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/pagemap.h>
  18 #include <linux/gfp.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                 else
 113                         ret->i_nlink = 1;
 114         }
 115         return ret;
 116 }
 117
 118 static void hypfs_drop_inode(struct inode *inode)
 119 {
 120         kfree(inode->i_private);
 121         generic_delete_inode(inode);
 122 }
 123
 124 static int hypfs_open(struct inode *inode, struct file *filp)
 125 {
 126         char *data = filp->f_path.dentry->d_inode->i_private;
 127         struct hypfs_sb_info *fs_info;
 128
 129         if (filp->f_mode & FMODE_WRITE) {
 130                 if (!(inode->i_mode & S_IWUGO))
 131                         return -EACCES;
 132         }
 133         if (filp->f_mode & FMODE_READ) {
 134                 if (!(inode->i_mode & S_IRUGO))
 135                         return -EACCES;
 136         }
 137
 138         fs_info = inode->i_sb->s_fs_info;
 139         if(data) {
 140                 mutex_lock(&fs_info->lock);
 141                 filp->private_data = kstrdup(data, GFP_KERNEL);
 142                 if (!filp->private_data) {
 143                         mutex_unlock(&fs_info->lock);
 144                         return -ENOMEM;
 145                 }
 146                 mutex_unlock(&fs_info->lock);
 147         }
 148         return 0;
 149 }
 150
 151 static ssize_t hypfs_aio_read(struct kiocb *iocb, const struct iovec *iov,
 152                               unsigned long nr_segs, loff_t offset)
 153 {
 154         char *data;
 155         ssize_t ret;
 156         struct file *filp = iocb->ki_filp;
 157         /* XXX: temporary */
 158         char __user *buf = iov[0].iov_base;
 159         size_t count = iov[0].iov_len;
 160
 161         if (nr_segs != 1)
 162                 return -EINVAL;
 163
 164         data = filp->private_data;
 165         ret = simple_read_from_buffer(buf, count, &offset, data, strlen(data));
 166         if (ret <= 0)
 167                 return ret;
 168
 169         iocb->ki_pos += ret;
 170         file_accessed(filp);
 171
 172         return ret;
 173 }
 174 static ssize_t hypfs_aio_write(struct kiocb *iocb, const struct iovec *iov,
 175                               unsigned long nr_segs, loff_t offset)
 176 {
 177         int rc;
 178         struct super_block *sb;
 179         struct hypfs_sb_info *fs_info;
 180         size_t count = iov_length(iov, nr_segs);
 181
 182         sb = iocb->ki_filp->f_path.dentry->d_inode->i_sb;
 183         fs_info = sb->s_fs_info;
 184         /*
 185          * Currently we only allow one update per second for two reasons:
 186          * 1. diag 204 is VERY expensive
 187          * 2. If several processes do updates in parallel and then read the
 188          *    hypfs data, the likelihood of collisions is reduced, if we restrict
 189          *    the minimum update interval. A collision occurs, if during the
 190          *    data gathering of one process another process triggers an update
 191          *    If the first process wants to ensure consistent data, it has
 192          *    to restart data collection in this case.
 193          */
 194         mutex_lock(&fs_info->lock);
 195         if (fs_info->last_update == get_seconds()) {
 196                 rc = -EBUSY;
 197                 goto out;
 198         }
 199         hypfs_delete_tree(sb->s_root);
 200         if (MACHINE_IS_VM)
 201                 rc = hypfs_vm_create_files(sb, sb->s_root);
 202         else
 203                 rc = hypfs_diag_create_files(sb, sb->s_root);
 204         if (rc) {
 205                 pr_err("Updating the hypfs tree failed\n");
 206                 hypfs_delete_tree(sb->s_root);
 207                 goto out;
 208         }
 209         hypfs_update_update(sb);
 210         rc = count;
 211 out:
 212         mutex_unlock(&fs_info->lock);
 213         return rc;
 214 }
 215
 216 static int hypfs_release(struct inode *inode, struct file *filp)
 217 {
 218         kfree(filp->private_data);
 219         return 0;
 220 }
 221
 222 enum { opt_uid, opt_gid, opt_err };
 223
 224 static const match_table_t hypfs_tokens = {
 225         {opt_uid, "uid=%u"},
 226         {opt_gid, "gid=%u"},
 227         {opt_err, NULL}
 228 };
 229
 230 static int hypfs_parse_options(char *options, struct super_block *sb)
 231 {
 232         char *str;
 233         substring_t args[MAX_OPT_ARGS];
 234
 235         if (!options)
 236                 return 0;
 237         while ((str = strsep(&options, ",")) != NULL) {
 238                 int token, option;
 239                 struct hypfs_sb_info *hypfs_info = sb->s_fs_info;
 240
 241                 if (!*str)
 242                         continue;
 243                 token = match_token(str, hypfs_tokens, args);
 244                 switch (token) {
 245                 case opt_uid:
 246                         if (match_int(&args[0], &option))
 247                                 return -EINVAL;
 248                         hypfs_info->uid = option;
 249                         break;
 250                 case opt_gid:
 251                         if (match_int(&args[0], &option))
 252                                 return -EINVAL;
 253                         hypfs_info->gid = option;
 254                         break;
 255                 case opt_err:
 256                 default:
 257                         pr_err("%s is not a valid mount option\n", str);
 258                         return -EINVAL;
 259                 }
 260         }
 261         return 0;
 262 }
 263
 264 static int hypfs_show_options(struct seq_file *s, struct vfsmount *mnt)
 265 {
 266         struct hypfs_sb_info *hypfs_info = mnt->mnt_sb->s_fs_info;
 267
 268         seq_printf(s, ",uid=%u", hypfs_info->uid);
 269         seq_printf(s, ",gid=%u", hypfs_info->gid);
 270         return 0;
 271 }
 272
 273 static int hypfs_fill_super(struct super_block *sb, void *data, int silent)
 274 {
 275         struct inode *root_inode;
 276         struct dentry *root_dentry;
 277         int rc = 0;
 278         struct hypfs_sb_info *sbi;
 279
 280         sbi = kzalloc(sizeof(struct hypfs_sb_info), GFP_KERNEL);
 281         if (!sbi)
 282                 return -ENOMEM;
 283         mutex_init(&sbi->lock);
 284         sbi->uid = current_uid();
 285         sbi->gid = current_gid();
 286         sb->s_fs_info = sbi;
 287         sb->s_blocksize = PAGE_CACHE_SIZE;
 288         sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
 289         sb->s_magic = HYPFS_MAGIC;
 290         sb->s_op = &hypfs_s_ops;
 291         if (hypfs_parse_options(data, sb)) {
 292                 rc = -EINVAL;
 293                 goto err_alloc;
 294         }
 295         root_inode = hypfs_make_inode(sb, S_IFDIR | 0755);
 296         if (!root_inode) {
 297                 rc = -ENOMEM;
 298                 goto err_alloc;
 299         }
 300         root_inode->i_op = &simple_dir_inode_operations;
 301         root_inode->i_fop = &simple_dir_operations;
 302         root_dentry = d_alloc_root(root_inode);
 303         if (!root_dentry) {
 304                 iput(root_inode);
 305                 rc = -ENOMEM;
 306                 goto err_alloc;
 307         }
 308         if (MACHINE_IS_VM)
 309                 rc = hypfs_vm_create_files(sb, root_dentry);
 310         else
 311                 rc = hypfs_diag_create_files(sb, root_dentry);
 312         if (rc)
 313                 goto err_tree;
 314         sbi->update_file = hypfs_create_update_file(sb, root_dentry);
 315         if (IS_ERR(sbi->update_file)) {
 316                 rc = PTR_ERR(sbi->update_file);
 317                 goto err_tree;
 318         }
 319         hypfs_update_update(sb);
 320         sb->s_root = root_dentry;
 321         pr_info("Hypervisor filesystem mounted\n");
 322         return 0;
 323
 324 err_tree:
 325         hypfs_delete_tree(root_dentry);
 326         d_genocide(root_dentry);
 327         dput(root_dentry);
 328 err_alloc:
 329         kfree(sbi);
 330         return rc;
 331 }
 332
 333 static int hypfs_get_super(struct file_system_type *fst, int flags,
 334                         const char *devname, void *data, struct vfsmount *mnt)
 335 {
 336         return get_sb_single(fst, flags, data, hypfs_fill_super, mnt);
 337 }
 338
 339 static void hypfs_kill_super(struct super_block *sb)
 340 {
 341         struct hypfs_sb_info *sb_info = sb->s_fs_info;
 342
 343         if (sb->s_root) {
 344                 hypfs_delete_tree(sb->s_root);
 345                 hypfs_remove(sb_info->update_file);
 346                 kfree(sb->s_fs_info);
 347                 sb->s_fs_info = NULL;
 348         }
 349         kill_litter_super(sb);
 350 }
 351
 352 static struct dentry *hypfs_create_file(struct super_block *sb,
 353                                         struct dentry *parent, const char *name,
 354                                         char *data, mode_t mode)
 355 {
 356         struct dentry *dentry;
 357         struct inode *inode;
 358
 359         mutex_lock(&parent->d_inode->i_mutex);
 360         dentry = lookup_one_len(name, parent, strlen(name));
 361         if (IS_ERR(dentry)) {
 362                 dentry = ERR_PTR(-ENOMEM);
 363                 goto fail;
 364         }
 365         inode = hypfs_make_inode(sb, mode);
 366         if (!inode) {
 367                 dput(dentry);
 368                 dentry = ERR_PTR(-ENOMEM);
 369                 goto fail;
 370         }
 371         if (mode & S_IFREG) {
 372                 inode->i_fop = &hypfs_file_ops;
 373                 if (data)
 374                         inode->i_size = strlen(data);
 375                 else
 376                         inode->i_size = 0;
 377         } else if (mode & S_IFDIR) {
 378                 inode->i_op = &simple_dir_inode_operations;
 379                 inode->i_fop = &simple_dir_operations;
 380                 parent->d_inode->i_nlink++;
 381         } else
 382                 BUG();
 383         inode->i_private = data;
 384         d_instantiate(dentry, inode);
 385         dget(dentry);
 386 fail:
 387         mutex_unlock(&parent->d_inode->i_mutex);
 388         return dentry;
 389 }
 390
 391 struct dentry *hypfs_mkdir(struct super_block *sb, struct dentry *parent,
 392                            const char *name)
 393 {
 394         struct dentry *dentry;
 395
 396         dentry = hypfs_create_file(sb, parent, name, NULL, S_IFDIR | DIR_MODE);
 397         if (IS_ERR(dentry))
 398                 return dentry;
 399         hypfs_add_dentry(dentry);
 400         return dentry;
 401 }
 402
 403 static struct dentry *hypfs_create_update_file(struct super_block *sb,
 404                                                struct dentry *dir)
 405 {
 406         struct dentry *dentry;
 407
 408         dentry = hypfs_create_file(sb, dir, "update", NULL,
 409                                    S_IFREG | UPDATE_FILE_MODE);
 410         /*
 411          * We do not put the update file on the 'delete' list with
 412          * hypfs_add_dentry(), since it should not be removed when the tree
 413          * is updated.
 414          */
 415         return dentry;
 416 }
 417
 418 struct dentry *hypfs_create_u64(struct super_block *sb, struct dentry *dir,
 419                                 const char *name, __u64 value)
 420 {
 421         char *buffer;
 422         char tmp[TMP_SIZE];
 423         struct dentry *dentry;
 424
 425         snprintf(tmp, TMP_SIZE, "%llu\n", (unsigned long long int)value);
 426         buffer = kstrdup(tmp, GFP_KERNEL);
 427         if (!buffer)
 428                 return ERR_PTR(-ENOMEM);
 429         dentry =
 430             hypfs_create_file(sb, dir, name, buffer, S_IFREG | REG_FILE_MODE);
 431         if (IS_ERR(dentry)) {
 432                 kfree(buffer);
 433                 return ERR_PTR(-ENOMEM);
 434         }
 435         hypfs_add_dentry(dentry);
 436         return dentry;
 437 }
 438
 439 struct dentry *hypfs_create_str(struct super_block *sb, struct dentry *dir,
 440                                 const char *name, char *string)
 441 {
 442         char *buffer;
 443         struct dentry *dentry;
 444
 445         buffer = kmalloc(strlen(string) + 2, GFP_KERNEL);
 446         if (!buffer)
 447                 return ERR_PTR(-ENOMEM);
 448         sprintf(buffer, "%s\n", string);
 449         dentry =
 450             hypfs_create_file(sb, dir, name, buffer, S_IFREG | REG_FILE_MODE);
 451         if (IS_ERR(dentry)) {
 452                 kfree(buffer);
 453                 return ERR_PTR(-ENOMEM);
 454         }
 455         hypfs_add_dentry(dentry);
 456         return dentry;
 457 }
 458
 459 static const struct file_operations hypfs_file_ops = {
 460         .open           = hypfs_open,
 461         .release        = hypfs_release,
 462         .read           = do_sync_read,
 463         .write          = do_sync_write,
 464         .aio_read       = hypfs_aio_read,
 465         .aio_write      = hypfs_aio_write,
 466 };
 467
 468 static struct file_system_type hypfs_type = {
 469         .owner          = THIS_MODULE,
 470         .name           = "s390_hypfs",
 471         .get_sb         = hypfs_get_super,
 472         .kill_sb        = hypfs_kill_super
 473 };
 474
 475 static const struct super_operations hypfs_s_ops = {
 476         .statfs         = simple_statfs,
 477         .drop_inode     = hypfs_drop_inode,
 478         .show_options   = hypfs_show_options,
 479 };
 480
 481 static struct kobject *s390_kobj;
 482
 483 static int __init hypfs_init(void)
 484 {
 485         int rc;
 486
 487         if (MACHINE_IS_VM) {
 488                 if (hypfs_vm_init())
 489                         /* no diag 2fc, just exit */
 490                         return -ENODATA;
 491         } else {
 492                 if (hypfs_diag_init()) {
 493                         rc = -ENODATA;
 494                         goto fail_diag;
 495                 }
 496         }
 497         s390_kobj = kobject_create_and_add("s390", hypervisor_kobj);
 498         if (!s390_kobj) {
 499                 rc = -ENOMEM;
 500                 goto fail_sysfs;
 501         }
 502         rc = register_filesystem(&hypfs_type);
 503         if (rc)
 504                 goto fail_filesystem;
 505         return 0;
 506
 507 fail_filesystem:
 508         kobject_put(s390_kobj);
 509 fail_sysfs:
 510         if (!MACHINE_IS_VM)
 511                 hypfs_diag_exit();
 512 fail_diag:
 513         pr_err("Initialization of hypfs failed with rc=%i\n", rc);
 514         return rc;
 515 }
 516
 517 static void __exit hypfs_exit(void)
 518 {
 519         if (!MACHINE_IS_VM)
 520                 hypfs_diag_exit();
 521         unregister_filesystem(&hypfs_type);
 522         kobject_put(s390_kobj);
 523 }
 524
 525 module_init(hypfs_init)
 526 module_exit(hypfs_exit)
 527
 528 MODULE_LICENSE("GPL");
 529 MODULE_AUTHOR("Michael Holzheu <holzheu@de.ibm.com>");
 530 MODULE_DESCRIPTION("s390 Hypervisor Filesystem");