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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 |
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