arch/s390/hypfs/inode.c

   1 /*
   2  *  fs/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 <asm/ebcdic.h>
  21 #include "hypfs.h"
  22 #include "hypfs_diag.h"
  23
  24 #define HYPFS_MAGIC 0x687970    /* ASCII 'hyp' */
  25 #define TMP_SIZE 64             /* size of temporary buffers */
  26
  27 static struct dentry *hypfs_create_update_file(struct super_block *sb,
  28                                                struct dentry *dir);
  29
  30 struct hypfs_sb_info {
  31         uid_t uid;                      /* uid used for files and dirs */
  32         gid_t gid;                      /* gid used for files and dirs */
  33         struct dentry *update_file;     /* file to trigger update */
  34         time_t last_update;             /* last update time in secs since 1970 */
  35         struct mutex lock;              /* lock to protect update process */
  36 };
  37
  38 static struct file_operations hypfs_file_ops;
  39 static struct file_system_type hypfs_type;
  40 static struct super_operations hypfs_s_ops;
  41
  42 /* start of list of all dentries, which have to be deleted on update */
  43 static struct dentry *hypfs_last_dentry;
  44
  45 static void hypfs_update_update(struct super_block *sb)
  46 {
  47         struct hypfs_sb_info *sb_info = sb->s_fs_info;
  48         struct inode *inode = sb_info->update_file->d_inode;
  49
  50         sb_info->last_update = get_seconds();
  51         inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
  52 }
  53
  54 /* directory tree removal functions */
  55
  56 static void hypfs_add_dentry(struct dentry *dentry)
  57 {
  58         dentry->d_fsdata = hypfs_last_dentry;
  59         hypfs_last_dentry = dentry;
  60 }
  61
  62 static void hypfs_remove(struct dentry *dentry)
  63 {
  64         struct dentry *parent;
  65
  66         parent = dentry->d_parent;
  67         if (S_ISDIR(dentry->d_inode->i_mode))
  68                 simple_rmdir(parent->d_inode, dentry);
  69         else
  70                 simple_unlink(parent->d_inode, dentry);
  71         d_delete(dentry);
  72         dput(dentry);
  73 }
  74
  75 static void hypfs_delete_tree(struct dentry *root)
  76 {
  77         while (hypfs_last_dentry) {
  78                 struct dentry *next_dentry;
  79                 next_dentry = hypfs_last_dentry->d_fsdata;
  80                 hypfs_remove(hypfs_last_dentry);
  81                 hypfs_last_dentry = next_dentry;
  82         }
  83 }
  84
  85 static struct inode *hypfs_make_inode(struct super_block *sb, int mode)
  86 {
  87         struct inode *ret = new_inode(sb);
  88
  89         if (ret) {
  90                 struct hypfs_sb_info *hypfs_info = sb->s_fs_info;
  91                 ret->i_mode = mode;
  92                 ret->i_uid = hypfs_info->uid;
  93                 ret->i_gid = hypfs_info->gid;
  94                 ret->i_blksize = PAGE_CACHE_SIZE;
  95                 ret->i_blocks = 0;
  96                 ret->i_atime = ret->i_mtime = ret->i_ctime = CURRENT_TIME;
  97                 if (mode & S_IFDIR)
  98                         ret->i_nlink = 2;
  99                 else
 100                         ret->i_nlink = 1;
 101         }
 102         return ret;
 103 }
 104
 105 static void hypfs_drop_inode(struct inode *inode)
 106 {
 107         kfree(inode->u.generic_ip);
 108         generic_delete_inode(inode);
 109 }
 110
 111 static int hypfs_open(struct inode *inode, struct file *filp)
 112 {
 113         char *data = filp->f_dentry->d_inode->u.generic_ip;
 114         struct hypfs_sb_info *fs_info;
 115
 116         if (filp->f_mode & FMODE_WRITE) {
 117                 if (!(inode->i_mode & S_IWUGO))
 118                         return -EACCES;
 119         }
 120         if (filp->f_mode & FMODE_READ) {
 121                 if (!(inode->i_mode & S_IRUGO))
 122                         return -EACCES;
 123         }
 124
 125         fs_info = inode->i_sb->s_fs_info;
 126         if(data) {
 127                 mutex_lock(&fs_info->lock);
 128                 filp->private_data = kstrdup(data, GFP_KERNEL);
 129                 if (!filp->private_data) {
 130                         mutex_unlock(&fs_info->lock);
 131                         return -ENOMEM;
 132                 }
 133                 mutex_unlock(&fs_info->lock);
 134         }
 135         return 0;
 136 }
 137
 138 static ssize_t hypfs_aio_read(struct kiocb *iocb, __user char *buf,
 139                               size_t count, loff_t offset)
 140 {
 141         char *data;
 142         size_t len;
 143         struct file *filp = iocb->ki_filp;
 144
 145         data = filp->private_data;
 146         len = strlen(data);
 147         if (offset > len) {
 148                 count = 0;
 149                 goto out;
 150         }
 151         if (count > len - offset)
 152                 count = len - offset;
 153         if (copy_to_user(buf, data + offset, count)) {
 154                 count = -EFAULT;
 155                 goto out;
 156         }
 157         iocb->ki_pos += count;
 158         file_accessed(filp);
 159 out:
 160         return count;
 161 }
 162 static ssize_t hypfs_aio_write(struct kiocb *iocb, const char __user *buf,
 163                                size_t count, loff_t pos)
 164 {
 165         int rc;
 166         struct super_block *sb;
 167         struct hypfs_sb_info *fs_info;
 168
 169         sb = iocb->ki_filp->f_dentry->d_inode->i_sb;
 170         fs_info = sb->s_fs_info;
 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         rc = hypfs_diag_create_files(sb, sb->s_root);
 188         if (rc) {
 189                 printk(KERN_ERR "hypfs: Update failed\n");
 190                 hypfs_delete_tree(sb->s_root);
 191                 goto out;
 192         }
 193         hypfs_update_update(sb);
 194         rc = count;
 195 out:
 196         mutex_unlock(&fs_info->lock);
 197         return rc;
 198 }
 199
 200 static int hypfs_release(struct inode *inode, struct file *filp)
 201 {
 202         kfree(filp->private_data);
 203         return 0;
 204 }
 205
 206 enum { opt_uid, opt_gid, opt_err };
 207
 208 static match_table_t hypfs_tokens = {
 209         {opt_uid, "uid=%u"},
 210         {opt_gid, "gid=%u"},
 211         {opt_err, NULL}
 212 };
 213
 214 static int hypfs_parse_options(char *options, struct super_block *sb)
 215 {
 216         char *str;
 217         substring_t args[MAX_OPT_ARGS];
 218
 219         if (!options)
 220                 return 0;
 221         while ((str = strsep(&options, ",")) != NULL) {
 222                 int token, option;
 223                 struct hypfs_sb_info *hypfs_info = sb->s_fs_info;
 224
 225                 if (!*str)
 226                         continue;
 227                 token = match_token(str, hypfs_tokens, args);
 228                 switch (token) {
 229                 case opt_uid:
 230                         if (match_int(&args[0], &option))
 231                                 return -EINVAL;
 232                         hypfs_info->uid = option;
 233                         break;
 234                 case opt_gid:
 235                         if (match_int(&args[0], &option))
 236                                 return -EINVAL;
 237                         hypfs_info->gid = option;
 238                         break;
 239                 case opt_err:
 240                 default:
 241                         printk(KERN_ERR "hypfs: Unrecognized mount option "
 242                                "\"%s\" or missing value\n", str);
 243                         return -EINVAL;
 244                 }
 245         }
 246         return 0;
 247 }
 248
 249 static int hypfs_fill_super(struct super_block *sb, void *data, int silent)
 250 {
 251         struct inode *root_inode;
 252         struct dentry *root_dentry;
 253         int rc = 0;
 254         struct hypfs_sb_info *sbi;
 255
 256         sbi = kzalloc(sizeof(struct hypfs_sb_info), GFP_KERNEL);
 257         if (!sbi)
 258                 return -ENOMEM;
 259         mutex_init(&sbi->lock);
 260         sbi->uid = current->uid;
 261         sbi->gid = current->gid;
 262         sb->s_fs_info = sbi;
 263         sb->s_blocksize = PAGE_CACHE_SIZE;
 264         sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
 265         sb->s_magic = HYPFS_MAGIC;
 266         sb->s_op = &hypfs_s_ops;
 267         if (hypfs_parse_options(data, sb)) {
 268                 rc = -EINVAL;
 269                 goto err_alloc;
 270         }
 271         root_inode = hypfs_make_inode(sb, S_IFDIR | 0755);
 272         if (!root_inode) {
 273                 rc = -ENOMEM;
 274                 goto err_alloc;
 275         }
 276         root_inode->i_op = &simple_dir_inode_operations;
 277         root_inode->i_fop = &simple_dir_operations;
 278         root_dentry = d_alloc_root(root_inode);
 279         if (!root_dentry) {
 280                 iput(root_inode);
 281                 rc = -ENOMEM;
 282                 goto err_alloc;
 283         }
 284         rc = hypfs_diag_create_files(sb, root_dentry);
 285         if (rc)
 286                 goto err_tree;
 287         sbi->update_file = hypfs_create_update_file(sb, root_dentry);
 288         if (IS_ERR(sbi->update_file)) {
 289                 rc = PTR_ERR(sbi->update_file);
 290                 goto err_tree;
 291         }
 292         hypfs_update_update(sb);
 293         sb->s_root = root_dentry;
 294         return 0;
 295
 296 err_tree:
 297         hypfs_delete_tree(root_dentry);
 298         d_genocide(root_dentry);
 299         dput(root_dentry);
 300 err_alloc:
 301         kfree(sbi);
 302         return rc;
 303 }
 304
 305 static int hypfs_get_super(struct file_system_type *fst, int flags,
 306                         const char *devname, void *data, struct vfsmount *mnt)
 307 {
 308         return get_sb_single(fst, flags, data, hypfs_fill_super, mnt);
 309 }
 310
 311 static void hypfs_kill_super(struct super_block *sb)
 312 {
 313         struct hypfs_sb_info *sb_info = sb->s_fs_info;
 314
 315         hypfs_delete_tree(sb->s_root);
 316         hypfs_remove(sb_info->update_file);
 317         kfree(sb->s_fs_info);
 318         sb->s_fs_info = NULL;
 319         kill_litter_super(sb);
 320 }
 321
 322 static struct dentry *hypfs_create_file(struct super_block *sb,
 323                                         struct dentry *parent, const char *name,
 324                                         char *data, mode_t mode)
 325 {
 326         struct dentry *dentry;
 327         struct inode *inode;
 328         struct qstr qname;
 329
 330         qname.name = name;
 331         qname.len = strlen(name);
 332         qname.hash = full_name_hash(name, qname.len);
 333         dentry = lookup_one_len(name, parent, strlen(name));
 334         if (IS_ERR(dentry))
 335                 return ERR_PTR(-ENOMEM);
 336         inode = hypfs_make_inode(sb, mode);
 337         if (!inode) {
 338                 dput(dentry);
 339                 return ERR_PTR(-ENOMEM);
 340         }
 341         if (mode & S_IFREG) {
 342                 inode->i_fop = &hypfs_file_ops;
 343                 if (data)
 344                         inode->i_size = strlen(data);
 345                 else
 346                         inode->i_size = 0;
 347         } else if (mode & S_IFDIR) {
 348                 inode->i_op = &simple_dir_inode_operations;
 349                 inode->i_fop = &simple_dir_operations;
 350                 parent->d_inode->i_nlink++;
 351         } else
 352                 BUG();
 353         inode->u.generic_ip = data;
 354         d_instantiate(dentry, inode);
 355         dget(dentry);
 356         return dentry;
 357 }
 358
 359 struct dentry *hypfs_mkdir(struct super_block *sb, struct dentry *parent,
 360                            const char *name)
 361 {
 362         struct dentry *dentry;
 363
 364         dentry = hypfs_create_file(sb, parent, name, NULL, S_IFDIR | DIR_MODE);
 365         if (IS_ERR(dentry))
 366                 return dentry;
 367         hypfs_add_dentry(dentry);
 368         parent->d_inode->i_nlink++;
 369         return dentry;
 370 }
 371
 372 static struct dentry *hypfs_create_update_file(struct super_block *sb,
 373                                                struct dentry *dir)
 374 {
 375         struct dentry *dentry;
 376
 377         dentry = hypfs_create_file(sb, dir, "update", NULL,
 378                                    S_IFREG | UPDATE_FILE_MODE);
 379         /*
 380          * We do not put the update file on the 'delete' list with
 381          * hypfs_add_dentry(), since it should not be removed when the tree
 382          * is updated.
 383          */
 384         return dentry;
 385 }
 386
 387 struct dentry *hypfs_create_u64(struct super_block *sb, struct dentry *dir,
 388                                 const char *name, __u64 value)
 389 {
 390         char *buffer;
 391         char tmp[TMP_SIZE];
 392         struct dentry *dentry;
 393
 394         snprintf(tmp, TMP_SIZE, "%lld\n", (unsigned long long int)value);
 395         buffer = kstrdup(tmp, GFP_KERNEL);
 396         if (!buffer)
 397                 return ERR_PTR(-ENOMEM);
 398         dentry =
 399             hypfs_create_file(sb, dir, name, buffer, S_IFREG | REG_FILE_MODE);
 400         if (IS_ERR(dentry)) {
 401                 kfree(buffer);
 402                 return ERR_PTR(-ENOMEM);
 403         }
 404         hypfs_add_dentry(dentry);
 405         return dentry;
 406 }
 407
 408 struct dentry *hypfs_create_str(struct super_block *sb, struct dentry *dir,
 409                                 const char *name, char *string)
 410 {
 411         char *buffer;
 412         struct dentry *dentry;
 413
 414         buffer = kmalloc(strlen(string) + 2, GFP_KERNEL);
 415         if (!buffer)
 416                 return ERR_PTR(-ENOMEM);
 417         sprintf(buffer, "%s\n", string);
 418         dentry =
 419             hypfs_create_file(sb, dir, name, buffer, S_IFREG | REG_FILE_MODE);
 420         if (IS_ERR(dentry)) {
 421                 kfree(buffer);
 422                 return ERR_PTR(-ENOMEM);
 423         }
 424         hypfs_add_dentry(dentry);
 425         return dentry;
 426 }
 427
 428 static struct file_operations hypfs_file_ops = {
 429         .open           = hypfs_open,
 430         .release        = hypfs_release,
 431         .read           = do_sync_read,
 432         .write          = do_sync_write,
 433         .aio_read       = hypfs_aio_read,
 434         .aio_write      = hypfs_aio_write,
 435 };
 436
 437 static struct file_system_type hypfs_type = {
 438         .owner          = THIS_MODULE,
 439         .name           = "s390_hypfs",
 440         .get_sb         = hypfs_get_super,
 441         .kill_sb        = hypfs_kill_super
 442 };
 443
 444 static struct super_operations hypfs_s_ops = {
 445         .statfs         = simple_statfs,
 446         .drop_inode     = hypfs_drop_inode,
 447 };
 448
 449 static decl_subsys(s390, NULL, NULL);
 450
 451 static int __init hypfs_init(void)
 452 {
 453         int rc;
 454
 455         if (MACHINE_IS_VM)
 456                 return -ENODATA;
 457         if (hypfs_diag_init()) {
 458                 rc = -ENODATA;
 459                 goto fail_diag;
 460         }
 461         kset_set_kset_s(&s390_subsys, hypervisor_subsys);
 462         rc = subsystem_register(&s390_subsys);
 463         if (rc)
 464                 goto fail_sysfs;
 465         rc = register_filesystem(&hypfs_type);
 466         if (rc)
 467                 goto fail_filesystem;
 468         return 0;
 469
 470 fail_filesystem:
 471         subsystem_unregister(&s390_subsys);
 472 fail_sysfs:
 473         hypfs_diag_exit();
 474 fail_diag:
 475         printk(KERN_ERR "hypfs: Initialization failed with rc = %i.\n", rc);
 476         return rc;
 477 }
 478
 479 static void __exit hypfs_exit(void)
 480 {
 481         hypfs_diag_exit();
 482         unregister_filesystem(&hypfs_type);
 483         subsystem_unregister(&s390_subsys);
 484 }
 485
 486 module_init(hypfs_init)
 487 module_exit(hypfs_exit)
 488
 489 MODULE_LICENSE("GPL");
 490 MODULE_AUTHOR("Michael Holzheu <holzheu@de.ibm.com>");
 491 MODULE_DESCRIPTION("s390 Hypervisor Filesystem");