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 <asm/ebcdic.h>
  25 #include "hypfs.h"
  26
  27 #define HYPFS_MAGIC 0x687970    /* ASCII 'hyp' */
  28 #define TMP_SIZE 64             /* size of temporary buffers */
  29
  30 static struct dentry *hypfs_create_update_file(struct super_block *sb,
  31                                                struct dentry *dir);
  32
  33 struct hypfs_sb_info {
  34         uid_t uid;                      /* uid used for files and dirs */
  35         gid_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 = sb_info->update_file->d_inode;
  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 dentry->d_inode && !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(&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, 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 = filp->f_path.dentry->d_inode->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_aio_read(struct kiocb *iocb, const struct iovec *iov,
 148                               unsigned long nr_segs, loff_t offset)
 149 {
 150         char *data;
 151         ssize_t ret;
 152         struct file *filp = iocb->ki_filp;
 153         /* XXX: temporary */
 154         char __user *buf = iov[0].iov_base;
 155         size_t count = iov[0].iov_len;
 156
 157         if (nr_segs != 1)
 158                 return -EINVAL;
 159
 160         data = filp->private_data;
 161         ret = simple_read_from_buffer(buf, count, &offset, data, strlen(data));
 162         if (ret <= 0)
 163                 return ret;
 164
 165         iocb->ki_pos += ret;
 166         file_accessed(filp);
 167
 168         return ret;
 169 }
 170 static ssize_t hypfs_aio_write(struct kiocb *iocb, const struct iovec *iov,
 171                               unsigned long nr_segs, loff_t offset)
 172 {
 173         int rc;
 174         struct super_block *sb;
 175         struct hypfs_sb_info *fs_info;
 176         size_t count = iov_length(iov, nr_segs);
 177
 178         sb = iocb->ki_filp->f_path.dentry->d_inode->i_sb;
 179         fs_info = sb->s_fs_info;
 180         /*
 181          * Currently we only allow one update per second for two reasons:
 182          * 1. diag 204 is VERY expensive
 183          * 2. If several processes do updates in parallel and then read the
 184          *    hypfs data, the likelihood of collisions is reduced, if we restrict
 185          *    the minimum update interval. A collision occurs, if during the
 186          *    data gathering of one process another process triggers an update
 187          *    If the first process wants to ensure consistent data, it has
 188          *    to restart data collection in this case.
 189          */
 190         mutex_lock(&fs_info->lock);
 191         if (fs_info->last_update == get_seconds()) {
 192                 rc = -EBUSY;
 193                 goto out;
 194         }
 195         hypfs_delete_tree(sb->s_root);
 196         if (MACHINE_IS_VM)
 197                 rc = hypfs_vm_create_files(sb, sb->s_root);
 198         else
 199                 rc = hypfs_diag_create_files(sb, sb->s_root);
 200         if (rc) {
 201                 pr_err("Updating the hypfs tree failed\n");
 202                 hypfs_delete_tree(sb->s_root);
 203                 goto out;
 204         }
 205         hypfs_update_update(sb);
 206         rc = count;
 207 out:
 208         mutex_unlock(&fs_info->lock);
 209         return rc;
 210 }
 211
 212 static int hypfs_release(struct inode *inode, struct file *filp)
 213 {
 214         kfree(filp->private_data);
 215         return 0;
 216 }
 217
 218 enum { opt_uid, opt_gid, opt_err };
 219
 220 static const match_table_t hypfs_tokens = {
 221         {opt_uid, "uid=%u"},
 222         {opt_gid, "gid=%u"},
 223         {opt_err, NULL}
 224 };
 225
 226 static int hypfs_parse_options(char *options, struct super_block *sb)
 227 {
 228         char *str;
 229         substring_t args[MAX_OPT_ARGS];
 230
 231         if (!options)
 232                 return 0;
 233         while ((str = strsep(&options, ",")) != NULL) {
 234                 int token, option;
 235                 struct hypfs_sb_info *hypfs_info = sb->s_fs_info;
 236
 237                 if (!*str)
 238                         continue;
 239                 token = match_token(str, hypfs_tokens, args);
 240                 switch (token) {
 241                 case opt_uid:
 242                         if (match_int(&args[0], &option))
 243                                 return -EINVAL;
 244                         hypfs_info->uid = option;
 245                         break;
 246                 case opt_gid:
 247                         if (match_int(&args[0], &option))
 248                                 return -EINVAL;
 249                         hypfs_info->gid = option;
 250                         break;
 251                 case opt_err:
 252                 default:
 253                         pr_err("%s is not a valid mount option\n", str);
 254                         return -EINVAL;
 255                 }
 256         }
 257         return 0;
 258 }
 259
 260 static int hypfs_show_options(struct seq_file *s, struct dentry *root)
 261 {
 262         struct hypfs_sb_info *hypfs_info = root->d_sb->s_fs_info;
 263
 264         seq_printf(s, ",uid=%u", hypfs_info->uid);
 265         seq_printf(s, ",gid=%u", hypfs_info->gid);
 266         return 0;
 267 }
 268
 269 static int hypfs_fill_super(struct super_block *sb, void *data, int silent)
 270 {
 271         struct inode *root_inode;
 272         struct dentry *root_dentry;
 273         int rc = 0;
 274         struct hypfs_sb_info *sbi;
 275
 276         sbi = kzalloc(sizeof(struct hypfs_sb_info), GFP_KERNEL);
 277         if (!sbi)
 278                 return -ENOMEM;
 279         mutex_init(&sbi->lock);
 280         sbi->uid = current_uid();
 281         sbi->gid = current_gid();
 282         sb->s_fs_info = sbi;
 283         sb->s_blocksize = PAGE_CACHE_SIZE;
 284         sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
 285         sb->s_magic = HYPFS_MAGIC;
 286         sb->s_op = &hypfs_s_ops;
 287         if (hypfs_parse_options(data, sb))
 288                 return -EINVAL;
 289         root_inode = hypfs_make_inode(sb, S_IFDIR | 0755);
 290         if (!root_inode)
 291                 return -ENOMEM;
 292         root_inode->i_op = &simple_dir_inode_operations;
 293         root_inode->i_fop = &simple_dir_operations;
 294         sb->s_root = root_dentry = d_make_root(root_inode);
 295         if (!root_dentry)
 296                 return -ENOMEM;
 297         if (MACHINE_IS_VM)
 298                 rc = hypfs_vm_create_files(sb, root_dentry);
 299         else
 300                 rc = hypfs_diag_create_files(sb, root_dentry);
 301         if (rc)
 302                 return rc;
 303         sbi->update_file = hypfs_create_update_file(sb, root_dentry);
 304         if (IS_ERR(sbi->update_file))
 305                 return PTR_ERR(sbi->update_file);
 306         hypfs_update_update(sb);
 307         pr_info("Hypervisor filesystem mounted\n");
 308         return 0;
 309 }
 310
 311 static struct dentry *hypfs_mount(struct file_system_type *fst, int flags,
 312                         const char *devname, void *data)
 313 {
 314         return mount_single(fst, flags, data, hypfs_fill_super);
 315 }
 316
 317 static void hypfs_kill_super(struct super_block *sb)
 318 {
 319         struct hypfs_sb_info *sb_info = sb->s_fs_info;
 320
 321         if (sb->s_root)
 322                 hypfs_delete_tree(sb->s_root);
 323         if (sb_info->update_file)
 324                 hypfs_remove(sb_info->update_file);
 325         kfree(sb->s_fs_info);
 326         sb->s_fs_info = NULL;
 327         kill_litter_super(sb);
 328 }
 329
 330 static struct dentry *hypfs_create_file(struct super_block *sb,
 331                                         struct dentry *parent, const char *name,
 332                                         char *data, umode_t mode)
 333 {
 334         struct dentry *dentry;
 335         struct inode *inode;
 336
 337         mutex_lock(&parent->d_inode->i_mutex);
 338         dentry = lookup_one_len(name, parent, strlen(name));
 339         if (IS_ERR(dentry)) {
 340                 dentry = ERR_PTR(-ENOMEM);
 341                 goto fail;
 342         }
 343         inode = hypfs_make_inode(sb, mode);
 344         if (!inode) {
 345                 dput(dentry);
 346                 dentry = ERR_PTR(-ENOMEM);
 347                 goto fail;
 348         }
 349         if (S_ISREG(mode)) {
 350                 inode->i_fop = &hypfs_file_ops;
 351                 if (data)
 352                         inode->i_size = strlen(data);
 353                 else
 354                         inode->i_size = 0;
 355         } else if (S_ISDIR(mode)) {
 356                 inode->i_op = &simple_dir_inode_operations;
 357                 inode->i_fop = &simple_dir_operations;
 358                 inc_nlink(parent->d_inode);
 359         } else
 360                 BUG();
 361         inode->i_private = data;
 362         d_instantiate(dentry, inode);
 363         dget(dentry);
 364 fail:
 365         mutex_unlock(&parent->d_inode->i_mutex);
 366         return dentry;
 367 }
 368
 369 struct dentry *hypfs_mkdir(struct super_block *sb, struct dentry *parent,
 370                            const char *name)
 371 {
 372         struct dentry *dentry;
 373
 374         dentry = hypfs_create_file(sb, parent, name, NULL, S_IFDIR | DIR_MODE);
 375         if (IS_ERR(dentry))
 376                 return dentry;
 377         hypfs_add_dentry(dentry);
 378         return dentry;
 379 }
 380
 381 static struct dentry *hypfs_create_update_file(struct super_block *sb,
 382                                                struct dentry *dir)
 383 {
 384         struct dentry *dentry;
 385
 386         dentry = hypfs_create_file(sb, 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 super_block *sb, 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(sb, 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 super_block *sb, 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(sb, 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           = do_sync_read,
 441         .write          = do_sync_write,
 442         .aio_read       = hypfs_aio_read,
 443         .aio_write      = hypfs_aio_write,
 444         .llseek         = no_llseek,
 445 };
 446
 447 static struct file_system_type hypfs_type = {
 448         .owner          = THIS_MODULE,
 449         .name           = "s390_hypfs",
 450         .mount          = hypfs_mount,
 451         .kill_sb        = hypfs_kill_super
 452 };
 453
 454 static const struct super_operations hypfs_s_ops = {
 455         .statfs         = simple_statfs,
 456         .evict_inode    = hypfs_evict_inode,
 457         .show_options   = hypfs_show_options,
 458 };
 459
 460 static struct kobject *s390_kobj;
 461
 462 static int __init hypfs_init(void)
 463 {
 464         int rc;
 465
 466         rc = hypfs_dbfs_init();
 467         if (rc)
 468                 return rc;
 469         if (hypfs_diag_init()) {
 470                 rc = -ENODATA;
 471                 goto fail_dbfs_exit;
 472         }
 473         if (hypfs_vm_init()) {
 474                 rc = -ENODATA;
 475                 goto fail_hypfs_diag_exit;
 476         }
 477         s390_kobj = kobject_create_and_add("s390", hypervisor_kobj);
 478         if (!s390_kobj) {
 479                 rc = -ENOMEM;
 480                 goto fail_hypfs_vm_exit;
 481         }
 482         rc = register_filesystem(&hypfs_type);
 483         if (rc)
 484                 goto fail_filesystem;
 485         return 0;
 486
 487 fail_filesystem:
 488         kobject_put(s390_kobj);
 489 fail_hypfs_vm_exit:
 490         hypfs_vm_exit();
 491 fail_hypfs_diag_exit:
 492         hypfs_diag_exit();
 493 fail_dbfs_exit:
 494         hypfs_dbfs_exit();
 495         pr_err("Initialization of hypfs failed with rc=%i\n", rc);
 496         return rc;
 497 }
 498
 499 static void __exit hypfs_exit(void)
 500 {
 501         hypfs_diag_exit();
 502         hypfs_vm_exit();
 503         hypfs_dbfs_exit();
 504         unregister_filesystem(&hypfs_type);
 505         kobject_put(s390_kobj);
 506 }
 507
 508 module_init(hypfs_init)
 509 module_exit(hypfs_exit)
 510
 511 MODULE_LICENSE("GPL");
 512 MODULE_AUTHOR("Michael Holzheu <holzheu@de.ibm.com>");
 513 MODULE_DESCRIPTION("s390 Hypervisor Filesystem");