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treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 35
[linux-block.git] / fs / fs_context.c
CommitLineData
9bc61ab1
DH		 1/* Provide a way to create a superblock configuration context within the kernel
2 * that allows a superblock to be set up prior to mounting.
3 *
4 * Copyright (C) 2017 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.com)
6 *
7 * This program is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public Licence
9 * as published by the Free Software Foundation; either version
10 * 2 of the Licence, or (at your option) any later version.
11 */
12
13#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
007ec26c 14#include <linux/module.h>
9bc61ab1 15#include <linux/fs_context.h>
3e1aeb00 16#include <linux/fs_parser.h>
9bc61ab1
DH		 17#include <linux/fs.h>
18#include <linux/mount.h>
19#include <linux/nsproxy.h>
20#include <linux/slab.h>
21#include <linux/magic.h>
22#include <linux/security.h>
23#include <linux/mnt_namespace.h>
24#include <linux/pid_namespace.h>
25#include <linux/user_namespace.h>
26#include <net/net_namespace.h>
007ec26c 27#include <asm/sections.h>
9bc61ab1
DH		 28#include "mount.h"
29#include "internal.h"
30
3e1aeb00
DH		 31enum legacy_fs_param {
32 LEGACY_FS_UNSET_PARAMS,
33 LEGACY_FS_MONOLITHIC_PARAMS,
34 LEGACY_FS_INDIVIDUAL_PARAMS,
35};
36
9bc61ab1
DH		 37struct legacy_fs_context {
38 char *legacy_data; /* Data page for legacy filesystems */
39 size_t data_size;
3e1aeb00 40 enum legacy_fs_param param_type;
9bc61ab1
DH		 41};
42
43static int legacy_init_fs_context(struct fs_context *fc);
44
3e1aeb00
DH		 45static const struct constant_table common_set_sb_flag[] = {
46 { "dirsync", SB_DIRSYNC },
47 { "lazytime", SB_LAZYTIME },
48 { "mand", SB_MANDLOCK },
49 { "posixacl", SB_POSIXACL },
50 { "ro", SB_RDONLY },
51 { "sync", SB_SYNCHRONOUS },
52};
53
54static const struct constant_table common_clear_sb_flag[] = {
55 { "async", SB_SYNCHRONOUS },
56 { "nolazytime", SB_LAZYTIME },
57 { "nomand", SB_MANDLOCK },
58 { "rw", SB_RDONLY },
59 { "silent", SB_SILENT },
60};
61
62static const char *const forbidden_sb_flag[] = {
63 "bind",
64 "dev",
65 "exec",
66 "move",
67 "noatime",
68 "nodev",
69 "nodiratime",
70 "noexec",
71 "norelatime",
72 "nostrictatime",
73 "nosuid",
74 "private",
75 "rec",
76 "relatime",
77 "remount",
78 "shared",
79 "slave",
80 "strictatime",
81 "suid",
82 "unbindable",
83};
84
85/*
86 * Check for a common mount option that manipulates s_flags.
87 */
88static int vfs_parse_sb_flag(struct fs_context *fc, const char *key)
89{
90 unsigned int token;
91 unsigned int i;
92
93 for (i = 0; i < ARRAY_SIZE(forbidden_sb_flag); i++)
94 if (strcmp(key, forbidden_sb_flag[i]) == 0)
95 return -EINVAL;
96
97 token = lookup_constant(common_set_sb_flag, key, 0);
98 if (token) {
99 fc->sb_flags |= token;
100 fc->sb_flags_mask |= token;
101 return 0;
102 }
103
104 token = lookup_constant(common_clear_sb_flag, key, 0);
105 if (token) {
106 fc->sb_flags &= ~token;
107 fc->sb_flags_mask |= token;
108 return 0;
109 }
110
111 return -ENOPARAM;
112}
113
114/**
115 * vfs_parse_fs_param - Add a single parameter to a superblock config
116 * @fc: The filesystem context to modify
117 * @param: The parameter
118 *
119 * A single mount option in string form is applied to the filesystem context
120 * being set up. Certain standard options (for example "ro") are translated
121 * into flag bits without going to the filesystem. The active security module
122 * is allowed to observe and poach options. Any other options are passed over
123 * to the filesystem to parse.
124 *
125 * This may be called multiple times for a context.
126 *
127 * Returns 0 on success and a negative error code on failure. In the event of
128 * failure, supplementary error information may have been set.
129 */
130int vfs_parse_fs_param(struct fs_context *fc, struct fs_parameter *param)
131{
132 int ret;
133
134 if (!param->key)
135 return invalf(fc, "Unnamed parameter\n");
136
137 ret = vfs_parse_sb_flag(fc, param->key);
138 if (ret != -ENOPARAM)
139 return ret;
140
141 ret = security_fs_context_parse_param(fc, param);
142 if (ret != -ENOPARAM)
143 /* Param belongs to the LSM or is disallowed by the LSM; so
144 * don't pass to the FS.
145 */
146 return ret;
147
148 if (fc->ops->parse_param) {
149 ret = fc->ops->parse_param(fc, param);
150 if (ret != -ENOPARAM)
151 return ret;
152 }
153
154 /* If the filesystem doesn't take any arguments, give it the
155 * default handling of source.
156 */
157 if (strcmp(param->key, "source") == 0) {
158 if (param->type != fs_value_is_string)
159 return invalf(fc, "VFS: Non-string source");
160 if (fc->source)
161 return invalf(fc, "VFS: Multiple sources");
162 fc->source = param->string;
163 param->string = NULL;
164 return 0;
165 }
166
167 return invalf(fc, "%s: Unknown parameter '%s'",
168 fc->fs_type->name, param->key);
169}
170EXPORT_SYMBOL(vfs_parse_fs_param);
171
172/**
173 * vfs_parse_fs_string - Convenience function to just parse a string.
174 */
175int vfs_parse_fs_string(struct fs_context *fc, const char *key,
176 const char *value, size_t v_size)
177{
178 int ret;
179
180 struct fs_parameter param = {
181 .key = key,
182 .type = fs_value_is_string,
183 .size = v_size,
184 };
185
186 if (v_size > 0) {
187 param.string = kmemdup_nul(value, v_size, GFP_KERNEL);
188 if (!param.string)
189 return -ENOMEM;
190 }
191
192 ret = vfs_parse_fs_param(fc, &param);
193 kfree(param.string);
194 return ret;
195}
196EXPORT_SYMBOL(vfs_parse_fs_string);
197
198/**
199 * generic_parse_monolithic - Parse key[=val][,key[=val]]* mount data
200 * @ctx: The superblock configuration to fill in.
201 * @data: The data to parse
202 *
203 * Parse a blob of data that's in key[=val][,key[=val]]* form. This can be
204 * called from the ->monolithic_mount_data() fs_context operation.
205 *
206 * Returns 0 on success or the error returned by the ->parse_option() fs_context
207 * operation on failure.
208 */
209int generic_parse_monolithic(struct fs_context *fc, void *data)
210{
211 char *options = data, *key;
212 int ret = 0;
213
214 if (!options)
215 return 0;
216
217 ret = security_sb_eat_lsm_opts(options, &fc->security);
218 if (ret)
219 return ret;
220
221 while ((key = strsep(&options, ",")) != NULL) {
222 if (*key) {
223 size_t v_len = 0;
224 char *value = strchr(key, '=');
225
226 if (value) {
227 if (value == key)
228 continue;
229 *value++ = 0;
230 v_len = strlen(value);
231 }
232 ret = vfs_parse_fs_string(fc, key, value, v_len);
233 if (ret < 0)
234 break;
235 }
236 }
237
238 return ret;
239}
240EXPORT_SYMBOL(generic_parse_monolithic);
241
9bc61ab1
DH		 242/**
243 * alloc_fs_context - Create a filesystem context.
244 * @fs_type: The filesystem type.
245 * @reference: The dentry from which this one derives (or NULL)
246 * @sb_flags: Filesystem/superblock flags (SB_*)
247 * @sb_flags_mask: Applicable members of @sb_flags
248 * @purpose: The purpose that this configuration shall be used for.
249 *
250 * Open a filesystem and create a mount context. The mount context is
251 * initialised with the supplied flags and, if a submount/automount from
252 * another superblock (referred to by @reference) is supplied, may have
253 * parameters such as namespaces copied across from that superblock.
254 */
255static struct fs_context *alloc_fs_context(struct file_system_type *fs_type,
256 struct dentry *reference,
257 unsigned int sb_flags,
258 unsigned int sb_flags_mask,
259 enum fs_context_purpose purpose)
260{
f3a09c92 261 int (*init_fs_context)(struct fs_context *);
9bc61ab1
DH		 262 struct fs_context *fc;
263 int ret = -ENOMEM;
264
265 fc = kzalloc(sizeof(struct fs_context), GFP_KERNEL);
266 if (!fc)
267 return ERR_PTR(-ENOMEM);
268
269 fc->purpose = purpose;
270 fc->sb_flags = sb_flags;
271 fc->sb_flags_mask = sb_flags_mask;
272 fc->fs_type = get_filesystem(fs_type);
273 fc->cred = get_current_cred();
274 fc->net_ns = get_net(current->nsproxy->net_ns);
275
24dcb3d9
DH		 276 mutex_init(&fc->uapi_mutex);
277
9bc61ab1
DH		 278 switch (purpose) {
279 case FS_CONTEXT_FOR_MOUNT:
280 fc->user_ns = get_user_ns(fc->cred->user_ns);
281 break;
e1a91586
AV		 282 case FS_CONTEXT_FOR_SUBMOUNT:
283 fc->user_ns = get_user_ns(reference->d_sb->s_user_ns);
284 break;
8d0347f6
DH		 285 case FS_CONTEXT_FOR_RECONFIGURE:
286 /* We don't pin any namespaces as the superblock's
287 * subscriptions cannot be changed at this point.
288 */
289 atomic_inc(&reference->d_sb->s_active);
290 fc->root = dget(reference);
291 break;
9bc61ab1
DH		 292 }
293
f3a09c92
AV		 294 /* TODO: Make all filesystems support this unconditionally */
295 init_fs_context = fc->fs_type->init_fs_context;
296 if (!init_fs_context)
297 init_fs_context = legacy_init_fs_context;
298
299 ret = init_fs_context(fc);
9bc61ab1
DH		 300 if (ret < 0)
301 goto err_fc;
302 fc->need_free = true;
303 return fc;
304
305err_fc:
306 put_fs_context(fc);
307 return ERR_PTR(ret);
308}
309
310struct fs_context *fs_context_for_mount(struct file_system_type *fs_type,
311 unsigned int sb_flags)
312{
313 return alloc_fs_context(fs_type, NULL, sb_flags, 0,
314 FS_CONTEXT_FOR_MOUNT);
315}
316EXPORT_SYMBOL(fs_context_for_mount);
317
8d0347f6
DH		 318struct fs_context *fs_context_for_reconfigure(struct dentry *dentry,
319 unsigned int sb_flags,
320 unsigned int sb_flags_mask)
321{
322 return alloc_fs_context(dentry->d_sb->s_type, dentry, sb_flags,
323 sb_flags_mask, FS_CONTEXT_FOR_RECONFIGURE);
324}
325EXPORT_SYMBOL(fs_context_for_reconfigure);
326
e1a91586
AV		 327struct fs_context *fs_context_for_submount(struct file_system_type *type,
328 struct dentry *reference)
329{
330 return alloc_fs_context(type, reference, 0, 0, FS_CONTEXT_FOR_SUBMOUNT);
331}
332EXPORT_SYMBOL(fs_context_for_submount);
333
c9ce29ed
AV		 334void fc_drop_locked(struct fs_context *fc)
335{
336 struct super_block *sb = fc->root->d_sb;
337 dput(fc->root);
338 fc->root = NULL;
339 deactivate_locked_super(sb);
340}
341
9bc61ab1 342static void legacy_fs_context_free(struct fs_context *fc);
8d0347f6 343
0b52075e
AV		 344/**
345 * vfs_dup_fc_config: Duplicate a filesystem context.
346 * @src_fc: The context to copy.
347 */
348struct fs_context *vfs_dup_fs_context(struct fs_context *src_fc)
349{
350 struct fs_context *fc;
351 int ret;
352
353 if (!src_fc->ops->dup)
354 return ERR_PTR(-EOPNOTSUPP);
355
356 fc = kmemdup(src_fc, sizeof(struct fs_context), GFP_KERNEL);
357 if (!fc)
358 return ERR_PTR(-ENOMEM);
359
24dcb3d9
DH		 360 mutex_init(&fc->uapi_mutex);
361
0b52075e
AV		 362 fc->fs_private = NULL;
363 fc->s_fs_info = NULL;
364 fc->source = NULL;
365 fc->security = NULL;
366 get_filesystem(fc->fs_type);
367 get_net(fc->net_ns);
368 get_user_ns(fc->user_ns);
369 get_cred(fc->cred);
007ec26c
DH		 370 if (fc->log)
371 refcount_inc(&fc->log->usage);
0b52075e
AV		 372
373 /* Can't call put until we've called ->dup */
374 ret = fc->ops->dup(fc, src_fc);
375 if (ret < 0)
376 goto err_fc;
377
378 ret = security_fs_context_dup(fc, src_fc);
379 if (ret < 0)
380 goto err_fc;
381 return fc;
382
383err_fc:
384 put_fs_context(fc);
385 return ERR_PTR(ret);
386}
387EXPORT_SYMBOL(vfs_dup_fs_context);
388
e7582e16
DH		 389/**
390 * logfc - Log a message to a filesystem context
391 * @fc: The filesystem context to log to.
392 * @fmt: The format of the buffer.
393 */
394void logfc(struct fs_context *fc, const char *fmt, ...)
395{
007ec26c
DH		 396 static const char store_failure[] = "OOM: Can't store error string";
397 struct fc_log *log = fc ? fc->log : NULL;
398 const char *p;
e7582e16 399 va_list va;
007ec26c
DH		 400 char *q;
401 u8 freeable;
e7582e16
DH		 402
403 va_start(va, fmt);
007ec26c
DH		 404 if (!strchr(fmt, '%')) {
405 p = fmt;
406 goto unformatted_string;
e7582e16 407 }
007ec26c
DH		 408 if (strcmp(fmt, "%s") == 0) {
409 p = va_arg(va, const char *);
410 goto unformatted_string;
411 }
412
413 q = kvasprintf(GFP_KERNEL, fmt, va);
414copied_string:
415 if (!q)
416 goto store_failure;
417 freeable = 1;
418 goto store_string;
419
420unformatted_string:
421 if ((unsigned long)p >= (unsigned long)__start_rodata &&
422 (unsigned long)p < (unsigned long)__end_rodata)
423 goto const_string;
424 if (log && within_module_core((unsigned long)p, log->owner))
425 goto const_string;
426 q = kstrdup(p, GFP_KERNEL);
427 goto copied_string;
428
429store_failure:
430 p = store_failure;
431const_string:
432 q = (char *)p;
433 freeable = 0;
434store_string:
435 if (!log) {
436 switch (fmt[0]) {
437 case 'w':
438 printk(KERN_WARNING "%s\n", q + 2);
439 break;
440 case 'e':
441 printk(KERN_ERR "%s\n", q + 2);
442 break;
443 default:
444 printk(KERN_NOTICE "%s\n", q + 2);
445 break;
446 }
447 if (freeable)
448 kfree(q);
449 } else {
450 unsigned int logsize = ARRAY_SIZE(log->buffer);
451 u8 index;
452
453 index = log->head & (logsize - 1);
454 BUILD_BUG_ON(sizeof(log->head) != sizeof(u8) ||
455 sizeof(log->tail) != sizeof(u8));
456 if ((u8)(log->head - log->tail) == logsize) {
457 /* The buffer is full, discard the oldest message */
458 if (log->need_free & (1 << index))
459 kfree(log->buffer[index]);
460 log->tail++;
461 }
e7582e16 462
007ec26c
DH		 463 log->buffer[index] = q;
464 log->need_free &= ~(1 << index);
465 log->need_free |= freeable << index;
466 log->head++;
467 }
e7582e16
DH		 468 va_end(va);
469}
470EXPORT_SYMBOL(logfc);
007ec26c
DH		 471
472/*
473 * Free a logging structure.
474 */
475static void put_fc_log(struct fs_context *fc)
476{
477 struct fc_log *log = fc->log;
478 int i;
479
480 if (log) {
481 if (refcount_dec_and_test(&log->usage)) {
482 fc->log = NULL;
483 for (i = 0; i <= 7; i++)
484 if (log->need_free & (1 << i))
485 kfree(log->buffer[i]);
486 kfree(log);
487 }
488 }
489}
e7582e16 490
9bc61ab1
DH		 491/**
492 * put_fs_context - Dispose of a superblock configuration context.
493 * @fc: The context to dispose of.
494 */
495void put_fs_context(struct fs_context *fc)
496{
497 struct super_block *sb;
498
499 if (fc->root) {
500 sb = fc->root->d_sb;
501 dput(fc->root);
502 fc->root = NULL;
503 deactivate_super(sb);
504 }
505
f3a09c92
AV		 506 if (fc->need_free && fc->ops && fc->ops->free)
507 fc->ops->free(fc);
9bc61ab1
DH		 508
509 security_free_mnt_opts(&fc->security);
8d0347f6 510 put_net(fc->net_ns);
9bc61ab1
DH		 511 put_user_ns(fc->user_ns);
512 put_cred(fc->cred);
513 kfree(fc->subtype);
007ec26c 514 put_fc_log(fc);
9bc61ab1
DH		 515 put_filesystem(fc->fs_type);
516 kfree(fc->source);
517 kfree(fc);
518}
519EXPORT_SYMBOL(put_fs_context);
520
521/*
522 * Free the config for a filesystem that doesn't support fs_context.
523 */
524static void legacy_fs_context_free(struct fs_context *fc)
525{
3e1aeb00
DH		 526 struct legacy_fs_context *ctx = fc->fs_private;
527
528 if (ctx) {
529 if (ctx->param_type == LEGACY_FS_INDIVIDUAL_PARAMS)
530 kfree(ctx->legacy_data);
531 kfree(ctx);
532 }
533}
534
0b52075e
AV		 535/*
536 * Duplicate a legacy config.
537 */
538static int legacy_fs_context_dup(struct fs_context *fc, struct fs_context *src_fc)
539{
540 struct legacy_fs_context *ctx;
541 struct legacy_fs_context *src_ctx = src_fc->fs_private;
542
543 ctx = kmemdup(src_ctx, sizeof(*src_ctx), GFP_KERNEL);
544 if (!ctx)
545 return -ENOMEM;
546
547 if (ctx->param_type == LEGACY_FS_INDIVIDUAL_PARAMS) {
548 ctx->legacy_data = kmemdup(src_ctx->legacy_data,
549 src_ctx->data_size, GFP_KERNEL);
550 if (!ctx->legacy_data) {
551 kfree(ctx);
552 return -ENOMEM;
553 }
554 }
555
556 fc->fs_private = ctx;
557 return 0;
558}
559
3e1aeb00
DH		 560/*
561 * Add a parameter to a legacy config. We build up a comma-separated list of
562 * options.
563 */
564static int legacy_parse_param(struct fs_context *fc, struct fs_parameter *param)
565{
566 struct legacy_fs_context *ctx = fc->fs_private;
567 unsigned int size = ctx->data_size;
568 size_t len = 0;
569
570 if (strcmp(param->key, "source") == 0) {
571 if (param->type != fs_value_is_string)
572 return invalf(fc, "VFS: Legacy: Non-string source");
573 if (fc->source)
574 return invalf(fc, "VFS: Legacy: Multiple sources");
575 fc->source = param->string;
576 param->string = NULL;
577 return 0;
578 }
579
580 if ((fc->fs_type->fs_flags & FS_HAS_SUBTYPE) &&
581 strcmp(param->key, "subtype") == 0) {
582 if (param->type != fs_value_is_string)
583 return invalf(fc, "VFS: Legacy: Non-string subtype");
584 if (fc->subtype)
585 return invalf(fc, "VFS: Legacy: Multiple subtype");
586 fc->subtype = param->string;
587 param->string = NULL;
588 return 0;
589 }
590
591 if (ctx->param_type == LEGACY_FS_MONOLITHIC_PARAMS)
592 return invalf(fc, "VFS: Legacy: Can't mix monolithic and individual options");
593
594 switch (param->type) {
595 case fs_value_is_string:
596 len = 1 + param->size;
597 /* Fall through */
598 case fs_value_is_flag:
599 len += strlen(param->key);
600 break;
601 default:
602 return invalf(fc, "VFS: Legacy: Parameter type for '%s' not supported",
603 param->key);
604 }
605
606 if (len > PAGE_SIZE - 2 - size)
607 return invalf(fc, "VFS: Legacy: Cumulative options too large");
608 if (strchr(param->key, ',') ||
609 (param->type == fs_value_is_string &&
610 memchr(param->string, ',', param->size)))
611 return invalf(fc, "VFS: Legacy: Option '%s' contained comma",
612 param->key);
613 if (!ctx->legacy_data) {
614 ctx->legacy_data = kmalloc(PAGE_SIZE, GFP_KERNEL);
615 if (!ctx->legacy_data)
616 return -ENOMEM;
617 }
618
619 ctx->legacy_data[size++] = ',';
620 len = strlen(param->key);
621 memcpy(ctx->legacy_data + size, param->key, len);
622 size += len;
623 if (param->type == fs_value_is_string) {
624 ctx->legacy_data[size++] = '=';
625 memcpy(ctx->legacy_data + size, param->string, param->size);
626 size += param->size;
627 }
628 ctx->legacy_data[size] = '\0';
629 ctx->data_size = size;
630 ctx->param_type = LEGACY_FS_INDIVIDUAL_PARAMS;
631 return 0;
9bc61ab1
DH		 632}
633
634/*
635 * Add monolithic mount data.
636 */
637static int legacy_parse_monolithic(struct fs_context *fc, void *data)
638{
639 struct legacy_fs_context *ctx = fc->fs_private;
3e1aeb00
DH		 640
641 if (ctx->param_type != LEGACY_FS_UNSET_PARAMS) {
642 pr_warn("VFS: Can't mix monolithic and individual options\n");
643 return -EINVAL;
644 }
645
9bc61ab1 646 ctx->legacy_data = data;
3e1aeb00 647 ctx->param_type = LEGACY_FS_MONOLITHIC_PARAMS;
9bc61ab1
DH		 648 if (!ctx->legacy_data)
649 return 0;
3e1aeb00 650
9bc61ab1
DH		 651 if (fc->fs_type->fs_flags & FS_BINARY_MOUNTDATA)
652 return 0;
653 return security_sb_eat_lsm_opts(ctx->legacy_data, &fc->security);
654}
655
656/*
657 * Get a mountable root with the legacy mount command.
658 */
f3a09c92 659static int legacy_get_tree(struct fs_context *fc)
9bc61ab1
DH		 660{
661 struct legacy_fs_context *ctx = fc->fs_private;
662 struct super_block *sb;
663 struct dentry *root;
664
665 root = fc->fs_type->mount(fc->fs_type, fc->sb_flags,
666 fc->source, ctx->legacy_data);
667 if (IS_ERR(root))
668 return PTR_ERR(root);
669
670 sb = root->d_sb;
671 BUG_ON(!sb);
672
673 fc->root = root;
674 return 0;
675}
676
8d0347f6
DH		 677/*
678 * Handle remount.
679 */
f3a09c92 680static int legacy_reconfigure(struct fs_context *fc)
8d0347f6
DH		 681{
682 struct legacy_fs_context *ctx = fc->fs_private;
683 struct super_block *sb = fc->root->d_sb;
684
685 if (!sb->s_op->remount_fs)
686 return 0;
687
688 return sb->s_op->remount_fs(sb, &fc->sb_flags,
689 ctx ? ctx->legacy_data : NULL);
690}
691
f3a09c92
AV		 692const struct fs_context_operations legacy_fs_context_ops = {
693 .free = legacy_fs_context_free,
0b52075e 694 .dup = legacy_fs_context_dup,
3e1aeb00 695 .parse_param = legacy_parse_param,
f3a09c92
AV		 696 .parse_monolithic = legacy_parse_monolithic,
697 .get_tree = legacy_get_tree,
698 .reconfigure = legacy_reconfigure,
699};
700
9bc61ab1
DH		 701/*
702 * Initialise a legacy context for a filesystem that doesn't support
703 * fs_context.
704 */
705static int legacy_init_fs_context(struct fs_context *fc)
706{
707 fc->fs_private = kzalloc(sizeof(struct legacy_fs_context), GFP_KERNEL);
708 if (!fc->fs_private)
709 return -ENOMEM;
f3a09c92 710 fc->ops = &legacy_fs_context_ops;
9bc61ab1
DH		 711 return 0;
712}
713
714int parse_monolithic_mount_data(struct fs_context *fc, void *data)
715{
f3a09c92 716 int (*monolithic_mount_data)(struct fs_context *, void *);
3e1aeb00 717
f3a09c92 718 monolithic_mount_data = fc->ops->parse_monolithic;
3e1aeb00
DH		 719 if (!monolithic_mount_data)
720 monolithic_mount_data = generic_parse_monolithic;
721
f3a09c92 722 return monolithic_mount_data(fc, data);
9bc61ab1 723}
ecdab150
DH		 724
725/*
726 * Clean up a context after performing an action on it and put it into a state
727 * from where it can be used to reconfigure a superblock.
728 *
729 * Note that here we do only the parts that can't fail; the rest is in
730 * finish_clean_context() below and in between those fs_context is marked
731 * FS_CONTEXT_AWAITING_RECONF. The reason for splitup is that after
732 * successful mount or remount we need to report success to userland.
733 * Trying to do full reinit (for the sake of possible subsequent remount)
734 * and failing to allocate memory would've put us into a nasty situation.
735 * So here we only discard the old state and reinitialization is left
736 * until we actually try to reconfigure.
737 */
738void vfs_clean_context(struct fs_context *fc)
739{
740 if (fc->need_free && fc->ops && fc->ops->free)
741 fc->ops->free(fc);
742 fc->need_free = false;
743 fc->fs_private = NULL;
744 fc->s_fs_info = NULL;
745 fc->sb_flags = 0;
746 security_free_mnt_opts(&fc->security);
747 kfree(fc->subtype);
748 fc->subtype = NULL;
749 kfree(fc->source);
750 fc->source = NULL;
751
752 fc->purpose = FS_CONTEXT_FOR_RECONFIGURE;
753 fc->phase = FS_CONTEXT_AWAITING_RECONF;
754}
755
756int finish_clean_context(struct fs_context *fc)
757{
758 int error;
759
760 if (fc->phase != FS_CONTEXT_AWAITING_RECONF)
761 return 0;
762
763 if (fc->fs_type->init_fs_context)
764 error = fc->fs_type->init_fs_context(fc);
765 else
766 error = legacy_init_fs_context(fc);
767 if (unlikely(error)) {
768 fc->phase = FS_CONTEXT_FAILED;
769 return error;
770 }
771 fc->need_free = true;
772 fc->phase = FS_CONTEXT_RECONF_PARAMS;
773 return 0;
774}
Linux 6.x block layer and io_uring tree(s)