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  *    License: GPL
   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/init.h>
  23 #include <linux/kobject.h>
  24 #include <linux/seq_file.h>
  25 #include <linux/mount.h>
  26 #include <linux/uio.h>
  27 #include <asm/ebcdic.h>
  28 #include "hypfs.h"
  29
  30 #define HYPFS_MAGIC 0x687970    /* ASCII 'hyp' */
  31 #define TMP_SIZE 64             /* size of temporary buffers */
  32
  33 static struct dentry *hypfs_create_update_file(struct dentry *dir);
  34
  35 struct hypfs_sb_info {
  36         kuid_t uid;                     /* uid used for files and dirs */
  37         kgid_t gid;                     /* gid used for files and dirs */
  38         struct dentry *update_file;     /* file to trigger update */
  39         time_t last_update;             /* last update time in secs since 1970 */
  40         struct mutex lock;              /* lock to protect update process */
  41 };
  42
  43 static const struct file_operations hypfs_file_ops;
  44 static struct file_system_type hypfs_type;
  45 static const struct super_operations hypfs_s_ops;
  46
  47 /* start of list of all dentries, which have to be deleted on update */
  48 static struct dentry *hypfs_last_dentry;
  49
  50 static void hypfs_update_update(struct super_block *sb)
  51 {
  52         struct hypfs_sb_info *sb_info = sb->s_fs_info;
  53         struct inode *inode = d_inode(sb_info->update_file);
  54
  55         sb_info->last_update = get_seconds();
  56         inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
  57 }
  58
  59 /* directory tree removal functions */
  60
  61 static void hypfs_add_dentry(struct dentry *dentry)
  62 {
  63         dentry->d_fsdata = hypfs_last_dentry;
  64         hypfs_last_dentry = dentry;
  65 }
  66
  67 static void hypfs_remove(struct dentry *dentry)
  68 {
  69         struct dentry *parent;
  70
  71         parent = dentry->d_parent;
  72         inode_lock(d_inode(parent));
  73         if (simple_positive(dentry)) {
  74                 if (d_is_dir(dentry))
  75                         simple_rmdir(d_inode(parent), dentry);
  76                 else
  77                         simple_unlink(d_inode(parent), dentry);
  78         }
  79         d_delete(dentry);
  80         dput(dentry);
  81         inode_unlock(d_inode(parent));
  82 }
  83
  84 static void hypfs_delete_tree(struct dentry *root)
  85 {
  86         while (hypfs_last_dentry) {
  87                 struct dentry *next_dentry;
  88                 next_dentry = hypfs_last_dentry->d_fsdata;
  89                 hypfs_remove(hypfs_last_dentry);
  90                 hypfs_last_dentry = next_dentry;
  91         }
  92 }
  93
  94 static struct inode *hypfs_make_inode(struct super_block *sb, umode_t mode)
  95 {
  96         struct inode *ret = new_inode(sb);
  97
  98         if (ret) {
  99                 struct hypfs_sb_info *hypfs_info = sb->s_fs_info;
 100                 ret->i_ino = get_next_ino();
 101                 ret->i_mode = mode;
 102                 ret->i_uid = hypfs_info->uid;
 103                 ret->i_gid = hypfs_info->gid;
 104                 ret->i_atime = ret->i_mtime = ret->i_ctime = current_time(ret);
 105                 if (S_ISDIR(mode))
 106                         set_nlink(ret, 2);
 107         }
 108         return ret;
 109 }
 110
 111 static void hypfs_evict_inode(struct inode *inode)
 112 {
 113         clear_inode(inode);
 114         kfree(inode->i_private);
 115 }
 116
 117 static int hypfs_open(struct inode *inode, struct file *filp)
 118 {
 119         char *data = file_inode(filp)->i_private;
 120         struct hypfs_sb_info *fs_info;
 121
 122         if (filp->f_mode & FMODE_WRITE) {
 123                 if (!(inode->i_mode & S_IWUGO))
 124                         return -EACCES;
 125         }
 126         if (filp->f_mode & FMODE_READ) {
 127                 if (!(inode->i_mode & S_IRUGO))
 128                         return -EACCES;
 129         }
 130
 131         fs_info = inode->i_sb->s_fs_info;
 132         if(data) {
 133                 mutex_lock(&fs_info->lock);
 134                 filp->private_data = kstrdup(data, GFP_KERNEL);
 135                 if (!filp->private_data) {
 136                         mutex_unlock(&fs_info->lock);
 137                         return -ENOMEM;
 138                 }
 139                 mutex_unlock(&fs_info->lock);
 140         }
 141         return nonseekable_open(inode, filp);
 142 }
 143
 144 static ssize_t hypfs_read_iter(struct kiocb *iocb, struct iov_iter *to)
 145 {
 146         struct file *file = iocb->ki_filp;
 147         char *data = file->private_data;
 148         size_t available = strlen(data);
 149         loff_t pos = iocb->ki_pos;
 150         size_t count;
 151
 152         if (pos < 0)
 153                 return -EINVAL;
 154         if (pos >= available || !iov_iter_count(to))
 155                 return 0;
 156         count = copy_to_iter(data + pos, available - pos, to);
 157         if (!count)
 158                 return -EFAULT;
 159         iocb->ki_pos = pos + count;
 160         file_accessed(file);
 161         return count;
 162 }
 163
 164 static ssize_t hypfs_write_iter(struct kiocb *iocb, struct iov_iter *from)
 165 {
 166         int rc;
 167         struct super_block *sb = file_inode(iocb->ki_filp)->i_sb;
 168         struct hypfs_sb_info *fs_info = sb->s_fs_info;
 169         size_t count = iov_iter_count(from);
 170
 171         /*
 172          * Currently we only allow one update per second for two reasons:
 173          * 1. diag 204 is VERY expensive
 174          * 2. If several processes do updates in parallel and then read the
 175          *    hypfs data, the likelihood of collisions is reduced, if we restrict
 176          *    the minimum update interval. A collision occurs, if during the
 177          *    data gathering of one process another process triggers an update
 178          *    If the first process wants to ensure consistent data, it has
 179          *    to restart data collection in this case.
 180          */
 181         mutex_lock(&fs_info->lock);
 182         if (fs_info->last_update == get_seconds()) {
 183                 rc = -EBUSY;
 184                 goto out;
 185         }
 186         hypfs_delete_tree(sb->s_root);
 187         if (MACHINE_IS_VM)
 188                 rc = hypfs_vm_create_files(sb->s_root);
 189         else
 190                 rc = hypfs_diag_create_files(sb->s_root);
 191         if (rc) {
 192                 pr_err("Updating the hypfs tree failed\n");
 193                 hypfs_delete_tree(sb->s_root);
 194                 goto out;
 195         }
 196         hypfs_update_update(sb);
 197         rc = count;
 198         iov_iter_advance(from, count);
 199 out:
 200         mutex_unlock(&fs_info->lock);
 201         return rc;
 202 }
 203
 204 static int hypfs_release(struct inode *inode, struct file *filp)
 205 {
 206         kfree(filp->private_data);
 207         return 0;
 208 }
 209
 210 enum { opt_uid, opt_gid, opt_err };
 211
 212 static const match_table_t hypfs_tokens = {
 213         {opt_uid, "uid=%u"},
 214         {opt_gid, "gid=%u"},
 215         {opt_err, NULL}
 216 };
 217
 218 static int hypfs_parse_options(char *options, struct super_block *sb)
 219 {
 220         char *str;
 221         substring_t args[MAX_OPT_ARGS];
 222         kuid_t uid;
 223         kgid_t gid;
 224
 225         if (!options)
 226                 return 0;
 227         while ((str = strsep(&options, ",")) != NULL) {
 228                 int token, option;
 229                 struct hypfs_sb_info *hypfs_info = sb->s_fs_info;
 230
 231                 if (!*str)
 232                         continue;
 233                 token = match_token(str, hypfs_tokens, args);
 234                 switch (token) {
 235                 case opt_uid:
 236                         if (match_int(&args[0], &option))
 237                                 return -EINVAL;
 238                         uid = make_kuid(current_user_ns(), option);
 239                         if (!uid_valid(uid))
 240                                 return -EINVAL;
 241                         hypfs_info->uid = uid;
 242                         break;
 243                 case opt_gid:
 244                         if (match_int(&args[0], &option))
 245                                 return -EINVAL;
 246                         gid = make_kgid(current_user_ns(), option);
 247                         if (!gid_valid(gid))
 248                                 return -EINVAL;
 249                         hypfs_info->gid = gid;
 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", from_kuid_munged(&init_user_ns, hypfs_info->uid));
 265         seq_printf(s, ",gid=%u", from_kgid_munged(&init_user_ns, 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, *update_file;
 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_SIZE;
 284         sb->s_blocksize_bits = PAGE_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(root_dentry);
 299         else
 300                 rc = hypfs_diag_create_files(root_dentry);
 301         if (rc)
 302                 return rc;
 303         update_file = hypfs_create_update_file(root_dentry);
 304         if (IS_ERR(update_file))
 305                 return PTR_ERR(update_file);
 306         sbi->update_file = update_file;
 307         hypfs_update_update(sb);
 308         pr_info("Hypervisor filesystem mounted\n");
 309         return 0;
 310 }
 311
 312 static struct dentry *hypfs_mount(struct file_system_type *fst, int flags,
 313                         const char *devname, void *data)
 314 {
 315         return mount_single(fst, flags, data, hypfs_fill_super);
 316 }
 317
 318 static void hypfs_kill_super(struct super_block *sb)
 319 {
 320         struct hypfs_sb_info *sb_info = sb->s_fs_info;
 321
 322         if (sb->s_root)
 323                 hypfs_delete_tree(sb->s_root);
 324         if (sb_info && sb_info->update_file)
 325                 hypfs_remove(sb_info->update_file);
 326         kfree(sb->s_fs_info);
 327         sb->s_fs_info = NULL;
 328         kill_litter_super(sb);
 329 }
 330
 331 static struct dentry *hypfs_create_file(struct dentry *parent, const char *name,
 332                                         char *data, umode_t mode)
 333 {
 334         struct dentry *dentry;
 335         struct inode *inode;
 336
 337         inode_lock(d_inode(parent));
 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(parent->d_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(d_inode(parent));
 359         } else
 360                 BUG();
 361         inode->i_private = data;
 362         d_instantiate(dentry, inode);
 363         dget(dentry);
 364 fail:
 365         inode_unlock(d_inode(parent));
 366         return dentry;
 367 }
 368
 369 struct dentry *hypfs_mkdir(struct dentry *parent, const char *name)
 370 {
 371         struct dentry *dentry;
 372
 373         dentry = hypfs_create_file(parent, name, NULL, S_IFDIR | DIR_MODE);
 374         if (IS_ERR(dentry))
 375                 return dentry;
 376         hypfs_add_dentry(dentry);
 377         return dentry;
 378 }
 379
 380 static struct dentry *hypfs_create_update_file(struct dentry *dir)
 381 {
 382         struct dentry *dentry;
 383
 384         dentry = hypfs_create_file(dir, "update", NULL,
 385                                    S_IFREG | UPDATE_FILE_MODE);
 386         /*
 387          * We do not put the update file on the 'delete' list with
 388          * hypfs_add_dentry(), since it should not be removed when the tree
 389          * is updated.
 390          */
 391         return dentry;
 392 }
 393
 394 struct dentry *hypfs_create_u64(struct dentry *dir,
 395                                 const char *name, __u64 value)
 396 {
 397         char *buffer;
 398         char tmp[TMP_SIZE];
 399         struct dentry *dentry;
 400
 401         snprintf(tmp, TMP_SIZE, "%llu\n", (unsigned long long int)value);
 402         buffer = kstrdup(tmp, GFP_KERNEL);
 403         if (!buffer)
 404                 return ERR_PTR(-ENOMEM);
 405         dentry =
 406             hypfs_create_file(dir, name, buffer, S_IFREG | REG_FILE_MODE);
 407         if (IS_ERR(dentry)) {
 408                 kfree(buffer);
 409                 return ERR_PTR(-ENOMEM);
 410         }
 411         hypfs_add_dentry(dentry);
 412         return dentry;
 413 }
 414
 415 struct dentry *hypfs_create_str(struct dentry *dir,
 416                                 const char *name, char *string)
 417 {
 418         char *buffer;
 419         struct dentry *dentry;
 420
 421         buffer = kmalloc(strlen(string) + 2, GFP_KERNEL);
 422         if (!buffer)
 423                 return ERR_PTR(-ENOMEM);
 424         sprintf(buffer, "%s\n", string);
 425         dentry =
 426             hypfs_create_file(dir, name, buffer, S_IFREG | REG_FILE_MODE);
 427         if (IS_ERR(dentry)) {
 428                 kfree(buffer);
 429                 return ERR_PTR(-ENOMEM);
 430         }
 431         hypfs_add_dentry(dentry);
 432         return dentry;
 433 }
 434
 435 static const struct file_operations hypfs_file_ops = {
 436         .open           = hypfs_open,
 437         .release        = hypfs_release,
 438         .read_iter      = hypfs_read_iter,
 439         .write_iter     = hypfs_write_iter,
 440         .llseek         = no_llseek,
 441 };
 442
 443 static struct file_system_type hypfs_type = {
 444         .owner          = THIS_MODULE,
 445         .name           = "s390_hypfs",
 446         .mount          = hypfs_mount,
 447         .kill_sb        = hypfs_kill_super
 448 };
 449
 450 static const struct super_operations hypfs_s_ops = {
 451         .statfs         = simple_statfs,
 452         .evict_inode    = hypfs_evict_inode,
 453         .show_options   = hypfs_show_options,
 454 };
 455
 456 static int __init hypfs_init(void)
 457 {
 458         int rc;
 459
 460         rc = hypfs_dbfs_init();
 461         if (rc)
 462                 return rc;
 463         if (hypfs_diag_init()) {
 464                 rc = -ENODATA;
 465                 goto fail_dbfs_exit;
 466         }
 467         if (hypfs_vm_init()) {
 468                 rc = -ENODATA;
 469                 goto fail_hypfs_diag_exit;
 470         }
 471         if (hypfs_sprp_init()) {
 472                 rc = -ENODATA;
 473                 goto fail_hypfs_vm_exit;
 474         }
 475         if (hypfs_diag0c_init()) {
 476                 rc = -ENODATA;
 477                 goto fail_hypfs_sprp_exit;
 478         }
 479         rc = sysfs_create_mount_point(hypervisor_kobj, "s390");
 480         if (rc)
 481                 goto fail_hypfs_diag0c_exit;
 482         rc = register_filesystem(&hypfs_type);
 483         if (rc)
 484                 goto fail_filesystem;
 485         return 0;
 486
 487 fail_filesystem:
 488         sysfs_remove_mount_point(hypervisor_kobj, "s390");
 489 fail_hypfs_diag0c_exit:
 490         hypfs_diag0c_exit();
 491 fail_hypfs_sprp_exit:
 492         hypfs_sprp_exit();
 493 fail_hypfs_vm_exit:
 494         hypfs_vm_exit();
 495 fail_hypfs_diag_exit:
 496         hypfs_diag_exit();
 497         pr_err("Initialization of hypfs failed with rc=%i\n", rc);
 498 fail_dbfs_exit:
 499         hypfs_dbfs_exit();
 500         return rc;
 501 }
 502 device_initcall(hypfs_init)