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