode->i_gid = 0;
115 		inode->i_mode = mode;
116 		inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
117 		switch (mode & S_IFMT) {
118 		case S_IFREG:
119 			inode->i_fop = &pstore_file_operations;
120 			break;
121 		case S_IFDIR:
122 			inode->i_op = &pstore_dir_inode_operations;
123 			inode->i_fop = &simple_dir_operations;
124 			inc_nlink(inode);
125 			break;
126 		}
127 	}
128 	return inode;
129 }
130 
131 enum {
132 	Opt_kmsg_bytes, Opt_err
133 };
134 
135 static const match_table_t tokens = {
136 	{Opt_kmsg_bytes, "kmsg_bytes=%u"},
137 	{Opt_err, NULL}
138 };
139 
140 static void parse_options(char *options)
141 {
142 	char		*p;
143 	substring_t	args[MAX_OPT_ARGS];
144 	int		option;
145 
146 	if (!options)
147 		return;
148 
149 	while ((p = strsep(&options, ",")) != NULL) {
150 		int token;
151 
152 		if (!*p)
153 			continue;
154 
155 		token = match_token(p, tokens, args);
156 		switch (token) {
157 		case Opt_kmsg_bytes:
158 			if (!match_int(&args[0], &option))
159 				pstore_set_kmsg_bytes(option);
160 			break;
161 		}
162 	}
163 }
164 
165 static int pstore_remount(struct super_block *sb, int *flags, char *data)
166 {
167 	parse_options(data);
168 
169 	return 0;
170 }
171 
172 static const struct super_operations pstore_ops = {
173 	.statfs		= simple_statfs,
174 	.drop_inode	= generic_delete_inode,
175 	.evict_inode	= pstore_evict_inode,
176 	.remount_fs	= pstore_remount,
177 	.show_options	= generic_show_options,
178 };
179 
180 static struct super_block *pstore_sb;
181 
182 int pstore_is_mounted(void)
183 {
184 	return pstore_sb != NULL;
185 }
186 
187 /*
188  * Make a regular file in the root directory of our file system.
189  * Load it up with "size" bytes of data from "buf".
190  * Set the mtime & ctime to the date that this record was originally stored.
191  */
192 int pstore_mkfile(enum pstore_type_id type, char *psname, u64 id,
193 		  char *data, size_t size, struct timespec time,
194 		  struct pstore_info *psi)
195 {
196 	struct dentry		*root = pstore_sb->s_root;
197 	struct dentry		*dentry;
198 	struct inode		*inode;
199 	int			rc = 0;
200 	char			name[PSTORE_NAMELEN];
201 	struct pstore_private	*private, *pos;
202 	unsigned long		flags;
203 
204 	spin_lock_irqsave(&allpstore_lock, flags);
205 	list_for_each_entry(pos, &allpstore, list) {
206 		if (pos->type == type &&
207 		    pos->id == id &&
208 		    pos->psi == psi) {
209 			rc = -EEXIST;
210 			break;
211 		}
212 	}
213 	spin_unlock_irqrestore(&allpstore_lock, flags);
214 	if (rc)
215 		return rc;
216 
217 	rc = -ENOMEM;
218 	inode = pstore_get_inode(pstore_sb, root->d_inode, S_IFREG | 0444, 0);
219 	if (!inode)
220 		goto fail;
221 	private = kmalloc(sizeof *private + size, GFP_KERNEL);
222 	if (!private)
223 		goto fail_alloc;
224 	private->type = type;
225 	private->id = id;
226 	private->psi = psi;
227 
228 	switch (type) {
229 	case PSTORE_TYPE_DMESG:
230 		sprintf(name, "dmesg-%s-%lld", psname, id);
231 		break;
232 	case PSTORE_TYPE_MCE:
233 		sprintf(name, "mce-%s-%lld", psname, id);
234 		break;
235 	case PSTORE_TYPE_UNKNOWN:
236 		sprintf(name, "unknown-%s-%lld", psname, id);
237 		break;
238 	default:
239 		sprintf(name, "type%d-%s-%lld", type, psname, id);
240 		break;
241 	}
242 
243 	mutex_lock(&root->d_inode->i_mutex);
244 
245 	rc = -ENOSPC;
246 	dentry = d_alloc_name(root, name);
247 	if (IS_ERR(dentry))
248 		goto fail_lockedalloc;
249 
250 	memcpy(private->data, data, size);
251 	inode->i_size = private->size = size;
252 
253 	inode->i_private = private;
254 
255 	if (time.tv_sec)
256 		inode->i_mtime = inode->i_ctime = time;
257 
258 	d_add(dentry, inode);
259 
260 	spin_lock_irqsave(&allpstore_lock, flags);
261 	list_add(&private->list, &allpstore);
262 	spin_unlock_irqrestore(&allpstore_lock, flags);
263 
264 	mutex_unlock(&root->d_inode->i_mutex);
265 
266 	return 0;
267 
268 fail_lockedalloc:
269 	mutex_unlock(&root->d_inode->i_mutex);
270 	kfree(private);
271 fail_alloc:
272 	iput(inode);
273 
274 fail:
275 	return rc;
276 }
277 
278 int pstore_fill_super(struct super_block *sb, void *data, int silent)
279 {
280 	struct inode *inode = NULL;
281 	struct dentry *root;
282 	int err;
283 
284 	save_mount_options(sb, data);
285 
286 	pstore_sb = sb;
287 
288 	sb->s_maxbytes		= MAX_LFS_FILESIZE;
289 	sb->s_blocksize		= PAGE_CACHE_SIZE;
290 	sb->s_blocksize_bits	= PAGE_CACHE_SHIFT;
291 	sb->s_magic		= PSTOREFS_MAGIC;
292 	sb->s_op		= &pstore_ops;
293 	sb->s_time_gran		= 1;
294 
295 	parse_options(data);
296 
297 	inode = pstore_get_inode(sb, NULL, S_IFDIR | 0755, 0);
298 	if (!inode) {
299 		err = -ENOMEM;
300 		goto fail;
301 	}
302 	/* override ramfs "dir" options so we catch unlink(2) */
303 	inode->i_op = &pstore_dir_inode_operations;
304 
305 	root = d_alloc_root(inode);
306 	sb->s_root = root;
307 	if (!root) {
308 		err = -ENOMEM;
309 		goto fail;
310 	}
311 
312 	pstore_get_records(0);
313 
314 	return 0;
315 fail:
316 	iput(inode);
317 	return err;
318 }
319 
320 static struct dentry *pstore_mount(struct file_system_type *fs_type,
321 	int flags, const char *dev_name, void *data)
322 {
323 	return mount_single(fs_type, flags, data, pstore_fill_super);
324 }
325 
326 static void pstore_kill_sb(struct super_block *sb)
327 {
328 	kill_litter_super(sb);
329 	pstore_sb = NULL;
330 }
331 
332 static struct file_system_type pstore_fs_type = {
333 	.name		= "pstore",
334 	.mount		= pstore_mount,
335 	.kill_sb	= pstore_kill_sb,
336 };
337 
338 static int __init init_pstore_fs(void)
339 {
340 	return register_filesystem(&pstore_fs_type);
341 }
342 module_init(init_pstore_fs)
343 
344 MODULE_AUTHOR("Tony Luck <tony.luck@intel.com>");
345 MODULE_LICENSE("GPL");
346