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