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

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

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