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, int 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 (mode & S_IFDIR)
 111                         ret->i_nlink = 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 vfsmount *mnt)
 263 {
 264         struct hypfs_sb_info *hypfs_info = mnt->mnt_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_alloc_root(root_inode);
 297         if (!root_dentry) {
 298                 iput(root_inode);
 299                 return -ENOMEM;
 300         }
 301         if (MACHINE_IS_VM)
 302                 rc = hypfs_vm_create_files(sb, root_dentry);
 303         else
 304                 rc = hypfs_diag_create_files(sb, root_dentry);
 305         if (rc)
 306                 return rc;
 307         sbi->update_file = hypfs_create_update_file(sb, root_dentry);
 308         if (IS_ERR(sbi->update_file))
 309                 return PTR_ERR(sbi->update_file);
 310         hypfs_update_update(sb);
 311         pr_info("Hypervisor filesystem mounted\n");
 312         return 0;
 313 }
 314
 315 static struct dentry *hypfs_mount(struct file_system_type *fst, int flags,
 316                         const char *devname, void *data)
 317 {
 318         return mount_single(fst, flags, data, hypfs_fill_super);
 319 }
 320
 321 static void hypfs_kill_super(struct super_block *sb)
 322 {
 323         struct hypfs_sb_info *sb_info = sb->s_fs_info;
 324
 325         if (sb->s_root)
 326                 hypfs_delete_tree(sb->s_root);
 327         if (sb_info->update_file)
 328                 hypfs_remove(sb_info->update_file);
 329         kfree(sb->s_fs_info);
 330         sb->s_fs_info = NULL;
 331         kill_litter_super(sb);
 332 }
 333
 334 static struct dentry *hypfs_create_file(struct super_block *sb,
 335                                         struct dentry *parent, const char *name,
 336                                         char *data, mode_t mode)
 337 {
 338         struct dentry *dentry;
 339         struct inode *inode;
 340
 341         mutex_lock(&parent->d_inode->i_mutex);
 342         dentry = lookup_one_len(name, parent, strlen(name));
 343         if (IS_ERR(dentry)) {
 344                 dentry = ERR_PTR(-ENOMEM);
 345                 goto fail;
 346         }
 347         inode = hypfs_make_inode(sb, mode);
 348         if (!inode) {
 349                 dput(dentry);
 350                 dentry = ERR_PTR(-ENOMEM);
 351                 goto fail;
 352         }
 353         if (mode & S_IFREG) {
 354                 inode->i_fop = &hypfs_file_ops;
 355                 if (data)
 356                         inode->i_size = strlen(data);
 357                 else
 358                         inode->i_size = 0;
 359         } else if (mode & S_IFDIR) {
 360                 inode->i_op = &simple_dir_inode_operations;
 361                 inode->i_fop = &simple_dir_operations;
 362                 inc_nlink(parent->d_inode);
 363         } else
 364                 BUG();
 365         inode->i_private = data;
 366         d_instantiate(dentry, inode);
 367         dget(dentry);
 368 fail:
 369         mutex_unlock(&parent->d_inode->i_mutex);
 370         return dentry;
 371 }
 372
 373 struct dentry *hypfs_mkdir(struct super_block *sb, struct dentry *parent,
 374                            const char *name)
 375 {
 376         struct dentry *dentry;
 377
 378         dentry = hypfs_create_file(sb, parent, name, NULL, S_IFDIR | DIR_MODE);
 379         if (IS_ERR(dentry))
 380                 return dentry;
 381         hypfs_add_dentry(dentry);
 382         return dentry;
 383 }
 384
 385 static struct dentry *hypfs_create_update_file(struct super_block *sb,
 386                                                struct dentry *dir)
 387 {
 388         struct dentry *dentry;
 389
 390         dentry = hypfs_create_file(sb, dir, "update", NULL,
 391                                    S_IFREG | UPDATE_FILE_MODE);
 392         /*
 393          * We do not put the update file on the 'delete' list with
 394          * hypfs_add_dentry(), since it should not be removed when the tree
 395          * is updated.
 396          */
 397         return dentry;
 398 }
 399
 400 struct dentry *hypfs_create_u64(struct super_block *sb, struct dentry *dir,
 401                                 const char *name, __u64 value)
 402 {
 403         char *buffer;
 404         char tmp[TMP_SIZE];
 405         struct dentry *dentry;
 406
 407         snprintf(tmp, TMP_SIZE, "%llu\n", (unsigned long long int)value);
 408         buffer = kstrdup(tmp, GFP_KERNEL);
 409         if (!buffer)
 410                 return ERR_PTR(-ENOMEM);
 411         dentry =
 412             hypfs_create_file(sb, dir, name, buffer, S_IFREG | REG_FILE_MODE);
 413         if (IS_ERR(dentry)) {
 414                 kfree(buffer);
 415                 return ERR_PTR(-ENOMEM);
 416         }
 417         hypfs_add_dentry(dentry);
 418         return dentry;
 419 }
 420
 421 struct dentry *hypfs_create_str(struct super_block *sb, struct dentry *dir,
 422                                 const char *name, char *string)
 423 {
 424         char *buffer;
 425         struct dentry *dentry;
 426
 427         buffer = kmalloc(strlen(string) + 2, GFP_KERNEL);
 428         if (!buffer)
 429                 return ERR_PTR(-ENOMEM);
 430         sprintf(buffer, "%s\n", string);
 431         dentry =
 432             hypfs_create_file(sb, dir, name, buffer, S_IFREG | REG_FILE_MODE);
 433         if (IS_ERR(dentry)) {
 434                 kfree(buffer);
 435                 return ERR_PTR(-ENOMEM);
 436         }
 437         hypfs_add_dentry(dentry);
 438         return dentry;
 439 }
 440
 441 static const struct file_operations hypfs_file_ops = {
 442         .open           = hypfs_open,
 443         .release        = hypfs_release,
 444         .read           = do_sync_read,
 445         .write          = do_sync_write,
 446         .aio_read       = hypfs_aio_read,
 447         .aio_write      = hypfs_aio_write,
 448         .llseek         = no_llseek,
 449 };
 450
 451 static struct file_system_type hypfs_type = {
 452         .owner          = THIS_MODULE,
 453         .name           = "s390_hypfs",
 454         .mount          = hypfs_mount,
 455         .kill_sb        = hypfs_kill_super
 456 };
 457
 458 static const struct super_operations hypfs_s_ops = {
 459         .statfs         = simple_statfs,
 460         .evict_inode    = hypfs_evict_inode,
 461         .show_options   = hypfs_show_options,
 462 };
 463
 464 static struct kobject *s390_kobj;
 465
 466 static int __init hypfs_init(void)
 467 {
 468         int rc;
 469
 470         rc = hypfs_dbfs_init();
 471         if (rc)
 472                 return rc;
 473         if (hypfs_diag_init()) {
 474                 rc = -ENODATA;
 475                 goto fail_dbfs_exit;
 476         }
 477         if (hypfs_vm_init()) {
 478                 rc = -ENODATA;
 479                 goto fail_hypfs_diag_exit;
 480         }
 481         s390_kobj = kobject_create_and_add("s390", hypervisor_kobj);
 482         if (!s390_kobj) {
 483                 rc = -ENOMEM;
 484                 goto fail_hypfs_vm_exit;
 485         }
 486         rc = register_filesystem(&hypfs_type);
 487         if (rc)
 488                 goto fail_filesystem;
 489         return 0;
 490
 491 fail_filesystem:
 492         kobject_put(s390_kobj);
 493 fail_hypfs_vm_exit:
 494         hypfs_vm_exit();
 495 fail_hypfs_diag_exit:
 496         hypfs_diag_exit();
 497 fail_dbfs_exit:
 498         hypfs_dbfs_exit();
 499         pr_err("Initialization of hypfs failed with rc=%i\n", rc);
 500         return rc;
 501 }
 502
 503 static void __exit hypfs_exit(void)
 504 {
 505         hypfs_diag_exit();
 506         hypfs_vm_exit();
 507         hypfs_dbfs_exit();
 508         unregister_filesystem(&hypfs_type);
 509         kobject_put(s390_kobj);
 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");