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