kernel/arch/s390/hypfs/inode.c

   1 /*
   2  *    Hypervisor filesystem for Linux on s390.
   3  *
   4  *    Copyright IBM Corp. 2006, 2008
   5  *    Author(s): Michael Holzheu <holzheu@de.ibm.com>
   6  */
   7
   8 #define KMSG_COMPONENT "hypfs"
   9 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
  10
  11 #include <linux/types.h>
  12 #include <linux/errno.h>
  13 #include <linux/fs.h>
  14 #include <linux/namei.h>
  15 #include <linux/vfs.h>
  16 #include <linux/slab.h>
  17 #include <linux/pagemap.h>
  18 #include <linux/time.h>
  19 #include <linux/parser.h>
  20 #include <linux/sysfs.h>
  21 #include <linux/module.h>
  22 #include <linux/seq_file.h>
  23 #include <linux/mount.h>
  24 #include <linux/uio.h>
  25 #include <asm/ebcdic.h>
  26 #include "hypfs.h"
  27
  28 #define HYPFS_MAGIC 0x687970    /* ASCII 'hyp' */
  29 #define TMP_SIZE 64             /* size of temporary buffers */
  30
  31 static struct dentry *hypfs_create_update_file(struct dentry *dir);
  32
  33 struct hypfs_sb_info {
  34         kuid_t uid;                     /* uid used for files and dirs */
  35         kgid_t gid;                     /* gid used for files and dirs */
  36         struct dentry *update_file;     /* file to trigger update */
  37         time_t last_update;             /* last update time in secs since 1970 */
  38         struct mutex lock;              /* lock to protect update process */
  39 };
  40
  41 static const struct file_operations hypfs_file_ops;
  42 static struct file_system_type hypfs_type;
  43 static const struct super_operations hypfs_s_ops;
  44
  45 /* start of list of all dentries, which have to be deleted on update */
  46 static struct dentry *hypfs_last_dentry;
  47
  48 static void hypfs_update_update(struct super_block *sb)
  49 {
  50         struct hypfs_sb_info *sb_info = sb->s_fs_info;
  51         struct inode *inode = d_inode(sb_info->update_file);
  52
  53         sb_info->last_update = get_seconds();
  54         inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
  55 }
  56
  57 /* directory tree removal functions */
  58
  59 static void hypfs_add_dentry(struct dentry *dentry)
  60 {
  61         dentry->d_fsdata = hypfs_last_dentry;
  62         hypfs_last_dentry = dentry;
  63 }
  64
  65 static inline int hypfs_positive(struct dentry *dentry)
  66 {
  67         return d_really_is_positive(dentry) && !d_unhashed(dentry);
  68 }
  69
  70 static void hypfs_remove(struct dentry *dentry)
  71 {
  72         struct dentry *parent;
  73
  74         parent = dentry->d_parent;
  75         mutex_lock(&d_inode(parent)->i_mutex);
  76         if (hypfs_positive(dentry)) {
  77                 if (d_is_dir(dentry))
  78                         simple_rmdir(d_inode(parent), dentry);
  79                 else
  80                         simple_unlink(d_inode(parent), dentry);
  81         }
  82         d_delete(dentry);
  83         dput(dentry);
  84         mutex_unlock(&d_inode(parent)->i_mutex);
  85 }
  86
  87 static void hypfs_delete_tree(struct dentry *root)
  88 {
  89         while (hypfs_last_dentry) {
  90                 struct dentry *next_dentry;
  91                 next_dentry = hypfs_last_dentry->d_fsdata;
  92                 hypfs_remove(hypfs_last_dentry);
  93                 hypfs_last_dentry = next_dentry;
  94         }
  95 }
  96
  97 static struct inode *hypfs_make_inode(struct super_block *sb, umode_t mode)
  98 {
  99         struct inode *ret = new_inode(sb);
 100
 101         if (ret) {
 102                 struct hypfs_sb_info *hypfs_info = sb->s_fs_info;
 103                 ret->i_ino = get_next_ino();
 104                 ret->i_mode = mode;
 105                 ret->i_uid = hypfs_info->uid;
 106                 ret->i_gid = hypfs_info->gid;
 107                 ret->i_atime = ret->i_mtime = ret->i_ctime = CURRENT_TIME;
 108                 if (S_ISDIR(mode))
 109                         set_nlink(ret, 2);
 110         }
 111         return ret;
 112 }
 113
 114 static void hypfs_evict_inode(struct inode *inode)
 115 {
 116         clear_inode(inode);
 117         kfree(inode->i_private);
 118 }
 119
 120 static int hypfs_open(struct inode *inode, struct file *filp)
 121 {
 122         char *data = file_inode(filp)->i_private;
 123         struct hypfs_sb_info *fs_info;
 124
 125         if (filp->f_mode & FMODE_WRITE) {
 126                 if (!(inode->i_mode & S_IWUGO))
 127                         return -EACCES;
 128         }
 129         if (filp->f_mode & FMODE_READ) {
 130                 if (!(inode->i_mode & S_IRUGO))
 131                         return -EACCES;
 132         }
 133
 134         fs_info = inode->i_sb->s_fs_info;
 135         if(data) {
 136                 mutex_lock(&fs_info->lock);
 137                 filp->private_data = kstrdup(data, GFP_KERNEL);
 138                 if (!filp->private_data) {
 139                         mutex_unlock(&fs_info->lock);
 140                         return -ENOMEM;
 141                 }
 142                 mutex_unlock(&fs_info->lock);
 143         }
 144         return nonseekable_open(inode, filp);
 145 }
 146
 147 static ssize_t hypfs_read_iter(struct kiocb *iocb, struct iov_iter *to)
 148 {
 149         struct file *file = iocb->ki_filp;
 150         char *data = file->private_data;
 151         size_t available = strlen(data);
 152         loff_t pos = iocb->ki_pos;
 153         size_t count;
 154
 155         if (pos < 0)
 156                 return -EINVAL;
 157         if (pos >= available || !iov_iter_count(to))
 158                 return 0;
 159         count = copy_to_iter(data + pos, available - pos, to);
 160         if (!count)
 161                 return -EFAULT;
 162         iocb->ki_pos = pos + count;
 163         file_accessed(file);
 164         return count;
 165 }
 166
 167 static ssize_t hypfs_write_iter(struct kiocb *iocb, struct iov_iter *from)
 168 {
 169         int rc;
 170         struct super_block *sb = file_inode(iocb->ki_filp)->i_sb;
 171         struct hypfs_sb_info *fs_info = sb->s_fs_info;
 172         size_t count = iov_iter_count(from);
 173
 174         /*
 175          * Currently we only allow one update per second for two reasons:
 176          * 1. diag 204 is VERY expensive
 177          * 2. If several processes do updates in parallel and then read the
 178          *    hypfs data, the likelihood of collisions is reduced, if we restrict
 179          *    the minimum update interval. A collision occurs, if during the
 180          *    data gathering of one process another process triggers an update
 181          *    If the first process wants to ensure consistent data, it has
 182          *    to restart data collection in this case.
 183          */
 184         mutex_lock(&fs_info->lock);
 185         if (fs_info->last_update == get_seconds()) {
 186                 rc = -EBUSY;
 187                 goto out;
 188         }
 189         hypfs_delete_tree(sb->s_root);
 190         if (MACHINE_IS_VM)
 191                 rc = hypfs_vm_create_files(sb->s_root);
 192         else
 193                 rc = hypfs_diag_create_files(sb->s_root);
 194         if (rc) {
 195                 pr_err("Updating the hypfs tree failed\n");
 196                 hypfs_delete_tree(sb->s_root);
 197                 goto out;
 198         }
 199         hypfs_update_update(sb);
 200         rc = count;
 201         iov_iter_advance(from, count);
 202 out:
 203         mutex_unlock(&fs_info->lock);
 204         return rc;
 205 }
 206
 207 static int hypfs_release(struct inode *inode, struct file *filp)
 208 {
 209         kfree(filp->private_data);
 210         return 0;
 211 }
 212
 213 enum { opt_uid, opt_gid, opt_err };
 214
 215 static const match_table_t hypfs_tokens = {
 216         {opt_uid, "uid=%u"},
 217         {opt_gid, "gid=%u"},
 218         {opt_err, NULL}
 219 };
 220
 221 static int hypfs_parse_options(char *options, struct super_block *sb)
 222 {
 223         char *str;
 224         substring_t args[MAX_OPT_ARGS];
 225         kuid_t uid;
 226         kgid_t gid;
 227
 228         if (!options)
 229                 return 0;
 230         while ((str = strsep(&options, ",")) != NULL) {
 231                 int token, option;
 232                 struct hypfs_sb_info *hypfs_info = sb->s_fs_info;
 233
 234                 if (!*str)
 235                         continue;
 236                 token = match_token(str, hypfs_tokens, args);
 237                 switch (token) {
 238                 case opt_uid:
 239                         if (match_int(&args[0], &option))
 240                                 return -EINVAL;
 241                         uid = make_kuid(current_user_ns(), option);
 242                         if (!uid_valid(uid))
 243                                 return -EINVAL;
 244                         hypfs_info->uid = uid;
 245                         break;
 246                 case opt_gid:
 247                         if (match_int(&args[0], &option))
 248                                 return -EINVAL;
 249                         gid = make_kgid(current_user_ns(), option);
 250                         if (!gid_valid(gid))
 251                                 return -EINVAL;
 252                         hypfs_info->gid = gid;
 253                         break;
 254                 case opt_err:
 255                 default:
 256                         pr_err("%s is not a valid mount option\n", str);
 257                         return -EINVAL;
 258                 }
 259         }
 260         return 0;
 261 }
 262
 263 static int hypfs_show_options(struct seq_file *s, struct dentry *root)
 264 {
 265         struct hypfs_sb_info *hypfs_info = root->d_sb->s_fs_info;
 266
 267         seq_printf(s, ",uid=%u", from_kuid_munged(&init_user_ns, hypfs_info->uid));
 268         seq_printf(s, ",gid=%u", from_kgid_munged(&init_user_ns, hypfs_info->gid));
 269         return 0;
 270 }
 271
 272 static int hypfs_fill_super(struct super_block *sb, void *data, int silent)
 273 {
 274         struct inode *root_inode;
 275         struct dentry *root_dentry;
 276         int rc = 0;
 277         struct hypfs_sb_info *sbi;
 278
 279         sbi = kzalloc(sizeof(struct hypfs_sb_info), GFP_KERNEL);
 280         if (!sbi)
 281                 return -ENOMEM;
 282         mutex_init(&sbi->lock);
 283         sbi->uid = current_uid();
 284         sbi->gid = current_gid();
 285         sb->s_fs_info = sbi;
 286         sb->s_blocksize = PAGE_CACHE_SIZE;
 287         sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
 288         sb->s_magic = HYPFS_MAGIC;
 289         sb->s_op = &hypfs_s_ops;
 290         if (hypfs_parse_options(data, sb))
 291                 return -EINVAL;
 292         root_inode = hypfs_make_inode(sb, S_IFDIR | 0755);
 293         if (!root_inode)
 294                 return -ENOMEM;
 295         root_inode->i_op = &simple_dir_inode_operations;
 296         root_inode->i_fop = &simple_dir_operations;
 297         sb->s_root = root_dentry = d_make_root(root_inode);
 298         if (!root_dentry)
 299                 return -ENOMEM;
 300         if (MACHINE_IS_VM)
 301                 rc = hypfs_vm_create_files(root_dentry);
 302         else
 303                 rc = hypfs_diag_create_files(root_dentry);
 304         if (rc)
 305                 return rc;
 306         sbi->update_file = hypfs_create_update_file(root_dentry);
 307         if (IS_ERR(sbi->update_file))
 308                 return PTR_ERR(sbi->update_file);
 309         hypfs_update_update(sb);
 310         pr_info("Hypervisor filesystem mounted\n");
 311         return 0;
 312 }
 313
 314 static struct dentry *hypfs_mount(struct file_system_type *fst, int flags,
 315                         const char *devname, void *data)
 316 {
 317         return mount_single(fst, flags, data, hypfs_fill_super);
 318 }
 319
 320 static void hypfs_kill_super(struct super_block *sb)
 321 {
 322         struct hypfs_sb_info *sb_info = sb->s_fs_info;
 323
 324         if (sb->s_root)
 325                 hypfs_delete_tree(sb->s_root);
 326         if (sb_info->update_file)
 327                 hypfs_remove(sb_info->update_file);
 328         kfree(sb->s_fs_info);
 329         sb->s_fs_info = NULL;
 330         kill_litter_super(sb);
 331 }
 332
 333 static struct dentry *hypfs_create_file(struct dentry *parent, const char *name,
 334                                         char *data, umode_t mode)
 335 {
 336         struct dentry *dentry;
 337         struct inode *inode;
 338
 339         mutex_lock(&d_inode(parent)->i_mutex);
 340         dentry = lookup_one_len(name, parent, strlen(name));
 341         if (IS_ERR(dentry)) {
 342                 dentry = ERR_PTR(-ENOMEM);
 343                 goto fail;
 344         }
 345         inode = hypfs_make_inode(parent->d_sb, mode);
 346         if (!inode) {
 347                 dput(dentry);
 348                 dentry = ERR_PTR(-ENOMEM);
 349                 goto fail;
 350         }
 351         if (S_ISREG(mode)) {
 352                 inode->i_fop = &hypfs_file_ops;
 353                 if (data)
 354                         inode->i_size = strlen(data);
 355                 else
 356                         inode->i_size = 0;
 357         } else if (S_ISDIR(mode)) {
 358                 inode->i_op = &simple_dir_inode_operations;
 359                 inode->i_fop = &simple_dir_operations;
 360                 inc_nlink(d_inode(parent));
 361         } else
 362                 BUG();
 363         inode->i_private = data;
 364         d_instantiate(dentry, inode);
 365         dget(dentry);
 366 fail:
 367         mutex_unlock(&d_inode(parent)->i_mutex);
 368         return dentry;
 369 }
 370
 371 struct dentry *hypfs_mkdir(struct dentry *parent, const char *name)
 372 {
 373         struct dentry *dentry;
 374
 375         dentry = hypfs_create_file(parent, name, NULL, S_IFDIR | DIR_MODE);
 376         if (IS_ERR(dentry))
 377                 return dentry;
 378         hypfs_add_dentry(dentry);
 379         return dentry;
 380 }
 381
 382 static struct dentry *hypfs_create_update_file(struct dentry *dir)
 383 {
 384         struct dentry *dentry;
 385
 386         dentry = hypfs_create_file(dir, "update", NULL,
 387                                    S_IFREG | UPDATE_FILE_MODE);
 388         /*
 389          * We do not put the update file on the 'delete' list with
 390          * hypfs_add_dentry(), since it should not be removed when the tree
 391          * is updated.
 392          */
 393         return dentry;
 394 }
 395
 396 struct dentry *hypfs_create_u64(struct dentry *dir,
 397                                 const char *name, __u64 value)
 398 {
 399         char *buffer;
 400         char tmp[TMP_SIZE];
 401         struct dentry *dentry;
 402
 403         snprintf(tmp, TMP_SIZE, "%llu\n", (unsigned long long int)value);
 404         buffer = kstrdup(tmp, GFP_KERNEL);
 405         if (!buffer)
 406                 return ERR_PTR(-ENOMEM);
 407         dentry =
 408             hypfs_create_file(dir, name, buffer, S_IFREG | REG_FILE_MODE);
 409         if (IS_ERR(dentry)) {
 410                 kfree(buffer);
 411                 return ERR_PTR(-ENOMEM);
 412         }
 413         hypfs_add_dentry(dentry);
 414         return dentry;
 415 }
 416
 417 struct dentry *hypfs_create_str(struct dentry *dir,
 418                                 const char *name, char *string)
 419 {
 420         char *buffer;
 421         struct dentry *dentry;
 422
 423         buffer = kmalloc(strlen(string) + 2, GFP_KERNEL);
 424         if (!buffer)
 425                 return ERR_PTR(-ENOMEM);
 426         sprintf(buffer, "%s\n", string);
 427         dentry =
 428             hypfs_create_file(dir, name, buffer, S_IFREG | REG_FILE_MODE);
 429         if (IS_ERR(dentry)) {
 430                 kfree(buffer);
 431                 return ERR_PTR(-ENOMEM);
 432         }
 433         hypfs_add_dentry(dentry);
 434         return dentry;
 435 }
 436
 437 static const struct file_operations hypfs_file_ops = {
 438         .open           = hypfs_open,
 439         .release        = hypfs_release,
 440         .read_iter      = hypfs_read_iter,
 441         .write_iter     = hypfs_write_iter,
 442         .llseek         = no_llseek,
 443 };
 444
 445 static struct file_system_type hypfs_type = {
 446         .owner          = THIS_MODULE,
 447         .name           = "s390_hypfs",
 448         .mount          = hypfs_mount,
 449         .kill_sb        = hypfs_kill_super
 450 };
 451 MODULE_ALIAS_FS("s390_hypfs");
 452
 453 static const struct super_operations hypfs_s_ops = {
 454         .statfs         = simple_statfs,
 455         .evict_inode    = hypfs_evict_inode,
 456         .show_options   = hypfs_show_options,
 457 };
 458
 459 static int __init hypfs_init(void)
 460 {
 461         int rc;
 462
 463         rc = hypfs_dbfs_init();
 464         if (rc)
 465                 return rc;
 466         if (hypfs_diag_init()) {
 467                 rc = -ENODATA;
 468                 goto fail_dbfs_exit;
 469         }
 470         if (hypfs_vm_init()) {
 471                 rc = -ENODATA;
 472                 goto fail_hypfs_diag_exit;
 473         }
 474         if (hypfs_sprp_init()) {
 475                 rc = -ENODATA;
 476                 goto fail_hypfs_vm_exit;
 477         }
 478         if (hypfs_diag0c_init()) {
 479                 rc = -ENODATA;
 480                 goto fail_hypfs_sprp_exit;
 481         }
 482         rc = sysfs_create_mount_point(hypervisor_kobj, "s390");
 483         if (rc)
 484                 goto fail_hypfs_diag0c_exit;
 485         rc = register_filesystem(&hypfs_type);
 486         if (rc)
 487                 goto fail_filesystem;
 488         return 0;
 489
 490 fail_filesystem:
 491         sysfs_remove_mount_point(hypervisor_kobj, "s390");
 492 fail_hypfs_diag0c_exit:
 493         hypfs_diag0c_exit();
 494 fail_hypfs_sprp_exit:
 495         hypfs_sprp_exit();
 496 fail_hypfs_vm_exit:
 497         hypfs_vm_exit();
 498 fail_hypfs_diag_exit:
 499         hypfs_diag_exit();
 500 fail_dbfs_exit:
 501         hypfs_dbfs_exit();
 502         pr_err("Initialization of hypfs failed with rc=%i\n", rc);
 503         return rc;
 504 }
 505
 506 static void __exit hypfs_exit(void)
 507 {
 508         unregister_filesystem(&hypfs_type);
 509         sysfs_remove_mount_point(hypervisor_kobj, "s390");
 510         hypfs_diag0c_exit();
 511         hypfs_sprp_exit();
 512         hypfs_vm_exit();
 513         hypfs_diag_exit();
 514         hypfs_dbfs_exit();
 515 }
 516
 517 module_init(hypfs_init)
 518 module_exit(hypfs_exit)
 519
 520 MODULE_LICENSE("GPL");
 521 MODULE_AUTHOR("Michael Holzheu <holzheu@de.ibm.com>");
 522 MODULE_DESCRIPTION("s390 Hypervisor Filesystem");