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/sched.h>
  31 #include <linux/magic.h>
  32 #include <linux/pstore.h>
  33 #include <linux/slab.h>
  34 #include <linux/uaccess.h>
  35
  36 #include "internal.h"
  37
  38 #define PSTORE_NAMELEN  64
  39
  40 struct pstore_private {
  41         u64     id;
  42         int     (*erase)(u64);
  43         ssize_t size;
  44         char    data[];
  45 };
  46
  47 static int pstore_file_open(struct inode *inode, struct file *file)
  48 {
  49         file->private_data = inode->i_private;
  50         return 0;
  51 }
  52
  53 static ssize_t pstore_file_read(struct file *file, char __user *userbuf,
  54                                                 size_t count, loff_t *ppos)
  55 {
  56         struct pstore_private *ps = file->private_data;
  57
  58         return simple_read_from_buffer(userbuf, count, ppos, ps->data, ps->size);
  59 }
  60
  61 static const struct file_operations pstore_file_operations = {
  62         .open   = pstore_file_open,
  63         .read   = pstore_file_read,
  64         .llseek = default_llseek,
  65 };
  66
  67 /*
  68  * When a file is unlinked from our file system we call the
  69  * platform driver to erase the record from persistent store.
  70  */
  71 static int pstore_unlink(struct inode *dir, struct dentry *dentry)
  72 {
  73         struct pstore_private *p = dentry->d_inode->i_private;
  74
  75         p->erase(p->id);
  76
  77         return simple_unlink(dir, dentry);
  78 }
  79
  80 static void pstore_evict_inode(struct inode *inode)
  81 {
  82         end_writeback(inode);
  83         kfree(inode->i_private);
  84 }
  85
  86 static const struct inode_operations pstore_dir_inode_operations = {
  87         .lookup         = simple_lookup,
  88         .unlink         = pstore_unlink,
  89 };
  90
  91 static struct inode *pstore_get_inode(struct super_block *sb,
  92                                         const struct inode *dir, int mode, dev_t dev)
  93 {
  94         struct inode *inode = new_inode(sb);
  95
  96         if (inode) {
  97                 inode->i_ino = get_next_ino();
  98                 inode->i_uid = inode->i_gid = 0;
  99                 inode->i_mode = mode;
 100                 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
 101                 switch (mode & S_IFMT) {
 102                 case S_IFREG:
 103                         inode->i_fop = &pstore_file_operations;
 104                         break;
 105                 case S_IFDIR:
 106                         inode->i_op = &pstore_dir_inode_operations;
 107                         inode->i_fop = &simple_dir_operations;
 108                         inc_nlink(inode);
 109                         break;
 110                 }
 111         }
 112         return inode;
 113 }
 114
 115 static const struct super_operations pstore_ops = {
 116         .statfs         = simple_statfs,
 117         .drop_inode     = generic_delete_inode,
 118         .evict_inode    = pstore_evict_inode,
 119         .show_options   = generic_show_options,
 120 };
 121
 122 static struct super_block *pstore_sb;
 123
 124 int pstore_is_mounted(void)
 125 {
 126         return pstore_sb != NULL;
 127 }
 128
 129 /*
 130  * Make a regular file in the root directory of our file system.
 131  * Load it up with "size" bytes of data from "buf".
 132  * Set the mtime & ctime to the date that this record was originally stored.
 133  */
 134 int pstore_mkfile(enum pstore_type_id type, char *psname, u64 id,
 135                               char *data, size_t size,
 136                               struct timespec time, int (*erase)(u64))
 137 {
 138         struct dentry           *root = pstore_sb->s_root;
 139         struct dentry           *dentry;
 140         struct inode            *inode;
 141         int                     rc;
 142         char                    name[PSTORE_NAMELEN];
 143         struct pstore_private   *private;
 144
 145         rc = -ENOMEM;
 146         inode = pstore_get_inode(pstore_sb, root->d_inode, S_IFREG | 0444, 0);
 147         if (!inode)
 148                 goto fail;
 149         private = kmalloc(sizeof *private + size, GFP_KERNEL);
 150         if (!private)
 151                 goto fail_alloc;
 152         private->id = id;
 153         private->erase = erase;
 154
 155         switch (type) {
 156         case PSTORE_TYPE_DMESG:
 157                 sprintf(name, "dmesg-%s-%lld", psname, id);
 158                 break;
 159         case PSTORE_TYPE_MCE:
 160                 sprintf(name, "mce-%s-%lld", psname, id);
 161                 break;
 162         case PSTORE_TYPE_UNKNOWN:
 163                 sprintf(name, "unknown-%s-%lld", psname, id);
 164                 break;
 165         default:
 166                 sprintf(name, "type%d-%s-%lld", type, psname, id);
 167                 break;
 168         }
 169
 170         mutex_lock(&root->d_inode->i_mutex);
 171
 172         rc = -ENOSPC;
 173         dentry = d_alloc_name(root, name);
 174         if (IS_ERR(dentry))
 175                 goto fail_lockedalloc;
 176
 177         memcpy(private->data, data, size);
 178         inode->i_size = private->size = size;
 179
 180         inode->i_private = private;
 181
 182         if (time.tv_sec)
 183                 inode->i_mtime = inode->i_ctime = time;
 184
 185         d_add(dentry, inode);
 186
 187         mutex_unlock(&root->d_inode->i_mutex);
 188
 189         return 0;
 190
 191 fail_lockedalloc:
 192         mutex_unlock(&root->d_inode->i_mutex);
 193         kfree(private);
 194 fail_alloc:
 195         iput(inode);
 196
 197 fail:
 198         return rc;
 199 }
 200
 201 int pstore_fill_super(struct super_block *sb, void *data, int silent)
 202 {
 203         struct inode *inode = NULL;
 204         struct dentry *root;
 205         int err;
 206
 207         save_mount_options(sb, data);
 208
 209         pstore_sb = sb;
 210
 211         sb->s_maxbytes          = MAX_LFS_FILESIZE;
 212         sb->s_blocksize         = PAGE_CACHE_SIZE;
 213         sb->s_blocksize_bits    = PAGE_CACHE_SHIFT;
 214         sb->s_magic             = PSTOREFS_MAGIC;
 215         sb->s_op                = &pstore_ops;
 216         sb->s_time_gran         = 1;
 217
 218         inode = pstore_get_inode(sb, NULL, S_IFDIR | 0755, 0);
 219         if (!inode) {
 220                 err = -ENOMEM;
 221                 goto fail;
 222         }
 223         /* override ramfs "dir" options so we catch unlink(2) */
 224         inode->i_op = &pstore_dir_inode_operations;
 225
 226         root = d_alloc_root(inode);
 227         sb->s_root = root;
 228         if (!root) {
 229                 err = -ENOMEM;
 230                 goto fail;
 231         }
 232
 233         pstore_get_records();
 234
 235         return 0;
 236 fail:
 237         iput(inode);
 238         return err;
 239 }
 240
 241 static struct dentry *pstore_mount(struct file_system_type *fs_type,
 242         int flags, const char *dev_name, void *data)
 243 {
 244         return mount_single(fs_type, flags, data, pstore_fill_super);
 245 }
 246
 247 static void pstore_kill_sb(struct super_block *sb)
 248 {
 249         kill_litter_super(sb);
 250         pstore_sb = NULL;
 251 }
 252
 253 static struct file_system_type pstore_fs_type = {
 254         .name           = "pstore",
 255         .mount          = pstore_mount,
 256         .kill_sb        = pstore_kill_sb,
 257 };
 258
 259 static int __init init_pstore_fs(void)
 260 {
 261         int rc = 0;
 262         struct kobject *pstorefs_kobj;
 263
 264         pstorefs_kobj = kobject_create_and_add("pstore", fs_kobj);
 265         if (!pstorefs_kobj) {
 266                 rc = -ENOMEM;
 267                 goto done;
 268         }
 269
 270         rc = sysfs_create_file(pstorefs_kobj, &pstore_kmsg_bytes_attr.attr);
 271         if (rc)
 272                 goto done1;
 273
 274         rc = register_filesystem(&pstore_fs_type);
 275         if (rc == 0)
 276                 goto done;
 277
 278         sysfs_remove_file(pstorefs_kobj, &pstore_kmsg_bytes_attr.attr);
 279 done1:
 280         kobject_put(pstorefs_kobj);
 281 done:
 282         return rc;
 283 }
 284 module_init(init_pstore_fs)
 285
 286 MODULE_AUTHOR("Tony Luck <tony.luck@intel.com>");
 287 MODULE_LICENSE("GPL");