xref: /linux/fs/erofs/super.c (revision f788bb2fb915a79eae0a160580766ba52984d61f) 
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Copyright (C) 2017-2018 HUAWEI, Inc.
4  *             http://www.huawei.com/
5  * Created by Gao Xiang <gaoxiang25@huawei.com>
6  */
7 #include <linux/module.h>
8 #include <linux/buffer_head.h>
9 #include <linux/statfs.h>
10 #include <linux/parser.h>
11 #include <linux/seq_file.h>
12 #include <linux/crc32c.h>
13 #include <linux/fs_context.h>
14 #include <linux/fs_parser.h>
15 #include "xattr.h"
16 
17 #define CREATE_TRACE_POINTS
18 #include <trace/events/erofs.h>
19 
20 static struct kmem_cache *erofs_inode_cachep __read_mostly;
21 
22 void _erofs_err(struct super_block *sb, const char *function,
23 		const char *fmt, ...)
24 {
25 	struct va_format vaf;
26 	va_list args;
27 
28 	va_start(args, fmt);
29 
30 	vaf.fmt = fmt;
31 	vaf.va = &args;
32 
33 	pr_err("(device %s): %s: %pV", sb->s_id, function, &vaf);
34 	va_end(args);
35 }
36 
37 void _erofs_info(struct super_block *sb, const char *function,
38 		 const char *fmt, ...)
39 {
40 	struct va_format vaf;
41 	va_list args;
42 
43 	va_start(args, fmt);
44 
45 	vaf.fmt = fmt;
46 	vaf.va = &args;
47 
48 	pr_info("(device %s): %pV", sb->s_id, &vaf);
49 	va_end(args);
50 }
51 
52 static int erofs_superblock_csum_verify(struct super_block *sb, void *sbdata)
53 {
54 	struct erofs_super_block *dsb;
55 	u32 expected_crc, crc;
56 
57 	dsb = kmemdup(sbdata + EROFS_SUPER_OFFSET,
58 		      EROFS_BLKSIZ - EROFS_SUPER_OFFSET, GFP_KERNEL);
59 	if (!dsb)
60 		return -ENOMEM;
61 
62 	expected_crc = le32_to_cpu(dsb->checksum);
63 	dsb->checksum = 0;
64 	/* to allow for x86 boot sectors and other oddities. */
65 	crc = crc32c(~0, dsb, EROFS_BLKSIZ - EROFS_SUPER_OFFSET);
66 	kfree(dsb);
67 
68 	if (crc != expected_crc) {
69 		erofs_err(sb, "invalid checksum 0x%08x, 0x%08x expected",
70 			  crc, expected_crc);
71 		return -EBADMSG;
72 	}
73 	return 0;
74 }
75 
76 static void erofs_inode_init_once(void *ptr)
77 {
78 	struct erofs_inode *vi = ptr;
79 
80 	inode_init_once(&vi->vfs_inode);
81 }
82 
83 static struct inode *erofs_alloc_inode(struct super_block *sb)
84 {
85 	struct erofs_inode *vi =
86 		kmem_cache_alloc(erofs_inode_cachep, GFP_KERNEL);
87 
88 	if (!vi)
89 		return NULL;
90 
91 	/* zero out everything except vfs_inode */
92 	memset(vi, 0, offsetof(struct erofs_inode, vfs_inode));
93 	return &vi->vfs_inode;
94 }
95 
96 static void erofs_free_inode(struct inode *inode)
97 {
98 	struct erofs_inode *vi = EROFS_I(inode);
99 
100 	/* be careful of RCU symlink path */
101 	if (inode->i_op == &erofs_fast_symlink_iops)
102 		kfree(inode->i_link);
103 	kfree(vi->xattr_shared_xattrs);
104 
105 	kmem_cache_free(erofs_inode_cachep, vi);
106 }
107 
108 static bool check_layout_compatibility(struct super_block *sb,
109 				       struct erofs_super_block *dsb)
110 {
111 	const unsigned int feature = le32_to_cpu(dsb->feature_incompat);
112 
113 	EROFS_SB(sb)->feature_incompat = feature;
114 
115 	/* check if current kernel meets all mandatory requirements */
116 	if (feature & (~EROFS_ALL_FEATURE_INCOMPAT)) {
117 		erofs_err(sb,
118 			  "unidentified incompatible feature %x, please upgrade kernel version",
119 			   feature & ~EROFS_ALL_FEATURE_INCOMPAT);
120 		return false;
121 	}
122 	return true;
123 }
124 
125 static int erofs_read_superblock(struct super_block *sb)
126 {
127 	struct erofs_sb_info *sbi;
128 	struct page *page;
129 	struct erofs_super_block *dsb;
130 	unsigned int blkszbits;
131 	void *data;
132 	int ret;
133 
134 	page = read_mapping_page(sb->s_bdev->bd_inode->i_mapping, 0, NULL);
135 	if (IS_ERR(page)) {
136 		erofs_err(sb, "cannot read erofs superblock");
137 		return PTR_ERR(page);
138 	}
139 
140 	sbi = EROFS_SB(sb);
141 
142 	data = kmap(page);
143 	dsb = (struct erofs_super_block *)(data + EROFS_SUPER_OFFSET);
144 
145 	ret = -EINVAL;
146 	if (le32_to_cpu(dsb->magic) != EROFS_SUPER_MAGIC_V1) {
147 		erofs_err(sb, "cannot find valid erofs superblock");
148 		goto out;
149 	}
150 
151 	sbi->feature_compat = le32_to_cpu(dsb->feature_compat);
152 	if (sbi->feature_compat & EROFS_FEATURE_COMPAT_SB_CHKSUM) {
153 		ret = erofs_superblock_csum_verify(sb, data);
154 		if (ret)
155 			goto out;
156 	}
157 
158 	blkszbits = dsb->blkszbits;
159 	/* 9(512 bytes) + LOG_SECTORS_PER_BLOCK == LOG_BLOCK_SIZE */
160 	if (blkszbits != LOG_BLOCK_SIZE) {
161 		erofs_err(sb, "blksize %u isn't supported on this platform",
162 			  1 << blkszbits);
163 		goto out;
164 	}
165 
166 	if (!check_layout_compatibility(sb, dsb))
167 		goto out;
168 
169 	sbi->blocks = le32_to_cpu(dsb->blocks);
170 	sbi->meta_blkaddr = le32_to_cpu(dsb->meta_blkaddr);
171 #ifdef CONFIG_EROFS_FS_XATTR
172 	sbi->xattr_blkaddr = le32_to_cpu(dsb->xattr_blkaddr);
173 #endif
174 	sbi->islotbits = ilog2(sizeof(struct erofs_inode_compact));
175 	sbi->root_nid = le16_to_cpu(dsb->root_nid);
176 	sbi->inos = le64_to_cpu(dsb->inos);
177 
178 	sbi->build_time = le64_to_cpu(dsb->build_time);
179 	sbi->build_time_nsec = le32_to_cpu(dsb->build_time_nsec);
180 
181 	memcpy(&sb->s_uuid, dsb->uuid, sizeof(dsb->uuid));
182 
183 	ret = strscpy(sbi->volume_name, dsb->volume_name,
184 		      sizeof(dsb->volume_name));
185 	if (ret < 0) {	/* -E2BIG */
186 		erofs_err(sb, "bad volume name without NIL terminator");
187 		ret = -EFSCORRUPTED;
188 		goto out;
189 	}
190 	ret = 0;
191 out:
192 	kunmap(page);
193 	put_page(page);
194 	return ret;
195 }
196 
197 /* set up default EROFS parameters */
198 static void erofs_default_options(struct erofs_fs_context *ctx)
199 {
200 #ifdef CONFIG_EROFS_FS_ZIP
201 	ctx->cache_strategy = EROFS_ZIP_CACHE_READAROUND;
202 	ctx->max_sync_decompress_pages = 3;
203 #endif
204 #ifdef CONFIG_EROFS_FS_XATTR
205 	set_opt(ctx, XATTR_USER);
206 #endif
207 #ifdef CONFIG_EROFS_FS_POSIX_ACL
208 	set_opt(ctx, POSIX_ACL);
209 #endif
210 }
211 
212 enum {
213 	Opt_user_xattr,
214 	Opt_nouser_xattr,
215 	Opt_acl,
216 	Opt_noacl,
217 	Opt_cache_strategy,
218 	Opt_err
219 };
220 
221 static const struct constant_table erofs_param_cache_strategy[] = {
222 	{"disabled",	EROFS_ZIP_CACHE_DISABLED},
223 	{"readahead",	EROFS_ZIP_CACHE_READAHEAD},
224 	{"readaround",	EROFS_ZIP_CACHE_READAROUND},
225 	{}
226 };
227 
228 static const struct fs_parameter_spec erofs_fs_parameters[] = {
229 	fsparam_flag_no("user_xattr",	Opt_user_xattr),
230 	fsparam_flag_no("acl",		Opt_acl),
231 	fsparam_enum("cache_strategy",	Opt_cache_strategy,
232 		     erofs_param_cache_strategy),
233 	{}
234 };
235 
236 static int erofs_fc_parse_param(struct fs_context *fc,
237 				struct fs_parameter *param)
238 {
239 	struct erofs_fs_context *ctx __maybe_unused = fc->fs_private;
240 	struct fs_parse_result result;
241 	int opt;
242 
243 	opt = fs_parse(fc, erofs_fs_parameters, param, &result);
244 	if (opt < 0)
245 		return opt;
246 
247 	switch (opt) {
248 	case Opt_user_xattr:
249 #ifdef CONFIG_EROFS_FS_XATTR
250 		if (result.boolean)
251 			set_opt(ctx, XATTR_USER);
252 		else
253 			clear_opt(ctx, XATTR_USER);
254 #else
255 		errorfc(fc, "{,no}user_xattr options not supported");
256 #endif
257 		break;
258 	case Opt_acl:
259 #ifdef CONFIG_EROFS_FS_POSIX_ACL
260 		if (result.boolean)
261 			set_opt(ctx, POSIX_ACL);
262 		else
263 			clear_opt(ctx, POSIX_ACL);
264 #else
265 		errorfc(fc, "{,no}acl options not supported");
266 #endif
267 		break;
268 	case Opt_cache_strategy:
269 #ifdef CONFIG_EROFS_FS_ZIP
270 		ctx->cache_strategy = result.uint_32;
271 #else
272 		errorfc(fc, "compression not supported, cache_strategy ignored");
273 #endif
274 		break;
275 	default:
276 		return -ENOPARAM;
277 	}
278 	return 0;
279 }
280 
281 #ifdef CONFIG_EROFS_FS_ZIP
282 static const struct address_space_operations managed_cache_aops;
283 
284 static int erofs_managed_cache_releasepage(struct page *page, gfp_t gfp_mask)
285 {
286 	int ret = 1;	/* 0 - busy */
287 	struct address_space *const mapping = page->mapping;
288 
289 	DBG_BUGON(!PageLocked(page));
290 	DBG_BUGON(mapping->a_ops != &managed_cache_aops);
291 
292 	if (PagePrivate(page))
293 		ret = erofs_try_to_free_cached_page(mapping, page);
294 
295 	return ret;
296 }
297 
298 static void erofs_managed_cache_invalidatepage(struct page *page,
299 					       unsigned int offset,
300 					       unsigned int length)
301 {
302 	const unsigned int stop = length + offset;
303 
304 	DBG_BUGON(!PageLocked(page));
305 
306 	/* Check for potential overflow in debug mode */
307 	DBG_BUGON(stop > PAGE_SIZE || stop < length);
308 
309 	if (offset == 0 && stop == PAGE_SIZE)
310 		while (!erofs_managed_cache_releasepage(page, GFP_NOFS))
311 			cond_resched();
312 }
313 
314 static const struct address_space_operations managed_cache_aops = {
315 	.releasepage = erofs_managed_cache_releasepage,
316 	.invalidatepage = erofs_managed_cache_invalidatepage,
317 };
318 
319 static int erofs_init_managed_cache(struct super_block *sb)
320 {
321 	struct erofs_sb_info *const sbi = EROFS_SB(sb);
322 	struct inode *const inode = new_inode(sb);
323 
324 	if (!inode)
325 		return -ENOMEM;
326 
327 	set_nlink(inode, 1);
328 	inode->i_size = OFFSET_MAX;
329 
330 	inode->i_mapping->a_ops = &managed_cache_aops;
331 	mapping_set_gfp_mask(inode->i_mapping,
332 			     GFP_NOFS | __GFP_HIGHMEM | __GFP_MOVABLE);
333 	sbi->managed_cache = inode;
334 	return 0;
335 }
336 #else
337 static int erofs_init_managed_cache(struct super_block *sb) { return 0; }
338 #endif
339 
340 static int erofs_fc_fill_super(struct super_block *sb, struct fs_context *fc)
341 {
342 	struct inode *inode;
343 	struct erofs_sb_info *sbi;
344 	struct erofs_fs_context *ctx = fc->fs_private;
345 	int err;
346 
347 	sb->s_magic = EROFS_SUPER_MAGIC;
348 
349 	if (!sb_set_blocksize(sb, EROFS_BLKSIZ)) {
350 		erofs_err(sb, "failed to set erofs blksize");
351 		return -EINVAL;
352 	}
353 
354 	sbi = kzalloc(sizeof(*sbi), GFP_KERNEL);
355 	if (!sbi)
356 		return -ENOMEM;
357 
358 	sb->s_fs_info = sbi;
359 	err = erofs_read_superblock(sb);
360 	if (err)
361 		return err;
362 
363 	sb->s_flags |= SB_RDONLY | SB_NOATIME;
364 	sb->s_maxbytes = MAX_LFS_FILESIZE;
365 	sb->s_time_gran = 1;
366 
367 	sb->s_op = &erofs_sops;
368 	sb->s_xattr = erofs_xattr_handlers;
369 
370 	if (test_opt(ctx, POSIX_ACL))
371 		sb->s_flags |= SB_POSIXACL;
372 	else
373 		sb->s_flags &= ~SB_POSIXACL;
374 
375 	sbi->ctx = *ctx;
376 
377 #ifdef CONFIG_EROFS_FS_ZIP
378 	xa_init(&sbi->managed_pslots);
379 #endif
380 
381 	/* get the root inode */
382 	inode = erofs_iget(sb, ROOT_NID(sbi), true);
383 	if (IS_ERR(inode))
384 		return PTR_ERR(inode);
385 
386 	if (!S_ISDIR(inode->i_mode)) {
387 		erofs_err(sb, "rootino(nid %llu) is not a directory(i_mode %o)",
388 			  ROOT_NID(sbi), inode->i_mode);
389 		iput(inode);
390 		return -EINVAL;
391 	}
392 
393 	sb->s_root = d_make_root(inode);
394 	if (!sb->s_root)
395 		return -ENOMEM;
396 
397 	erofs_shrinker_register(sb);
398 	/* sb->s_umount is already locked, SB_ACTIVE and SB_BORN are not set */
399 	err = erofs_init_managed_cache(sb);
400 	if (err)
401 		return err;
402 
403 	erofs_info(sb, "mounted with root inode @ nid %llu.", ROOT_NID(sbi));
404 	return 0;
405 }
406 
407 static int erofs_fc_get_tree(struct fs_context *fc)
408 {
409 	return get_tree_bdev(fc, erofs_fc_fill_super);
410 }
411 
412 static int erofs_fc_reconfigure(struct fs_context *fc)
413 {
414 	struct super_block *sb = fc->root->d_sb;
415 	struct erofs_sb_info *sbi = EROFS_SB(sb);
416 	struct erofs_fs_context *ctx = fc->fs_private;
417 
418 	DBG_BUGON(!sb_rdonly(sb));
419 
420 	if (test_opt(ctx, POSIX_ACL))
421 		fc->sb_flags |= SB_POSIXACL;
422 	else
423 		fc->sb_flags &= ~SB_POSIXACL;
424 
425 	sbi->ctx = *ctx;
426 
427 	fc->sb_flags |= SB_RDONLY;
428 	return 0;
429 }
430 
431 static void erofs_fc_free(struct fs_context *fc)
432 {
433 	kfree(fc->fs_private);
434 }
435 
436 static const struct fs_context_operations erofs_context_ops = {
437 	.parse_param	= erofs_fc_parse_param,
438 	.get_tree       = erofs_fc_get_tree,
439 	.reconfigure    = erofs_fc_reconfigure,
440 	.free		= erofs_fc_free,
441 };
442 
443 static int erofs_init_fs_context(struct fs_context *fc)
444 {
445 	fc->fs_private = kzalloc(sizeof(struct erofs_fs_context), GFP_KERNEL);
446 	if (!fc->fs_private)
447 		return -ENOMEM;
448 
449 	/* set default mount options */
450 	erofs_default_options(fc->fs_private);
451 
452 	fc->ops = &erofs_context_ops;
453 
454 	return 0;
455 }
456 
457 /*
458  * could be triggered after deactivate_locked_super()
459  * is called, thus including umount and failed to initialize.
460  */
461 static void erofs_kill_sb(struct super_block *sb)
462 {
463 	struct erofs_sb_info *sbi;
464 
465 	WARN_ON(sb->s_magic != EROFS_SUPER_MAGIC);
466 
467 	kill_block_super(sb);
468 
469 	sbi = EROFS_SB(sb);
470 	if (!sbi)
471 		return;
472 	kfree(sbi);
473 	sb->s_fs_info = NULL;
474 }
475 
476 /* called when ->s_root is non-NULL */
477 static void erofs_put_super(struct super_block *sb)
478 {
479 	struct erofs_sb_info *const sbi = EROFS_SB(sb);
480 
481 	DBG_BUGON(!sbi);
482 
483 	erofs_shrinker_unregister(sb);
484 #ifdef CONFIG_EROFS_FS_ZIP
485 	iput(sbi->managed_cache);
486 	sbi->managed_cache = NULL;
487 #endif
488 }
489 
490 static struct file_system_type erofs_fs_type = {
491 	.owner          = THIS_MODULE,
492 	.name           = "erofs",
493 	.init_fs_context = erofs_init_fs_context,
494 	.kill_sb        = erofs_kill_sb,
495 	.fs_flags       = FS_REQUIRES_DEV,
496 };
497 MODULE_ALIAS_FS("erofs");
498 
499 static int __init erofs_module_init(void)
500 {
501 	int err;
502 
503 	erofs_check_ondisk_layout_definitions();
504 
505 	erofs_inode_cachep = kmem_cache_create("erofs_inode",
506 					       sizeof(struct erofs_inode), 0,
507 					       SLAB_RECLAIM_ACCOUNT,
508 					       erofs_inode_init_once);
509 	if (!erofs_inode_cachep) {
510 		err = -ENOMEM;
511 		goto icache_err;
512 	}
513 
514 	err = erofs_init_shrinker();
515 	if (err)
516 		goto shrinker_err;
517 
518 	err = z_erofs_init_zip_subsystem();
519 	if (err)
520 		goto zip_err;
521 
522 	err = register_filesystem(&erofs_fs_type);
523 	if (err)
524 		goto fs_err;
525 
526 	return 0;
527 
528 fs_err:
529 	z_erofs_exit_zip_subsystem();
530 zip_err:
531 	erofs_exit_shrinker();
532 shrinker_err:
533 	kmem_cache_destroy(erofs_inode_cachep);
534 icache_err:
535 	return err;
536 }
537 
538 static void __exit erofs_module_exit(void)
539 {
540 	unregister_filesystem(&erofs_fs_type);
541 	z_erofs_exit_zip_subsystem();
542 	erofs_exit_shrinker();
543 
544 	/* Ensure all RCU free inodes are safe before cache is destroyed. */
545 	rcu_barrier();
546 	kmem_cache_destroy(erofs_inode_cachep);
547 }
548 
549 /* get filesystem statistics */
550 static int erofs_statfs(struct dentry *dentry, struct kstatfs *buf)
551 {
552 	struct super_block *sb = dentry->d_sb;
553 	struct erofs_sb_info *sbi = EROFS_SB(sb);
554 	u64 id = huge_encode_dev(sb->s_bdev->bd_dev);
555 
556 	buf->f_type = sb->s_magic;
557 	buf->f_bsize = EROFS_BLKSIZ;
558 	buf->f_blocks = sbi->blocks;
559 	buf->f_bfree = buf->f_bavail = 0;
560 
561 	buf->f_files = ULLONG_MAX;
562 	buf->f_ffree = ULLONG_MAX - sbi->inos;
563 
564 	buf->f_namelen = EROFS_NAME_LEN;
565 
566 	buf->f_fsid.val[0] = (u32)id;
567 	buf->f_fsid.val[1] = (u32)(id >> 32);
568 	return 0;
569 }
570 
571 static int erofs_show_options(struct seq_file *seq, struct dentry *root)
572 {
573 	struct erofs_sb_info *sbi __maybe_unused = EROFS_SB(root->d_sb);
574 	struct erofs_fs_context *ctx __maybe_unused = &sbi->ctx;
575 
576 #ifdef CONFIG_EROFS_FS_XATTR
577 	if (test_opt(ctx, XATTR_USER))
578 		seq_puts(seq, ",user_xattr");
579 	else
580 		seq_puts(seq, ",nouser_xattr");
581 #endif
582 #ifdef CONFIG_EROFS_FS_POSIX_ACL
583 	if (test_opt(ctx, POSIX_ACL))
584 		seq_puts(seq, ",acl");
585 	else
586 		seq_puts(seq, ",noacl");
587 #endif
588 #ifdef CONFIG_EROFS_FS_ZIP
589 	if (ctx->cache_strategy == EROFS_ZIP_CACHE_DISABLED)
590 		seq_puts(seq, ",cache_strategy=disabled");
591 	else if (ctx->cache_strategy == EROFS_ZIP_CACHE_READAHEAD)
592 		seq_puts(seq, ",cache_strategy=readahead");
593 	else if (ctx->cache_strategy == EROFS_ZIP_CACHE_READAROUND)
594 		seq_puts(seq, ",cache_strategy=readaround");
595 #endif
596 	return 0;
597 }
598 
599 const struct super_operations erofs_sops = {
600 	.put_super = erofs_put_super,
601 	.alloc_inode = erofs_alloc_inode,
602 	.free_inode = erofs_free_inode,
603 	.statfs = erofs_statfs,
604 	.show_options = erofs_show_options,
605 };
606 
607 module_init(erofs_module_init);
608 module_exit(erofs_module_exit);
609 
610 MODULE_DESCRIPTION("Enhanced ROM File System");
611 MODULE_AUTHOR("Gao Xiang, Chao Yu, Miao Xie, CONSUMER BG, HUAWEI Inc.");
612 MODULE_LICENSE("GPL");
613 
614