arch/s390/hypfs/inode.c

   1 /*
   2  *  arch/s390/hypfs/inode.c
   3  *    Hypervisor filesystem for Linux on s390.
   4  *
   5  *    Copyright (C) IBM Corp. 2006
   6  *    Author(s): Michael Holzheu <holzheu@de.ibm.com>
   7  */
   8
   9 #include <linux/types.h>
  10 #include <linux/errno.h>
  11 #include <linux/fs.h>
  12 #include <linux/namei.h>
  13 #include <linux/vfs.h>
  14 #include <linux/pagemap.h>
  15 #include <linux/gfp.h>
  16 #include <linux/time.h>
  17 #include <linux/parser.h>
  18 #include <linux/sysfs.h>
  19 #include <linux/module.h>
  20 #include <linux/seq_file.h>
  21 #include <linux/mount.h>
  22 #include <asm/ebcdic.h>
  23 #include "hypfs.h"
  24
  25 #define HYPFS_MAGIC 0x687970    /* ASCII 'hyp' */
  26 #define TMP_SIZE 64             /* size of temporary buffers */
  27
  28 static struct dentry *hypfs_create_update_file(struct super_block *sb,
  29                                                struct dentry *dir);
  30
  31 struct hypfs_sb_info {
  32         uid_t uid;                      /* uid used for files and dirs */
  33         gid_t gid;                      /* gid used for files and dirs */
  34         struct dentry *update_file;     /* file to trigger update */
  35         time_t last_update;             /* last update time in secs since 1970 */
  36         struct mutex lock;              /* lock to protect update process */
  37 };
  38
  39 static const struct file_operations hypfs_file_ops;
  40 static struct file_system_type hypfs_type;
  41 static struct super_operations hypfs_s_ops;
  42
  43 /* start of list of all dentries, which have to be deleted on update */
  44 static struct dentry *hypfs_last_dentry;
  45
  46 static void hypfs_update_update(struct super_block *sb)
  47 {
  48         struct hypfs_sb_info *sb_info = sb->s_fs_info;
  49         struct inode *inode = sb_info->update_file->d_inode;
  50
  51         sb_info->last_update = get_seconds();
  52         inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
  53 }
  54
  55 /* directory tree removal functions */
  56
  57 static void hypfs_add_dentry(struct dentry *dentry)
  58 {
  59         dentry->d_fsdata = hypfs_last_dentry;
  60         hypfs_last_dentry = dentry;
  61 }
  62
  63 static inline int hypfs_positive(struct dentry *dentry)
  64 {
  65         return dentry->d_inode && !d_unhashed(dentry);
  66 }
  67
  68 static void hypfs_remove(struct dentry *dentry)
  69 {
  70         struct dentry *parent;
  71
  72         parent = dentry->d_parent;
  73         if (!parent || !parent->d_inode)
  74                 return;
  75         mutex_lock(&parent->d_inode->i_mutex);
  76         if (hypfs_positive(dentry)) {
  77                 if (S_ISDIR(dentry->d_inode->i_mode))
  78                         simple_rmdir(parent->d_inode, dentry);
  79                 else
  80                         simple_unlink(parent->d_inode, dentry);
  81         }
  82         d_delete(dentry);
  83         dput(dentry);
  84         mutex_unlock(&parent->d_inode->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, int 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_mode = mode;
 104                 ret->i_uid = hypfs_info->uid;
 105                 ret->i_gid = hypfs_info->gid;
 106                 ret->i_blocks = 0;
 107                 ret->i_atime = ret->i_mtime = ret->i_ctime = CURRENT_TIME;
 108                 if (mode & S_IFDIR)
 109                         ret->i_nlink = 2;
 110                 else
 111                         ret->i_nlink = 1;
 112         }
 113         return ret;
 114 }
 115
 116 static void hypfs_drop_inode(struct inode *inode)
 117 {
 118         kfree(inode->i_private);
 119         generic_delete_inode(inode);
 120 }
 121
 122 static int hypfs_open(struct inode *inode, struct file *filp)
 123 {
 124         char *data = filp->f_path.dentry->d_inode->i_private;
 125         struct hypfs_sb_info *fs_info;
 126
 127         if (filp->f_mode & FMODE_WRITE) {
 128                 if (!(inode->i_mode & S_IWUGO))
 129                         return -EACCES;
 130         }
 131         if (filp->f_mode & FMODE_READ) {
 132                 if (!(inode->i_mode & S_IRUGO))
 133                         return -EACCES;
 134         }
 135
 136         fs_info = inode->i_sb->s_fs_info;
 137         if(data) {
 138                 mutex_lock(&fs_info->lock);
 139                 filp->private_data = kstrdup(data, GFP_KERNEL);
 140                 if (!filp->private_data) {
 141                         mutex_unlock(&fs_info->lock);
 142                         return -ENOMEM;
 143                 }
 144                 mutex_unlock(&fs_info->lock);
 145         }
 146         return 0;
 147 }
 148
 149 static ssize_t hypfs_aio_read(struct kiocb *iocb, const struct iovec *iov,
 150                               unsigned long nr_segs, loff_t offset)
 151 {
 152         char *data;
 153         size_t len;
 154         struct file *filp = iocb->ki_filp;
 155         /* XXX: temporary */
 156         char __user *buf = iov[0].iov_base;
 157         size_t count = iov[0].iov_len;
 158
 159         if (nr_segs != 1) {
 160                 count = -EINVAL;
 161                 goto out;
 162         }
 163
 164         data = filp->private_data;
 165         len = strlen(data);
 166         if (offset > len) {
 167                 count = 0;
 168                 goto out;
 169         }
 170         if (count > len - offset)
 171                 count = len - offset;
 172         if (copy_to_user(buf, data + offset, count)) {
 173                 count = -EFAULT;
 174                 goto out;
 175         }
 176         iocb->ki_pos += count;
 177         file_accessed(filp);
 178 out:
 179         return count;
 180 }
 181 static ssize_t hypfs_aio_write(struct kiocb *iocb, const struct iovec *iov,
 182                               unsigned long nr_segs, loff_t offset)
 183 {
 184         int rc;
 185         struct super_block *sb;
 186         struct hypfs_sb_info *fs_info;
 187         size_t count = iov_length(iov, nr_segs);
 188
 189         sb = iocb->ki_filp->f_path.dentry->d_inode->i_sb;
 190         fs_info = sb->s_fs_info;
 191         /*
 192          * Currently we only allow one update per second for two reasons:
 193          * 1. diag 204 is VERY expensive
 194          * 2. If several processes do updates in parallel and then read the
 195          *    hypfs data, the likelihood of collisions is reduced, if we restrict
 196          *    the minimum update interval. A collision occurs, if during the
 197          *    data gathering of one process another process triggers an update
 198          *    If the first process wants to ensure consistent data, it has
 199          *    to restart data collection in this case.
 200          */
 201         mutex_lock(&fs_info->lock);
 202         if (fs_info->last_update == get_seconds()) {
 203                 rc = -EBUSY;
 204                 goto out;
 205         }
 206         hypfs_delete_tree(sb->s_root);
 207         if (MACHINE_IS_VM)
 208                 rc = hypfs_vm_create_files(sb, sb->s_root);
 209         else
 210                 rc = hypfs_diag_create_files(sb, sb->s_root);
 211         if (rc) {
 212                 printk(KERN_ERR "hypfs: Update failed\n");
 213                 hypfs_delete_tree(sb->s_root);
 214                 goto out;
 215         }
 216         hypfs_update_update(sb);
 217         rc = count;
 218 out:
 219         mutex_unlock(&fs_info->lock);
 220         return rc;
 221 }
 222
 223 static int hypfs_release(struct inode *inode, struct file *filp)
 224 {
 225         kfree(filp->private_data);
 226         return 0;
 227 }
 228
 229 enum { opt_uid, opt_gid, opt_err };
 230
 231 static match_table_t hypfs_tokens = {
 232         {opt_uid, "uid=%u"},
 233         {opt_gid, "gid=%u"},
 234         {opt_err, NULL}
 235 };
 236
 237 static int hypfs_parse_options(char *options, struct super_block *sb)
 238 {
 239         char *str;
 240         substring_t args[MAX_OPT_ARGS];
 241
 242         if (!options)
 243                 return 0;
 244         while ((str = strsep(&options, ",")) != NULL) {
 245                 int token, option;
 246                 struct hypfs_sb_info *hypfs_info = sb->s_fs_info;
 247
 248                 if (!*str)
 249                         continue;
 250                 token = match_token(str, hypfs_tokens, args);
 251                 switch (token) {
 252                 case opt_uid:
 253                         if (match_int(&args[0], &option))
 254                                 return -EINVAL;
 255                         hypfs_info->uid = option;
 256                         break;
 257                 case opt_gid:
 258                         if (match_int(&args[0], &option))
 259                                 return -EINVAL;
 260                         hypfs_info->gid = option;
 261                         break;
 262                 case opt_err:
 263                 default:
 264                         printk(KERN_ERR "hypfs: Unrecognized mount option "
 265                                "\"%s\" or missing value\n", str);
 266                         return -EINVAL;
 267                 }
 268         }
 269         return 0;
 270 }
 271
 272 static int hypfs_show_options(struct seq_file *s, struct vfsmount *mnt)
 273 {
 274         struct hypfs_sb_info *hypfs_info = mnt->mnt_sb->s_fs_info;
 275
 276         seq_printf(s, ",uid=%u", hypfs_info->uid);
 277         seq_printf(s, ",gid=%u", hypfs_info->gid);
 278         return 0;
 279 }
 280
 281 static int hypfs_fill_super(struct super_block *sb, void *data, int silent)
 282 {
 283         struct inode *root_inode;
 284         struct dentry *root_dentry;
 285         int rc = 0;
 286         struct hypfs_sb_info *sbi;
 287
 288         sbi = kzalloc(sizeof(struct hypfs_sb_info), GFP_KERNEL);
 289         if (!sbi)
 290                 return -ENOMEM;
 291         mutex_init(&sbi->lock);
 292         sbi->uid = current->uid;
 293         sbi->gid = current->gid;
 294         sb->s_fs_info = sbi;
 295         sb->s_blocksize = PAGE_CACHE_SIZE;
 296         sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
 297         sb->s_magic = HYPFS_MAGIC;
 298         sb->s_op = &hypfs_s_ops;
 299         if (hypfs_parse_options(data, sb)) {
 300                 rc = -EINVAL;
 301                 goto err_alloc;
 302         }
 303         root_inode = hypfs_make_inode(sb, S_IFDIR | 0755);
 304         if (!root_inode) {
 305                 rc = -ENOMEM;
 306                 goto err_alloc;
 307         }
 308         root_inode->i_op = &simple_dir_inode_operations;
 309         root_inode->i_fop = &simple_dir_operations;
 310         root_dentry = d_alloc_root(root_inode);
 311         if (!root_dentry) {
 312                 iput(root_inode);
 313                 rc = -ENOMEM;
 314                 goto err_alloc;
 315         }
 316         if (MACHINE_IS_VM)
 317                 rc = hypfs_vm_create_files(sb, root_dentry);
 318         else
 319                 rc = hypfs_diag_create_files(sb, root_dentry);
 320         if (rc)
 321                 goto err_tree;
 322         sbi->update_file = hypfs_create_update_file(sb, root_dentry);
 323         if (IS_ERR(sbi->update_file)) {
 324                 rc = PTR_ERR(sbi->update_file);
 325                 goto err_tree;
 326         }
 327         hypfs_update_update(sb);
 328         sb->s_root = root_dentry;
 329         printk(KERN_INFO "hypfs: Hypervisor filesystem mounted\n");
 330         return 0;
 331
 332 err_tree:
 333         hypfs_delete_tree(root_dentry);
 334         d_genocide(root_dentry);
 335         dput(root_dentry);
 336 err_alloc:
 337         kfree(sbi);
 338         return rc;
 339 }
 340
 341 static int hypfs_get_super(struct file_system_type *fst, int flags,
 342                         const char *devname, void *data, struct vfsmount *mnt)
 343 {
 344         return get_sb_single(fst, flags, data, hypfs_fill_super, mnt);
 345 }
 346
 347 static void hypfs_kill_super(struct super_block *sb)
 348 {
 349         struct hypfs_sb_info *sb_info = sb->s_fs_info;
 350
 351         if (sb->s_root) {
 352                 hypfs_delete_tree(sb->s_root);
 353                 hypfs_remove(sb_info->update_file);
 354                 kfree(sb->s_fs_info);
 355                 sb->s_fs_info = NULL;
 356         }
 357         kill_litter_super(sb);
 358 }
 359
 360 static struct dentry *hypfs_create_file(struct super_block *sb,
 361                                         struct dentry *parent, const char *name,
 362                                         char *data, mode_t mode)
 363 {
 364         struct dentry *dentry;
 365         struct inode *inode;
 366         struct qstr qname;
 367
 368         qname.name = name;
 369         qname.len = strlen(name);
 370         qname.hash = full_name_hash(name, qname.len);
 371         mutex_lock(&parent->d_inode->i_mutex);
 372         dentry = lookup_one_len(name, parent, strlen(name));
 373         if (IS_ERR(dentry)) {
 374                 dentry = ERR_PTR(-ENOMEM);
 375                 goto fail;
 376         }
 377         inode = hypfs_make_inode(sb, mode);
 378         if (!inode) {
 379                 dput(dentry);
 380                 dentry = ERR_PTR(-ENOMEM);
 381                 goto fail;
 382         }
 383         if (mode & S_IFREG) {
 384                 inode->i_fop = &hypfs_file_ops;
 385                 if (data)
 386                         inode->i_size = strlen(data);
 387                 else
 388                         inode->i_size = 0;
 389         } else if (mode & S_IFDIR) {
 390                 inode->i_op = &simple_dir_inode_operations;
 391                 inode->i_fop = &simple_dir_operations;
 392                 parent->d_inode->i_nlink++;
 393         } else
 394                 BUG();
 395         inode->i_private = data;
 396         d_instantiate(dentry, inode);
 397         dget(dentry);
 398 fail:
 399         mutex_unlock(&parent->d_inode->i_mutex);
 400         return dentry;
 401 }
 402
 403 struct dentry *hypfs_mkdir(struct super_block *sb, struct dentry *parent,
 404                            const char *name)
 405 {
 406         struct dentry *dentry;
 407
 408         dentry = hypfs_create_file(sb, parent, name, NULL, S_IFDIR | DIR_MODE);
 409         if (IS_ERR(dentry))
 410                 return dentry;
 411         hypfs_add_dentry(dentry);
 412         return dentry;
 413 }
 414
 415 static struct dentry *hypfs_create_update_file(struct super_block *sb,
 416                                                struct dentry *dir)
 417 {
 418         struct dentry *dentry;
 419
 420         dentry = hypfs_create_file(sb, dir, "update", NULL,
 421                                    S_IFREG | UPDATE_FILE_MODE);
 422         /*
 423          * We do not put the update file on the 'delete' list with
 424          * hypfs_add_dentry(), since it should not be removed when the tree
 425          * is updated.
 426          */
 427         return dentry;
 428 }
 429
 430 struct dentry *hypfs_create_u64(struct super_block *sb, struct dentry *dir,
 431                                 const char *name, __u64 value)
 432 {
 433         char *buffer;
 434         char tmp[TMP_SIZE];
 435         struct dentry *dentry;
 436
 437         snprintf(tmp, TMP_SIZE, "%lld\n", (unsigned long long int)value);
 438         buffer = kstrdup(tmp, GFP_KERNEL);
 439         if (!buffer)
 440                 return ERR_PTR(-ENOMEM);
 441         dentry =
 442             hypfs_create_file(sb, dir, name, buffer, S_IFREG | REG_FILE_MODE);
 443         if (IS_ERR(dentry)) {
 444                 kfree(buffer);
 445                 return ERR_PTR(-ENOMEM);
 446         }
 447         hypfs_add_dentry(dentry);
 448         return dentry;
 449 }
 450
 451 struct dentry *hypfs_create_str(struct super_block *sb, struct dentry *dir,
 452                                 const char *name, char *string)
 453 {
 454         char *buffer;
 455         struct dentry *dentry;
 456
 457         buffer = kmalloc(strlen(string) + 2, GFP_KERNEL);
 458         if (!buffer)
 459                 return ERR_PTR(-ENOMEM);
 460         sprintf(buffer, "%s\n", string);
 461         dentry =
 462             hypfs_create_file(sb, dir, name, buffer, S_IFREG | REG_FILE_MODE);
 463         if (IS_ERR(dentry)) {
 464                 kfree(buffer);
 465                 return ERR_PTR(-ENOMEM);
 466         }
 467         hypfs_add_dentry(dentry);
 468         return dentry;
 469 }
 470
 471 static const struct file_operations hypfs_file_ops = {
 472         .open           = hypfs_open,
 473         .release        = hypfs_release,
 474         .read           = do_sync_read,
 475         .write          = do_sync_write,
 476         .aio_read       = hypfs_aio_read,
 477         .aio_write      = hypfs_aio_write,
 478 };
 479
 480 static struct file_system_type hypfs_type = {
 481         .owner          = THIS_MODULE,
 482         .name           = "s390_hypfs",
 483         .get_sb         = hypfs_get_super,
 484         .kill_sb        = hypfs_kill_super
 485 };
 486
 487 static struct super_operations hypfs_s_ops = {
 488         .statfs         = simple_statfs,
 489         .drop_inode     = hypfs_drop_inode,
 490         .show_options   = hypfs_show_options,
 491 };
 492
 493 static decl_subsys(s390, NULL, NULL);
 494
 495 static int __init hypfs_init(void)
 496 {
 497         int rc;
 498
 499         if (MACHINE_IS_VM) {
 500                 if (hypfs_vm_init())
 501                         /* no diag 2fc, just exit */
 502                         return -ENODATA;
 503         } else {
 504                 if (hypfs_diag_init()) {
 505                         rc = -ENODATA;
 506                         goto fail_diag;
 507                 }
 508         }
 509         kobj_set_kset_s(&s390_subsys, hypervisor_subsys);
 510         rc = subsystem_register(&s390_subsys);
 511         if (rc)
 512                 goto fail_sysfs;
 513         rc = register_filesystem(&hypfs_type);
 514         if (rc)
 515                 goto fail_filesystem;
 516         return 0;
 517
 518 fail_filesystem:
 519         subsystem_unregister(&s390_subsys);
 520 fail_sysfs:
 521         if (!MACHINE_IS_VM)
 522                 hypfs_diag_exit();
 523 fail_diag:
 524         printk(KERN_ERR "hypfs: Initialization failed with rc = %i.\n", rc);
 525         return rc;
 526 }
 527
 528 static void __exit hypfs_exit(void)
 529 {
 530         if (!MACHINE_IS_VM)
 531                 hypfs_diag_exit();
 532         unregister_filesystem(&hypfs_type);
 533         subsystem_unregister(&s390_subsys);
 534 }
 535
 536 module_init(hypfs_init)
 537 module_exit(hypfs_exit)
 538
 539 MODULE_LICENSE("GPL");
 540 MODULE_AUTHOR("Michael Holzheu <holzheu@de.ibm.com>");
 541 MODULE_DESCRIPTION("s390 Hypervisor Filesystem");