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