arch/s390/hypfs/inode.c

   1 /*
   2  *  arch/s390/hypfs/inode.c
   3  *    Hypervisor filesystem for Linux on s390.
   4  *
   5  *    Copyright (C) IBM Corp. 2006
   6  *    Author(s): Michael Holzheu <holzheu@de.ibm.com>
   7  */
   8
   9 #include <linux/types.h>
  10 #include <linux/errno.h>
  11 #include <linux/fs.h>
  12 #include <linux/namei.h>
  13 #include <linux/vfs.h>
  14 #include <linux/pagemap.h>
  15 #include <linux/gfp.h>
  16 #include <linux/time.h>
  17 #include <linux/parser.h>
  18 #include <linux/sysfs.h>
  19 #include <linux/module.h>
  20 #include <linux/seq_file.h>
  21 #include <linux/mount.h>
  22 #include <asm/ebcdic.h>
  23 #include "hypfs.h"
  24
  25 #define HYPFS_MAGIC 0x687970    /* ASCII 'hyp' */
  26 #define TMP_SIZE 64             /* size of temporary buffers */
  27
  28 static struct dentry *hypfs_create_update_file(struct super_block *sb,
  29                                                struct dentry *dir);
  30
  31 struct hypfs_sb_info {
  32         uid_t uid;                      /* uid used for files and dirs */
  33         gid_t gid;                      /* gid used for files and dirs */
  34         struct dentry *update_file;     /* file to trigger update */
  35         time_t last_update;             /* last update time in secs since 1970 */
  36         struct mutex lock;              /* lock to protect update process */
  37 };
  38
  39 static const struct file_operations hypfs_file_ops;
  40 static struct file_system_type hypfs_type;
  41 static struct super_operations hypfs_s_ops;
  42
  43 /* start of list of all dentries, which have to be deleted on update */
  44 static struct dentry *hypfs_last_dentry;
  45
  46 static void hypfs_update_update(struct super_block *sb)
  47 {
  48         struct hypfs_sb_info *sb_info = sb->s_fs_info;
  49         struct inode *inode = sb_info->update_file->d_inode;
  50
  51         sb_info->last_update = get_seconds();
  52         inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
  53 }
  54
  55 /* directory tree removal functions */
  56
  57 static void hypfs_add_dentry(struct dentry *dentry)
  58 {
  59         dentry->d_fsdata = hypfs_last_dentry;
  60         hypfs_last_dentry = dentry;
  61 }
  62
  63 static inline int hypfs_positive(struct dentry *dentry)
  64 {
  65         return dentry->d_inode && !d_unhashed(dentry);
  66 }
  67
  68 static void hypfs_remove(struct dentry *dentry)
  69 {
  70         struct dentry *parent;
  71
  72         parent = dentry->d_parent;
  73         if (!parent || !parent->d_inode)
  74                 return;
  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, int 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_mode = mode;
 104                 ret->i_uid = hypfs_info->uid;
 105                 ret->i_gid = hypfs_info->gid;
 106                 ret->i_blocks = 0;
 107                 ret->i_atime = ret->i_mtime = ret->i_ctime = CURRENT_TIME;
 108                 if (mode & S_IFDIR)
 109                         ret->i_nlink = 2;
 110                 else
 111                         ret->i_nlink = 1;
 112         }
 113         return ret;
 114 }
 115
 116 static void hypfs_drop_inode(struct inode *inode)
 117 {
 118         kfree(inode->i_private);
 119         generic_delete_inode(inode);
 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 0;
 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                 printk(KERN_ERR "hypfs: Update 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 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                         printk(KERN_ERR "hypfs: Unrecognized mount option "
 256                                "\"%s\" or missing value\n", str);
 257                         return -EINVAL;
 258                 }
 259         }
 260         return 0;
 261 }
 262
 263 static int hypfs_show_options(struct seq_file *s, struct vfsmount *mnt)
 264 {
 265         struct hypfs_sb_info *hypfs_info = mnt->mnt_sb->s_fs_info;
 266
 267         seq_printf(s, ",uid=%u", hypfs_info->uid);
 268         seq_printf(s, ",gid=%u", hypfs_info->gid);
 269         return 0;
 270 }
 271
 272 static int hypfs_fill_super(struct super_block *sb, void *data, int silent)
 273 {
 274         struct inode *root_inode;
 275         struct dentry *root_dentry;
 276         int rc = 0;
 277         struct hypfs_sb_info *sbi;
 278
 279         sbi = kzalloc(sizeof(struct hypfs_sb_info), GFP_KERNEL);
 280         if (!sbi)
 281                 return -ENOMEM;
 282         mutex_init(&sbi->lock);
 283         sbi->uid = current->uid;
 284         sbi->gid = current->gid;
 285         sb->s_fs_info = sbi;
 286         sb->s_blocksize = PAGE_CACHE_SIZE;
 287         sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
 288         sb->s_magic = HYPFS_MAGIC;
 289         sb->s_op = &hypfs_s_ops;
 290         if (hypfs_parse_options(data, sb)) {
 291                 rc = -EINVAL;
 292                 goto err_alloc;
 293         }
 294         root_inode = hypfs_make_inode(sb, S_IFDIR | 0755);
 295         if (!root_inode) {
 296                 rc = -ENOMEM;
 297                 goto err_alloc;
 298         }
 299         root_inode->i_op = &simple_dir_inode_operations;
 300         root_inode->i_fop = &simple_dir_operations;
 301         root_dentry = d_alloc_root(root_inode);
 302         if (!root_dentry) {
 303                 iput(root_inode);
 304                 rc = -ENOMEM;
 305                 goto err_alloc;
 306         }
 307         if (MACHINE_IS_VM)
 308                 rc = hypfs_vm_create_files(sb, root_dentry);
 309         else
 310                 rc = hypfs_diag_create_files(sb, root_dentry);
 311         if (rc)
 312                 goto err_tree;
 313         sbi->update_file = hypfs_create_update_file(sb, root_dentry);
 314         if (IS_ERR(sbi->update_file)) {
 315                 rc = PTR_ERR(sbi->update_file);
 316                 goto err_tree;
 317         }
 318         hypfs_update_update(sb);
 319         sb->s_root = root_dentry;
 320         printk(KERN_INFO "hypfs: Hypervisor filesystem mounted\n");
 321         return 0;
 322
 323 err_tree:
 324         hypfs_delete_tree(root_dentry);
 325         d_genocide(root_dentry);
 326         dput(root_dentry);
 327 err_alloc:
 328         kfree(sbi);
 329         return rc;
 330 }
 331
 332 static int hypfs_get_super(struct file_system_type *fst, int flags,
 333                         const char *devname, void *data, struct vfsmount *mnt)
 334 {
 335         return get_sb_single(fst, flags, data, hypfs_fill_super, mnt);
 336 }
 337
 338 static void hypfs_kill_super(struct super_block *sb)
 339 {
 340         struct hypfs_sb_info *sb_info = sb->s_fs_info;
 341
 342         if (sb->s_root) {
 343                 hypfs_delete_tree(sb->s_root);
 344                 hypfs_remove(sb_info->update_file);
 345                 kfree(sb->s_fs_info);
 346                 sb->s_fs_info = NULL;
 347         }
 348         kill_litter_super(sb);
 349 }
 350
 351 static struct dentry *hypfs_create_file(struct super_block *sb,
 352                                         struct dentry *parent, const char *name,
 353                                         char *data, mode_t mode)
 354 {
 355         struct dentry *dentry;
 356         struct inode *inode;
 357         struct qstr qname;
 358
 359         qname.name = name;
 360         qname.len = strlen(name);
 361         qname.hash = full_name_hash(name, qname.len);
 362         mutex_lock(&parent->d_inode->i_mutex);
 363         dentry = lookup_one_len(name, parent, strlen(name));
 364         if (IS_ERR(dentry)) {
 365                 dentry = ERR_PTR(-ENOMEM);
 366                 goto fail;
 367         }
 368         inode = hypfs_make_inode(sb, mode);
 369         if (!inode) {
 370                 dput(dentry);
 371                 dentry = ERR_PTR(-ENOMEM);
 372                 goto fail;
 373         }
 374         if (mode & S_IFREG) {
 375                 inode->i_fop = &hypfs_file_ops;
 376                 if (data)
 377                         inode->i_size = strlen(data);
 378                 else
 379                         inode->i_size = 0;
 380         } else if (mode & S_IFDIR) {
 381                 inode->i_op = &simple_dir_inode_operations;
 382                 inode->i_fop = &simple_dir_operations;
 383                 parent->d_inode->i_nlink++;
 384         } else
 385                 BUG();
 386         inode->i_private = data;
 387         d_instantiate(dentry, inode);
 388         dget(dentry);
 389 fail:
 390         mutex_unlock(&parent->d_inode->i_mutex);
 391         return dentry;
 392 }
 393
 394 struct dentry *hypfs_mkdir(struct super_block *sb, struct dentry *parent,
 395                            const char *name)
 396 {
 397         struct dentry *dentry;
 398
 399         dentry = hypfs_create_file(sb, parent, name, NULL, S_IFDIR | DIR_MODE);
 400         if (IS_ERR(dentry))
 401                 return dentry;
 402         hypfs_add_dentry(dentry);
 403         return dentry;
 404 }
 405
 406 static struct dentry *hypfs_create_update_file(struct super_block *sb,
 407                                                struct dentry *dir)
 408 {
 409         struct dentry *dentry;
 410
 411         dentry = hypfs_create_file(sb, dir, "update", NULL,
 412                                    S_IFREG | UPDATE_FILE_MODE);
 413         /*
 414          * We do not put the update file on the 'delete' list with
 415          * hypfs_add_dentry(), since it should not be removed when the tree
 416          * is updated.
 417          */
 418         return dentry;
 419 }
 420
 421 struct dentry *hypfs_create_u64(struct super_block *sb, struct dentry *dir,
 422                                 const char *name, __u64 value)
 423 {
 424         char *buffer;
 425         char tmp[TMP_SIZE];
 426         struct dentry *dentry;
 427
 428         snprintf(tmp, TMP_SIZE, "%lld\n", (unsigned long long int)value);
 429         buffer = kstrdup(tmp, GFP_KERNEL);
 430         if (!buffer)
 431                 return ERR_PTR(-ENOMEM);
 432         dentry =
 433             hypfs_create_file(sb, dir, name, buffer, S_IFREG | REG_FILE_MODE);
 434         if (IS_ERR(dentry)) {
 435                 kfree(buffer);
 436                 return ERR_PTR(-ENOMEM);
 437         }
 438         hypfs_add_dentry(dentry);
 439         return dentry;
 440 }
 441
 442 struct dentry *hypfs_create_str(struct super_block *sb, struct dentry *dir,
 443                                 const char *name, char *string)
 444 {
 445         char *buffer;
 446         struct dentry *dentry;
 447
 448         buffer = kmalloc(strlen(string) + 2, GFP_KERNEL);
 449         if (!buffer)
 450                 return ERR_PTR(-ENOMEM);
 451         sprintf(buffer, "%s\n", string);
 452         dentry =
 453             hypfs_create_file(sb, dir, name, buffer, S_IFREG | REG_FILE_MODE);
 454         if (IS_ERR(dentry)) {
 455                 kfree(buffer);
 456                 return ERR_PTR(-ENOMEM);
 457         }
 458         hypfs_add_dentry(dentry);
 459         return dentry;
 460 }
 461
 462 static const struct file_operations hypfs_file_ops = {
 463         .open           = hypfs_open,
 464         .release        = hypfs_release,
 465         .read           = do_sync_read,
 466         .write          = do_sync_write,
 467         .aio_read       = hypfs_aio_read,
 468         .aio_write      = hypfs_aio_write,
 469 };
 470
 471 static struct file_system_type hypfs_type = {
 472         .owner          = THIS_MODULE,
 473         .name           = "s390_hypfs",
 474         .get_sb         = hypfs_get_super,
 475         .kill_sb        = hypfs_kill_super
 476 };
 477
 478 static struct super_operations hypfs_s_ops = {
 479         .statfs         = simple_statfs,
 480         .drop_inode     = hypfs_drop_inode,
 481         .show_options   = hypfs_show_options,
 482 };
 483
 484 static struct kobject *s390_kobj;
 485
 486 static int __init hypfs_init(void)
 487 {
 488         int rc;
 489
 490         if (MACHINE_IS_VM) {
 491                 if (hypfs_vm_init())
 492                         /* no diag 2fc, just exit */
 493                         return -ENODATA;
 494         } else {
 495                 if (hypfs_diag_init()) {
 496                         rc = -ENODATA;
 497                         goto fail_diag;
 498                 }
 499         }
 500         s390_kobj = kobject_create_and_add("s390", hypervisor_kobj);
 501         if (!s390_kobj) {
 502                 rc = -ENOMEM;;
 503                 goto fail_sysfs;
 504         }
 505         rc = register_filesystem(&hypfs_type);
 506         if (rc)
 507                 goto fail_filesystem;
 508         return 0;
 509
 510 fail_filesystem:
 511         kobject_put(s390_kobj);
 512 fail_sysfs:
 513         if (!MACHINE_IS_VM)
 514                 hypfs_diag_exit();
 515 fail_diag:
 516         printk(KERN_ERR "hypfs: Initialization failed with rc = %i.\n", rc);
 517         return rc;
 518 }
 519
 520 static void __exit hypfs_exit(void)
 521 {
 522         if (!MACHINE_IS_VM)
 523                 hypfs_diag_exit();
 524         unregister_filesystem(&hypfs_type);
 525         kobject_put(s390_kobj);
 526 }
 527
 528 module_init(hypfs_init)
 529 module_exit(hypfs_exit)
 530
 531 MODULE_LICENSE("GPL");
 532 MODULE_AUTHOR("Michael Holzheu <holzheu@de.ibm.com>");
 533 MODULE_DESCRIPTION("s390 Hypervisor Filesystem");