xref: /openbmc/linux/fs/pstore/inode.c (revision 7490ca1e) 
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 	if (p->psi->erase)
84 		p->psi->erase(p->type, p->id, p->psi);
85 
86 	return simple_unlink(dir, dentry);
87 }
88 
89 static void pstore_evict_inode(struct inode *inode)
90 {
91 	struct pstore_private	*p = inode->i_private;
92 	unsigned long		flags;
93 
94 	end_writeback(inode);
95 	if (p) {
96 		spin_lock_irqsave(&allpstore_lock, flags);
97 		list_del(&p->list);
98 		spin_unlock_irqrestore(&allpstore_lock, flags);
99 		kfree(p);
100 	}
101 }
102 
103 static const struct inode_operations pstore_dir_inode_operations = {
104 	.lookup		= simple_lookup,
105 	.unlink		= pstore_unlink,
106 };
107 
108 static struct inode *pstore_get_inode(struct super_block *sb,
109 					const struct inode *dir, int mode, dev_t dev)
110 {
111 	struct inode *inode = new_inode(sb);
112 
113 	if (inode) {
114 		inode->i_ino = get_next_ino();
115 		inode->i_uid = inode->i_gid = 0;
116 		inode->i_mode = mode;
117 		inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
118 		switch (mode & S_IFMT) {
119 		case S_IFREG:
120 			inode->i_fop = &pstore_file_operations;
121 			break;
122 		case S_IFDIR:
123 			inode->i_op = &pstore_dir_inode_operations;
124 			inode->i_fop = &simple_dir_operations;
125 			inc_nlink(inode);
126 			break;
127 		}
128 	}
129 	return inode;
130 }
131 
132 enum {
133 	Opt_kmsg_bytes, Opt_err
134 };
135 
136 static const match_table_t tokens = {
137 	{Opt_kmsg_bytes, "kmsg_bytes=%u"},
138 	{Opt_err, NULL}
139 };
140 
141 static void parse_options(char *options)
142 {
143 	char		*p;
144 	substring_t	args[MAX_OPT_ARGS];
145 	int		option;
146 
147 	if (!options)
148 		return;
149 
150 	while ((p = strsep(&options, ",")) != NULL) {
151 		int token;
152 
153 		if (!*p)
154 			continue;
155 
156 		token = match_token(p, tokens, args);
157 		switch (token) {
158 		case Opt_kmsg_bytes:
159 			if (!match_int(&args[0], &option))
160 				pstore_set_kmsg_bytes(option);
161 			break;
162 		}
163 	}
164 }
165 
166 static int pstore_remount(struct super_block *sb, int *flags, char *data)
167 {
168 	parse_options(data);
169 
170 	return 0;
171 }
172 
173 static const struct super_operations pstore_ops = {
174 	.statfs		= simple_statfs,
175 	.drop_inode	= generic_delete_inode,
176 	.evict_inode	= pstore_evict_inode,
177 	.remount_fs	= pstore_remount,
178 	.show_options	= generic_show_options,
179 };
180 
181 static struct super_block *pstore_sb;
182 
183 int pstore_is_mounted(void)
184 {
185 	return pstore_sb != NULL;
186 }
187 
188 /*
189  * Make a regular file in the root directory of our file system.
190  * Load it up with "size" bytes of data from "buf".
191  * Set the mtime & ctime to the date that this record was originally stored.
192  */
193 int pstore_mkfile(enum pstore_type_id type, char *psname, u64 id,
194 		  char *data, size_t size, struct timespec time,
195 		  struct pstore_info *psi)
196 {
197 	struct dentry		*root = pstore_sb->s_root;
198 	struct dentry		*dentry;
199 	struct inode		*inode;
200 	int			rc = 0;
201 	char			name[PSTORE_NAMELEN];
202 	struct pstore_private	*private, *pos;
203 	unsigned long		flags;
204 
205 	spin_lock_irqsave(&allpstore_lock, flags);
206 	list_for_each_entry(pos, &allpstore, list) {
207 		if (pos->type == type &&
208 		    pos->id == id &&
209 		    pos->psi == psi) {
210 			rc = -EEXIST;
211 			break;
212 		}
213 	}
214 	spin_unlock_irqrestore(&allpstore_lock, flags);
215 	if (rc)
216 		return rc;
217 
218 	rc = -ENOMEM;
219 	inode = pstore_get_inode(pstore_sb, root->d_inode, S_IFREG | 0444, 0);
220 	if (!inode)
221 		goto fail;
222 	private = kmalloc(sizeof *private + size, GFP_KERNEL);
223 	if (!private)
224 		goto fail_alloc;
225 	private->type = type;
226 	private->id = id;
227 	private->psi = psi;
228 
229 	switch (type) {
230 	case PSTORE_TYPE_DMESG:
231 		sprintf(name, "dmesg-%s-%lld", psname, id);
232 		break;
233 	case PSTORE_TYPE_MCE:
234 		sprintf(name, "mce-%s-%lld", psname, id);
235 		break;
236 	case PSTORE_TYPE_UNKNOWN:
237 		sprintf(name, "unknown-%s-%lld", psname, id);
238 		break;
239 	default:
240 		sprintf(name, "type%d-%s-%lld", type, psname, id);
241 		break;
242 	}
243 
244 	mutex_lock(&root->d_inode->i_mutex);
245 
246 	rc = -ENOSPC;
247 	dentry = d_alloc_name(root, name);
248 	if (IS_ERR(dentry))
249 		goto fail_lockedalloc;
250 
251 	memcpy(private->data, data, size);
252 	inode->i_size = private->size = size;
253 
254 	inode->i_private = private;
255 
256 	if (time.tv_sec)
257 		inode->i_mtime = inode->i_ctime = time;
258 
259 	d_add(dentry, inode);
260 
261 	spin_lock_irqsave(&allpstore_lock, flags);
262 	list_add(&private->list, &allpstore);
263 	spin_unlock_irqrestore(&allpstore_lock, flags);
264 
265 	mutex_unlock(&root->d_inode->i_mutex);
266 
267 	return 0;
268 
269 fail_lockedalloc:
270 	mutex_unlock(&root->d_inode->i_mutex);
271 	kfree(private);
272 fail_alloc:
273 	iput(inode);
274 
275 fail:
276 	return rc;
277 }
278 
279 int pstore_fill_super(struct super_block *sb, void *data, int silent)
280 {
281 	struct inode *inode = NULL;
282 	struct dentry *root;
283 	int err;
284 
285 	save_mount_options(sb, data);
286 
287 	pstore_sb = sb;
288 
289 	sb->s_maxbytes		= MAX_LFS_FILESIZE;
290 	sb->s_blocksize		= PAGE_CACHE_SIZE;
291 	sb->s_blocksize_bits	= PAGE_CACHE_SHIFT;
292 	sb->s_magic		= PSTOREFS_MAGIC;
293 	sb->s_op		= &pstore_ops;
294 	sb->s_time_gran		= 1;
295 
296 	parse_options(data);
297 
298 	inode = pstore_get_inode(sb, NULL, S_IFDIR | 0755, 0);
299 	if (!inode) {
300 		err = -ENOMEM;
301 		goto fail;
302 	}
303 	/* override ramfs "dir" options so we catch unlink(2) */
304 	inode->i_op = &pstore_dir_inode_operations;
305 
306 	root = d_alloc_root(inode);
307 	sb->s_root = root;
308 	if (!root) {
309 		err = -ENOMEM;
310 		goto fail;
311 	}
312 
313 	pstore_get_records(0);
314 
315 	return 0;
316 fail:
317 	iput(inode);
318 	return err;
319 }
320 
321 static struct dentry *pstore_mount(struct file_system_type *fs_type,
322 	int flags, const char *dev_name, void *data)
323 {
324 	return mount_single(fs_type, flags, data, pstore_fill_super);
325 }
326 
327 static void pstore_kill_sb(struct super_block *sb)
328 {
329 	kill_litter_super(sb);
330 	pstore_sb = NULL;
331 }
332 
333 static struct file_system_type pstore_fs_type = {
334 	.name		= "pstore",
335 	.mount		= pstore_mount,
336 	.kill_sb	= pstore_kill_sb,
337 };
338 
339 static int __init init_pstore_fs(void)
340 {
341 	return register_filesystem(&pstore_fs_type);
342 }
343 module_init(init_pstore_fs)
344 
345 MODULE_AUTHOR("Tony Luck <tony.luck@intel.com>");
346 MODULE_LICENSE("GPL");
347