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Linux/fs/pstore/inode.c

  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/seq_file.h>
 31 #include <linux/ramfs.h>
 32 #include <linux/parser.h>
 33 #include <linux/sched.h>
 34 #include <linux/magic.h>
 35 #include <linux/pstore.h>
 36 #include <linux/slab.h>
 37 #include <linux/spinlock.h>
 38 #include <linux/uaccess.h>
 39 
 40 #include "internal.h"
 41 
 42 #define PSTORE_NAMELEN  64
 43 
 44 static DEFINE_SPINLOCK(allpstore_lock);
 45 static LIST_HEAD(allpstore);
 46 
 47 struct pstore_private {
 48         struct list_head list;
 49         struct pstore_info *psi;
 50         enum pstore_type_id type;
 51         u64     id;
 52         int     count;
 53         ssize_t size;
 54         char    data[];
 55 };
 56 
 57 struct pstore_ftrace_seq_data {
 58         const void *ptr;
 59         size_t off;
 60         size_t size;
 61 };
 62 
 63 #define REC_SIZE sizeof(struct pstore_ftrace_record)
 64 
 65 static void *pstore_ftrace_seq_start(struct seq_file *s, loff_t *pos)
 66 {
 67         struct pstore_private *ps = s->private;
 68         struct pstore_ftrace_seq_data *data;
 69 
 70         data = kzalloc(sizeof(*data), GFP_KERNEL);
 71         if (!data)
 72                 return NULL;
 73 
 74         data->off = ps->size % REC_SIZE;
 75         data->off += *pos * REC_SIZE;
 76         if (data->off + REC_SIZE > ps->size) {
 77                 kfree(data);
 78                 return NULL;
 79         }
 80 
 81         return data;
 82 
 83 }
 84 
 85 static void pstore_ftrace_seq_stop(struct seq_file *s, void *v)
 86 {
 87         kfree(v);
 88 }
 89 
 90 static void *pstore_ftrace_seq_next(struct seq_file *s, void *v, loff_t *pos)
 91 {
 92         struct pstore_private *ps = s->private;
 93         struct pstore_ftrace_seq_data *data = v;
 94 
 95         data->off += REC_SIZE;
 96         if (data->off + REC_SIZE > ps->size)
 97                 return NULL;
 98 
 99         (*pos)++;
100         return data;
101 }
102 
103 static int pstore_ftrace_seq_show(struct seq_file *s, void *v)
104 {
105         struct pstore_private *ps = s->private;
106         struct pstore_ftrace_seq_data *data = v;
107         struct pstore_ftrace_record *rec = (void *)(ps->data + data->off);
108 
109         seq_printf(s, "%d %08lx  %08lx  %pf <- %pF\n",
110                 pstore_ftrace_decode_cpu(rec), rec->ip, rec->parent_ip,
111                 (void *)rec->ip, (void *)rec->parent_ip);
112 
113         return 0;
114 }
115 
116 static const struct seq_operations pstore_ftrace_seq_ops = {
117         .start  = pstore_ftrace_seq_start,
118         .next   = pstore_ftrace_seq_next,
119         .stop   = pstore_ftrace_seq_stop,
120         .show   = pstore_ftrace_seq_show,
121 };
122 
123 static ssize_t pstore_file_read(struct file *file, char __user *userbuf,
124                                                 size_t count, loff_t *ppos)
125 {
126         struct seq_file *sf = file->private_data;
127         struct pstore_private *ps = sf->private;
128 
129         if (ps->type == PSTORE_TYPE_FTRACE)
130                 return seq_read(file, userbuf, count, ppos);
131         return simple_read_from_buffer(userbuf, count, ppos, ps->data, ps->size);
132 }
133 
134 static int pstore_file_open(struct inode *inode, struct file *file)
135 {
136         struct pstore_private *ps = inode->i_private;
137         struct seq_file *sf;
138         int err;
139         const struct seq_operations *sops = NULL;
140 
141         if (ps->type == PSTORE_TYPE_FTRACE)
142                 sops = &pstore_ftrace_seq_ops;
143 
144         err = seq_open(file, sops);
145         if (err < 0)
146                 return err;
147 
148         sf = file->private_data;
149         sf->private = ps;
150 
151         return 0;
152 }
153 
154 static loff_t pstore_file_llseek(struct file *file, loff_t off, int whence)
155 {
156         struct seq_file *sf = file->private_data;
157 
158         if (sf->op)
159                 return seq_lseek(file, off, whence);
160         return default_llseek(file, off, whence);
161 }
162 
163 static const struct file_operations pstore_file_operations = {
164         .open           = pstore_file_open,
165         .read           = pstore_file_read,
166         .llseek         = pstore_file_llseek,
167         .release        = seq_release,
168 };
169 
170 /*
171  * When a file is unlinked from our file system we call the
172  * platform driver to erase the record from persistent store.
173  */
174 static int pstore_unlink(struct inode *dir, struct dentry *dentry)
175 {
176         struct pstore_private *p = dentry->d_inode->i_private;
177 
178         if (p->psi->erase)
179                 p->psi->erase(p->type, p->id, p->count,
180                               dentry->d_inode->i_ctime, p->psi);
181         else
182                 return -EPERM;
183 
184         return simple_unlink(dir, dentry);
185 }
186 
187 static void pstore_evict_inode(struct inode *inode)
188 {
189         struct pstore_private   *p = inode->i_private;
190         unsigned long           flags;
191 
192         clear_inode(inode);
193         if (p) {
194                 spin_lock_irqsave(&allpstore_lock, flags);
195                 list_del(&p->list);
196                 spin_unlock_irqrestore(&allpstore_lock, flags);
197                 kfree(p);
198         }
199 }
200 
201 static const struct inode_operations pstore_dir_inode_operations = {
202         .lookup         = simple_lookup,
203         .unlink         = pstore_unlink,
204 };
205 
206 static struct inode *pstore_get_inode(struct super_block *sb)
207 {
208         struct inode *inode = new_inode(sb);
209         if (inode) {
210                 inode->i_ino = get_next_ino();
211                 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
212         }
213         return inode;
214 }
215 
216 enum {
217         Opt_kmsg_bytes, Opt_err
218 };
219 
220 static const match_table_t tokens = {
221         {Opt_kmsg_bytes, "kmsg_bytes=%u"},
222         {Opt_err, NULL}
223 };
224 
225 static void parse_options(char *options)
226 {
227         char            *p;
228         substring_t     args[MAX_OPT_ARGS];
229         int             option;
230 
231         if (!options)
232                 return;
233 
234         while ((p = strsep(&options, ",")) != NULL) {
235                 int token;
236 
237                 if (!*p)
238                         continue;
239 
240                 token = match_token(p, tokens, args);
241                 switch (token) {
242                 case Opt_kmsg_bytes:
243                         if (!match_int(&args[0], &option))
244                                 pstore_set_kmsg_bytes(option);
245                         break;
246                 }
247         }
248 }
249 
250 static int pstore_remount(struct super_block *sb, int *flags, char *data)
251 {
252         parse_options(data);
253 
254         return 0;
255 }
256 
257 static const struct super_operations pstore_ops = {
258         .statfs         = simple_statfs,
259         .drop_inode     = generic_delete_inode,
260         .evict_inode    = pstore_evict_inode,
261         .remount_fs     = pstore_remount,
262         .show_options   = generic_show_options,
263 };
264 
265 static struct super_block *pstore_sb;
266 
267 int pstore_is_mounted(void)
268 {
269         return pstore_sb != NULL;
270 }
271 
272 /*
273  * Make a regular file in the root directory of our file system.
274  * Load it up with "size" bytes of data from "buf".
275  * Set the mtime & ctime to the date that this record was originally stored.
276  */
277 int pstore_mkfile(enum pstore_type_id type, char *psname, u64 id, int count,
278                   char *data, bool compressed, size_t size,
279                   struct timespec time, struct pstore_info *psi)
280 {
281         struct dentry           *root = pstore_sb->s_root;
282         struct dentry           *dentry;
283         struct inode            *inode;
284         int                     rc = 0;
285         char                    name[PSTORE_NAMELEN];
286         struct pstore_private   *private, *pos;
287         unsigned long           flags;
288 
289         spin_lock_irqsave(&allpstore_lock, flags);
290         list_for_each_entry(pos, &allpstore, list) {
291                 if (pos->type == type &&
292                     pos->id == id &&
293                     pos->psi == psi) {
294                         rc = -EEXIST;
295                         break;
296                 }
297         }
298         spin_unlock_irqrestore(&allpstore_lock, flags);
299         if (rc)
300                 return rc;
301 
302         rc = -ENOMEM;
303         inode = pstore_get_inode(pstore_sb);
304         if (!inode)
305                 goto fail;
306         inode->i_mode = S_IFREG | 0444;
307         inode->i_fop = &pstore_file_operations;
308         private = kmalloc(sizeof *private + size, GFP_KERNEL);
309         if (!private)
310                 goto fail_alloc;
311         private->type = type;
312         private->id = id;
313         private->count = count;
314         private->psi = psi;
315 
316         switch (type) {
317         case PSTORE_TYPE_DMESG:
318                 sprintf(name, "dmesg-%s-%lld%s", psname, id,
319                                                 compressed ? ".enc.z" : "");
320                 break;
321         case PSTORE_TYPE_CONSOLE:
322                 sprintf(name, "console-%s", psname);
323                 break;
324         case PSTORE_TYPE_FTRACE:
325                 sprintf(name, "ftrace-%s", psname);
326                 break;
327         case PSTORE_TYPE_MCE:
328                 sprintf(name, "mce-%s-%lld", psname, id);
329                 break;
330         case PSTORE_TYPE_PPC_RTAS:
331                 sprintf(name, "rtas-%s-%lld", psname, id);
332                 break;
333         case PSTORE_TYPE_PPC_OF:
334                 sprintf(name, "powerpc-ofw-%s-%lld", psname, id);
335                 break;
336         case PSTORE_TYPE_PPC_COMMON:
337                 sprintf(name, "powerpc-common-%s-%lld", psname, id);
338                 break;
339         case PSTORE_TYPE_UNKNOWN:
340                 sprintf(name, "unknown-%s-%lld", psname, id);
341                 break;
342         default:
343                 sprintf(name, "type%d-%s-%lld", type, psname, id);
344                 break;
345         }
346 
347         mutex_lock(&root->d_inode->i_mutex);
348 
349         dentry = d_alloc_name(root, name);
350         if (!dentry)
351                 goto fail_lockedalloc;
352 
353         memcpy(private->data, data, size);
354         inode->i_size = private->size = size;
355 
356         inode->i_private = private;
357 
358         if (time.tv_sec)
359                 inode->i_mtime = inode->i_ctime = time;
360 
361         d_add(dentry, inode);
362 
363         spin_lock_irqsave(&allpstore_lock, flags);
364         list_add(&private->list, &allpstore);
365         spin_unlock_irqrestore(&allpstore_lock, flags);
366 
367         mutex_unlock(&root->d_inode->i_mutex);
368 
369         return 0;
370 
371 fail_lockedalloc:
372         mutex_unlock(&root->d_inode->i_mutex);
373         kfree(private);
374 fail_alloc:
375         iput(inode);
376 
377 fail:
378         return rc;
379 }
380 
381 static int pstore_fill_super(struct super_block *sb, void *data, int silent)
382 {
383         struct inode *inode;
384 
385         save_mount_options(sb, data);
386 
387         pstore_sb = sb;
388 
389         sb->s_maxbytes          = MAX_LFS_FILESIZE;
390         sb->s_blocksize         = PAGE_CACHE_SIZE;
391         sb->s_blocksize_bits    = PAGE_CACHE_SHIFT;
392         sb->s_magic             = PSTOREFS_MAGIC;
393         sb->s_op                = &pstore_ops;
394         sb->s_time_gran         = 1;
395 
396         parse_options(data);
397 
398         inode = pstore_get_inode(sb);
399         if (inode) {
400                 inode->i_mode = S_IFDIR | 0755;
401                 inode->i_op = &pstore_dir_inode_operations;
402                 inode->i_fop = &simple_dir_operations;
403                 inc_nlink(inode);
404         }
405         sb->s_root = d_make_root(inode);
406         if (!sb->s_root)
407                 return -ENOMEM;
408 
409         pstore_get_records(0);
410 
411         return 0;
412 }
413 
414 static struct dentry *pstore_mount(struct file_system_type *fs_type,
415         int flags, const char *dev_name, void *data)
416 {
417         return mount_single(fs_type, flags, data, pstore_fill_super);
418 }
419 
420 static void pstore_kill_sb(struct super_block *sb)
421 {
422         kill_litter_super(sb);
423         pstore_sb = NULL;
424 }
425 
426 static struct file_system_type pstore_fs_type = {
427         .name           = "pstore",
428         .mount          = pstore_mount,
429         .kill_sb        = pstore_kill_sb,
430 };
431 
432 static struct kobject *pstore_kobj;
433 
434 static int __init init_pstore_fs(void)
435 {
436         int err = 0;
437 
438         /* Create a convenient mount point for people to access pstore */
439         pstore_kobj = kobject_create_and_add("pstore", fs_kobj);
440         if (!pstore_kobj) {
441                 err = -ENOMEM;
442                 goto out;
443         }
444 
445         err = register_filesystem(&pstore_fs_type);
446         if (err < 0)
447                 kobject_put(pstore_kobj);
448 
449 out:
450         return err;
451 }
452 module_init(init_pstore_fs)
453 
454 MODULE_AUTHOR("Tony Luck <tony.luck@intel.com>");
455 MODULE_LICENSE("GPL");
456 

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