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 static void hypfs_update_update(struct super_block *sb)
  50 {
  51         struct hypfs_sb_info *sb_info = sb->s_fs_info;
  52         struct inode *inode = sb_info->update_file->d_inode;
  53
  54         sb_info->last_update = get_seconds();
  55         inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
  56 }
  57
  58 /* directory tree removal functions */
  59
  60 static void hypfs_add_dentry(struct dentry *dentry)
  61 {
  62         dentry->d_fsdata = hypfs_last_dentry;
  63         hypfs_last_dentry = dentry;
  64 }
  65
  66 static inline int hypfs_positive(struct dentry *dentry)
  67 {
  68         return dentry->d_inode && !d_unhashed(dentry);
  69 }
  70
  71 static void hypfs_remove(struct dentry *dentry)
  72 {
  73         struct dentry *parent;
  74
  75         parent = dentry->d_parent;
  76         if (!parent || !parent->d_inode)
  77                 return;
  78         mutex_lock(&parent->d_inode->i_mutex);
  79         if (hypfs_positive(dentry)) {
  80                 if (S_ISDIR(dentry->d_inode->i_mode))
  81                         simple_rmdir(parent->d_inode, dentry);
  82                 else
  83                         simple_unlink(parent->d_inode, dentry);
  84         }
  85         d_delete(dentry);
  86         dput(dentry);
  87         mutex_unlock(&parent->d_inode->i_mutex);
  88 }
  89
  90 static void hypfs_delete_tree(struct dentry *root)
  91 {
  92         while (hypfs_last_dentry) {
  93                 struct dentry *next_dentry;
  94                 next_dentry = hypfs_last_dentry->d_fsdata;
  95                 hypfs_remove(hypfs_last_dentry);
  96                 hypfs_last_dentry = next_dentry;
  97         }
  98 }
  99
 100 static struct inode *hypfs_make_inode(struct super_block *sb, umode_t mode)
 101 {
 102         struct inode *ret = new_inode(sb);
 103
 104         if (ret) {
 105                 struct hypfs_sb_info *hypfs_info = sb->s_fs_info;
 106                 ret->i_mode = mode;
 107                 ret->i_uid = hypfs_info->uid;
 108                 ret->i_gid = hypfs_info->gid;
 109                 ret->i_atime = ret->i_mtime = ret->i_ctime = CURRENT_TIME;
 110                 if (S_ISDIR(mode))
 111                         set_nlink(ret, 2);
 112         }
 113         return ret;
 114 }
 115
 116 static void hypfs_evict_inode(struct inode *inode)
 117 {
 118         end_writeback(inode);
 119         kfree(inode->i_private);
 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 nonseekable_open(inode, filp);
 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         ssize_t ret;
 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                 return -EINVAL;
 161
 162         data = filp->private_data;
 163         ret = simple_read_from_buffer(buf, count, &offset, data, strlen(data));
 164         if (ret <= 0)
 165                 return ret;
 166
 167         iocb->ki_pos += ret;
 168         file_accessed(filp);
 169
 170         return ret;
 171 }
 172 static ssize_t hypfs_aio_write(struct kiocb *iocb, const struct iovec *iov,
 173                               unsigned long nr_segs, loff_t offset)
 174 {
 175         int rc;
 176         struct super_block *sb;
 177         struct hypfs_sb_info *fs_info;
 178         size_t count = iov_length(iov, nr_segs);
 179
 180         sb = iocb->ki_filp->f_path.dentry->d_inode->i_sb;
 181         fs_info = sb->s_fs_info;
 182         /*
 183          * Currently we only allow one update per second for two reasons:
 184          * 1. diag 204 is VERY expensive
 185          * 2. If several processes do updates in parallel and then read the
 186          *    hypfs data, the likelihood of collisions is reduced, if we restrict
 187          *    the minimum update interval. A collision occurs, if during the
 188          *    data gathering of one process another process triggers an update
 189          *    If the first process wants to ensure consistent data, it has
 190          *    to restart data collection in this case.
 191          */
 192         mutex_lock(&fs_info->lock);
 193         if (fs_info->last_update == get_seconds()) {
 194                 rc = -EBUSY;
 195                 goto out;
 196         }
 197         hypfs_delete_tree(sb->s_root);
 198         if (MACHINE_IS_VM)
 199                 rc = hypfs_vm_create_files(sb, sb->s_root);
 200         else
 201                 rc = hypfs_diag_create_files(sb, sb->s_root);
 202         if (rc) {
 203                 pr_err("Updating the hypfs tree failed\n");
 204                 hypfs_delete_tree(sb->s_root);
 205                 goto out;
 206         }
 207         hypfs_update_update(sb);
 208         rc = count;
 209 out:
 210         mutex_unlock(&fs_info->lock);
 211         return rc;
 212 }
 213
 214 static int hypfs_release(struct inode *inode, struct file *filp)
 215 {
 216         kfree(filp->private_data);
 217         return 0;
 218 }
 219
 220 enum { opt_uid, opt_gid, opt_err };
 221
 222 static const match_table_t hypfs_tokens = {
 223         {opt_uid, "uid=%u"},
 224         {opt_gid, "gid=%u"},
 225         {opt_err, NULL}
 226 };
 227
 228 static int hypfs_parse_options(char *options, struct super_block *sb)
 229 {
 230         char *str;
 231         substring_t args[MAX_OPT_ARGS];
 232
 233         if (!options)
 234                 return 0;
 235         while ((str = strsep(&options, ",")) != NULL) {
 236                 int token, option;
 237                 struct hypfs_sb_info *hypfs_info = sb->s_fs_info;
 238
 239                 if (!*str)
 240                         continue;
 241                 token = match_token(str, hypfs_tokens, args);
 242                 switch (token) {
 243                 case opt_uid:
 244                         if (match_int(&args[0], &option))
 245                                 return -EINVAL;
 246                         hypfs_info->uid = option;
 247                         break;
 248                 case opt_gid:
 249                         if (match_int(&args[0], &option))
 250                                 return -EINVAL;
 251                         hypfs_info->gid = option;
 252                         break;
 253                 case opt_err:
 254                 default:
 255                         pr_err("%s is not a valid mount option\n", str);
 256                         return -EINVAL;
 257                 }
 258         }
 259         return 0;
 260 }
 261
 262 static int hypfs_show_options(struct seq_file *s, struct dentry *root)
 263 {
 264         struct hypfs_sb_info *hypfs_info = root->d_sb->s_fs_info;
 265
 266         seq_printf(s, ",uid=%u", hypfs_info->uid);
 267         seq_printf(s, ",gid=%u", hypfs_info->gid);
 268         return 0;
 269 }
 270
 271 static int hypfs_fill_super(struct super_block *sb, void *data, int silent)
 272 {
 273         struct inode *root_inode;
 274         struct dentry *root_dentry;
 275         int rc = 0;
 276         struct hypfs_sb_info *sbi;
 277
 278         sbi = kzalloc(sizeof(struct hypfs_sb_info), GFP_KERNEL);
 279         if (!sbi)
 280                 return -ENOMEM;
 281         mutex_init(&sbi->lock);
 282         sbi->uid = current_uid();
 283         sbi->gid = current_gid();
 284         sb->s_fs_info = sbi;
 285         sb->s_blocksize = PAGE_CACHE_SIZE;
 286         sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
 287         sb->s_magic = HYPFS_MAGIC;
 288         sb->s_op = &hypfs_s_ops;
 289         if (hypfs_parse_options(data, sb))
 290                 return -EINVAL;
 291         root_inode = hypfs_make_inode(sb, S_IFDIR | 0755);
 292         if (!root_inode)
 293                 return -ENOMEM;
 294         root_inode->i_op = &simple_dir_inode_operations;
 295         root_inode->i_fop = &simple_dir_operations;
 296         sb->s_root = root_dentry = d_make_root(root_inode);
 297         if (!root_dentry)
 298                 return -ENOMEM;
 299         if (MACHINE_IS_VM)
 300                 rc = hypfs_vm_create_files(sb, root_dentry);
 301         else
 302                 rc = hypfs_diag_create_files(sb, root_dentry);
 303         if (rc)
 304                 return rc;
 305         sbi->update_file = hypfs_create_update_file(sb, root_dentry);
 306         if (IS_ERR(sbi->update_file))
 307                 return PTR_ERR(sbi->update_file);
 308         hypfs_update_update(sb);
 309         pr_info("Hypervisor filesystem mounted\n");
 310         return 0;
 311 }
 312
 313 static struct dentry *hypfs_mount(struct file_system_type *fst, int flags,
 314                         const char *devname, void *data)
 315 {
 316         return mount_single(fst, flags, data, hypfs_fill_super);
 317 }
 318
 319 static void hypfs_kill_super(struct super_block *sb)
 320 {
 321         struct hypfs_sb_info *sb_info = sb->s_fs_info;
 322
 323         if (sb->s_root)
 324                 hypfs_delete_tree(sb->s_root);
 325         if (sb_info->update_file)
 326                 hypfs_remove(sb_info->update_file);
 327         kfree(sb->s_fs_info);
 328         sb->s_fs_info = NULL;
 329         kill_litter_super(sb);
 330 }
 331
 332 static struct dentry *hypfs_create_file(struct super_block *sb,
 333                                         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(&parent->d_inode->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(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(parent->d_inode);
 361         } else
 362                 BUG();
 363         inode->i_private = data;
 364         d_instantiate(dentry, inode);
 365         dget(dentry);
 366 fail:
 367         mutex_unlock(&parent->d_inode->i_mutex);
 368         return dentry;
 369 }
 370
 371 struct dentry *hypfs_mkdir(struct super_block *sb, struct dentry *parent,
 372                            const char *name)
 373 {
 374         struct dentry *dentry;
 375
 376         dentry = hypfs_create_file(sb, parent, name, NULL, S_IFDIR | DIR_MODE);
 377         if (IS_ERR(dentry))
 378                 return dentry;
 379         hypfs_add_dentry(dentry);
 380         return dentry;
 381 }
 382
 383 static struct dentry *hypfs_create_update_file(struct super_block *sb,
 384                                                struct dentry *dir)
 385 {
 386         struct dentry *dentry;
 387
 388         dentry = hypfs_create_file(sb, dir, "update", NULL,
 389                                    S_IFREG | UPDATE_FILE_MODE);
 390         /*
 391          * We do not put the update file on the 'delete' list with
 392          * hypfs_add_dentry(), since it should not be removed when the tree
 393          * is updated.
 394          */
 395         return dentry;
 396 }
 397
 398 struct dentry *hypfs_create_u64(struct super_block *sb, struct dentry *dir,
 399                                 const char *name, __u64 value)
 400 {
 401         char *buffer;
 402         char tmp[TMP_SIZE];
 403         struct dentry *dentry;
 404
 405         snprintf(tmp, TMP_SIZE, "%llu\n", (unsigned long long int)value);
 406         buffer = kstrdup(tmp, GFP_KERNEL);
 407         if (!buffer)
 408                 return ERR_PTR(-ENOMEM);
 409         dentry =
 410             hypfs_create_file(sb, dir, name, buffer, S_IFREG | REG_FILE_MODE);
 411         if (IS_ERR(dentry)) {
 412                 kfree(buffer);
 413                 return ERR_PTR(-ENOMEM);
 414         }
 415         hypfs_add_dentry(dentry);
 416         return dentry;
 417 }
 418
 419 struct dentry *hypfs_create_str(struct super_block *sb, struct dentry *dir,
 420                                 const char *name, char *string)
 421 {
 422         char *buffer;
 423         struct dentry *dentry;
 424
 425         buffer = kmalloc(strlen(string) + 2, GFP_KERNEL);
 426         if (!buffer)
 427                 return ERR_PTR(-ENOMEM);
 428         sprintf(buffer, "%s\n", string);
 429         dentry =
 430             hypfs_create_file(sb, dir, name, buffer, S_IFREG | REG_FILE_MODE);
 431         if (IS_ERR(dentry)) {
 432                 kfree(buffer);
 433                 return ERR_PTR(-ENOMEM);
 434         }
 435         hypfs_add_dentry(dentry);
 436         return dentry;
 437 }
 438
 439 static const struct file_operations hypfs_file_ops = {
 440         .open           = hypfs_open,
 441         .release        = hypfs_release,
 442         .read           = do_sync_read,
 443         .write          = do_sync_write,
 444         .aio_read       = hypfs_aio_read,
 445         .aio_write      = hypfs_aio_write,
 446         .llseek         = no_llseek,
 447 };
 448
 449 static struct file_system_type hypfs_type = {
 450         .owner          = THIS_MODULE,
 451         .name           = "s390_hypfs",
 452         .mount          = hypfs_mount,
 453         .kill_sb        = hypfs_kill_super
 454 };
 455
 456 static const struct super_operations hypfs_s_ops = {
 457         .statfs         = simple_statfs,
 458         .evict_inode    = hypfs_evict_inode,
 459         .show_options   = hypfs_show_options,
 460 };
 461
 462 static struct kobject *s390_kobj;
 463
 464 static int __init hypfs_init(void)
 465 {
 466         int rc;
 467
 468         rc = hypfs_dbfs_init();
 469         if (rc)
 470                 return rc;
 471         if (hypfs_diag_init()) {
 472                 rc = -ENODATA;
 473                 goto fail_dbfs_exit;
 474         }
 475         if (hypfs_vm_init()) {
 476                 rc = -ENODATA;
 477                 goto fail_hypfs_diag_exit;
 478         }
 479         s390_kobj = kobject_create_and_add("s390", hypervisor_kobj);
 480         if (!s390_kobj) {
 481                 rc = -ENOMEM;
 482                 goto fail_hypfs_vm_exit;
 483         }
 484         rc = register_filesystem(&hypfs_type);
 485         if (rc)
 486                 goto fail_filesystem;
 487         return 0;
 488
 489 fail_filesystem:
 490         kobject_put(s390_kobj);
 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         hypfs_diag_exit();
 504         hypfs_vm_exit();
 505         hypfs_dbfs_exit();
 506         unregister_filesystem(&hypfs_type);
 507         kobject_put(s390_kobj);
 508 }
 509
 510 module_init(hypfs_init)
 511 module_exit(hypfs_exit)
 512
 513 MODULE_LICENSE("GPL");
 514 MODULE_AUTHOR("Michael Holzheu <holzheu@de.ibm.com>");
 515 MODULE_DESCRIPTION("s390 Hypervisor Filesystem");