summaryrefslogtreecommitdiff
path: root/fs/erofs/super.c
blob: b9a09806512aeea1af714041af57091c02437cae (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2017-2018 HUAWEI, Inc.
 *             https://www.huawei.com/
 * Created by Gao Xiang <gaoxiang25@huawei.com>
 */
#include <linux/module.h>
#include <linux/buffer_head.h>
#include <linux/statfs.h>
#include <linux/parser.h>
#include <linux/seq_file.h>
#include <linux/crc32c.h>
#include <linux/fs_context.h>
#include <linux/fs_parser.h>
#include "xattr.h"

#define CREATE_TRACE_POINTS
#include <trace/events/erofs.h>

static struct kmem_cache *erofs_inode_cachep __read_mostly;

void _erofs_err(struct super_block *sb, const char *function,
		const char *fmt, ...)
{
	struct va_format vaf;
	va_list args;

	va_start(args, fmt);

	vaf.fmt = fmt;
	vaf.va = &args;

	pr_err("(device %s): %s: %pV", sb->s_id, function, &vaf);
	va_end(args);
}

void _erofs_info(struct super_block *sb, const char *function,
		 const char *fmt, ...)
{
	struct va_format vaf;
	va_list args;

	va_start(args, fmt);

	vaf.fmt = fmt;
	vaf.va = &args;

	pr_info("(device %s): %pV", sb->s_id, &vaf);
	va_end(args);
}

static int erofs_superblock_csum_verify(struct super_block *sb, void *sbdata)
{
	struct erofs_super_block *dsb;
	u32 expected_crc, crc;

	dsb = kmemdup(sbdata + EROFS_SUPER_OFFSET,
		      EROFS_BLKSIZ - EROFS_SUPER_OFFSET, GFP_KERNEL);
	if (!dsb)
		return -ENOMEM;

	expected_crc = le32_to_cpu(dsb->checksum);
	dsb->checksum = 0;
	/* to allow for x86 boot sectors and other oddities. */
	crc = crc32c(~0, dsb, EROFS_BLKSIZ - EROFS_SUPER_OFFSET);
	kfree(dsb);

	if (crc != expected_crc) {
		erofs_err(sb, "invalid checksum 0x%08x, 0x%08x expected",
			  crc, expected_crc);
		return -EBADMSG;
	}
	return 0;
}

static void erofs_inode_init_once(void *ptr)
{
	struct erofs_inode *vi = ptr;

	inode_init_once(&vi->vfs_inode);
}

static struct inode *erofs_alloc_inode(struct super_block *sb)
{
	struct erofs_inode *vi =
		kmem_cache_alloc(erofs_inode_cachep, GFP_KERNEL);

	if (!vi)
		return NULL;

	/* zero out everything except vfs_inode */
	memset(vi, 0, offsetof(struct erofs_inode, vfs_inode));
	return &vi->vfs_inode;
}

static void erofs_free_inode(struct inode *inode)
{
	struct erofs_inode *vi = EROFS_I(inode);

	/* be careful of RCU symlink path */
	if (inode->i_op == &erofs_fast_symlink_iops)
		kfree(inode->i_link);
	kfree(vi->xattr_shared_xattrs);

	kmem_cache_free(erofs_inode_cachep, vi);
}

static bool check_layout_compatibility(struct super_block *sb,
				       struct erofs_super_block *dsb)
{
	const unsigned int feature = le32_to_cpu(dsb->feature_incompat);

	EROFS_SB(sb)->feature_incompat = feature;

	/* check if current kernel meets all mandatory requirements */
	if (feature & (~EROFS_ALL_FEATURE_INCOMPAT)) {
		erofs_err(sb,
			  "unidentified incompatible feature %x, please upgrade kernel version",
			   feature & ~EROFS_ALL_FEATURE_INCOMPAT);
		return false;
	}
	return true;
}

static int erofs_read_superblock(struct super_block *sb)
{
	struct erofs_sb_info *sbi;
	struct page *page;
	struct erofs_super_block *dsb;
	unsigned int blkszbits;
	void *data;
	int ret;

	page = read_mapping_page(sb->s_bdev->bd_inode->i_mapping, 0, NULL);
	if (IS_ERR(page)) {
		erofs_err(sb, "cannot read erofs superblock");
		return PTR_ERR(page);
	}

	sbi = EROFS_SB(sb);

	data = kmap(page);
	dsb = (struct erofs_super_block *)(data + EROFS_SUPER_OFFSET);

	ret = -EINVAL;
	if (le32_to_cpu(dsb->magic) != EROFS_SUPER_MAGIC_V1) {
		erofs_err(sb, "cannot find valid erofs superblock");
		goto out;
	}

	sbi->feature_compat = le32_to_cpu(dsb->feature_compat);
	if (sbi->feature_compat & EROFS_FEATURE_COMPAT_SB_CHKSUM) {
		ret = erofs_superblock_csum_verify(sb, data);
		if (ret)
			goto out;
	}

	blkszbits = dsb->blkszbits;
	/* 9(512 bytes) + LOG_SECTORS_PER_BLOCK == LOG_BLOCK_SIZE */
	if (blkszbits != LOG_BLOCK_SIZE) {
		erofs_err(sb, "blksize %u isn't supported on this platform",
			  1 << blkszbits);
		goto out;
	}

	if (!check_layout_compatibility(sb, dsb))
		goto out;

	sbi->blocks = le32_to_cpu(dsb->blocks);
	sbi->meta_blkaddr = le32_to_cpu(dsb->meta_blkaddr);
#ifdef CONFIG_EROFS_FS_XATTR
	sbi->xattr_blkaddr = le32_to_cpu(dsb->xattr_blkaddr);
#endif
	sbi->islotbits = ilog2(sizeof(struct erofs_inode_compact));
	sbi->root_nid = le16_to_cpu(dsb->root_nid);
	sbi->inos = le64_to_cpu(dsb->inos);

	sbi->build_time = le64_to_cpu(dsb->build_time);
	sbi->build_time_nsec = le32_to_cpu(dsb->build_time_nsec);

	memcpy(&sb->s_uuid, dsb->uuid, sizeof(dsb->uuid));

	ret = strscpy(sbi->volume_name, dsb->volume_name,
		      sizeof(dsb->volume_name));
	if (ret < 0) {	/* -E2BIG */
		erofs_err(sb, "bad volume name without NIL terminator");
		ret = -EFSCORRUPTED;
		goto out;
	}
	ret = 0;
out:
	kunmap(page);
	put_page(page);
	return ret;
}

/* set up default EROFS parameters */
static void erofs_default_options(struct erofs_fs_context *ctx)
{
#ifdef CONFIG_EROFS_FS_ZIP
	ctx->cache_strategy = EROFS_ZIP_CACHE_READAROUND;
	ctx->max_sync_decompress_pages = 3;
#endif
#ifdef CONFIG_EROFS_FS_XATTR
	set_opt(ctx, XATTR_USER);
#endif
#ifdef CONFIG_EROFS_FS_POSIX_ACL
	set_opt(ctx, POSIX_ACL);
#endif
}

enum {
	Opt_user_xattr,
	Opt_acl,
	Opt_cache_strategy,
	Opt_err
};

static const struct constant_table erofs_param_cache_strategy[] = {
	{"disabled",	EROFS_ZIP_CACHE_DISABLED},
	{"readahead",	EROFS_ZIP_CACHE_READAHEAD},
	{"readaround",	EROFS_ZIP_CACHE_READAROUND},
	{}
};

static const struct fs_parameter_spec erofs_fs_parameters[] = {
	fsparam_flag_no("user_xattr",	Opt_user_xattr),
	fsparam_flag_no("acl",		Opt_acl),
	fsparam_enum("cache_strategy",	Opt_cache_strategy,
		     erofs_param_cache_strategy),
	{}
};

static int erofs_fc_parse_param(struct fs_context *fc,
				struct fs_parameter *param)
{
	struct erofs_fs_context *ctx __maybe_unused = fc->fs_private;
	struct fs_parse_result result;
	int opt;

	opt = fs_parse(fc, erofs_fs_parameters, param, &result);
	if (opt < 0)
		return opt;

	switch (opt) {
	case Opt_user_xattr:
#ifdef CONFIG_EROFS_FS_XATTR
		if (result.boolean)
			set_opt(ctx, XATTR_USER);
		else
			clear_opt(ctx, XATTR_USER);
#else
		errorfc(fc, "{,no}user_xattr options not supported");
#endif
		break;
	case Opt_acl:
#ifdef CONFIG_EROFS_FS_POSIX_ACL
		if (result.boolean)
			set_opt(ctx, POSIX_ACL);
		else
			clear_opt(ctx, POSIX_ACL);
#else
		errorfc(fc, "{,no}acl options not supported");
#endif
		break;
	case Opt_cache_strategy:
#ifdef CONFIG_EROFS_FS_ZIP
		ctx->cache_strategy = result.uint_32;
#else
		errorfc(fc, "compression not supported, cache_strategy ignored");
#endif
		break;
	default:
		return -ENOPARAM;
	}
	return 0;
}

#ifdef CONFIG_EROFS_FS_ZIP
static const struct address_space_operations managed_cache_aops;

static int erofs_managed_cache_releasepage(struct page *page, gfp_t gfp_mask)
{
	int ret = 1;	/* 0 - busy */
	struct address_space *const mapping = page->mapping;

	DBG_BUGON(!PageLocked(page));
	DBG_BUGON(mapping->a_ops != &managed_cache_aops);

	if (PagePrivate(page))
		ret = erofs_try_to_free_cached_page(mapping, page);

	return ret;
}

static void erofs_managed_cache_invalidatepage(struct page *page,
					       unsigned int offset,
					       unsigned int length)
{
	const unsigned int stop = length + offset;

	DBG_BUGON(!PageLocked(page));

	/* Check for potential overflow in debug mode */
	DBG_BUGON(stop > PAGE_SIZE || stop < length);

	if (offset == 0 && stop == PAGE_SIZE)
		while (!erofs_managed_cache_releasepage(page, GFP_NOFS))
			cond_resched();
}

static const struct address_space_operations managed_cache_aops = {
	.releasepage = erofs_managed_cache_releasepage,
	.invalidatepage = erofs_managed_cache_invalidatepage,
};

static int erofs_init_managed_cache(struct super_block *sb)
{
	struct erofs_sb_info *const sbi = EROFS_SB(sb);
	struct inode *const inode = new_inode(sb);

	if (!inode)
		return -ENOMEM;

	set_nlink(inode, 1);
	inode->i_size = OFFSET_MAX;

	inode->i_mapping->a_ops = &managed_cache_aops;
	mapping_set_gfp_mask(inode->i_mapping,
			     GFP_NOFS | __GFP_HIGHMEM | __GFP_MOVABLE);
	sbi->managed_cache = inode;
	return 0;
}
#else
static int erofs_init_managed_cache(struct super_block *sb) { return 0; }
#endif

static int erofs_fc_fill_super(struct super_block *sb, struct fs_context *fc)
{
	struct inode *inode;
	struct erofs_sb_info *sbi;
	struct erofs_fs_context *ctx = fc->fs_private;
	int err;

	sb->s_magic = EROFS_SUPER_MAGIC;

	if (!sb_set_blocksize(sb, EROFS_BLKSIZ)) {
		erofs_err(sb, "failed to set erofs blksize");
		return -EINVAL;
	}

	sbi = kzalloc(sizeof(*sbi), GFP_KERNEL);
	if (!sbi)
		return -ENOMEM;

	sb->s_fs_info = sbi;
	err = erofs_read_superblock(sb);
	if (err)
		return err;

	sb->s_flags |= SB_RDONLY | SB_NOATIME;
	sb->s_maxbytes = MAX_LFS_FILESIZE;
	sb->s_time_gran = 1;

	sb->s_op = &erofs_sops;
	sb->s_xattr = erofs_xattr_handlers;

	if (test_opt(ctx, POSIX_ACL))
		sb->s_flags |= SB_POSIXACL;
	else
		sb->s_flags &= ~SB_POSIXACL;

	sbi->ctx = *ctx;

#ifdef CONFIG_EROFS_FS_ZIP
	xa_init(&sbi->managed_pslots);
#endif

	/* get the root inode */
	inode = erofs_iget(sb, ROOT_NID(sbi), true);
	if (IS_ERR(inode))
		return PTR_ERR(inode);

	if (!S_ISDIR(inode->i_mode)) {
		erofs_err(sb, "rootino(nid %llu) is not a directory(i_mode %o)",
			  ROOT_NID(sbi), inode->i_mode);
		iput(inode);
		return -EINVAL;
	}

	sb->s_root = d_make_root(inode);
	if (!sb->s_root)
		return -ENOMEM;

	erofs_shrinker_register(sb);
	/* sb->s_umount is already locked, SB_ACTIVE and SB_BORN are not set */
	err = erofs_init_managed_cache(sb);
	if (err)
		return err;

	erofs_info(sb, "mounted with root inode @ nid %llu.", ROOT_NID(sbi));
	return 0;
}

static int erofs_fc_get_tree(struct fs_context *fc)
{
	return get_tree_bdev(fc, erofs_fc_fill_super);
}

static int erofs_fc_reconfigure(struct fs_context *fc)
{
	struct super_block *sb = fc->root->d_sb;
	struct erofs_sb_info *sbi = EROFS_SB(sb);
	struct erofs_fs_context *ctx = fc->fs_private;

	DBG_BUGON(!sb_rdonly(sb));

	if (test_opt(ctx, POSIX_ACL))
		fc->sb_flags |= SB_POSIXACL;
	else
		fc->sb_flags &= ~SB_POSIXACL;

	sbi->ctx = *ctx;

	fc->sb_flags |= SB_RDONLY;
	return 0;
}

static void erofs_fc_free(struct fs_context *fc)
{
	kfree(fc->fs_private);
}

static const struct fs_context_operations erofs_context_ops = {
	.parse_param	= erofs_fc_parse_param,
	.get_tree       = erofs_fc_get_tree,
	.reconfigure    = erofs_fc_reconfigure,
	.free		= erofs_fc_free,
};

static int erofs_init_fs_context(struct fs_context *fc)
{
	fc->fs_private = kzalloc(sizeof(struct erofs_fs_context), GFP_KERNEL);
	if (!fc->fs_private)
		return -ENOMEM;

	/* set default mount options */
	erofs_default_options(fc->fs_private);

	fc->ops = &erofs_context_ops;

	return 0;
}

/*
 * could be triggered after deactivate_locked_super()
 * is called, thus including umount and failed to initialize.
 */
static void erofs_kill_sb(struct super_block *sb)
{
	struct erofs_sb_info *sbi;

	WARN_ON(sb->s_magic != EROFS_SUPER_MAGIC);

	kill_block_super(sb);

	sbi = EROFS_SB(sb);
	if (!sbi)
		return;
	kfree(sbi);
	sb->s_fs_info = NULL;
}

/* called when ->s_root is non-NULL */
static void erofs_put_super(struct super_block *sb)
{
	struct erofs_sb_info *const sbi = EROFS_SB(sb);

	DBG_BUGON(!sbi);

	erofs_shrinker_unregister(sb);
#ifdef CONFIG_EROFS_FS_ZIP
	iput(sbi->managed_cache);
	sbi->managed_cache = NULL;
#endif
}

static struct file_system_type erofs_fs_type = {
	.owner          = THIS_MODULE,
	.name           = "erofs",
	.init_fs_context = erofs_init_fs_context,
	.kill_sb        = erofs_kill_sb,
	.fs_flags       = FS_REQUIRES_DEV,
};
MODULE_ALIAS_FS("erofs");

static int __init erofs_module_init(void)
{
	int err;

	erofs_check_ondisk_layout_definitions();

	erofs_inode_cachep = kmem_cache_create("erofs_inode",
					       sizeof(struct erofs_inode), 0,
					       SLAB_RECLAIM_ACCOUNT,
					       erofs_inode_init_once);
	if (!erofs_inode_cachep) {
		err = -ENOMEM;
		goto icache_err;
	}

	err = erofs_init_shrinker();
	if (err)
		goto shrinker_err;

	err = z_erofs_init_zip_subsystem();
	if (err)
		goto zip_err;

	err = register_filesystem(&erofs_fs_type);
	if (err)
		goto fs_err;

	return 0;

fs_err:
	z_erofs_exit_zip_subsystem();
zip_err:
	erofs_exit_shrinker();
shrinker_err:
	kmem_cache_destroy(erofs_inode_cachep);
icache_err:
	return err;
}

static void __exit erofs_module_exit(void)
{
	unregister_filesystem(&erofs_fs_type);
	z_erofs_exit_zip_subsystem();
	erofs_exit_shrinker();

	/* Ensure all RCU free inodes are safe before cache is destroyed. */
	rcu_barrier();
	kmem_cache_destroy(erofs_inode_cachep);
}

/* get filesystem statistics */
static int erofs_statfs(struct dentry *dentry, struct kstatfs *buf)
{
	struct super_block *sb = dentry->d_sb;
	struct erofs_sb_info *sbi = EROFS_SB(sb);
	u64 id = huge_encode_dev(sb->s_bdev->bd_dev);

	buf->f_type = sb->s_magic;
	buf->f_bsize = EROFS_BLKSIZ;
	buf->f_blocks = sbi->blocks;
	buf->f_bfree = buf->f_bavail = 0;

	buf->f_files = ULLONG_MAX;
	buf->f_ffree = ULLONG_MAX - sbi->inos;

	buf->f_namelen = EROFS_NAME_LEN;

	buf->f_fsid.val[0] = (u32)id;
	buf->f_fsid.val[1] = (u32)(id >> 32);
	return 0;
}

static int erofs_show_options(struct seq_file *seq, struct dentry *root)
{
	struct erofs_sb_info *sbi __maybe_unused = EROFS_SB(root->d_sb);
	struct erofs_fs_context *ctx __maybe_unused = &sbi->ctx;

#ifdef CONFIG_EROFS_FS_XATTR
	if (test_opt(ctx, XATTR_USER))
		seq_puts(seq, ",user_xattr");
	else
		seq_puts(seq, ",nouser_xattr");
#endif
#ifdef CONFIG_EROFS_FS_POSIX_ACL
	if (test_opt(ctx, POSIX_ACL))
		seq_puts(seq, ",acl");
	else
		seq_puts(seq, ",noacl");
#endif
#ifdef CONFIG_EROFS_FS_ZIP
	if (ctx->cache_strategy == EROFS_ZIP_CACHE_DISABLED)
		seq_puts(seq, ",cache_strategy=disabled");
	else if (ctx->cache_strategy == EROFS_ZIP_CACHE_READAHEAD)
		seq_puts(seq, ",cache_strategy=readahead");
	else if (ctx->cache_strategy == EROFS_ZIP_CACHE_READAROUND)
		seq_puts(seq, ",cache_strategy=readaround");
#endif
	return 0;
}

const struct super_operations erofs_sops = {
	.put_super = erofs_put_super,
	.alloc_inode = erofs_alloc_inode,
	.free_inode = erofs_free_inode,
	.statfs = erofs_statfs,
	.show_options = erofs_show_options,
};

module_init(erofs_module_init);
module_exit(erofs_module_exit);

MODULE_DESCRIPTION("Enhanced ROM File System");
MODULE_AUTHOR("Gao Xiang, Chao Yu, Miao Xie, CONSUMER BG, HUAWEI Inc.");
MODULE_LICENSE("GPL");