linux/arch/s390/hypfs/inode.c
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   1// SPDX-License-Identifier: GPL-1.0+
   2/*
   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/init.h>
  23#include <linux/kobject.h>
  24#include <linux/seq_file.h>
  25#include <linux/mount.h>
  26#include <linux/uio.h>
  27#include <asm/ebcdic.h>
  28#include "hypfs.h"
  29
  30#define HYPFS_MAGIC 0x687970    /* ASCII 'hyp' */
  31#define TMP_SIZE 64             /* size of temporary buffers */
  32
  33static struct dentry *hypfs_create_update_file(struct dentry *dir);
  34
  35struct hypfs_sb_info {
  36        kuid_t uid;                     /* uid used for files and dirs */
  37        kgid_t gid;                     /* gid used for files and dirs */
  38        struct dentry *update_file;     /* file to trigger update */
  39        time64_t last_update;           /* last update, CLOCK_MONOTONIC time */
  40        struct mutex lock;              /* lock to protect update process */
  41};
  42
  43static const struct file_operations hypfs_file_ops;
  44static struct file_system_type hypfs_type;
  45static const struct super_operations hypfs_s_ops;
  46
  47/* start of list of all dentries, which have to be deleted on update */
  48static struct dentry *hypfs_last_dentry;
  49
  50static void hypfs_update_update(struct super_block *sb)
  51{
  52        struct hypfs_sb_info *sb_info = sb->s_fs_info;
  53        struct inode *inode = d_inode(sb_info->update_file);
  54
  55        sb_info->last_update = ktime_get_seconds();
  56        inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
  57}
  58
  59/* directory tree removal functions */
  60
  61static void hypfs_add_dentry(struct dentry *dentry)
  62{
  63        dentry->d_fsdata = hypfs_last_dentry;
  64        hypfs_last_dentry = dentry;
  65}
  66
  67static void hypfs_remove(struct dentry *dentry)
  68{
  69        struct dentry *parent;
  70
  71        parent = dentry->d_parent;
  72        inode_lock(d_inode(parent));
  73        if (simple_positive(dentry)) {
  74                if (d_is_dir(dentry))
  75                        simple_rmdir(d_inode(parent), dentry);
  76                else
  77                        simple_unlink(d_inode(parent), dentry);
  78        }
  79        d_delete(dentry);
  80        dput(dentry);
  81        inode_unlock(d_inode(parent));
  82}
  83
  84static void hypfs_delete_tree(struct dentry *root)
  85{
  86        while (hypfs_last_dentry) {
  87                struct dentry *next_dentry;
  88                next_dentry = hypfs_last_dentry->d_fsdata;
  89                hypfs_remove(hypfs_last_dentry);
  90                hypfs_last_dentry = next_dentry;
  91        }
  92}
  93
  94static struct inode *hypfs_make_inode(struct super_block *sb, umode_t mode)
  95{
  96        struct inode *ret = new_inode(sb);
  97
  98        if (ret) {
  99                struct hypfs_sb_info *hypfs_info = sb->s_fs_info;
 100                ret->i_ino = get_next_ino();
 101                ret->i_mode = mode;
 102                ret->i_uid = hypfs_info->uid;
 103                ret->i_gid = hypfs_info->gid;
 104                ret->i_atime = ret->i_mtime = ret->i_ctime = current_time(ret);
 105                if (S_ISDIR(mode))
 106                        set_nlink(ret, 2);
 107        }
 108        return ret;
 109}
 110
 111static void hypfs_evict_inode(struct inode *inode)
 112{
 113        clear_inode(inode);
 114        kfree(inode->i_private);
 115}
 116
 117static int hypfs_open(struct inode *inode, struct file *filp)
 118{
 119        char *data = file_inode(filp)->i_private;
 120        struct hypfs_sb_info *fs_info;
 121
 122        if (filp->f_mode & FMODE_WRITE) {
 123                if (!(inode->i_mode & S_IWUGO))
 124                        return -EACCES;
 125        }
 126        if (filp->f_mode & FMODE_READ) {
 127                if (!(inode->i_mode & S_IRUGO))
 128                        return -EACCES;
 129        }
 130
 131        fs_info = inode->i_sb->s_fs_info;
 132        if(data) {
 133                mutex_lock(&fs_info->lock);
 134                filp->private_data = kstrdup(data, GFP_KERNEL);
 135                if (!filp->private_data) {
 136                        mutex_unlock(&fs_info->lock);
 137                        return -ENOMEM;
 138                }
 139                mutex_unlock(&fs_info->lock);
 140        }
 141        return nonseekable_open(inode, filp);
 142}
 143
 144static ssize_t hypfs_read_iter(struct kiocb *iocb, struct iov_iter *to)
 145{
 146        struct file *file = iocb->ki_filp;
 147        char *data = file->private_data;
 148        size_t available = strlen(data);
 149        loff_t pos = iocb->ki_pos;
 150        size_t count;
 151
 152        if (pos < 0)
 153                return -EINVAL;
 154        if (pos >= available || !iov_iter_count(to))
 155                return 0;
 156        count = copy_to_iter(data + pos, available - pos, to);
 157        if (!count)
 158                return -EFAULT;
 159        iocb->ki_pos = pos + count;
 160        file_accessed(file);
 161        return count;
 162}
 163
 164static ssize_t hypfs_write_iter(struct kiocb *iocb, struct iov_iter *from)
 165{
 166        int rc;
 167        struct super_block *sb = file_inode(iocb->ki_filp)->i_sb;
 168        struct hypfs_sb_info *fs_info = sb->s_fs_info;
 169        size_t count = iov_iter_count(from);
 170
 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 == ktime_get_seconds()) {
 183                rc = -EBUSY;
 184                goto out;
 185        }
 186        hypfs_delete_tree(sb->s_root);
 187        if (MACHINE_IS_VM)
 188                rc = hypfs_vm_create_files(sb->s_root);
 189        else
 190                rc = hypfs_diag_create_files(sb->s_root);
 191        if (rc) {
 192                pr_err("Updating the hypfs tree failed\n");
 193                hypfs_delete_tree(sb->s_root);
 194                goto out;
 195        }
 196        hypfs_update_update(sb);
 197        rc = count;
 198        iov_iter_advance(from, count);
 199out:
 200        mutex_unlock(&fs_info->lock);
 201        return rc;
 202}
 203
 204static int hypfs_release(struct inode *inode, struct file *filp)
 205{
 206        kfree(filp->private_data);
 207        return 0;
 208}
 209
 210enum { opt_uid, opt_gid, opt_err };
 211
 212static const match_table_t hypfs_tokens = {
 213        {opt_uid, "uid=%u"},
 214        {opt_gid, "gid=%u"},
 215        {opt_err, NULL}
 216};
 217
 218static int hypfs_parse_options(char *options, struct super_block *sb)
 219{
 220        char *str;
 221        substring_t args[MAX_OPT_ARGS];
 222        kuid_t uid;
 223        kgid_t gid;
 224
 225        if (!options)
 226                return 0;
 227        while ((str = strsep(&options, ",")) != NULL) {
 228                int token, option;
 229                struct hypfs_sb_info *hypfs_info = sb->s_fs_info;
 230
 231                if (!*str)
 232                        continue;
 233                token = match_token(str, hypfs_tokens, args);
 234                switch (token) {
 235                case opt_uid:
 236                        if (match_int(&args[0], &option))
 237                                return -EINVAL;
 238                        uid = make_kuid(current_user_ns(), option);
 239                        if (!uid_valid(uid))
 240                                return -EINVAL;
 241                        hypfs_info->uid = uid;
 242                        break;
 243                case opt_gid:
 244                        if (match_int(&args[0], &option))
 245                                return -EINVAL;
 246                        gid = make_kgid(current_user_ns(), option);
 247                        if (!gid_valid(gid))
 248                                return -EINVAL;
 249                        hypfs_info->gid = gid;
 250                        break;
 251                case opt_err:
 252                default:
 253                        pr_err("%s is not a valid mount option\n", str);
 254                        return -EINVAL;
 255                }
 256        }
 257        return 0;
 258}
 259
 260static int hypfs_show_options(struct seq_file *s, struct dentry *root)
 261{
 262        struct hypfs_sb_info *hypfs_info = root->d_sb->s_fs_info;
 263
 264        seq_printf(s, ",uid=%u", from_kuid_munged(&init_user_ns, hypfs_info->uid));
 265        seq_printf(s, ",gid=%u", from_kgid_munged(&init_user_ns, hypfs_info->gid));
 266        return 0;
 267}
 268
 269static int hypfs_fill_super(struct super_block *sb, void *data, int silent)
 270{
 271        struct inode *root_inode;
 272        struct dentry *root_dentry;
 273        int rc = 0;
 274        struct hypfs_sb_info *sbi;
 275
 276        sbi = kzalloc(sizeof(struct hypfs_sb_info), GFP_KERNEL);
 277        if (!sbi)
 278                return -ENOMEM;
 279        mutex_init(&sbi->lock);
 280        sbi->uid = current_uid();
 281        sbi->gid = current_gid();
 282        sb->s_fs_info = sbi;
 283        sb->s_blocksize = PAGE_SIZE;
 284        sb->s_blocksize_bits = PAGE_SHIFT;
 285        sb->s_magic = HYPFS_MAGIC;
 286        sb->s_op = &hypfs_s_ops;
 287        if (hypfs_parse_options(data, sb))
 288                return -EINVAL;
 289        root_inode = hypfs_make_inode(sb, S_IFDIR | 0755);
 290        if (!root_inode)
 291                return -ENOMEM;
 292        root_inode->i_op = &simple_dir_inode_operations;
 293        root_inode->i_fop = &simple_dir_operations;
 294        sb->s_root = root_dentry = d_make_root(root_inode);
 295        if (!root_dentry)
 296                return -ENOMEM;
 297        if (MACHINE_IS_VM)
 298                rc = hypfs_vm_create_files(root_dentry);
 299        else
 300                rc = hypfs_diag_create_files(root_dentry);
 301        if (rc)
 302                return rc;
 303        sbi->update_file = hypfs_create_update_file(root_dentry);
 304        if (IS_ERR(sbi->update_file))
 305                return PTR_ERR(sbi->update_file);
 306        hypfs_update_update(sb);
 307        pr_info("Hypervisor filesystem mounted\n");
 308        return 0;
 309}
 310
 311static struct dentry *hypfs_mount(struct file_system_type *fst, int flags,
 312                        const char *devname, void *data)
 313{
 314        return mount_single(fst, flags, data, hypfs_fill_super);
 315}
 316
 317static void hypfs_kill_super(struct super_block *sb)
 318{
 319        struct hypfs_sb_info *sb_info = sb->s_fs_info;
 320
 321        if (sb->s_root)
 322                hypfs_delete_tree(sb->s_root);
 323        if (sb_info && sb_info->update_file)
 324                hypfs_remove(sb_info->update_file);
 325        kfree(sb->s_fs_info);
 326        sb->s_fs_info = NULL;
 327        kill_litter_super(sb);
 328}
 329
 330static struct dentry *hypfs_create_file(struct dentry *parent, const char *name,
 331                                        char *data, umode_t mode)
 332{
 333        struct dentry *dentry;
 334        struct inode *inode;
 335
 336        inode_lock(d_inode(parent));
 337        dentry = lookup_one_len(name, parent, strlen(name));
 338        if (IS_ERR(dentry)) {
 339                dentry = ERR_PTR(-ENOMEM);
 340                goto fail;
 341        }
 342        inode = hypfs_make_inode(parent->d_sb, mode);
 343        if (!inode) {
 344                dput(dentry);
 345                dentry = ERR_PTR(-ENOMEM);
 346                goto fail;
 347        }
 348        if (S_ISREG(mode)) {
 349                inode->i_fop = &hypfs_file_ops;
 350                if (data)
 351                        inode->i_size = strlen(data);
 352                else
 353                        inode->i_size = 0;
 354        } else if (S_ISDIR(mode)) {
 355                inode->i_op = &simple_dir_inode_operations;
 356                inode->i_fop = &simple_dir_operations;
 357                inc_nlink(d_inode(parent));
 358        } else
 359                BUG();
 360        inode->i_private = data;
 361        d_instantiate(dentry, inode);
 362        dget(dentry);
 363fail:
 364        inode_unlock(d_inode(parent));
 365        return dentry;
 366}
 367
 368struct dentry *hypfs_mkdir(struct dentry *parent, const char *name)
 369{
 370        struct dentry *dentry;
 371
 372        dentry = hypfs_create_file(parent, name, NULL, S_IFDIR | DIR_MODE);
 373        if (IS_ERR(dentry))
 374                return dentry;
 375        hypfs_add_dentry(dentry);
 376        return dentry;
 377}
 378
 379static struct dentry *hypfs_create_update_file(struct dentry *dir)
 380{
 381        struct dentry *dentry;
 382
 383        dentry = hypfs_create_file(dir, "update", NULL,
 384                                   S_IFREG | UPDATE_FILE_MODE);
 385        /*
 386         * We do not put the update file on the 'delete' list with
 387         * hypfs_add_dentry(), since it should not be removed when the tree
 388         * is updated.
 389         */
 390        return dentry;
 391}
 392
 393struct dentry *hypfs_create_u64(struct dentry *dir,
 394                                const char *name, __u64 value)
 395{
 396        char *buffer;
 397        char tmp[TMP_SIZE];
 398        struct dentry *dentry;
 399
 400        snprintf(tmp, TMP_SIZE, "%llu\n", (unsigned long long int)value);
 401        buffer = kstrdup(tmp, GFP_KERNEL);
 402        if (!buffer)
 403                return ERR_PTR(-ENOMEM);
 404        dentry =
 405            hypfs_create_file(dir, name, buffer, S_IFREG | REG_FILE_MODE);
 406        if (IS_ERR(dentry)) {
 407                kfree(buffer);
 408                return ERR_PTR(-ENOMEM);
 409        }
 410        hypfs_add_dentry(dentry);
 411        return dentry;
 412}
 413
 414struct dentry *hypfs_create_str(struct dentry *dir,
 415                                const char *name, char *string)
 416{
 417        char *buffer;
 418        struct dentry *dentry;
 419
 420        buffer = kmalloc(strlen(string) + 2, GFP_KERNEL);
 421        if (!buffer)
 422                return ERR_PTR(-ENOMEM);
 423        sprintf(buffer, "%s\n", string);
 424        dentry =
 425            hypfs_create_file(dir, name, buffer, S_IFREG | REG_FILE_MODE);
 426        if (IS_ERR(dentry)) {
 427                kfree(buffer);
 428                return ERR_PTR(-ENOMEM);
 429        }
 430        hypfs_add_dentry(dentry);
 431        return dentry;
 432}
 433
 434static const struct file_operations hypfs_file_ops = {
 435        .open           = hypfs_open,
 436        .release        = hypfs_release,
 437        .read_iter      = hypfs_read_iter,
 438        .write_iter     = hypfs_write_iter,
 439        .llseek         = no_llseek,
 440};
 441
 442static struct file_system_type hypfs_type = {
 443        .owner          = THIS_MODULE,
 444        .name           = "s390_hypfs",
 445        .mount          = hypfs_mount,
 446        .kill_sb        = hypfs_kill_super
 447};
 448
 449static const struct super_operations hypfs_s_ops = {
 450        .statfs         = simple_statfs,
 451        .evict_inode    = hypfs_evict_inode,
 452        .show_options   = hypfs_show_options,
 453};
 454
 455static int __init hypfs_init(void)
 456{
 457        int rc;
 458
 459        rc = hypfs_dbfs_init();
 460        if (rc)
 461                return rc;
 462        if (hypfs_diag_init()) {
 463                rc = -ENODATA;
 464                goto fail_dbfs_exit;
 465        }
 466        if (hypfs_vm_init()) {
 467                rc = -ENODATA;
 468                goto fail_hypfs_diag_exit;
 469        }
 470        if (hypfs_sprp_init()) {
 471                rc = -ENODATA;
 472                goto fail_hypfs_vm_exit;
 473        }
 474        if (hypfs_diag0c_init()) {
 475                rc = -ENODATA;
 476                goto fail_hypfs_sprp_exit;
 477        }
 478        rc = sysfs_create_mount_point(hypervisor_kobj, "s390");
 479        if (rc)
 480                goto fail_hypfs_diag0c_exit;
 481        rc = register_filesystem(&hypfs_type);
 482        if (rc)
 483                goto fail_filesystem;
 484        return 0;
 485
 486fail_filesystem:
 487        sysfs_remove_mount_point(hypervisor_kobj, "s390");
 488fail_hypfs_diag0c_exit:
 489        hypfs_diag0c_exit();
 490fail_hypfs_sprp_exit:
 491        hypfs_sprp_exit();
 492fail_hypfs_vm_exit:
 493        hypfs_vm_exit();
 494fail_hypfs_diag_exit:
 495        hypfs_diag_exit();
 496fail_dbfs_exit:
 497        hypfs_dbfs_exit();
 498        pr_err("Initialization of hypfs failed with rc=%i\n", rc);
 499        return rc;
 500}
 501device_initcall(hypfs_init)
 502