linux/arch/s390/hypfs/inode.c
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   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/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/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
  31static struct dentry *hypfs_create_update_file(struct super_block *sb,
  32                                               struct dentry *dir);
  33
  34struct 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
  42static const struct file_operations hypfs_file_ops;
  43static struct file_system_type hypfs_type;
  44static const struct super_operations hypfs_s_ops;
  45
  46/* start of list of all dentries, which have to be deleted on update */
  47static struct dentry *hypfs_last_dentry;
  48
  49static 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
  60static void hypfs_add_dentry(struct dentry *dentry)
  61{
  62        dentry->d_fsdata = hypfs_last_dentry;
  63        hypfs_last_dentry = dentry;
  64}
  65
  66static inline int hypfs_positive(struct dentry *dentry)
  67{
  68        return dentry->d_inode && !d_unhashed(dentry);
  69}
  70
  71static 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
  90static 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
 100static struct inode *hypfs_make_inode(struct super_block *sb, umode_t 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 (S_ISDIR(mode))
 111                        set_nlink(ret, 2);
 112        }
 113        return ret;
 114}
 115
 116static void hypfs_evict_inode(struct inode *inode)
 117{
 118        end_writeback(inode);
 119        kfree(inode->i_private);
 120}
 121
 122static 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 nonseekable_open(inode, filp);
 147}
 148
 149static 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}
 172static 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                pr_err("Updating the hypfs tree failed\n");
 204                hypfs_delete_tree(sb->s_root);
 205                goto out;
 206        }
 207        hypfs_update_update(sb);
 208        rc = count;
 209out:
 210        mutex_unlock(&fs_info->lock);
 211        return rc;
 212}
 213
 214static int hypfs_release(struct inode *inode, struct file *filp)
 215{
 216        kfree(filp->private_data);
 217        return 0;
 218}
 219
 220enum { opt_uid, opt_gid, opt_err };
 221
 222static const match_table_t hypfs_tokens = {
 223        {opt_uid, "uid=%u"},
 224        {opt_gid, "gid=%u"},
 225        {opt_err, NULL}
 226};
 227
 228static 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                        pr_err("%s is not a valid mount option\n", str);
 256                        return -EINVAL;
 257                }
 258        }
 259        return 0;
 260}
 261
 262static int hypfs_show_options(struct seq_file *s, struct dentry *root)
 263{
 264        struct hypfs_sb_info *hypfs_info = root->d_sb->s_fs_info;
 265
 266        seq_printf(s, ",uid=%u", hypfs_info->uid);
 267        seq_printf(s, ",gid=%u", hypfs_info->gid);
 268        return 0;
 269}
 270
 271static int hypfs_fill_super(struct super_block *sb, void *data, int silent)
 272{
 273        struct inode *root_inode;
 274        struct dentry *root_dentry;
 275        int rc = 0;
 276        struct hypfs_sb_info *sbi;
 277
 278        sbi = kzalloc(sizeof(struct hypfs_sb_info), GFP_KERNEL);
 279        if (!sbi)
 280                return -ENOMEM;
 281        mutex_init(&sbi->lock);
 282        sbi->uid = current_uid();
 283        sbi->gid = current_gid();
 284        sb->s_fs_info = sbi;
 285        sb->s_blocksize = PAGE_CACHE_SIZE;
 286        sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
 287        sb->s_magic = HYPFS_MAGIC;
 288        sb->s_op = &hypfs_s_ops;
 289        if (hypfs_parse_options(data, sb))
 290                return -EINVAL;
 291        root_inode = hypfs_make_inode(sb, S_IFDIR | 0755);
 292        if (!root_inode)
 293                return -ENOMEM;
 294        root_inode->i_op = &simple_dir_inode_operations;
 295        root_inode->i_fop = &simple_dir_operations;
 296        sb->s_root = root_dentry = d_alloc_root(root_inode);
 297        if (!root_dentry) {
 298                iput(root_inode);
 299                return -ENOMEM;
 300        }
 301        if (MACHINE_IS_VM)
 302                rc = hypfs_vm_create_files(sb, root_dentry);
 303        else
 304                rc = hypfs_diag_create_files(sb, root_dentry);
 305        if (rc)
 306                return rc;
 307        sbi->update_file = hypfs_create_update_file(sb, root_dentry);
 308        if (IS_ERR(sbi->update_file))
 309                return PTR_ERR(sbi->update_file);
 310        hypfs_update_update(sb);
 311        pr_info("Hypervisor filesystem mounted\n");
 312        return 0;
 313}
 314
 315static struct dentry *hypfs_mount(struct file_system_type *fst, int flags,
 316                        const char *devname, void *data)
 317{
 318        return mount_single(fst, flags, data, hypfs_fill_super);
 319}
 320
 321static void hypfs_kill_super(struct super_block *sb)
 322{
 323        struct hypfs_sb_info *sb_info = sb->s_fs_info;
 324
 325        if (sb->s_root)
 326                hypfs_delete_tree(sb->s_root);
 327        if (sb_info->update_file)
 328                hypfs_remove(sb_info->update_file);
 329        kfree(sb->s_fs_info);
 330        sb->s_fs_info = NULL;
 331        kill_litter_super(sb);
 332}
 333
 334static struct dentry *hypfs_create_file(struct super_block *sb,
 335                                        struct dentry *parent, const char *name,
 336                                        char *data, umode_t mode)
 337{
 338        struct dentry *dentry;
 339        struct inode *inode;
 340
 341        mutex_lock(&parent->d_inode->i_mutex);
 342        dentry = lookup_one_len(name, parent, strlen(name));
 343        if (IS_ERR(dentry)) {
 344                dentry = ERR_PTR(-ENOMEM);
 345                goto fail;
 346        }
 347        inode = hypfs_make_inode(sb, mode);
 348        if (!inode) {
 349                dput(dentry);
 350                dentry = ERR_PTR(-ENOMEM);
 351                goto fail;
 352        }
 353        if (S_ISREG(mode)) {
 354                inode->i_fop = &hypfs_file_ops;
 355                if (data)
 356                        inode->i_size = strlen(data);
 357                else
 358                        inode->i_size = 0;
 359        } else if (S_ISDIR(mode)) {
 360                inode->i_op = &simple_dir_inode_operations;
 361                inode->i_fop = &simple_dir_operations;
 362                inc_nlink(parent->d_inode);
 363        } else
 364                BUG();
 365        inode->i_private = data;
 366        d_instantiate(dentry, inode);
 367        dget(dentry);
 368fail:
 369        mutex_unlock(&parent->d_inode->i_mutex);
 370        return dentry;
 371}
 372
 373struct dentry *hypfs_mkdir(struct super_block *sb, struct dentry *parent,
 374                           const char *name)
 375{
 376        struct dentry *dentry;
 377
 378        dentry = hypfs_create_file(sb, parent, name, NULL, S_IFDIR | DIR_MODE);
 379        if (IS_ERR(dentry))
 380                return dentry;
 381        hypfs_add_dentry(dentry);
 382        return dentry;
 383}
 384
 385static struct dentry *hypfs_create_update_file(struct super_block *sb,
 386                                               struct dentry *dir)
 387{
 388        struct dentry *dentry;
 389
 390        dentry = hypfs_create_file(sb, dir, "update", NULL,
 391                                   S_IFREG | UPDATE_FILE_MODE);
 392        /*
 393         * We do not put the update file on the 'delete' list with
 394         * hypfs_add_dentry(), since it should not be removed when the tree
 395         * is updated.
 396         */
 397        return dentry;
 398}
 399
 400struct dentry *hypfs_create_u64(struct super_block *sb, struct dentry *dir,
 401                                const char *name, __u64 value)
 402{
 403        char *buffer;
 404        char tmp[TMP_SIZE];
 405        struct dentry *dentry;
 406
 407        snprintf(tmp, TMP_SIZE, "%llu\n", (unsigned long long int)value);
 408        buffer = kstrdup(tmp, GFP_KERNEL);
 409        if (!buffer)
 410                return ERR_PTR(-ENOMEM);
 411        dentry =
 412            hypfs_create_file(sb, dir, name, buffer, S_IFREG | REG_FILE_MODE);
 413        if (IS_ERR(dentry)) {
 414                kfree(buffer);
 415                return ERR_PTR(-ENOMEM);
 416        }
 417        hypfs_add_dentry(dentry);
 418        return dentry;
 419}
 420
 421struct dentry *hypfs_create_str(struct super_block *sb, struct dentry *dir,
 422                                const char *name, char *string)
 423{
 424        char *buffer;
 425        struct dentry *dentry;
 426
 427        buffer = kmalloc(strlen(string) + 2, GFP_KERNEL);
 428        if (!buffer)
 429                return ERR_PTR(-ENOMEM);
 430        sprintf(buffer, "%s\n", string);
 431        dentry =
 432            hypfs_create_file(sb, dir, name, buffer, S_IFREG | REG_FILE_MODE);
 433        if (IS_ERR(dentry)) {
 434                kfree(buffer);
 435                return ERR_PTR(-ENOMEM);
 436        }
 437        hypfs_add_dentry(dentry);
 438        return dentry;
 439}
 440
 441static const struct file_operations hypfs_file_ops = {
 442        .open           = hypfs_open,
 443        .release        = hypfs_release,
 444        .read           = do_sync_read,
 445        .write          = do_sync_write,
 446        .aio_read       = hypfs_aio_read,
 447        .aio_write      = hypfs_aio_write,
 448        .llseek         = no_llseek,
 449};
 450
 451static struct file_system_type hypfs_type = {
 452        .owner          = THIS_MODULE,
 453        .name           = "s390_hypfs",
 454        .mount          = hypfs_mount,
 455        .kill_sb        = hypfs_kill_super
 456};
 457
 458static const struct super_operations hypfs_s_ops = {
 459        .statfs         = simple_statfs,
 460        .evict_inode    = hypfs_evict_inode,
 461        .show_options   = hypfs_show_options,
 462};
 463
 464static struct kobject *s390_kobj;
 465
 466static int __init hypfs_init(void)
 467{
 468        int rc;
 469
 470        rc = hypfs_dbfs_init();
 471        if (rc)
 472                return rc;
 473        if (hypfs_diag_init()) {
 474                rc = -ENODATA;
 475                goto fail_dbfs_exit;
 476        }
 477        if (hypfs_vm_init()) {
 478                rc = -ENODATA;
 479                goto fail_hypfs_diag_exit;
 480        }
 481        s390_kobj = kobject_create_and_add("s390", hypervisor_kobj);
 482        if (!s390_kobj) {
 483                rc = -ENOMEM;
 484                goto fail_hypfs_vm_exit;
 485        }
 486        rc = register_filesystem(&hypfs_type);
 487        if (rc)
 488                goto fail_filesystem;
 489        return 0;
 490
 491fail_filesystem:
 492        kobject_put(s390_kobj);
 493fail_hypfs_vm_exit:
 494        hypfs_vm_exit();
 495fail_hypfs_diag_exit:
 496        hypfs_diag_exit();
 497fail_dbfs_exit:
 498        hypfs_dbfs_exit();
 499        pr_err("Initialization of hypfs failed with rc=%i\n", rc);
 500        return rc;
 501}
 502
 503static void __exit hypfs_exit(void)
 504{
 505        hypfs_diag_exit();
 506        hypfs_vm_exit();
 507        hypfs_dbfs_exit();
 508        unregister_filesystem(&hypfs_type);
 509        kobject_put(s390_kobj);
 510}
 511
 512module_init(hypfs_init)
 513module_exit(hypfs_exit)
 514
 515MODULE_LICENSE("GPL");
 516MODULE_AUTHOR("Michael Holzheu <holzheu@de.ibm.com>");
 517MODULE_DESCRIPTION("s390 Hypervisor Filesystem");
 518