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 <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_blocks = 0;
  95                 ret->i_atime = ret->i_mtime = ret->i_ctime = CURRENT_TIME;
  96                 if (mode & S_IFDIR)
  97                         ret->i_nlink = 2;
  98                 else
  99                         ret->i_nlink = 1;
 100         }
 101         return ret;
 102 }
 103
 104 static void hypfs_drop_inode(struct inode *inode)
 105 {
 106         kfree(inode->i_private);
 107         generic_delete_inode(inode);
 108 }
 109
 110 static int hypfs_open(struct inode *inode, struct file *filp)
 111 {
 112         char *data = filp->f_dentry->d_inode->i_private;
 113         struct hypfs_sb_info *fs_info;
 114
 115         if (filp->f_mode & FMODE_WRITE) {
 116                 if (!(inode->i_mode & S_IWUGO))
 117                         return -EACCES;
 118         }
 119         if (filp->f_mode & FMODE_READ) {
 120                 if (!(inode->i_mode & S_IRUGO))
 121                         return -EACCES;
 122         }
 123
 124         fs_info = inode->i_sb->s_fs_info;
 125         if(data) {
 126                 mutex_lock(&fs_info->lock);
 127                 filp->private_data = kstrdup(data, GFP_KERNEL);
 128                 if (!filp->private_data) {
 129                         mutex_unlock(&fs_info->lock);
 130                         return -ENOMEM;
 131                 }
 132                 mutex_unlock(&fs_info->lock);
 133         }
 134         return 0;
 135 }
 136
 137 static ssize_t hypfs_aio_read(struct kiocb *iocb, const struct iovec *iov,
 138                               unsigned long nr_segs, loff_t offset)
 139 {
 140         char *data;
 141         size_t len;
 142         struct file *filp = iocb->ki_filp;
 143         /* XXX: temporary */
 144         char __user *buf = iov[0].iov_base;
 145         size_t count = iov[0].iov_len;
 146
 147         if (nr_segs != 1) {
 148                 count = -EINVAL;
 149                 goto out;
 150         }
 151
 152         data = filp->private_data;
 153         len = strlen(data);
 154         if (offset > len) {
 155                 count = 0;
 156                 goto out;
 157         }
 158         if (count > len - offset)
 159                 count = len - offset;
 160         if (copy_to_user(buf, data + offset, count)) {
 161                 count = -EFAULT;
 162                 goto out;
 163         }
 164         iocb->ki_pos += count;
 165         file_accessed(filp);
 166 out:
 167         return count;
 168 }
 169 static ssize_t hypfs_aio_write(struct kiocb *iocb, const struct iovec *iov,
 170                               unsigned long nr_segs, loff_t offset)
 171 {
 172         int rc;
 173         struct super_block *sb;
 174         struct hypfs_sb_info *fs_info;
 175         size_t count = iov_length(iov, nr_segs);
 176
 177         sb = iocb->ki_filp->f_dentry->d_inode->i_sb;
 178         fs_info = sb->s_fs_info;
 179         /*
 180          * Currently we only allow one update per second for two reasons:
 181          * 1. diag 204 is VERY expensive
 182          * 2. If several processes do updates in parallel and then read the
 183          *    hypfs data, the likelihood of collisions is reduced, if we restrict
 184          *    the minimum update interval. A collision occurs, if during the
 185          *    data gathering of one process another process triggers an update
 186          *    If the first process wants to ensure consistent data, it has
 187          *    to restart data collection in this case.
 188          */
 189         mutex_lock(&fs_info->lock);
 190         if (fs_info->last_update == get_seconds()) {
 191                 rc = -EBUSY;
 192                 goto out;
 193         }
 194         hypfs_delete_tree(sb->s_root);
 195         rc = hypfs_diag_create_files(sb, sb->s_root);
 196         if (rc) {
 197                 printk(KERN_ERR "hypfs: Update failed\n");
 198                 hypfs_delete_tree(sb->s_root);
 199                 goto out;
 200         }
 201         hypfs_update_update(sb);
 202         rc = count;
 203 out:
 204         mutex_unlock(&fs_info->lock);
 205         return rc;
 206 }
 207
 208 static int hypfs_release(struct inode *inode, struct file *filp)
 209 {
 210         kfree(filp->private_data);
 211         return 0;
 212 }
 213
 214 enum { opt_uid, opt_gid, opt_err };
 215
 216 static match_table_t hypfs_tokens = {
 217         {opt_uid, "uid=%u"},
 218         {opt_gid, "gid=%u"},
 219         {opt_err, NULL}
 220 };
 221
 222 static int hypfs_parse_options(char *options, struct super_block *sb)
 223 {
 224         char *str;
 225         substring_t args[MAX_OPT_ARGS];
 226
 227         if (!options)
 228                 return 0;
 229         while ((str = strsep(&options, ",")) != NULL) {
 230                 int token, option;
 231                 struct hypfs_sb_info *hypfs_info = sb->s_fs_info;
 232
 233                 if (!*str)
 234                         continue;
 235                 token = match_token(str, hypfs_tokens, args);
 236                 switch (token) {
 237                 case opt_uid:
 238                         if (match_int(&args[0], &option))
 239                                 return -EINVAL;
 240                         hypfs_info->uid = option;
 241                         break;
 242                 case opt_gid:
 243                         if (match_int(&args[0], &option))
 244                                 return -EINVAL;
 245                         hypfs_info->gid = option;
 246                         break;
 247                 case opt_err:
 248                 default:
 249                         printk(KERN_ERR "hypfs: Unrecognized mount option "
 250                                "\"%s\" or missing value\n", str);
 251                         return -EINVAL;
 252                 }
 253         }
 254         return 0;
 255 }
 256
 257 static int hypfs_fill_super(struct super_block *sb, void *data, int silent)
 258 {
 259         struct inode *root_inode;
 260         struct dentry *root_dentry;
 261         int rc = 0;
 262         struct hypfs_sb_info *sbi;
 263
 264         sbi = kzalloc(sizeof(struct hypfs_sb_info), GFP_KERNEL);
 265         if (!sbi)
 266                 return -ENOMEM;
 267         mutex_init(&sbi->lock);
 268         sbi->uid = current->uid;
 269         sbi->gid = current->gid;
 270         sb->s_fs_info = sbi;
 271         sb->s_blocksize = PAGE_CACHE_SIZE;
 272         sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
 273         sb->s_magic = HYPFS_MAGIC;
 274         sb->s_op = &hypfs_s_ops;
 275         if (hypfs_parse_options(data, sb)) {
 276                 rc = -EINVAL;
 277                 goto err_alloc;
 278         }
 279         root_inode = hypfs_make_inode(sb, S_IFDIR | 0755);
 280         if (!root_inode) {
 281                 rc = -ENOMEM;
 282                 goto err_alloc;
 283         }
 284         root_inode->i_op = &simple_dir_inode_operations;
 285         root_inode->i_fop = &simple_dir_operations;
 286         root_dentry = d_alloc_root(root_inode);
 287         if (!root_dentry) {
 288                 iput(root_inode);
 289                 rc = -ENOMEM;
 290                 goto err_alloc;
 291         }
 292         rc = hypfs_diag_create_files(sb, root_dentry);
 293         if (rc)
 294                 goto err_tree;
 295         sbi->update_file = hypfs_create_update_file(sb, root_dentry);
 296         if (IS_ERR(sbi->update_file)) {
 297                 rc = PTR_ERR(sbi->update_file);
 298                 goto err_tree;
 299         }
 300         hypfs_update_update(sb);
 301         sb->s_root = root_dentry;
 302         return 0;
 303
 304 err_tree:
 305         hypfs_delete_tree(root_dentry);
 306         d_genocide(root_dentry);
 307         dput(root_dentry);
 308 err_alloc:
 309         kfree(sbi);
 310         return rc;
 311 }
 312
 313 static int hypfs_get_super(struct file_system_type *fst, int flags,
 314                         const char *devname, void *data, struct vfsmount *mnt)
 315 {
 316         return get_sb_single(fst, flags, data, hypfs_fill_super, mnt);
 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                 hypfs_remove(sb_info->update_file);
 326                 kfree(sb->s_fs_info);
 327                 sb->s_fs_info = NULL;
 328         }
 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, mode_t mode)
 335 {
 336         struct dentry *dentry;
 337         struct inode *inode;
 338         struct qstr qname;
 339
 340         qname.name = name;
 341         qname.len = strlen(name);
 342         qname.hash = full_name_hash(name, qname.len);
 343         dentry = lookup_one_len(name, parent, strlen(name));
 344         if (IS_ERR(dentry))
 345                 return ERR_PTR(-ENOMEM);
 346         inode = hypfs_make_inode(sb, mode);
 347         if (!inode) {
 348                 dput(dentry);
 349                 return ERR_PTR(-ENOMEM);
 350         }
 351         if (mode & S_IFREG) {
 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 (mode & S_IFDIR) {
 358                 inode->i_op = &simple_dir_inode_operations;
 359                 inode->i_fop = &simple_dir_operations;
 360                 parent->d_inode->i_nlink++;
 361         } else
 362                 BUG();
 363         inode->i_private = data;
 364         d_instantiate(dentry, inode);
 365         dget(dentry);
 366         return dentry;
 367 }
 368
 369 struct dentry *hypfs_mkdir(struct super_block *sb, struct dentry *parent,
 370                            const char *name)
 371 {
 372         struct dentry *dentry;
 373
 374         dentry = hypfs_create_file(sb, parent, name, NULL, S_IFDIR | DIR_MODE);
 375         if (IS_ERR(dentry))
 376                 return dentry;
 377         hypfs_add_dentry(dentry);
 378         parent->d_inode->i_nlink++;
 379         return dentry;
 380 }
 381
 382 static struct dentry *hypfs_create_update_file(struct super_block *sb,
 383                                                struct dentry *dir)
 384 {
 385         struct dentry *dentry;
 386
 387         dentry = hypfs_create_file(sb, dir, "update", NULL,
 388                                    S_IFREG | UPDATE_FILE_MODE);
 389         /*
 390          * We do not put the update file on the 'delete' list with
 391          * hypfs_add_dentry(), since it should not be removed when the tree
 392          * is updated.
 393          */
 394         return dentry;
 395 }
 396
 397 struct dentry *hypfs_create_u64(struct super_block *sb, struct dentry *dir,
 398                                 const char *name, __u64 value)
 399 {
 400         char *buffer;
 401         char tmp[TMP_SIZE];
 402         struct dentry *dentry;
 403
 404         snprintf(tmp, TMP_SIZE, "%lld\n", (unsigned long long int)value);
 405         buffer = kstrdup(tmp, GFP_KERNEL);
 406         if (!buffer)
 407                 return ERR_PTR(-ENOMEM);
 408         dentry =
 409             hypfs_create_file(sb, dir, name, buffer, S_IFREG | REG_FILE_MODE);
 410         if (IS_ERR(dentry)) {
 411                 kfree(buffer);
 412                 return ERR_PTR(-ENOMEM);
 413         }
 414         hypfs_add_dentry(dentry);
 415         return dentry;
 416 }
 417
 418 struct dentry *hypfs_create_str(struct super_block *sb, struct dentry *dir,
 419                                 const char *name, char *string)
 420 {
 421         char *buffer;
 422         struct dentry *dentry;
 423
 424         buffer = kmalloc(strlen(string) + 2, GFP_KERNEL);
 425         if (!buffer)
 426                 return ERR_PTR(-ENOMEM);
 427         sprintf(buffer, "%s\n", string);
 428         dentry =
 429             hypfs_create_file(sb, dir, name, buffer, S_IFREG | REG_FILE_MODE);
 430         if (IS_ERR(dentry)) {
 431                 kfree(buffer);
 432                 return ERR_PTR(-ENOMEM);
 433         }
 434         hypfs_add_dentry(dentry);
 435         return dentry;
 436 }
 437
 438 static struct file_operations hypfs_file_ops = {
 439         .open           = hypfs_open,
 440         .release        = hypfs_release,
 441         .read           = do_sync_read,
 442         .write          = do_sync_write,
 443         .aio_read       = hypfs_aio_read,
 444         .aio_write      = hypfs_aio_write,
 445 };
 446
 447 static struct file_system_type hypfs_type = {
 448         .owner          = THIS_MODULE,
 449         .name           = "s390_hypfs",
 450         .get_sb         = hypfs_get_super,
 451         .kill_sb        = hypfs_kill_super
 452 };
 453
 454 static struct super_operations hypfs_s_ops = {
 455         .statfs         = simple_statfs,
 456         .drop_inode     = hypfs_drop_inode,
 457 };
 458
 459 static decl_subsys(s390, NULL, NULL);
 460
 461 static int __init hypfs_init(void)
 462 {
 463         int rc;
 464
 465         if (MACHINE_IS_VM)
 466                 return -ENODATA;
 467         if (hypfs_diag_init()) {
 468                 rc = -ENODATA;
 469                 goto fail_diag;
 470         }
 471         kset_set_kset_s(&s390_subsys, hypervisor_subsys);
 472         rc = subsystem_register(&s390_subsys);
 473         if (rc)
 474                 goto fail_sysfs;
 475         rc = register_filesystem(&hypfs_type);
 476         if (rc)
 477                 goto fail_filesystem;
 478         return 0;
 479
 480 fail_filesystem:
 481         subsystem_unregister(&s390_subsys);
 482 fail_sysfs:
 483         hypfs_diag_exit();
 484 fail_diag:
 485         printk(KERN_ERR "hypfs: Initialization failed with rc = %i.\n", rc);
 486         return rc;
 487 }
 488
 489 static void __exit hypfs_exit(void)
 490 {
 491         hypfs_diag_exit();
 492         unregister_filesystem(&hypfs_type);
 493         subsystem_unregister(&s390_subsys);
 494 }
 495
 496 module_init(hypfs_init)
 497 module_exit(hypfs_exit)
 498
 499 MODULE_LICENSE("GPL");
 500 MODULE_AUTHOR("Michael Holzheu <holzheu@de.ibm.com>");
 501 MODULE_DESCRIPTION("s390 Hypervisor Filesystem");