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TOMOYO Linux Cross Reference
Linux/fs/pstore/inode.c

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  1 // SPDX-License-Identifier: GPL-2.0-only
  2 /*
  3  * Persistent Storage - ramfs parts.
  4  *
  5  * Copyright (C) 2010 Intel Corporation <tony.luck@intel.com>
  6  */
  7 
  8 #include <linux/module.h>
  9 #include <linux/fs.h>
 10 #include <linux/fsnotify.h>
 11 #include <linux/pagemap.h>
 12 #include <linux/highmem.h>
 13 #include <linux/time.h>
 14 #include <linux/init.h>
 15 #include <linux/list.h>
 16 #include <linux/string.h>
 17 #include <linux/mount.h>
 18 #include <linux/seq_file.h>
 19 #include <linux/ramfs.h>
 20 #include <linux/parser.h>
 21 #include <linux/sched.h>
 22 #include <linux/magic.h>
 23 #include <linux/pstore.h>
 24 #include <linux/slab.h>
 25 #include <linux/spinlock.h>
 26 #include <linux/uaccess.h>
 27 
 28 #include "internal.h"
 29 
 30 #define PSTORE_NAMELEN  64
 31 
 32 static DEFINE_SPINLOCK(allpstore_lock);
 33 static LIST_HEAD(allpstore);
 34 
 35 struct pstore_private {
 36         struct list_head list;
 37         struct pstore_record *record;
 38         size_t total_size;
 39 };
 40 
 41 struct pstore_ftrace_seq_data {
 42         const void *ptr;
 43         size_t off;
 44         size_t size;
 45 };
 46 
 47 #define REC_SIZE sizeof(struct pstore_ftrace_record)
 48 
 49 static void free_pstore_private(struct pstore_private *private)
 50 {
 51         if (!private)
 52                 return;
 53         if (private->record) {
 54                 kfree(private->record->buf);
 55                 kfree(private->record);
 56         }
 57         kfree(private);
 58 }
 59 
 60 static void *pstore_ftrace_seq_start(struct seq_file *s, loff_t *pos)
 61 {
 62         struct pstore_private *ps = s->private;
 63         struct pstore_ftrace_seq_data *data;
 64 
 65         data = kzalloc(sizeof(*data), GFP_KERNEL);
 66         if (!data)
 67                 return NULL;
 68 
 69         data->off = ps->total_size % REC_SIZE;
 70         data->off += *pos * REC_SIZE;
 71         if (data->off + REC_SIZE > ps->total_size) {
 72                 kfree(data);
 73                 return NULL;
 74         }
 75 
 76         return data;
 77 
 78 }
 79 
 80 static void pstore_ftrace_seq_stop(struct seq_file *s, void *v)
 81 {
 82         kfree(v);
 83 }
 84 
 85 static void *pstore_ftrace_seq_next(struct seq_file *s, void *v, loff_t *pos)
 86 {
 87         struct pstore_private *ps = s->private;
 88         struct pstore_ftrace_seq_data *data = v;
 89 
 90         (*pos)++;
 91         data->off += REC_SIZE;
 92         if (data->off + REC_SIZE > ps->total_size)
 93                 return NULL;
 94 
 95         return data;
 96 }
 97 
 98 static int pstore_ftrace_seq_show(struct seq_file *s, void *v)
 99 {
100         struct pstore_private *ps = s->private;
101         struct pstore_ftrace_seq_data *data = v;
102         struct pstore_ftrace_record *rec;
103 
104         if (!data)
105                 return 0;
106 
107         rec = (struct pstore_ftrace_record *)(ps->record->buf + data->off);
108 
109         seq_printf(s, "CPU:%d ts:%llu %08lx  %08lx  %ps <- %pS\n",
110                    pstore_ftrace_decode_cpu(rec),
111                    pstore_ftrace_read_timestamp(rec),
112                    rec->ip, rec->parent_ip, (void *)rec->ip,
113                    (void *)rec->parent_ip);
114 
115         return 0;
116 }
117 
118 static const struct seq_operations pstore_ftrace_seq_ops = {
119         .start  = pstore_ftrace_seq_start,
120         .next   = pstore_ftrace_seq_next,
121         .stop   = pstore_ftrace_seq_stop,
122         .show   = pstore_ftrace_seq_show,
123 };
124 
125 static ssize_t pstore_file_read(struct file *file, char __user *userbuf,
126                                                 size_t count, loff_t *ppos)
127 {
128         struct seq_file *sf = file->private_data;
129         struct pstore_private *ps = sf->private;
130 
131         if (ps->record->type == PSTORE_TYPE_FTRACE)
132                 return seq_read(file, userbuf, count, ppos);
133         return simple_read_from_buffer(userbuf, count, ppos,
134                                        ps->record->buf, ps->total_size);
135 }
136 
137 static int pstore_file_open(struct inode *inode, struct file *file)
138 {
139         struct pstore_private *ps = inode->i_private;
140         struct seq_file *sf;
141         int err;
142         const struct seq_operations *sops = NULL;
143 
144         if (ps->record->type == PSTORE_TYPE_FTRACE)
145                 sops = &pstore_ftrace_seq_ops;
146 
147         err = seq_open(file, sops);
148         if (err < 0)
149                 return err;
150 
151         sf = file->private_data;
152         sf->private = ps;
153 
154         return 0;
155 }
156 
157 static loff_t pstore_file_llseek(struct file *file, loff_t off, int whence)
158 {
159         struct seq_file *sf = file->private_data;
160 
161         if (sf->op)
162                 return seq_lseek(file, off, whence);
163         return default_llseek(file, off, whence);
164 }
165 
166 static const struct file_operations pstore_file_operations = {
167         .open           = pstore_file_open,
168         .read           = pstore_file_read,
169         .llseek         = pstore_file_llseek,
170         .release        = seq_release,
171 };
172 
173 /*
174  * When a file is unlinked from our file system we call the
175  * platform driver to erase the record from persistent store.
176  */
177 static int pstore_unlink(struct inode *dir, struct dentry *dentry)
178 {
179         struct pstore_private *p = d_inode(dentry)->i_private;
180         struct pstore_record *record = p->record;
181 
182         if (!record->psi->erase)
183                 return -EPERM;
184 
185         mutex_lock(&record->psi->read_mutex);
186         record->psi->erase(record);
187         mutex_unlock(&record->psi->read_mutex);
188 
189         return simple_unlink(dir, dentry);
190 }
191 
192 static void pstore_evict_inode(struct inode *inode)
193 {
194         struct pstore_private   *p = inode->i_private;
195         unsigned long           flags;
196 
197         clear_inode(inode);
198         if (p) {
199                 spin_lock_irqsave(&allpstore_lock, flags);
200                 list_del(&p->list);
201                 spin_unlock_irqrestore(&allpstore_lock, flags);
202                 free_pstore_private(p);
203         }
204 }
205 
206 static const struct inode_operations pstore_dir_inode_operations = {
207         .lookup         = simple_lookup,
208         .unlink         = pstore_unlink,
209 };
210 
211 static struct inode *pstore_get_inode(struct super_block *sb)
212 {
213         struct inode *inode = new_inode(sb);
214         if (inode) {
215                 inode->i_ino = get_next_ino();
216                 inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
217         }
218         return inode;
219 }
220 
221 enum {
222         Opt_kmsg_bytes, Opt_err
223 };
224 
225 static const match_table_t tokens = {
226         {Opt_kmsg_bytes, "kmsg_bytes=%u"},
227         {Opt_err, NULL}
228 };
229 
230 static void parse_options(char *options)
231 {
232         char            *p;
233         substring_t     args[MAX_OPT_ARGS];
234         int             option;
235 
236         if (!options)
237                 return;
238 
239         while ((p = strsep(&options, ",")) != NULL) {
240                 int token;
241 
242                 if (!*p)
243                         continue;
244 
245                 token = match_token(p, tokens, args);
246                 switch (token) {
247                 case Opt_kmsg_bytes:
248                         if (!match_int(&args[0], &option))
249                                 pstore_set_kmsg_bytes(option);
250                         break;
251                 }
252         }
253 }
254 
255 /*
256  * Display the mount options in /proc/mounts.
257  */
258 static int pstore_show_options(struct seq_file *m, struct dentry *root)
259 {
260         if (kmsg_bytes != PSTORE_DEFAULT_KMSG_BYTES)
261                 seq_printf(m, ",kmsg_bytes=%lu", kmsg_bytes);
262         return 0;
263 }
264 
265 static int pstore_remount(struct super_block *sb, int *flags, char *data)
266 {
267         sync_filesystem(sb);
268         parse_options(data);
269 
270         return 0;
271 }
272 
273 static const struct super_operations pstore_ops = {
274         .statfs         = simple_statfs,
275         .drop_inode     = generic_delete_inode,
276         .evict_inode    = pstore_evict_inode,
277         .remount_fs     = pstore_remount,
278         .show_options   = pstore_show_options,
279 };
280 
281 static struct super_block *pstore_sb;
282 
283 bool pstore_is_mounted(void)
284 {
285         return pstore_sb != NULL;
286 }
287 
288 /*
289  * Make a regular file in the root directory of our file system.
290  * Load it up with "size" bytes of data from "buf".
291  * Set the mtime & ctime to the date that this record was originally stored.
292  */
293 int pstore_mkfile(struct dentry *root, struct pstore_record *record)
294 {
295         struct dentry           *dentry;
296         struct inode            *inode;
297         int                     rc = 0;
298         char                    name[PSTORE_NAMELEN];
299         struct pstore_private   *private, *pos;
300         unsigned long           flags;
301         size_t                  size = record->size + record->ecc_notice_size;
302 
303         WARN_ON(!inode_is_locked(d_inode(root)));
304 
305         spin_lock_irqsave(&allpstore_lock, flags);
306         list_for_each_entry(pos, &allpstore, list) {
307                 if (pos->record->type == record->type &&
308                     pos->record->id == record->id &&
309                     pos->record->psi == record->psi) {
310                         rc = -EEXIST;
311                         break;
312                 }
313         }
314         spin_unlock_irqrestore(&allpstore_lock, flags);
315         if (rc)
316                 return rc;
317 
318         rc = -ENOMEM;
319         inode = pstore_get_inode(root->d_sb);
320         if (!inode)
321                 goto fail;
322         inode->i_mode = S_IFREG | 0444;
323         inode->i_fop = &pstore_file_operations;
324         scnprintf(name, sizeof(name), "%s-%s-%llu%s",
325                         pstore_type_to_name(record->type),
326                         record->psi->name, record->id,
327                         record->compressed ? ".enc.z" : "");
328 
329         private = kzalloc(sizeof(*private), GFP_KERNEL);
330         if (!private)
331                 goto fail_inode;
332 
333         dentry = d_alloc_name(root, name);
334         if (!dentry)
335                 goto fail_private;
336 
337         private->record = record;
338         inode->i_size = private->total_size = size;
339         inode->i_private = private;
340 
341         if (record->time.tv_sec)
342                 inode->i_mtime = inode->i_ctime = record->time;
343 
344         d_add(dentry, inode);
345 
346         spin_lock_irqsave(&allpstore_lock, flags);
347         list_add(&private->list, &allpstore);
348         spin_unlock_irqrestore(&allpstore_lock, flags);
349 
350         return 0;
351 
352 fail_private:
353         free_pstore_private(private);
354 fail_inode:
355         iput(inode);
356 
357 fail:
358         return rc;
359 }
360 
361 /*
362  * Read all the records from the persistent store. Create
363  * files in our filesystem.  Don't warn about -EEXIST errors
364  * when we are re-scanning the backing store looking to add new
365  * error records.
366  */
367 void pstore_get_records(int quiet)
368 {
369         struct pstore_info *psi = psinfo;
370         struct dentry *root;
371 
372         if (!psi || !pstore_sb)
373                 return;
374 
375         root = pstore_sb->s_root;
376 
377         inode_lock(d_inode(root));
378         pstore_get_backend_records(psi, root, quiet);
379         inode_unlock(d_inode(root));
380 }
381 
382 static int pstore_fill_super(struct super_block *sb, void *data, int silent)
383 {
384         struct inode *inode;
385 
386         pstore_sb = sb;
387 
388         sb->s_maxbytes          = MAX_LFS_FILESIZE;
389         sb->s_blocksize         = PAGE_SIZE;
390         sb->s_blocksize_bits    = PAGE_SHIFT;
391         sb->s_magic             = PSTOREFS_MAGIC;
392         sb->s_op                = &pstore_ops;
393         sb->s_time_gran         = 1;
394 
395         parse_options(data);
396 
397         inode = pstore_get_inode(sb);
398         if (inode) {
399                 inode->i_mode = S_IFDIR | 0750;
400                 inode->i_op = &pstore_dir_inode_operations;
401                 inode->i_fop = &simple_dir_operations;
402                 inc_nlink(inode);
403         }
404         sb->s_root = d_make_root(inode);
405         if (!sb->s_root)
406                 return -ENOMEM;
407 
408         pstore_get_records(0);
409 
410         return 0;
411 }
412 
413 static struct dentry *pstore_mount(struct file_system_type *fs_type,
414         int flags, const char *dev_name, void *data)
415 {
416         return mount_single(fs_type, flags, data, pstore_fill_super);
417 }
418 
419 static void pstore_kill_sb(struct super_block *sb)
420 {
421         kill_litter_super(sb);
422         pstore_sb = NULL;
423 }
424 
425 static struct file_system_type pstore_fs_type = {
426         .owner          = THIS_MODULE,
427         .name           = "pstore",
428         .mount          = pstore_mount,
429         .kill_sb        = pstore_kill_sb,
430 };
431 
432 int __init pstore_init_fs(void)
433 {
434         int err;
435 
436         /* Create a convenient mount point for people to access pstore */
437         err = sysfs_create_mount_point(fs_kobj, "pstore");
438         if (err)
439                 goto out;
440 
441         err = register_filesystem(&pstore_fs_type);
442         if (err < 0)
443                 sysfs_remove_mount_point(fs_kobj, "pstore");
444 
445 out:
446         return err;
447 }
448 
449 void __exit pstore_exit_fs(void)
450 {
451         unregister_filesystem(&pstore_fs_type);
452         sysfs_remove_mount_point(fs_kobj, "pstore");
453 }
454 

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