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