arch/s390/hypfs/inode.c

   1 /*
   2  *  arch/s390/hypfs/inode.c
   3  *    Hypervisor filesystem for Linux on s390.
   4  *
   5  *    Copyright IBM Corp. 2006, 2008
   6  *    Author(s): Michael Holzheu <holzheu@de.ibm.com>
   7  */
   8
   9 #define KMSG_COMPONENT "hypfs"
  10 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
  11
  12 #include <linux/types.h>
  13 #include <linux/errno.h>
  14 #include <linux/fs.h>
  15 #include <linux/namei.h>
  16 #include <linux/vfs.h>
  17 #include <linux/slab.h>
  18 #include <linux/pagemap.h>
  19 #include <linux/time.h>
  20 #include <linux/parser.h>
  21 #include <linux/sysfs.h>
  22 #include <linux/module.h>
  23 #include <linux/seq_file.h>
  24 #include <linux/mount.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 super_block *sb,
  32                                                struct dentry *dir);
  33
  34 struct hypfs_sb_info {
  35         uid_t uid;                      /* uid used for files and dirs */
  36         gid_t gid;                      /* gid used for files and dirs */
  37         struct dentry *update_file;     /* file to trigger update */
  38         time_t last_update;             /* last update time in secs since 1970 */
  39         struct mutex lock;              /* lock to protect update process */
  40 };
  41
  42 static const struct file_operations hypfs_file_ops;
  43 static struct file_system_type hypfs_type;
  44 static const struct super_operations hypfs_s_ops;
  45
  46 /* start of list of all dentries, which have to be deleted on update */
  47 static struct dentry *hypfs_last_dentry;
  48
  49 struct dentry *hypfs_dbfs_dir;
  50
  51 static void hypfs_update_update(struct super_block *sb)
  52 {
  53         struct hypfs_sb_info *sb_info = sb->s_fs_info;
  54         struct inode *inode = sb_info->update_file->d_inode;
  55
  56         sb_info->last_update = get_seconds();
  57         inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
  58 }
  59
  60 /* directory tree removal functions */
  61
  62 static void hypfs_add_dentry(struct dentry *dentry)
  63 {
  64         dentry->d_fsdata = hypfs_last_dentry;
  65         hypfs_last_dentry = dentry;
  66 }
  67
  68 static inline int hypfs_positive(struct dentry *dentry)
  69 {
  70         return dentry->d_inode && !d_unhashed(dentry);
  71 }
  72
  73 static void hypfs_remove(struct dentry *dentry)
  74 {
  75         struct dentry *parent;
  76
  77         parent = dentry->d_parent;
  78         if (!parent || !parent->d_inode)
  79                 return;
  80         mutex_lock(&parent->d_inode->i_mutex);
  81         if (hypfs_positive(dentry)) {
  82                 if (S_ISDIR(dentry->d_inode->i_mode))
  83                         simple_rmdir(parent->d_inode, dentry);
  84                 else
  85                         simple_unlink(parent->d_inode, dentry);
  86         }
  87         d_delete(dentry);
  88         dput(dentry);
  89         mutex_unlock(&parent->d_inode->i_mutex);
  90 }
  91
  92 static void hypfs_delete_tree(struct dentry *root)
  93 {
  94         while (hypfs_last_dentry) {
  95                 struct dentry *next_dentry;
  96                 next_dentry = hypfs_last_dentry->d_fsdata;
  97                 hypfs_remove(hypfs_last_dentry);
  98                 hypfs_last_dentry = next_dentry;
  99         }
 100 }
 101
 102 static struct inode *hypfs_make_inode(struct super_block *sb, int mode)
 103 {
 104         struct inode *ret = new_inode(sb);
 105
 106         if (ret) {
 107                 struct hypfs_sb_info *hypfs_info = sb->s_fs_info;
 108                 ret->i_mode = mode;
 109                 ret->i_uid = hypfs_info->uid;
 110                 ret->i_gid = hypfs_info->gid;
 111                 ret->i_atime = ret->i_mtime = ret->i_ctime = CURRENT_TIME;
 112                 if (mode & S_IFDIR)
 113                         ret->i_nlink = 2;
 114                 else
 115                         ret->i_nlink = 1;
 116         }
 117         return ret;
 118 }
 119
 120 static void hypfs_drop_inode(struct inode *inode)
 121 {
 122         kfree(inode->i_private);
 123         generic_delete_inode(inode);
 124 }
 125
 126 static int hypfs_open(struct inode *inode, struct file *filp)
 127 {
 128         char *data = filp->f_path.dentry->d_inode->i_private;
 129         struct hypfs_sb_info *fs_info;
 130
 131         if (filp->f_mode & FMODE_WRITE) {
 132                 if (!(inode->i_mode & S_IWUGO))
 133                         return -EACCES;
 134         }
 135         if (filp->f_mode & FMODE_READ) {
 136                 if (!(inode->i_mode & S_IRUGO))
 137                         return -EACCES;
 138         }
 139
 140         fs_info = inode->i_sb->s_fs_info;
 141         if(data) {
 142                 mutex_lock(&fs_info->lock);
 143                 filp->private_data = kstrdup(data, GFP_KERNEL);
 144                 if (!filp->private_data) {
 145                         mutex_unlock(&fs_info->lock);
 146                         return -ENOMEM;
 147                 }
 148                 mutex_unlock(&fs_info->lock);
 149         }
 150         return nonseekable_open(inode, filp);
 151 }
 152
 153 static ssize_t hypfs_aio_read(struct kiocb *iocb, const struct iovec *iov,
 154                               unsigned long nr_segs, loff_t offset)
 155 {
 156         char *data;
 157         ssize_t ret;
 158         struct file *filp = iocb->ki_filp;
 159         /* XXX: temporary */
 160         char __user *buf = iov[0].iov_base;
 161         size_t count = iov[0].iov_len;
 162
 163         if (nr_segs != 1)
 164                 return -EINVAL;
 165
 166         data = filp->private_data;
 167         ret = simple_read_from_buffer(buf, count, &offset, data, strlen(data));
 168         if (ret <= 0)
 169                 return ret;
 170
 171         iocb->ki_pos += ret;
 172         file_accessed(filp);
 173
 174         return ret;
 175 }
 176 static ssize_t hypfs_aio_write(struct kiocb *iocb, const struct iovec *iov,
 177                               unsigned long nr_segs, loff_t offset)
 178 {
 179         int rc;
 180         struct super_block *sb;
 181         struct hypfs_sb_info *fs_info;
 182         size_t count = iov_length(iov, nr_segs);
 183
 184         sb = iocb->ki_filp->f_path.dentry->d_inode->i_sb;
 185         fs_info = sb->s_fs_info;
 186         /*
 187          * Currently we only allow one update per second for two reasons:
 188          * 1. diag 204 is VERY expensive
 189          * 2. If several processes do updates in parallel and then read the
 190          *    hypfs data, the likelihood of collisions is reduced, if we restrict
 191          *    the minimum update interval. A collision occurs, if during the
 192          *    data gathering of one process another process triggers an update
 193          *    If the first process wants to ensure consistent data, it has
 194          *    to restart data collection in this case.
 195          */
 196         mutex_lock(&fs_info->lock);
 197         if (fs_info->last_update == get_seconds()) {
 198                 rc = -EBUSY;
 199                 goto out;
 200         }
 201         hypfs_delete_tree(sb->s_root);
 202         if (MACHINE_IS_VM)
 203                 rc = hypfs_vm_create_files(sb, sb->s_root);
 204         else
 205                 rc = hypfs_diag_create_files(sb, sb->s_root);
 206         if (rc) {
 207                 pr_err("Updating the hypfs tree failed\n");
 208                 hypfs_delete_tree(sb->s_root);
 209                 goto out;
 210         }
 211         hypfs_update_update(sb);
 212         rc = count;
 213 out:
 214         mutex_unlock(&fs_info->lock);
 215         return rc;
 216 }
 217
 218 static int hypfs_release(struct inode *inode, struct file *filp)
 219 {
 220         kfree(filp->private_data);
 221         return 0;
 222 }
 223
 224 enum { opt_uid, opt_gid, opt_err };
 225
 226 static const match_table_t hypfs_tokens = {
 227         {opt_uid, "uid=%u"},
 228         {opt_gid, "gid=%u"},
 229         {opt_err, NULL}
 230 };
 231
 232 static int hypfs_parse_options(char *options, struct super_block *sb)
 233 {
 234         char *str;
 235         substring_t args[MAX_OPT_ARGS];
 236
 237         if (!options)
 238                 return 0;
 239         while ((str = strsep(&options, ",")) != NULL) {
 240                 int token, option;
 241                 struct hypfs_sb_info *hypfs_info = sb->s_fs_info;
 242
 243                 if (!*str)
 244                         continue;
 245                 token = match_token(str, hypfs_tokens, args);
 246                 switch (token) {
 247                 case opt_uid:
 248                         if (match_int(&args[0], &option))
 249                                 return -EINVAL;
 250                         hypfs_info->uid = option;
 251                         break;
 252                 case opt_gid:
 253                         if (match_int(&args[0], &option))
 254                                 return -EINVAL;
 255                         hypfs_info->gid = option;
 256                         break;
 257                 case opt_err:
 258                 default:
 259                         pr_err("%s is not a valid mount option\n", str);
 260                         return -EINVAL;
 261                 }
 262         }
 263         return 0;
 264 }
 265
 266 static int hypfs_show_options(struct seq_file *s, struct vfsmount *mnt)
 267 {
 268         struct hypfs_sb_info *hypfs_info = mnt->mnt_sb->s_fs_info;
 269
 270         seq_printf(s, ",uid=%u", hypfs_info->uid);
 271         seq_printf(s, ",gid=%u", hypfs_info->gid);
 272         return 0;
 273 }
 274
 275 static int hypfs_fill_super(struct super_block *sb, void *data, int silent)
 276 {
 277         struct inode *root_inode;
 278         struct dentry *root_dentry;
 279         int rc = 0;
 280         struct hypfs_sb_info *sbi;
 281
 282         sbi = kzalloc(sizeof(struct hypfs_sb_info), GFP_KERNEL);
 283         if (!sbi)
 284                 return -ENOMEM;
 285         mutex_init(&sbi->lock);
 286         sbi->uid = current_uid();
 287         sbi->gid = current_gid();
 288         sb->s_fs_info = sbi;
 289         sb->s_blocksize = PAGE_CACHE_SIZE;
 290         sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
 291         sb->s_magic = HYPFS_MAGIC;
 292         sb->s_op = &hypfs_s_ops;
 293         if (hypfs_parse_options(data, sb))
 294                 return -EINVAL;
 295         root_inode = hypfs_make_inode(sb, S_IFDIR | 0755);
 296         if (!root_inode)
 297                 return -ENOMEM;
 298         root_inode->i_op = &simple_dir_inode_operations;
 299         root_inode->i_fop = &simple_dir_operations;
 300         sb->s_root = root_dentry = d_alloc_root(root_inode);
 301         if (!root_dentry) {
 302                 iput(root_inode);
 303                 return -ENOMEM;
 304         }
 305         if (MACHINE_IS_VM)
 306                 rc = hypfs_vm_create_files(sb, root_dentry);
 307         else
 308                 rc = hypfs_diag_create_files(sb, root_dentry);
 309         if (rc)
 310                 return rc;
 311         sbi->update_file = hypfs_create_update_file(sb, root_dentry);
 312         if (IS_ERR(sbi->update_file))
 313                 return PTR_ERR(sbi->update_file);
 314         hypfs_update_update(sb);
 315         pr_info("Hypervisor filesystem mounted\n");
 316         return 0;
 317 }
 318
 319 static int hypfs_get_super(struct file_system_type *fst, int flags,
 320                         const char *devname, void *data, struct vfsmount *mnt)
 321 {
 322         return get_sb_single(fst, flags, data, hypfs_fill_super, mnt);
 323 }
 324
 325 static void hypfs_kill_super(struct super_block *sb)
 326 {
 327         struct hypfs_sb_info *sb_info = sb->s_fs_info;
 328
 329         if (sb->s_root)
 330                 hypfs_delete_tree(sb->s_root);
 331         if (sb_info->update_file)
 332                 hypfs_remove(sb_info->update_file);
 333         kfree(sb->s_fs_info);
 334         sb->s_fs_info = NULL;
 335         kill_litter_super(sb);
 336 }
 337
 338 static struct dentry *hypfs_create_file(struct super_block *sb,
 339                                         struct dentry *parent, const char *name,
 340                                         char *data, mode_t mode)
 341 {
 342         struct dentry *dentry;
 343         struct inode *inode;
 344
 345         mutex_lock(&parent->d_inode->i_mutex);
 346         dentry = lookup_one_len(name, parent, strlen(name));
 347         if (IS_ERR(dentry)) {
 348                 dentry = ERR_PTR(-ENOMEM);
 349                 goto fail;
 350         }
 351         inode = hypfs_make_inode(sb, mode);
 352         if (!inode) {
 353                 dput(dentry);
 354                 dentry = ERR_PTR(-ENOMEM);
 355                 goto fail;
 356         }
 357         if (mode & S_IFREG) {
 358                 inode->i_fop = &hypfs_file_ops;
 359                 if (data)
 360                         inode->i_size = strlen(data);
 361                 else
 362                         inode->i_size = 0;
 363         } else if (mode & S_IFDIR) {
 364                 inode->i_op = &simple_dir_inode_operations;
 365                 inode->i_fop = &simple_dir_operations;
 366                 parent->d_inode->i_nlink++;
 367         } else
 368                 BUG();
 369         inode->i_private = data;
 370         d_instantiate(dentry, inode);
 371         dget(dentry);
 372 fail:
 373         mutex_unlock(&parent->d_inode->i_mutex);
 374         return dentry;
 375 }
 376
 377 struct dentry *hypfs_mkdir(struct super_block *sb, struct dentry *parent,
 378                            const char *name)
 379 {
 380         struct dentry *dentry;
 381
 382         dentry = hypfs_create_file(sb, parent, name, NULL, S_IFDIR | DIR_MODE);
 383         if (IS_ERR(dentry))
 384                 return dentry;
 385         hypfs_add_dentry(dentry);
 386         return dentry;
 387 }
 388
 389 static struct dentry *hypfs_create_update_file(struct super_block *sb,
 390                                                struct dentry *dir)
 391 {
 392         struct dentry *dentry;
 393
 394         dentry = hypfs_create_file(sb, dir, "update", NULL,
 395                                    S_IFREG | UPDATE_FILE_MODE);
 396         /*
 397          * We do not put the update file on the 'delete' list with
 398          * hypfs_add_dentry(), since it should not be removed when the tree
 399          * is updated.
 400          */
 401         return dentry;
 402 }
 403
 404 struct dentry *hypfs_create_u64(struct super_block *sb, struct dentry *dir,
 405                                 const char *name, __u64 value)
 406 {
 407         char *buffer;
 408         char tmp[TMP_SIZE];
 409         struct dentry *dentry;
 410
 411         snprintf(tmp, TMP_SIZE, "%llu\n", (unsigned long long int)value);
 412         buffer = kstrdup(tmp, GFP_KERNEL);
 413         if (!buffer)
 414                 return ERR_PTR(-ENOMEM);
 415         dentry =
 416             hypfs_create_file(sb, dir, name, buffer, S_IFREG | REG_FILE_MODE);
 417         if (IS_ERR(dentry)) {
 418                 kfree(buffer);
 419                 return ERR_PTR(-ENOMEM);
 420         }
 421         hypfs_add_dentry(dentry);
 422         return dentry;
 423 }
 424
 425 struct dentry *hypfs_create_str(struct super_block *sb, struct dentry *dir,
 426                                 const char *name, char *string)
 427 {
 428         char *buffer;
 429         struct dentry *dentry;
 430
 431         buffer = kmalloc(strlen(string) + 2, GFP_KERNEL);
 432         if (!buffer)
 433                 return ERR_PTR(-ENOMEM);
 434         sprintf(buffer, "%s\n", string);
 435         dentry =
 436             hypfs_create_file(sb, dir, name, buffer, S_IFREG | REG_FILE_MODE);
 437         if (IS_ERR(dentry)) {
 438                 kfree(buffer);
 439                 return ERR_PTR(-ENOMEM);
 440         }
 441         hypfs_add_dentry(dentry);
 442         return dentry;
 443 }
 444
 445 static const struct file_operations hypfs_file_ops = {
 446         .open           = hypfs_open,
 447         .release        = hypfs_release,
 448         .read           = do_sync_read,
 449         .write          = do_sync_write,
 450         .aio_read       = hypfs_aio_read,
 451         .aio_write      = hypfs_aio_write,
 452 };
 453
 454 static struct file_system_type hypfs_type = {
 455         .owner          = THIS_MODULE,
 456         .name           = "s390_hypfs",
 457         .get_sb         = hypfs_get_super,
 458         .kill_sb        = hypfs_kill_super
 459 };
 460
 461 static const struct super_operations hypfs_s_ops = {
 462         .statfs         = simple_statfs,
 463         .drop_inode     = hypfs_drop_inode,
 464         .show_options   = hypfs_show_options,
 465 };
 466
 467 static struct kobject *s390_kobj;
 468
 469 static int __init hypfs_init(void)
 470 {
 471         int rc;
 472
 473         hypfs_dbfs_dir = debugfs_create_dir("s390_hypfs", NULL);
 474         if (IS_ERR(hypfs_dbfs_dir))
 475                 return PTR_ERR(hypfs_dbfs_dir);
 476
 477         if (hypfs_diag_init()) {
 478                 rc = -ENODATA;
 479                 goto fail_debugfs_remove;
 480         }
 481         if (hypfs_vm_init()) {
 482                 rc = -ENODATA;
 483                 goto fail_hypfs_diag_exit;
 484         }
 485         s390_kobj = kobject_create_and_add("s390", hypervisor_kobj);
 486         if (!s390_kobj) {
 487                 rc = -ENOMEM;
 488                 goto fail_hypfs_vm_exit;
 489         }
 490         rc = register_filesystem(&hypfs_type);
 491         if (rc)
 492                 goto fail_filesystem;
 493         return 0;
 494
 495 fail_filesystem:
 496         kobject_put(s390_kobj);
 497 fail_hypfs_vm_exit:
 498         hypfs_vm_exit();
 499 fail_hypfs_diag_exit:
 500         hypfs_diag_exit();
 501 fail_debugfs_remove:
 502         debugfs_remove(hypfs_dbfs_dir);
 503
 504         pr_err("Initialization of hypfs failed with rc=%i\n", rc);
 505         return rc;
 506 }
 507
 508 static void __exit hypfs_exit(void)
 509 {
 510         hypfs_diag_exit();
 511         hypfs_vm_exit();
 512         debugfs_remove(hypfs_dbfs_dir);
 513         unregister_filesystem(&hypfs_type);
 514         kobject_put(s390_kobj);
 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");