xref: /linux/fs/erofs/super.c (revision 17cfcb68af3bc7d5e8ae08779b1853310a2949f3) 
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 "xattr.h"
13 
14 #define CREATE_TRACE_POINTS
15 #include <trace/events/erofs.h>
16 
17 static struct kmem_cache *erofs_inode_cachep __read_mostly;
18 
19 void _erofs_err(struct super_block *sb, const char *function,
20 		const char *fmt, ...)
21 {
22 	struct va_format vaf;
23 	va_list args;
24 
25 	va_start(args, fmt);
26 
27 	vaf.fmt = fmt;
28 	vaf.va = &args;
29 
30 	pr_err("(device %s): %s: %pV", sb->s_id, function, &vaf);
31 	va_end(args);
32 }
33 
34 void _erofs_info(struct super_block *sb, const char *function,
35 		 const char *fmt, ...)
36 {
37 	struct va_format vaf;
38 	va_list args;
39 
40 	va_start(args, fmt);
41 
42 	vaf.fmt = fmt;
43 	vaf.va = &args;
44 
45 	pr_info("(device %s): %pV", sb->s_id, &vaf);
46 	va_end(args);
47 }
48 
49 static void erofs_inode_init_once(void *ptr)
50 {
51 	struct erofs_inode *vi = ptr;
52 
53 	inode_init_once(&vi->vfs_inode);
54 }
55 
56 static struct inode *erofs_alloc_inode(struct super_block *sb)
57 {
58 	struct erofs_inode *vi =
59 		kmem_cache_alloc(erofs_inode_cachep, GFP_KERNEL);
60 
61 	if (!vi)
62 		return NULL;
63 
64 	/* zero out everything except vfs_inode */
65 	memset(vi, 0, offsetof(struct erofs_inode, vfs_inode));
66 	return &vi->vfs_inode;
67 }
68 
69 static void erofs_free_inode(struct inode *inode)
70 {
71 	struct erofs_inode *vi = EROFS_I(inode);
72 
73 	/* be careful of RCU symlink path */
74 	if (inode->i_op == &erofs_fast_symlink_iops)
75 		kfree(inode->i_link);
76 	kfree(vi->xattr_shared_xattrs);
77 
78 	kmem_cache_free(erofs_inode_cachep, vi);
79 }
80 
81 static bool check_layout_compatibility(struct super_block *sb,
82 				       struct erofs_super_block *dsb)
83 {
84 	const unsigned int feature = le32_to_cpu(dsb->feature_incompat);
85 
86 	EROFS_SB(sb)->feature_incompat = feature;
87 
88 	/* check if current kernel meets all mandatory requirements */
89 	if (feature & (~EROFS_ALL_FEATURE_INCOMPAT)) {
90 		erofs_err(sb,
91 			  "unidentified incompatible feature %x, please upgrade kernel version",
92 			   feature & ~EROFS_ALL_FEATURE_INCOMPAT);
93 		return false;
94 	}
95 	return true;
96 }
97 
98 static int erofs_read_superblock(struct super_block *sb)
99 {
100 	struct erofs_sb_info *sbi;
101 	struct page *page;
102 	struct erofs_super_block *dsb;
103 	unsigned int blkszbits;
104 	void *data;
105 	int ret;
106 
107 	page = read_mapping_page(sb->s_bdev->bd_inode->i_mapping, 0, NULL);
108 	if (IS_ERR(page)) {
109 		erofs_err(sb, "cannot read erofs superblock");
110 		return PTR_ERR(page);
111 	}
112 
113 	sbi = EROFS_SB(sb);
114 
115 	data = kmap_atomic(page);
116 	dsb = (struct erofs_super_block *)(data + EROFS_SUPER_OFFSET);
117 
118 	ret = -EINVAL;
119 	if (le32_to_cpu(dsb->magic) != EROFS_SUPER_MAGIC_V1) {
120 		erofs_err(sb, "cannot find valid erofs superblock");
121 		goto out;
122 	}
123 
124 	blkszbits = dsb->blkszbits;
125 	/* 9(512 bytes) + LOG_SECTORS_PER_BLOCK == LOG_BLOCK_SIZE */
126 	if (blkszbits != LOG_BLOCK_SIZE) {
127 		erofs_err(sb, "blksize %u isn't supported on this platform",
128 			  1 << blkszbits);
129 		goto out;
130 	}
131 
132 	if (!check_layout_compatibility(sb, dsb))
133 		goto out;
134 
135 	sbi->blocks = le32_to_cpu(dsb->blocks);
136 	sbi->meta_blkaddr = le32_to_cpu(dsb->meta_blkaddr);
137 #ifdef CONFIG_EROFS_FS_XATTR
138 	sbi->xattr_blkaddr = le32_to_cpu(dsb->xattr_blkaddr);
139 #endif
140 	sbi->islotbits = ilog2(sizeof(struct erofs_inode_compact));
141 	sbi->root_nid = le16_to_cpu(dsb->root_nid);
142 	sbi->inos = le64_to_cpu(dsb->inos);
143 
144 	sbi->build_time = le64_to_cpu(dsb->build_time);
145 	sbi->build_time_nsec = le32_to_cpu(dsb->build_time_nsec);
146 
147 	memcpy(&sb->s_uuid, dsb->uuid, sizeof(dsb->uuid));
148 
149 	ret = strscpy(sbi->volume_name, dsb->volume_name,
150 		      sizeof(dsb->volume_name));
151 	if (ret < 0) {	/* -E2BIG */
152 		erofs_err(sb, "bad volume name without NIL terminator");
153 		ret = -EFSCORRUPTED;
154 		goto out;
155 	}
156 	ret = 0;
157 out:
158 	kunmap_atomic(data);
159 	put_page(page);
160 	return ret;
161 }
162 
163 #ifdef CONFIG_EROFS_FS_ZIP
164 static int erofs_build_cache_strategy(struct super_block *sb,
165 				      substring_t *args)
166 {
167 	struct erofs_sb_info *sbi = EROFS_SB(sb);
168 	const char *cs = match_strdup(args);
169 	int err = 0;
170 
171 	if (!cs) {
172 		erofs_err(sb, "Not enough memory to store cache strategy");
173 		return -ENOMEM;
174 	}
175 
176 	if (!strcmp(cs, "disabled")) {
177 		sbi->cache_strategy = EROFS_ZIP_CACHE_DISABLED;
178 	} else if (!strcmp(cs, "readahead")) {
179 		sbi->cache_strategy = EROFS_ZIP_CACHE_READAHEAD;
180 	} else if (!strcmp(cs, "readaround")) {
181 		sbi->cache_strategy = EROFS_ZIP_CACHE_READAROUND;
182 	} else {
183 		erofs_err(sb, "Unrecognized cache strategy \"%s\"", cs);
184 		err = -EINVAL;
185 	}
186 	kfree(cs);
187 	return err;
188 }
189 #else
190 static int erofs_build_cache_strategy(struct super_block *sb,
191 				      substring_t *args)
192 {
193 	erofs_info(sb, "EROFS compression is disabled, so cache strategy is ignored");
194 	return 0;
195 }
196 #endif
197 
198 /* set up default EROFS parameters */
199 static void erofs_default_options(struct erofs_sb_info *sbi)
200 {
201 #ifdef CONFIG_EROFS_FS_ZIP
202 	sbi->cache_strategy = EROFS_ZIP_CACHE_READAROUND;
203 	sbi->max_sync_decompress_pages = 3;
204 #endif
205 #ifdef CONFIG_EROFS_FS_XATTR
206 	set_opt(sbi, XATTR_USER);
207 #endif
208 #ifdef CONFIG_EROFS_FS_POSIX_ACL
209 	set_opt(sbi, POSIX_ACL);
210 #endif
211 }
212 
213 enum {
214 	Opt_user_xattr,
215 	Opt_nouser_xattr,
216 	Opt_acl,
217 	Opt_noacl,
218 	Opt_cache_strategy,
219 	Opt_err
220 };
221 
222 static match_table_t erofs_tokens = {
223 	{Opt_user_xattr, "user_xattr"},
224 	{Opt_nouser_xattr, "nouser_xattr"},
225 	{Opt_acl, "acl"},
226 	{Opt_noacl, "noacl"},
227 	{Opt_cache_strategy, "cache_strategy=%s"},
228 	{Opt_err, NULL}
229 };
230 
231 static int erofs_parse_options(struct super_block *sb, char *options)
232 {
233 	substring_t args[MAX_OPT_ARGS];
234 	char *p;
235 	int err;
236 
237 	if (!options)
238 		return 0;
239 
240 	while ((p = strsep(&options, ","))) {
241 		int token;
242 
243 		if (!*p)
244 			continue;
245 
246 		args[0].to = args[0].from = NULL;
247 		token = match_token(p, erofs_tokens, args);
248 
249 		switch (token) {
250 #ifdef CONFIG_EROFS_FS_XATTR
251 		case Opt_user_xattr:
252 			set_opt(EROFS_SB(sb), XATTR_USER);
253 			break;
254 		case Opt_nouser_xattr:
255 			clear_opt(EROFS_SB(sb), XATTR_USER);
256 			break;
257 #else
258 		case Opt_user_xattr:
259 			erofs_info(sb, "user_xattr options not supported");
260 			break;
261 		case Opt_nouser_xattr:
262 			erofs_info(sb, "nouser_xattr options not supported");
263 			break;
264 #endif
265 #ifdef CONFIG_EROFS_FS_POSIX_ACL
266 		case Opt_acl:
267 			set_opt(EROFS_SB(sb), POSIX_ACL);
268 			break;
269 		case Opt_noacl:
270 			clear_opt(EROFS_SB(sb), POSIX_ACL);
271 			break;
272 #else
273 		case Opt_acl:
274 			erofs_info(sb, "acl options not supported");
275 			break;
276 		case Opt_noacl:
277 			erofs_info(sb, "noacl options not supported");
278 			break;
279 #endif
280 		case Opt_cache_strategy:
281 			err = erofs_build_cache_strategy(sb, args);
282 			if (err)
283 				return err;
284 			break;
285 		default:
286 			erofs_err(sb, "Unrecognized mount option \"%s\" or missing value", p);
287 			return -EINVAL;
288 		}
289 	}
290 	return 0;
291 }
292 
293 #ifdef CONFIG_EROFS_FS_ZIP
294 static const struct address_space_operations managed_cache_aops;
295 
296 static int erofs_managed_cache_releasepage(struct page *page, gfp_t gfp_mask)
297 {
298 	int ret = 1;	/* 0 - busy */
299 	struct address_space *const mapping = page->mapping;
300 
301 	DBG_BUGON(!PageLocked(page));
302 	DBG_BUGON(mapping->a_ops != &managed_cache_aops);
303 
304 	if (PagePrivate(page))
305 		ret = erofs_try_to_free_cached_page(mapping, page);
306 
307 	return ret;
308 }
309 
310 static void erofs_managed_cache_invalidatepage(struct page *page,
311 					       unsigned int offset,
312 					       unsigned int length)
313 {
314 	const unsigned int stop = length + offset;
315 
316 	DBG_BUGON(!PageLocked(page));
317 
318 	/* Check for potential overflow in debug mode */
319 	DBG_BUGON(stop > PAGE_SIZE || stop < length);
320 
321 	if (offset == 0 && stop == PAGE_SIZE)
322 		while (!erofs_managed_cache_releasepage(page, GFP_NOFS))
323 			cond_resched();
324 }
325 
326 static const struct address_space_operations managed_cache_aops = {
327 	.releasepage = erofs_managed_cache_releasepage,
328 	.invalidatepage = erofs_managed_cache_invalidatepage,
329 };
330 
331 static int erofs_init_managed_cache(struct super_block *sb)
332 {
333 	struct erofs_sb_info *const sbi = EROFS_SB(sb);
334 	struct inode *const inode = new_inode(sb);
335 
336 	if (!inode)
337 		return -ENOMEM;
338 
339 	set_nlink(inode, 1);
340 	inode->i_size = OFFSET_MAX;
341 
342 	inode->i_mapping->a_ops = &managed_cache_aops;
343 	mapping_set_gfp_mask(inode->i_mapping,
344 			     GFP_NOFS | __GFP_HIGHMEM | __GFP_MOVABLE);
345 	sbi->managed_cache = inode;
346 	return 0;
347 }
348 #else
349 static int erofs_init_managed_cache(struct super_block *sb) { return 0; }
350 #endif
351 
352 static int erofs_fill_super(struct super_block *sb, void *data, int silent)
353 {
354 	struct inode *inode;
355 	struct erofs_sb_info *sbi;
356 	int err;
357 
358 	sb->s_magic = EROFS_SUPER_MAGIC;
359 
360 	if (!sb_set_blocksize(sb, EROFS_BLKSIZ)) {
361 		erofs_err(sb, "failed to set erofs blksize");
362 		return -EINVAL;
363 	}
364 
365 	sbi = kzalloc(sizeof(*sbi), GFP_KERNEL);
366 	if (!sbi)
367 		return -ENOMEM;
368 
369 	sb->s_fs_info = sbi;
370 	err = erofs_read_superblock(sb);
371 	if (err)
372 		return err;
373 
374 	sb->s_flags |= SB_RDONLY | SB_NOATIME;
375 	sb->s_maxbytes = MAX_LFS_FILESIZE;
376 	sb->s_time_gran = 1;
377 
378 	sb->s_op = &erofs_sops;
379 
380 #ifdef CONFIG_EROFS_FS_XATTR
381 	sb->s_xattr = erofs_xattr_handlers;
382 #endif
383 	/* set erofs default mount options */
384 	erofs_default_options(sbi);
385 
386 	err = erofs_parse_options(sb, data);
387 	if (err)
388 		return err;
389 
390 	if (test_opt(sbi, POSIX_ACL))
391 		sb->s_flags |= SB_POSIXACL;
392 	else
393 		sb->s_flags &= ~SB_POSIXACL;
394 
395 #ifdef CONFIG_EROFS_FS_ZIP
396 	INIT_RADIX_TREE(&sbi->workstn_tree, GFP_ATOMIC);
397 #endif
398 
399 	/* get the root inode */
400 	inode = erofs_iget(sb, ROOT_NID(sbi), true);
401 	if (IS_ERR(inode))
402 		return PTR_ERR(inode);
403 
404 	if (!S_ISDIR(inode->i_mode)) {
405 		erofs_err(sb, "rootino(nid %llu) is not a directory(i_mode %o)",
406 			  ROOT_NID(sbi), inode->i_mode);
407 		iput(inode);
408 		return -EINVAL;
409 	}
410 
411 	sb->s_root = d_make_root(inode);
412 	if (!sb->s_root)
413 		return -ENOMEM;
414 
415 	erofs_shrinker_register(sb);
416 	/* sb->s_umount is already locked, SB_ACTIVE and SB_BORN are not set */
417 	err = erofs_init_managed_cache(sb);
418 	if (err)
419 		return err;
420 
421 	erofs_info(sb, "mounted with opts: %s, root inode @ nid %llu.",
422 		   (char *)data, ROOT_NID(sbi));
423 	return 0;
424 }
425 
426 static struct dentry *erofs_mount(struct file_system_type *fs_type, int flags,
427 				  const char *dev_name, void *data)
428 {
429 	return mount_bdev(fs_type, flags, dev_name, data, erofs_fill_super);
430 }
431 
432 /*
433  * could be triggered after deactivate_locked_super()
434  * is called, thus including umount and failed to initialize.
435  */
436 static void erofs_kill_sb(struct super_block *sb)
437 {
438 	struct erofs_sb_info *sbi;
439 
440 	WARN_ON(sb->s_magic != EROFS_SUPER_MAGIC);
441 
442 	kill_block_super(sb);
443 
444 	sbi = EROFS_SB(sb);
445 	if (!sbi)
446 		return;
447 	kfree(sbi);
448 	sb->s_fs_info = NULL;
449 }
450 
451 /* called when ->s_root is non-NULL */
452 static void erofs_put_super(struct super_block *sb)
453 {
454 	struct erofs_sb_info *const sbi = EROFS_SB(sb);
455 
456 	DBG_BUGON(!sbi);
457 
458 	erofs_shrinker_unregister(sb);
459 #ifdef CONFIG_EROFS_FS_ZIP
460 	iput(sbi->managed_cache);
461 	sbi->managed_cache = NULL;
462 #endif
463 }
464 
465 static struct file_system_type erofs_fs_type = {
466 	.owner          = THIS_MODULE,
467 	.name           = "erofs",
468 	.mount          = erofs_mount,
469 	.kill_sb        = erofs_kill_sb,
470 	.fs_flags       = FS_REQUIRES_DEV,
471 };
472 MODULE_ALIAS_FS("erofs");
473 
474 static int __init erofs_module_init(void)
475 {
476 	int err;
477 
478 	erofs_check_ondisk_layout_definitions();
479 
480 	erofs_inode_cachep = kmem_cache_create("erofs_inode",
481 					       sizeof(struct erofs_inode), 0,
482 					       SLAB_RECLAIM_ACCOUNT,
483 					       erofs_inode_init_once);
484 	if (!erofs_inode_cachep) {
485 		err = -ENOMEM;
486 		goto icache_err;
487 	}
488 
489 	err = erofs_init_shrinker();
490 	if (err)
491 		goto shrinker_err;
492 
493 	err = z_erofs_init_zip_subsystem();
494 	if (err)
495 		goto zip_err;
496 
497 	err = register_filesystem(&erofs_fs_type);
498 	if (err)
499 		goto fs_err;
500 
501 	return 0;
502 
503 fs_err:
504 	z_erofs_exit_zip_subsystem();
505 zip_err:
506 	erofs_exit_shrinker();
507 shrinker_err:
508 	kmem_cache_destroy(erofs_inode_cachep);
509 icache_err:
510 	return err;
511 }
512 
513 static void __exit erofs_module_exit(void)
514 {
515 	unregister_filesystem(&erofs_fs_type);
516 	z_erofs_exit_zip_subsystem();
517 	erofs_exit_shrinker();
518 
519 	/* Ensure all RCU free inodes are safe before cache is destroyed. */
520 	rcu_barrier();
521 	kmem_cache_destroy(erofs_inode_cachep);
522 }
523 
524 /* get filesystem statistics */
525 static int erofs_statfs(struct dentry *dentry, struct kstatfs *buf)
526 {
527 	struct super_block *sb = dentry->d_sb;
528 	struct erofs_sb_info *sbi = EROFS_SB(sb);
529 	u64 id = huge_encode_dev(sb->s_bdev->bd_dev);
530 
531 	buf->f_type = sb->s_magic;
532 	buf->f_bsize = EROFS_BLKSIZ;
533 	buf->f_blocks = sbi->blocks;
534 	buf->f_bfree = buf->f_bavail = 0;
535 
536 	buf->f_files = ULLONG_MAX;
537 	buf->f_ffree = ULLONG_MAX - sbi->inos;
538 
539 	buf->f_namelen = EROFS_NAME_LEN;
540 
541 	buf->f_fsid.val[0] = (u32)id;
542 	buf->f_fsid.val[1] = (u32)(id >> 32);
543 	return 0;
544 }
545 
546 static int erofs_show_options(struct seq_file *seq, struct dentry *root)
547 {
548 	struct erofs_sb_info *sbi __maybe_unused = EROFS_SB(root->d_sb);
549 
550 #ifdef CONFIG_EROFS_FS_XATTR
551 	if (test_opt(sbi, XATTR_USER))
552 		seq_puts(seq, ",user_xattr");
553 	else
554 		seq_puts(seq, ",nouser_xattr");
555 #endif
556 #ifdef CONFIG_EROFS_FS_POSIX_ACL
557 	if (test_opt(sbi, POSIX_ACL))
558 		seq_puts(seq, ",acl");
559 	else
560 		seq_puts(seq, ",noacl");
561 #endif
562 #ifdef CONFIG_EROFS_FS_ZIP
563 	if (sbi->cache_strategy == EROFS_ZIP_CACHE_DISABLED) {
564 		seq_puts(seq, ",cache_strategy=disabled");
565 	} else if (sbi->cache_strategy == EROFS_ZIP_CACHE_READAHEAD) {
566 		seq_puts(seq, ",cache_strategy=readahead");
567 	} else if (sbi->cache_strategy == EROFS_ZIP_CACHE_READAROUND) {
568 		seq_puts(seq, ",cache_strategy=readaround");
569 	} else {
570 		seq_puts(seq, ",cache_strategy=(unknown)");
571 		DBG_BUGON(1);
572 	}
573 #endif
574 	return 0;
575 }
576 
577 static int erofs_remount(struct super_block *sb, int *flags, char *data)
578 {
579 	struct erofs_sb_info *sbi = EROFS_SB(sb);
580 	unsigned int org_mnt_opt = sbi->mount_opt;
581 	int err;
582 
583 	DBG_BUGON(!sb_rdonly(sb));
584 	err = erofs_parse_options(sb, data);
585 	if (err)
586 		goto out;
587 
588 	if (test_opt(sbi, POSIX_ACL))
589 		sb->s_flags |= SB_POSIXACL;
590 	else
591 		sb->s_flags &= ~SB_POSIXACL;
592 
593 	*flags |= SB_RDONLY;
594 	return 0;
595 out:
596 	sbi->mount_opt = org_mnt_opt;
597 	return err;
598 }
599 
600 const struct super_operations erofs_sops = {
601 	.put_super = erofs_put_super,
602 	.alloc_inode = erofs_alloc_inode,
603 	.free_inode = erofs_free_inode,
604 	.statfs = erofs_statfs,
605 	.show_options = erofs_show_options,
606 	.remount_fs = erofs_remount,
607 };
608 
609 module_init(erofs_module_init);
610 module_exit(erofs_module_exit);
611 
612 MODULE_DESCRIPTION("Enhanced ROM File System");
613 MODULE_AUTHOR("Gao Xiang, Chao Yu, Miao Xie, CONSUMER BG, HUAWEI Inc.");
614 MODULE_LICENSE("GPL");
615 
616