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         struct pstore_info *psi;
  43         enum pstore_type_id type;
  44         u64     id;
  45         ssize_t size;
  46         char    data[];
  47 };
  48
  49 static int pstore_file_open(struct inode *inode, struct file *file)
  50 {
  51         file->private_data = inode->i_private;
  52         return 0;
  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   = pstore_file_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         p->psi->erase(p->type, p->id, p->psi);
  78
  79         return simple_unlink(dir, dentry);
  80 }
  81
  82 static void pstore_evict_inode(struct inode *inode)
  83 {
  84         end_writeback(inode);
  85         kfree(inode->i_private);
  86 }
  87
  88 static const struct inode_operations pstore_dir_inode_operations = {
  89         .lookup         = simple_lookup,
  90         .unlink         = pstore_unlink,
  91 };
  92
  93 static struct inode *pstore_get_inode(struct super_block *sb,
  94                                         const struct inode *dir, int mode, dev_t dev)
  95 {
  96         struct inode *inode = new_inode(sb);
  97
  98         if (inode) {
  99                 inode->i_ino = get_next_ino();
 100                 inode->i_uid = inode->i_gid = 0;
 101                 inode->i_mode = mode;
 102                 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
 103                 switch (mode & S_IFMT) {
 104                 case S_IFREG:
 105                         inode->i_fop = &pstore_file_operations;
 106                         break;
 107                 case S_IFDIR:
 108                         inode->i_op = &pstore_dir_inode_operations;
 109                         inode->i_fop = &simple_dir_operations;
 110                         inc_nlink(inode);
 111                         break;
 112                 }
 113         }
 114         return inode;
 115 }
 116
 117 enum {
 118         Opt_kmsg_bytes, Opt_err
 119 };
 120
 121 static const match_table_t tokens = {
 122         {Opt_kmsg_bytes, "kmsg_bytes=%u"},
 123         {Opt_err, NULL}
 124 };
 125
 126 static void parse_options(char *options)
 127 {
 128         char            *p;
 129         substring_t     args[MAX_OPT_ARGS];
 130         int             option;
 131
 132         if (!options)
 133                 return;
 134
 135         while ((p = strsep(&options, ",")) != NULL) {
 136                 int token;
 137
 138                 if (!*p)
 139                         continue;
 140
 141                 token = match_token(p, tokens, args);
 142                 switch (token) {
 143                 case Opt_kmsg_bytes:
 144                         if (!match_int(&args[0], &option))
 145                                 pstore_set_kmsg_bytes(option);
 146                         break;
 147                 }
 148         }
 149 }
 150
 151 static int pstore_remount(struct super_block *sb, int *flags, char *data)
 152 {
 153         parse_options(data);
 154
 155         return 0;
 156 }
 157
 158 static const struct super_operations pstore_ops = {
 159         .statfs         = simple_statfs,
 160         .drop_inode     = generic_delete_inode,
 161         .evict_inode    = pstore_evict_inode,
 162         .remount_fs     = pstore_remount,
 163         .show_options   = generic_show_options,
 164 };
 165
 166 static struct super_block *pstore_sb;
 167
 168 int pstore_is_mounted(void)
 169 {
 170         return pstore_sb != NULL;
 171 }
 172
 173 /*
 174  * Make a regular file in the root directory of our file system.
 175  * Load it up with "size" bytes of data from "buf".
 176  * Set the mtime & ctime to the date that this record was originally stored.
 177  */
 178 int pstore_mkfile(enum pstore_type_id type, char *psname, u64 id,
 179                   char *data, size_t size, struct timespec time,
 180                   struct pstore_info *psi)
 181 {
 182         struct dentry           *root = pstore_sb->s_root;
 183         struct dentry           *dentry;
 184         struct inode            *inode;
 185         int                     rc;
 186         char                    name[PSTORE_NAMELEN];
 187         struct pstore_private   *private;
 188
 189         rc = -ENOMEM;
 190         inode = pstore_get_inode(pstore_sb, root->d_inode, S_IFREG | 0444, 0);
 191         if (!inode)
 192                 goto fail;
 193         private = kmalloc(sizeof *private + size, GFP_KERNEL);
 194         if (!private)
 195                 goto fail_alloc;
 196         private->type = type;
 197         private->id = id;
 198         private->psi = psi;
 199
 200         switch (type) {
 201         case PSTORE_TYPE_DMESG:
 202                 sprintf(name, "dmesg-%s-%lld", psname, id);
 203                 break;
 204         case PSTORE_TYPE_MCE:
 205                 sprintf(name, "mce-%s-%lld", psname, id);
 206                 break;
 207         case PSTORE_TYPE_UNKNOWN:
 208                 sprintf(name, "unknown-%s-%lld", psname, id);
 209                 break;
 210         default:
 211                 sprintf(name, "type%d-%s-%lld", type, psname, id);
 212                 break;
 213         }
 214
 215         mutex_lock(&root->d_inode->i_mutex);
 216
 217         rc = -ENOSPC;
 218         dentry = d_alloc_name(root, name);
 219         if (IS_ERR(dentry))
 220                 goto fail_lockedalloc;
 221
 222         memcpy(private->data, data, size);
 223         inode->i_size = private->size = size;
 224
 225         inode->i_private = private;
 226
 227         if (time.tv_sec)
 228                 inode->i_mtime = inode->i_ctime = time;
 229
 230         d_add(dentry, inode);
 231
 232         mutex_unlock(&root->d_inode->i_mutex);
 233
 234         return 0;
 235
 236 fail_lockedalloc:
 237         mutex_unlock(&root->d_inode->i_mutex);
 238         kfree(private);
 239 fail_alloc:
 240         iput(inode);
 241
 242 fail:
 243         return rc;
 244 }
 245
 246 int pstore_fill_super(struct super_block *sb, void *data, int silent)
 247 {
 248         struct inode *inode = NULL;
 249         struct dentry *root;
 250         int err;
 251
 252         save_mount_options(sb, data);
 253
 254         pstore_sb = sb;
 255
 256         sb->s_maxbytes          = MAX_LFS_FILESIZE;
 257         sb->s_blocksize         = PAGE_CACHE_SIZE;
 258         sb->s_blocksize_bits    = PAGE_CACHE_SHIFT;
 259         sb->s_magic             = PSTOREFS_MAGIC;
 260         sb->s_op                = &pstore_ops;
 261         sb->s_time_gran         = 1;
 262
 263         parse_options(data);
 264
 265         inode = pstore_get_inode(sb, NULL, S_IFDIR | 0755, 0);
 266         if (!inode) {
 267                 err = -ENOMEM;
 268                 goto fail;
 269         }
 270         /* override ramfs "dir" options so we catch unlink(2) */
 271         inode->i_op = &pstore_dir_inode_operations;
 272
 273         root = d_alloc_root(inode);
 274         sb->s_root = root;
 275         if (!root) {
 276                 err = -ENOMEM;
 277                 goto fail;
 278         }
 279
 280         pstore_get_records();
 281
 282         return 0;
 283 fail:
 284         iput(inode);
 285         return err;
 286 }
 287
 288 static struct dentry *pstore_mount(struct file_system_type *fs_type,
 289         int flags, const char *dev_name, void *data)
 290 {
 291         return mount_single(fs_type, flags, data, pstore_fill_super);
 292 }
 293
 294 static void pstore_kill_sb(struct super_block *sb)
 295 {
 296         kill_litter_super(sb);
 297         pstore_sb = NULL;
 298 }
 299
 300 static struct file_system_type pstore_fs_type = {
 301         .name           = "pstore",
 302         .mount          = pstore_mount,
 303         .kill_sb        = pstore_kill_sb,
 304 };
 305
 306 static int __init init_pstore_fs(void)
 307 {
 308         return register_filesystem(&pstore_fs_type);
 309 }
 310 module_init(init_pstore_fs)
 311
 312 MODULE_AUTHOR("Tony Luck <tony.luck@intel.com>");
 313 MODULE_LICENSE("GPL");