fs/fs_context.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /* Provide a way to create a superblock configuration context within the kernel
   3  * that allows a superblock to be set up prior to mounting.
   4  *
   5  * Copyright (C) 2017 Red Hat, Inc. All Rights Reserved.
   6  * Written by David Howells (dhowells@redhat.com)
   7  */
   8
   9 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  10 #include <linux/module.h>
  11 #include <linux/fs_context.h>
  12 #include <linux/fs_parser.h>
  13 #include <linux/fs.h>
  14 #include <linux/mount.h>
  15 #include <linux/nsproxy.h>
  16 #include <linux/slab.h>
  17 #include <linux/magic.h>
  18 #include <linux/security.h>
  19 #include <linux/mnt_namespace.h>
  20 #include <linux/pid_namespace.h>
  21 #include <linux/user_namespace.h>
  22 #include <net/net_namespace.h>
  23 #include <asm/sections.h>
  24 #include "mount.h"
  25 #include "internal.h"
  26
  27 enum legacy_fs_param {
  28         LEGACY_FS_UNSET_PARAMS,
  29         LEGACY_FS_MONOLITHIC_PARAMS,
  30         LEGACY_FS_INDIVIDUAL_PARAMS,
  31 };
  32
  33 struct legacy_fs_context {
  34         char                    *legacy_data;   /* Data page for legacy filesystems */
  35         size_t                  data_size;
  36         enum legacy_fs_param    param_type;
  37 };
  38
  39 static int legacy_init_fs_context(struct fs_context *fc);
  40
  41 static const struct constant_table common_set_sb_flag[] = {
  42         { "dirsync",    SB_DIRSYNC },
  43         { "lazytime",   SB_LAZYTIME },
  44         { "mand",       SB_MANDLOCK },
  45         { "ro",         SB_RDONLY },
  46         { "sync",       SB_SYNCHRONOUS },
  47         { },
  48 };
  49
  50 static const struct constant_table common_clear_sb_flag[] = {
  51         { "async",      SB_SYNCHRONOUS },
  52         { "nolazytime", SB_LAZYTIME },
  53         { "nomand",     SB_MANDLOCK },
  54         { "rw",         SB_RDONLY },
  55         { },
  56 };
  57
  58 /*
  59  * Check for a common mount option that manipulates s_flags.
  60  */
  61 static int vfs_parse_sb_flag(struct fs_context *fc, const char *key)
  62 {
  63         unsigned int token;
  64
  65         token = lookup_constant(common_set_sb_flag, key, 0);
  66         if (token) {
  67                 fc->sb_flags |= token;
  68                 fc->sb_flags_mask |= token;
  69                 return 0;
  70         }
  71
  72         token = lookup_constant(common_clear_sb_flag, key, 0);
  73         if (token) {
  74                 fc->sb_flags &= ~token;
  75                 fc->sb_flags_mask |= token;
  76                 return 0;
  77         }
  78
  79         return -ENOPARAM;
  80 }
  81
  82 /**
  83  * vfs_parse_fs_param - Add a single parameter to a superblock config
  84  * @fc: The filesystem context to modify
  85  * @param: The parameter
  86  *
  87  * A single mount option in string form is applied to the filesystem context
  88  * being set up.  Certain standard options (for example "ro") are translated
  89  * into flag bits without going to the filesystem.  The active security module
  90  * is allowed to observe and poach options.  Any other options are passed over
  91  * to the filesystem to parse.
  92  *
  93  * This may be called multiple times for a context.
  94  *
  95  * Returns 0 on success and a negative error code on failure.  In the event of
  96  * failure, supplementary error information may have been set.
  97  */
  98 int vfs_parse_fs_param(struct fs_context *fc, struct fs_parameter *param)
  99 {
 100         int ret;
 101
 102         if (!param->key)
 103                 return invalf(fc, "Unnamed parameter\n");
 104
 105         ret = vfs_parse_sb_flag(fc, param->key);
 106         if (ret != -ENOPARAM)
 107                 return ret;
 108
 109         ret = security_fs_context_parse_param(fc, param);
 110         if (ret != -ENOPARAM)
 111                 /* Param belongs to the LSM or is disallowed by the LSM; so
 112                  * don't pass to the FS.
 113                  */
 114                 return ret;
 115
 116         if (fc->ops->parse_param) {
 117                 ret = fc->ops->parse_param(fc, param);
 118                 if (ret != -ENOPARAM)
 119                         return ret;
 120         }
 121
 122         /* If the filesystem doesn't take any arguments, give it the
 123          * default handling of source.
 124          */
 125         if (strcmp(param->key, "source") == 0) {
 126                 if (param->type != fs_value_is_string)
 127                         return invalf(fc, "VFS: Non-string source");
 128                 if (fc->source)
 129                         return invalf(fc, "VFS: Multiple sources");
 130                 fc->source = param->string;
 131                 param->string = NULL;
 132                 return 0;
 133         }
 134
 135         return invalf(fc, "%s: Unknown parameter '%s'",
 136                       fc->fs_type->name, param->key);
 137 }
 138 EXPORT_SYMBOL(vfs_parse_fs_param);
 139
 140 /**
 141  * vfs_parse_fs_string - Convenience function to just parse a string.
 142  */
 143 int vfs_parse_fs_string(struct fs_context *fc, const char *key,
 144                         const char *value, size_t v_size)
 145 {
 146         int ret;
 147
 148         struct fs_parameter param = {
 149                 .key    = key,
 150                 .type   = fs_value_is_flag,
 151                 .size   = v_size,
 152         };
 153
 154         if (value) {
 155                 param.string = kmemdup_nul(value, v_size, GFP_KERNEL);
 156                 if (!param.string)
 157                         return -ENOMEM;
 158                 param.type = fs_value_is_string;
 159         }
 160
 161         ret = vfs_parse_fs_param(fc, &param);
 162         kfree(param.string);
 163         return ret;
 164 }
 165 EXPORT_SYMBOL(vfs_parse_fs_string);
 166
 167 /**
 168  * generic_parse_monolithic - Parse key[=val][,key[=val]]* mount data
 169  * @ctx: The superblock configuration to fill in.
 170  * @data: The data to parse
 171  *
 172  * Parse a blob of data that's in key[=val][,key[=val]]* form.  This can be
 173  * called from the ->monolithic_mount_data() fs_context operation.
 174  *
 175  * Returns 0 on success or the error returned by the ->parse_option() fs_context
 176  * operation on failure.
 177  */
 178 int generic_parse_monolithic(struct fs_context *fc, void *data)
 179 {
 180         char *options = data, *key;
 181         int ret = 0;
 182
 183         if (!options)
 184                 return 0;
 185
 186         ret = security_sb_eat_lsm_opts(options, &fc->security);
 187         if (ret)
 188                 return ret;
 189
 190         while ((key = strsep(&options, ",")) != NULL) {
 191                 if (*key) {
 192                         size_t v_len = 0;
 193                         char *value = strchr(key, '=');
 194
 195                         if (value) {
 196                                 if (value == key)
 197                                         continue;
 198                                 *value++ = 0;
 199                                 v_len = strlen(value);
 200                         }
 201                         ret = vfs_parse_fs_string(fc, key, value, v_len);
 202                         if (ret < 0)
 203                                 break;
 204                 }
 205         }
 206
 207         return ret;
 208 }
 209 EXPORT_SYMBOL(generic_parse_monolithic);
 210
 211 /**
 212  * alloc_fs_context - Create a filesystem context.
 213  * @fs_type: The filesystem type.
 214  * @reference: The dentry from which this one derives (or NULL)
 215  * @sb_flags: Filesystem/superblock flags (SB_*)
 216  * @sb_flags_mask: Applicable members of @sb_flags
 217  * @purpose: The purpose that this configuration shall be used for.
 218  *
 219  * Open a filesystem and create a mount context.  The mount context is
 220  * initialised with the supplied flags and, if a submount/automount from
 221  * another superblock (referred to by @reference) is supplied, may have
 222  * parameters such as namespaces copied across from that superblock.
 223  */
 224 static struct fs_context *alloc_fs_context(struct file_system_type *fs_type,
 225                                       struct dentry *reference,
 226                                       unsigned int sb_flags,
 227                                       unsigned int sb_flags_mask,
 228                                       enum fs_context_purpose purpose)
 229 {
 230         int (*init_fs_context)(struct fs_context *);
 231         struct fs_context *fc;
 232         int ret = -ENOMEM;
 233
 234         fc = kzalloc(sizeof(struct fs_context), GFP_KERNEL);
 235         if (!fc)
 236                 return ERR_PTR(-ENOMEM);
 237
 238         fc->purpose     = purpose;
 239         fc->sb_flags    = sb_flags;
 240         fc->sb_flags_mask = sb_flags_mask;
 241         fc->fs_type     = get_filesystem(fs_type);
 242         fc->cred        = get_current_cred();
 243         fc->net_ns      = get_net(current->nsproxy->net_ns);
 244         fc->log.prefix  = fs_type->name;
 245
 246         mutex_init(&fc->uapi_mutex);
 247
 248         switch (purpose) {
 249         case FS_CONTEXT_FOR_MOUNT:
 250                 fc->user_ns = get_user_ns(fc->cred->user_ns);
 251                 break;
 252         case FS_CONTEXT_FOR_SUBMOUNT:
 253                 fc->user_ns = get_user_ns(reference->d_sb->s_user_ns);
 254                 break;
 255         case FS_CONTEXT_FOR_RECONFIGURE:
 256                 atomic_inc(&reference->d_sb->s_active);
 257                 fc->user_ns = get_user_ns(reference->d_sb->s_user_ns);
 258                 fc->root = dget(reference);
 259                 break;
 260         }
 261
 262         /* TODO: Make all filesystems support this unconditionally */
 263         init_fs_context = fc->fs_type->init_fs_context;
 264         if (!init_fs_context)
 265                 init_fs_context = legacy_init_fs_context;
 266
 267         ret = init_fs_context(fc);
 268         if (ret < 0)
 269                 goto err_fc;
 270         fc->need_free = true;
 271         return fc;
 272
 273 err_fc:
 274         put_fs_context(fc);
 275         return ERR_PTR(ret);
 276 }
 277
 278 struct fs_context *fs_context_for_mount(struct file_system_type *fs_type,
 279                                         unsigned int sb_flags)
 280 {
 281         return alloc_fs_context(fs_type, NULL, sb_flags, 0,
 282                                         FS_CONTEXT_FOR_MOUNT);
 283 }
 284 EXPORT_SYMBOL(fs_context_for_mount);
 285
 286 struct fs_context *fs_context_for_reconfigure(struct dentry *dentry,
 287                                         unsigned int sb_flags,
 288                                         unsigned int sb_flags_mask)
 289 {
 290         return alloc_fs_context(dentry->d_sb->s_type, dentry, sb_flags,
 291                                 sb_flags_mask, FS_CONTEXT_FOR_RECONFIGURE);
 292 }
 293 EXPORT_SYMBOL(fs_context_for_reconfigure);
 294
 295 struct fs_context *fs_context_for_submount(struct file_system_type *type,
 296                                            struct dentry *reference)
 297 {
 298         return alloc_fs_context(type, reference, 0, 0, FS_CONTEXT_FOR_SUBMOUNT);
 299 }
 300 EXPORT_SYMBOL(fs_context_for_submount);
 301
 302 void fc_drop_locked(struct fs_context *fc)
 303 {
 304         struct super_block *sb = fc->root->d_sb;
 305         dput(fc->root);
 306         fc->root = NULL;
 307         deactivate_locked_super(sb);
 308 }
 309
 310 static void legacy_fs_context_free(struct fs_context *fc);
 311
 312 /**
 313  * vfs_dup_fc_config: Duplicate a filesystem context.
 314  * @src_fc: The context to copy.
 315  */
 316 struct fs_context *vfs_dup_fs_context(struct fs_context *src_fc)
 317 {
 318         struct fs_context *fc;
 319         int ret;
 320
 321         if (!src_fc->ops->dup)
 322                 return ERR_PTR(-EOPNOTSUPP);
 323
 324         fc = kmemdup(src_fc, sizeof(struct fs_context), GFP_KERNEL);
 325         if (!fc)
 326                 return ERR_PTR(-ENOMEM);
 327
 328         mutex_init(&fc->uapi_mutex);
 329
 330         fc->fs_private  = NULL;
 331         fc->s_fs_info   = NULL;
 332         fc->source      = NULL;
 333         fc->security    = NULL;
 334         get_filesystem(fc->fs_type);
 335         get_net(fc->net_ns);
 336         get_user_ns(fc->user_ns);
 337         get_cred(fc->cred);
 338         if (fc->log.log)
 339                 refcount_inc(&fc->log.log->usage);
 340
 341         /* Can't call put until we've called ->dup */
 342         ret = fc->ops->dup(fc, src_fc);
 343         if (ret < 0)
 344                 goto err_fc;
 345
 346         ret = security_fs_context_dup(fc, src_fc);
 347         if (ret < 0)
 348                 goto err_fc;
 349         return fc;
 350
 351 err_fc:
 352         put_fs_context(fc);
 353         return ERR_PTR(ret);
 354 }
 355 EXPORT_SYMBOL(vfs_dup_fs_context);
 356
 357 /**
 358  * logfc - Log a message to a filesystem context
 359  * @fc: The filesystem context to log to.
 360  * @fmt: The format of the buffer.
 361  */
 362 void logfc(struct fc_log *log, const char *prefix, char level, const char *fmt, ...)
 363 {
 364         va_list va;
 365         struct va_format vaf = {.fmt = fmt, .va = &va};
 366
 367         va_start(va, fmt);
 368         if (!log) {
 369                 switch (level) {
 370                 case 'w':
 371                         printk(KERN_WARNING "%s%s%pV\n", prefix ? prefix : "",
 372                                                 prefix ? ": " : "", &vaf);
 373                         break;
 374                 case 'e':
 375                         printk(KERN_ERR "%s%s%pV\n", prefix ? prefix : "",
 376                                                 prefix ? ": " : "", &vaf);
 377                         break;
 378                 default:
 379                         printk(KERN_NOTICE "%s%s%pV\n", prefix ? prefix : "",
 380                                                 prefix ? ": " : "", &vaf);
 381                         break;
 382                 }
 383         } else {
 384                 unsigned int logsize = ARRAY_SIZE(log->buffer);
 385                 u8 index;
 386                 char *q = kasprintf(GFP_KERNEL, "%c %s%s%pV\n", level,
 387                                                 prefix ? prefix : "",
 388                                                 prefix ? ": " : "", &vaf);
 389
 390                 index = log->head & (logsize - 1);
 391                 BUILD_BUG_ON(sizeof(log->head) != sizeof(u8) ||
 392                              sizeof(log->tail) != sizeof(u8));
 393                 if ((u8)(log->head - log->tail) == logsize) {
 394                         /* The buffer is full, discard the oldest message */
 395                         if (log->need_free & (1 << index))
 396                                 kfree(log->buffer[index]);
 397                         log->tail++;
 398                 }
 399
 400                 log->buffer[index] = q ? q : "OOM: Can't store error string";
 401                 if (q)
 402                         log->need_free |= 1 << index;
 403                 else
 404                         log->need_free &= ~(1 << index);
 405                 log->head++;
 406         }
 407         va_end(va);
 408 }
 409 EXPORT_SYMBOL(logfc);
 410
 411 /*
 412  * Free a logging structure.
 413  */
 414 static void put_fc_log(struct fs_context *fc)
 415 {
 416         struct fc_log *log = fc->log.log;
 417         int i;
 418
 419         if (log) {
 420                 if (refcount_dec_and_test(&log->usage)) {
 421                         fc->log.log = NULL;
 422                         for (i = 0; i <= 7; i++)
 423                                 if (log->need_free & (1 << i))
 424                                         kfree(log->buffer[i]);
 425                         kfree(log);
 426                 }
 427         }
 428 }
 429
 430 /**
 431  * put_fs_context - Dispose of a superblock configuration context.
 432  * @fc: The context to dispose of.
 433  */
 434 void put_fs_context(struct fs_context *fc)
 435 {
 436         struct super_block *sb;
 437
 438         if (fc->root) {
 439                 sb = fc->root->d_sb;
 440                 dput(fc->root);
 441                 fc->root = NULL;
 442                 deactivate_super(sb);
 443         }
 444
 445         if (fc->need_free && fc->ops && fc->ops->free)
 446                 fc->ops->free(fc);
 447
 448         security_free_mnt_opts(&fc->security);
 449         put_net(fc->net_ns);
 450         put_user_ns(fc->user_ns);
 451         put_cred(fc->cred);
 452         put_fc_log(fc);
 453         put_filesystem(fc->fs_type);
 454         kfree(fc->source);
 455         kfree(fc);
 456 }
 457 EXPORT_SYMBOL(put_fs_context);
 458
 459 /*
 460  * Free the config for a filesystem that doesn't support fs_context.
 461  */
 462 static void legacy_fs_context_free(struct fs_context *fc)
 463 {
 464         struct legacy_fs_context *ctx = fc->fs_private;
 465
 466         if (ctx) {
 467                 if (ctx->param_type == LEGACY_FS_INDIVIDUAL_PARAMS)
 468                         kfree(ctx->legacy_data);
 469                 kfree(ctx);
 470         }
 471 }
 472
 473 /*
 474  * Duplicate a legacy config.
 475  */
 476 static int legacy_fs_context_dup(struct fs_context *fc, struct fs_context *src_fc)
 477 {
 478         struct legacy_fs_context *ctx;
 479         struct legacy_fs_context *src_ctx = src_fc->fs_private;
 480
 481         ctx = kmemdup(src_ctx, sizeof(*src_ctx), GFP_KERNEL);
 482         if (!ctx)
 483                 return -ENOMEM;
 484
 485         if (ctx->param_type == LEGACY_FS_INDIVIDUAL_PARAMS) {
 486                 ctx->legacy_data = kmemdup(src_ctx->legacy_data,
 487                                            src_ctx->data_size, GFP_KERNEL);
 488                 if (!ctx->legacy_data) {
 489                         kfree(ctx);
 490                         return -ENOMEM;
 491                 }
 492         }
 493
 494         fc->fs_private = ctx;
 495         return 0;
 496 }
 497
 498 /*
 499  * Add a parameter to a legacy config.  We build up a comma-separated list of
 500  * options.
 501  */
 502 static int legacy_parse_param(struct fs_context *fc, struct fs_parameter *param)
 503 {
 504         struct legacy_fs_context *ctx = fc->fs_private;
 505         unsigned int size = ctx->data_size;
 506         size_t len = 0;
 507
 508         if (strcmp(param->key, "source") == 0) {
 509                 if (param->type != fs_value_is_string)
 510                         return invalf(fc, "VFS: Legacy: Non-string source");
 511                 if (fc->source)
 512                         return invalf(fc, "VFS: Legacy: Multiple sources");
 513                 fc->source = param->string;
 514                 param->string = NULL;
 515                 return 0;
 516         }
 517
 518         if (ctx->param_type == LEGACY_FS_MONOLITHIC_PARAMS)
 519                 return invalf(fc, "VFS: Legacy: Can't mix monolithic and individual options");
 520
 521         switch (param->type) {
 522         case fs_value_is_string:
 523                 len = 1 + param->size;
 524                 fallthrough;
 525         case fs_value_is_flag:
 526                 len += strlen(param->key);
 527                 break;
 528         default:
 529                 return invalf(fc, "VFS: Legacy: Parameter type for '%s' not supported",
 530                               param->key);
 531         }
 532
 533         if (len > PAGE_SIZE - 2 - size)
 534                 return invalf(fc, "VFS: Legacy: Cumulative options too large");
 535         if (strchr(param->key, ',') ||
 536             (param->type == fs_value_is_string &&
 537              memchr(param->string, ',', param->size)))
 538                 return invalf(fc, "VFS: Legacy: Option '%s' contained comma",
 539                               param->key);
 540         if (!ctx->legacy_data) {
 541                 ctx->legacy_data = kmalloc(PAGE_SIZE, GFP_KERNEL);
 542                 if (!ctx->legacy_data)
 543                         return -ENOMEM;
 544         }
 545
 546         ctx->legacy_data[size++] = ',';
 547         len = strlen(param->key);
 548         memcpy(ctx->legacy_data + size, param->key, len);
 549         size += len;
 550         if (param->type == fs_value_is_string) {
 551                 ctx->legacy_data[size++] = '=';
 552                 memcpy(ctx->legacy_data + size, param->string, param->size);
 553                 size += param->size;
 554         }
 555         ctx->legacy_data[size] = '\0';
 556         ctx->data_size = size;
 557         ctx->param_type = LEGACY_FS_INDIVIDUAL_PARAMS;
 558         return 0;
 559 }
 560
 561 /*
 562  * Add monolithic mount data.
 563  */
 564 static int legacy_parse_monolithic(struct fs_context *fc, void *data)
 565 {
 566         struct legacy_fs_context *ctx = fc->fs_private;
 567
 568         if (ctx->param_type != LEGACY_FS_UNSET_PARAMS) {
 569                 pr_warn("VFS: Can't mix monolithic and individual options\n");
 570                 return -EINVAL;
 571         }
 572
 573         ctx->legacy_data = data;
 574         ctx->param_type = LEGACY_FS_MONOLITHIC_PARAMS;
 575         if (!ctx->legacy_data)
 576                 return 0;
 577
 578         if (fc->fs_type->fs_flags & FS_BINARY_MOUNTDATA)
 579                 return 0;
 580         return security_sb_eat_lsm_opts(ctx->legacy_data, &fc->security);
 581 }
 582
 583 /*
 584  * Get a mountable root with the legacy mount command.
 585  */
 586 static int legacy_get_tree(struct fs_context *fc)
 587 {
 588         struct legacy_fs_context *ctx = fc->fs_private;
 589         struct super_block *sb;
 590         struct dentry *root;
 591
 592         root = fc->fs_type->mount(fc->fs_type, fc->sb_flags,
 593                                       fc->source, ctx->legacy_data);
 594         if (IS_ERR(root))
 595                 return PTR_ERR(root);
 596
 597         sb = root->d_sb;
 598         BUG_ON(!sb);
 599
 600         fc->root = root;
 601         return 0;
 602 }
 603
 604 /*
 605  * Handle remount.
 606  */
 607 static int legacy_reconfigure(struct fs_context *fc)
 608 {
 609         struct legacy_fs_context *ctx = fc->fs_private;
 610         struct super_block *sb = fc->root->d_sb;
 611
 612         if (!sb->s_op->remount_fs)
 613                 return 0;
 614
 615         return sb->s_op->remount_fs(sb, &fc->sb_flags,
 616                                     ctx ? ctx->legacy_data : NULL);
 617 }
 618
 619 const struct fs_context_operations legacy_fs_context_ops = {
 620         .free                   = legacy_fs_context_free,
 621         .dup                    = legacy_fs_context_dup,
 622         .parse_param            = legacy_parse_param,
 623         .parse_monolithic       = legacy_parse_monolithic,
 624         .get_tree               = legacy_get_tree,
 625         .reconfigure            = legacy_reconfigure,
 626 };
 627
 628 /*
 629  * Initialise a legacy context for a filesystem that doesn't support
 630  * fs_context.
 631  */
 632 static int legacy_init_fs_context(struct fs_context *fc)
 633 {
 634         fc->fs_private = kzalloc(sizeof(struct legacy_fs_context), GFP_KERNEL);
 635         if (!fc->fs_private)
 636                 return -ENOMEM;
 637         fc->ops = &legacy_fs_context_ops;
 638         return 0;
 639 }
 640
 641 int parse_monolithic_mount_data(struct fs_context *fc, void *data)
 642 {
 643         int (*monolithic_mount_data)(struct fs_context *, void *);
 644
 645         monolithic_mount_data = fc->ops->parse_monolithic;
 646         if (!monolithic_mount_data)
 647                 monolithic_mount_data = generic_parse_monolithic;
 648
 649         return monolithic_mount_data(fc, data);
 650 }
 651
 652 /*
 653  * Clean up a context after performing an action on it and put it into a state
 654  * from where it can be used to reconfigure a superblock.
 655  *
 656  * Note that here we do only the parts that can't fail; the rest is in
 657  * finish_clean_context() below and in between those fs_context is marked
 658  * FS_CONTEXT_AWAITING_RECONF.  The reason for splitup is that after
 659  * successful mount or remount we need to report success to userland.
 660  * Trying to do full reinit (for the sake of possible subsequent remount)
 661  * and failing to allocate memory would've put us into a nasty situation.
 662  * So here we only discard the old state and reinitialization is left
 663  * until we actually try to reconfigure.
 664  */
 665 void vfs_clean_context(struct fs_context *fc)
 666 {
 667         if (fc->need_free && fc->ops && fc->ops->free)
 668                 fc->ops->free(fc);
 669         fc->need_free = false;
 670         fc->fs_private = NULL;
 671         fc->s_fs_info = NULL;
 672         fc->sb_flags = 0;
 673         security_free_mnt_opts(&fc->security);
 674         kfree(fc->source);
 675         fc->source = NULL;
 676
 677         fc->purpose = FS_CONTEXT_FOR_RECONFIGURE;
 678         fc->phase = FS_CONTEXT_AWAITING_RECONF;
 679 }
 680
 681 int finish_clean_context(struct fs_context *fc)
 682 {
 683         int error;
 684
 685         if (fc->phase != FS_CONTEXT_AWAITING_RECONF)
 686                 return 0;
 687
 688         if (fc->fs_type->init_fs_context)
 689                 error = fc->fs_type->init_fs_context(fc);
 690         else
 691                 error = legacy_init_fs_context(fc);
 692         if (unlikely(error)) {
 693                 fc->phase = FS_CONTEXT_FAILED;
 694                 return error;
 695         }
 696         fc->need_free = true;
 697         fc->phase = FS_CONTEXT_RECONF_PARAMS;
 698         return 0;
 699 }