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 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   = simple_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         if (p->psi->erase)
  78                 p->psi->erase(p->type, p->id, p->psi);
  79
  80         return simple_unlink(dir, dentry);
  81 }
  82
  83 static void pstore_evict_inode(struct inode *inode)
  84 {
  85         struct pstore_private   *p = inode->i_private;
  86         unsigned long           flags;
  87
  88         end_writeback(inode);
  89         if (p) {
  90                 spin_lock_irqsave(&allpstore_lock, flags);
  91                 list_del(&p->list);
  92                 spin_unlock_irqrestore(&allpstore_lock, flags);
  93                 kfree(p);
  94         }
  95 }
  96
  97 static const struct inode_operations pstore_dir_inode_operations = {
  98         .lookup         = simple_lookup,
  99         .unlink         = pstore_unlink,
 100 };
 101
 102 static struct inode *pstore_get_inode(struct super_block *sb)
 103 {
 104         struct inode *inode = new_inode(sb);
 105         if (inode) {
 106                 inode->i_ino = get_next_ino();
 107                 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
 108         }
 109         return inode;
 110 }
 111
 112 enum {
 113         Opt_kmsg_bytes, Opt_err
 114 };
 115
 116 static const match_table_t tokens = {
 117         {Opt_kmsg_bytes, "kmsg_bytes=%u"},
 118         {Opt_err, NULL}
 119 };
 120
 121 static void parse_options(char *options)
 122 {
 123         char            *p;
 124         substring_t     args[MAX_OPT_ARGS];
 125         int             option;
 126
 127         if (!options)
 128                 return;
 129
 130         while ((p = strsep(&options, ",")) != NULL) {
 131                 int token;
 132
 133                 if (!*p)
 134                         continue;
 135
 136                 token = match_token(p, tokens, args);
 137                 switch (token) {
 138                 case Opt_kmsg_bytes:
 139                         if (!match_int(&args[0], &option))
 140                                 pstore_set_kmsg_bytes(option);
 141                         break;
 142                 }
 143         }
 144 }
 145
 146 static int pstore_remount(struct super_block *sb, int *flags, char *data)
 147 {
 148         parse_options(data);
 149
 150         return 0;
 151 }
 152
 153 static const struct super_operations pstore_ops = {
 154         .statfs         = simple_statfs,
 155         .drop_inode     = generic_delete_inode,
 156         .evict_inode    = pstore_evict_inode,
 157         .remount_fs     = pstore_remount,
 158         .show_options   = generic_show_options,
 159 };
 160
 161 static struct super_block *pstore_sb;
 162
 163 int pstore_is_mounted(void)
 164 {
 165         return pstore_sb != NULL;
 166 }
 167
 168 /*
 169  * Make a regular file in the root directory of our file system.
 170  * Load it up with "size" bytes of data from "buf".
 171  * Set the mtime & ctime to the date that this record was originally stored.
 172  */
 173 int pstore_mkfile(enum pstore_type_id type, char *psname, u64 id,
 174                   char *data, size_t size, struct timespec time,
 175                   struct pstore_info *psi)
 176 {
 177         struct dentry           *root = pstore_sb->s_root;
 178         struct dentry           *dentry;
 179         struct inode            *inode;
 180         int                     rc = 0;
 181         char                    name[PSTORE_NAMELEN];
 182         struct pstore_private   *private, *pos;
 183         unsigned long           flags;
 184
 185         spin_lock_irqsave(&allpstore_lock, flags);
 186         list_for_each_entry(pos, &allpstore, list) {
 187                 if (pos->type == type &&
 188                     pos->id == id &&
 189                     pos->psi == psi) {
 190                         rc = -EEXIST;
 191                         break;
 192                 }
 193         }
 194         spin_unlock_irqrestore(&allpstore_lock, flags);
 195         if (rc)
 196                 return rc;
 197
 198         rc = -ENOMEM;
 199         inode = pstore_get_inode(pstore_sb);
 200         if (!inode)
 201                 goto fail;
 202         inode->i_mode = S_IFREG | 0444;
 203         inode->i_fop = &pstore_file_operations;
 204         private = kmalloc(sizeof *private + size, GFP_KERNEL);
 205         if (!private)
 206                 goto fail_alloc;
 207         private->type = type;
 208         private->id = id;
 209         private->psi = psi;
 210
 211         switch (type) {
 212         case PSTORE_TYPE_DMESG:
 213                 sprintf(name, "dmesg-%s-%lld", psname, id);
 214                 break;
 215         case PSTORE_TYPE_MCE:
 216                 sprintf(name, "mce-%s-%lld", psname, id);
 217                 break;
 218         case PSTORE_TYPE_UNKNOWN:
 219                 sprintf(name, "unknown-%s-%lld", psname, id);
 220                 break;
 221         default:
 222                 sprintf(name, "type%d-%s-%lld", type, psname, id);
 223                 break;
 224         }
 225
 226         mutex_lock(&root->d_inode->i_mutex);
 227
 228         rc = -ENOSPC;
 229         dentry = d_alloc_name(root, name);
 230         if (IS_ERR(dentry))
 231                 goto fail_lockedalloc;
 232
 233         memcpy(private->data, data, size);
 234         inode->i_size = private->size = size;
 235
 236         inode->i_private = private;
 237
 238         if (time.tv_sec)
 239                 inode->i_mtime = inode->i_ctime = time;
 240
 241         d_add(dentry, inode);
 242
 243         spin_lock_irqsave(&allpstore_lock, flags);
 244         list_add(&private->list, &allpstore);
 245         spin_unlock_irqrestore(&allpstore_lock, flags);
 246
 247         mutex_unlock(&root->d_inode->i_mutex);
 248
 249         return 0;
 250
 251 fail_lockedalloc:
 252         mutex_unlock(&root->d_inode->i_mutex);
 253         kfree(private);
 254 fail_alloc:
 255         iput(inode);
 256
 257 fail:
 258         return rc;
 259 }
 260
 261 int pstore_fill_super(struct super_block *sb, void *data, int silent)
 262 {
 263         struct inode *inode;
 264
 265         save_mount_options(sb, data);
 266
 267         pstore_sb = sb;
 268
 269         sb->s_maxbytes          = MAX_LFS_FILESIZE;
 270         sb->s_blocksize         = PAGE_CACHE_SIZE;
 271         sb->s_blocksize_bits    = PAGE_CACHE_SHIFT;
 272         sb->s_magic             = PSTOREFS_MAGIC;
 273         sb->s_op                = &pstore_ops;
 274         sb->s_time_gran         = 1;
 275
 276         parse_options(data);
 277
 278         inode = pstore_get_inode(sb);
 279         if (inode) {
 280                 inode->i_mode = S_IFDIR | 0755;
 281                 inode->i_op = &pstore_dir_inode_operations;
 282                 inode->i_fop = &simple_dir_operations;
 283                 inc_nlink(inode);
 284         }
 285         sb->s_root = d_make_root(inode);
 286         if (!sb->s_root)
 287                 return -ENOMEM;
 288
 289         pstore_get_records(0);
 290
 291         return 0;
 292 }
 293
 294 static struct dentry *pstore_mount(struct file_system_type *fs_type,
 295         int flags, const char *dev_name, void *data)
 296 {
 297         return mount_single(fs_type, flags, data, pstore_fill_super);
 298 }
 299
 300 static void pstore_kill_sb(struct super_block *sb)
 301 {
 302         kill_litter_super(sb);
 303         pstore_sb = NULL;
 304 }
 305
 306 static struct file_system_type pstore_fs_type = {
 307         .name           = "pstore",
 308         .mount          = pstore_mount,
 309         .kill_sb        = pstore_kill_sb,
 310 };
 311
 312 static int __init init_pstore_fs(void)
 313 {
 314         return register_filesystem(&pstore_fs_type);
 315 }
 316 module_init(init_pstore_fs)
 317
 318 MODULE_AUTHOR("Tony Luck <tony.luck@intel.com>");
 319 MODULE_LICENSE("GPL");