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/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");