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1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Optimized MPEG FS - inode and super operations.
4  * Copyright (C) 2006 Bob Copeland <me@bobcopeland.com>
5  */
6 #include <linux/module.h>
7 #include <linux/sched.h>
8 #include <linux/slab.h>
9 #include <linux/fs.h>
10 #include <linux/vfs.h>
11 #include <linux/cred.h>
12 #include <linux/parser.h>
13 #include <linux/buffer_head.h>
14 #include <linux/vmalloc.h>
15 #include <linux/writeback.h>
16 #include <linux/seq_file.h>
17 #include <linux/crc-itu-t.h>
18 #include "omfs.h"
19 
20 MODULE_AUTHOR("Bob Copeland <me@bobcopeland.com>");
21 MODULE_DESCRIPTION("OMFS (ReplayTV/Karma) Filesystem for Linux");
22 MODULE_LICENSE("GPL");
23 MODULE_IMPORT_NS(ANDROID_GKI_VFS_EXPORT_ONLY);
24 
omfs_bread(struct super_block * sb,sector_t block)25 struct buffer_head *omfs_bread(struct super_block *sb, sector_t block)
26 {
27 	struct omfs_sb_info *sbi = OMFS_SB(sb);
28 	if (block >= sbi->s_num_blocks)
29 		return NULL;
30 
31 	return sb_bread(sb, clus_to_blk(sbi, block));
32 }
33 
omfs_new_inode(struct inode * dir,umode_t mode)34 struct inode *omfs_new_inode(struct inode *dir, umode_t mode)
35 {
36 	struct inode *inode;
37 	u64 new_block;
38 	int err;
39 	int len;
40 	struct omfs_sb_info *sbi = OMFS_SB(dir->i_sb);
41 
42 	inode = new_inode(dir->i_sb);
43 	if (!inode)
44 		return ERR_PTR(-ENOMEM);
45 
46 	err = omfs_allocate_range(dir->i_sb, sbi->s_mirrors, sbi->s_mirrors,
47 			&new_block, &len);
48 	if (err)
49 		goto fail;
50 
51 	inode->i_ino = new_block;
52 	inode_init_owner(&init_user_ns, inode, NULL, mode);
53 	inode->i_mapping->a_ops = &omfs_aops;
54 
55 	inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
56 	switch (mode & S_IFMT) {
57 	case S_IFDIR:
58 		inode->i_op = &omfs_dir_inops;
59 		inode->i_fop = &omfs_dir_operations;
60 		inode->i_size = sbi->s_sys_blocksize;
61 		inc_nlink(inode);
62 		break;
63 	case S_IFREG:
64 		inode->i_op = &omfs_file_inops;
65 		inode->i_fop = &omfs_file_operations;
66 		inode->i_size = 0;
67 		break;
68 	}
69 
70 	insert_inode_hash(inode);
71 	mark_inode_dirty(inode);
72 	return inode;
73 fail:
74 	make_bad_inode(inode);
75 	iput(inode);
76 	return ERR_PTR(err);
77 }
78 
79 /*
80  * Update the header checksums for a dirty inode based on its contents.
81  * Caller is expected to hold the buffer head underlying oi and mark it
82  * dirty.
83  */
omfs_update_checksums(struct omfs_inode * oi)84 static void omfs_update_checksums(struct omfs_inode *oi)
85 {
86 	int xor, i, ofs = 0, count;
87 	u16 crc = 0;
88 	unsigned char *ptr = (unsigned char *) oi;
89 
90 	count = be32_to_cpu(oi->i_head.h_body_size);
91 	ofs = sizeof(struct omfs_header);
92 
93 	crc = crc_itu_t(crc, ptr + ofs, count);
94 	oi->i_head.h_crc = cpu_to_be16(crc);
95 
96 	xor = ptr[0];
97 	for (i = 1; i < OMFS_XOR_COUNT; i++)
98 		xor ^= ptr[i];
99 
100 	oi->i_head.h_check_xor = xor;
101 }
102 
__omfs_write_inode(struct inode * inode,int wait)103 static int __omfs_write_inode(struct inode *inode, int wait)
104 {
105 	struct omfs_inode *oi;
106 	struct omfs_sb_info *sbi = OMFS_SB(inode->i_sb);
107 	struct buffer_head *bh, *bh2;
108 	u64 ctime;
109 	int i;
110 	int ret = -EIO;
111 	int sync_failed = 0;
112 
113 	/* get current inode since we may have written sibling ptrs etc. */
114 	bh = omfs_bread(inode->i_sb, inode->i_ino);
115 	if (!bh)
116 		goto out;
117 
118 	oi = (struct omfs_inode *) bh->b_data;
119 
120 	oi->i_head.h_self = cpu_to_be64(inode->i_ino);
121 	if (S_ISDIR(inode->i_mode))
122 		oi->i_type = OMFS_DIR;
123 	else if (S_ISREG(inode->i_mode))
124 		oi->i_type = OMFS_FILE;
125 	else {
126 		printk(KERN_WARNING "omfs: unknown file type: %d\n",
127 			inode->i_mode);
128 		goto out_brelse;
129 	}
130 
131 	oi->i_head.h_body_size = cpu_to_be32(sbi->s_sys_blocksize -
132 		sizeof(struct omfs_header));
133 	oi->i_head.h_version = 1;
134 	oi->i_head.h_type = OMFS_INODE_NORMAL;
135 	oi->i_head.h_magic = OMFS_IMAGIC;
136 	oi->i_size = cpu_to_be64(inode->i_size);
137 
138 	ctime = inode->i_ctime.tv_sec * 1000LL +
139 		((inode->i_ctime.tv_nsec + 999)/1000);
140 	oi->i_ctime = cpu_to_be64(ctime);
141 
142 	omfs_update_checksums(oi);
143 
144 	mark_buffer_dirty(bh);
145 	if (wait) {
146 		sync_dirty_buffer(bh);
147 		if (buffer_req(bh) && !buffer_uptodate(bh))
148 			sync_failed = 1;
149 	}
150 
151 	/* if mirroring writes, copy to next fsblock */
152 	for (i = 1; i < sbi->s_mirrors; i++) {
153 		bh2 = omfs_bread(inode->i_sb, inode->i_ino + i);
154 		if (!bh2)
155 			goto out_brelse;
156 
157 		memcpy(bh2->b_data, bh->b_data, bh->b_size);
158 		mark_buffer_dirty(bh2);
159 		if (wait) {
160 			sync_dirty_buffer(bh2);
161 			if (buffer_req(bh2) && !buffer_uptodate(bh2))
162 				sync_failed = 1;
163 		}
164 		brelse(bh2);
165 	}
166 	ret = (sync_failed) ? -EIO : 0;
167 out_brelse:
168 	brelse(bh);
169 out:
170 	return ret;
171 }
172 
omfs_write_inode(struct inode * inode,struct writeback_control * wbc)173 static int omfs_write_inode(struct inode *inode, struct writeback_control *wbc)
174 {
175 	return __omfs_write_inode(inode, wbc->sync_mode == WB_SYNC_ALL);
176 }
177 
omfs_sync_inode(struct inode * inode)178 int omfs_sync_inode(struct inode *inode)
179 {
180 	return __omfs_write_inode(inode, 1);
181 }
182 
183 /*
184  * called when an entry is deleted, need to clear the bits in the
185  * bitmaps.
186  */
omfs_evict_inode(struct inode * inode)187 static void omfs_evict_inode(struct inode *inode)
188 {
189 	truncate_inode_pages_final(&inode->i_data);
190 	clear_inode(inode);
191 
192 	if (inode->i_nlink)
193 		return;
194 
195 	if (S_ISREG(inode->i_mode)) {
196 		inode->i_size = 0;
197 		omfs_shrink_inode(inode);
198 	}
199 
200 	omfs_clear_range(inode->i_sb, inode->i_ino, 2);
201 }
202 
omfs_iget(struct super_block * sb,ino_t ino)203 struct inode *omfs_iget(struct super_block *sb, ino_t ino)
204 {
205 	struct omfs_sb_info *sbi = OMFS_SB(sb);
206 	struct omfs_inode *oi;
207 	struct buffer_head *bh;
208 	u64 ctime;
209 	unsigned long nsecs;
210 	struct inode *inode;
211 
212 	inode = iget_locked(sb, ino);
213 	if (!inode)
214 		return ERR_PTR(-ENOMEM);
215 	if (!(inode->i_state & I_NEW))
216 		return inode;
217 
218 	bh = omfs_bread(inode->i_sb, ino);
219 	if (!bh)
220 		goto iget_failed;
221 
222 	oi = (struct omfs_inode *)bh->b_data;
223 
224 	/* check self */
225 	if (ino != be64_to_cpu(oi->i_head.h_self))
226 		goto fail_bh;
227 
228 	inode->i_uid = sbi->s_uid;
229 	inode->i_gid = sbi->s_gid;
230 
231 	ctime = be64_to_cpu(oi->i_ctime);
232 	nsecs = do_div(ctime, 1000) * 1000L;
233 
234 	inode->i_atime.tv_sec = ctime;
235 	inode->i_mtime.tv_sec = ctime;
236 	inode->i_ctime.tv_sec = ctime;
237 	inode->i_atime.tv_nsec = nsecs;
238 	inode->i_mtime.tv_nsec = nsecs;
239 	inode->i_ctime.tv_nsec = nsecs;
240 
241 	inode->i_mapping->a_ops = &omfs_aops;
242 
243 	switch (oi->i_type) {
244 	case OMFS_DIR:
245 		inode->i_mode = S_IFDIR | (S_IRWXUGO & ~sbi->s_dmask);
246 		inode->i_op = &omfs_dir_inops;
247 		inode->i_fop = &omfs_dir_operations;
248 		inode->i_size = sbi->s_sys_blocksize;
249 		inc_nlink(inode);
250 		break;
251 	case OMFS_FILE:
252 		inode->i_mode = S_IFREG | (S_IRWXUGO & ~sbi->s_fmask);
253 		inode->i_fop = &omfs_file_operations;
254 		inode->i_size = be64_to_cpu(oi->i_size);
255 		break;
256 	}
257 	brelse(bh);
258 	unlock_new_inode(inode);
259 	return inode;
260 fail_bh:
261 	brelse(bh);
262 iget_failed:
263 	iget_failed(inode);
264 	return ERR_PTR(-EIO);
265 }
266 
omfs_put_super(struct super_block * sb)267 static void omfs_put_super(struct super_block *sb)
268 {
269 	struct omfs_sb_info *sbi = OMFS_SB(sb);
270 	kfree(sbi->s_imap);
271 	kfree(sbi);
272 	sb->s_fs_info = NULL;
273 }
274 
omfs_statfs(struct dentry * dentry,struct kstatfs * buf)275 static int omfs_statfs(struct dentry *dentry, struct kstatfs *buf)
276 {
277 	struct super_block *s = dentry->d_sb;
278 	struct omfs_sb_info *sbi = OMFS_SB(s);
279 	u64 id = huge_encode_dev(s->s_bdev->bd_dev);
280 
281 	buf->f_type = OMFS_MAGIC;
282 	buf->f_bsize = sbi->s_blocksize;
283 	buf->f_blocks = sbi->s_num_blocks;
284 	buf->f_files = sbi->s_num_blocks;
285 	buf->f_namelen = OMFS_NAMELEN;
286 	buf->f_fsid = u64_to_fsid(id);
287 
288 	buf->f_bfree = buf->f_bavail = buf->f_ffree =
289 		omfs_count_free(s);
290 
291 	return 0;
292 }
293 
294 /*
295  * Display the mount options in /proc/mounts.
296  */
omfs_show_options(struct seq_file * m,struct dentry * root)297 static int omfs_show_options(struct seq_file *m, struct dentry *root)
298 {
299 	struct omfs_sb_info *sbi = OMFS_SB(root->d_sb);
300 	umode_t cur_umask = current_umask();
301 
302 	if (!uid_eq(sbi->s_uid, current_uid()))
303 		seq_printf(m, ",uid=%u",
304 			   from_kuid_munged(&init_user_ns, sbi->s_uid));
305 	if (!gid_eq(sbi->s_gid, current_gid()))
306 		seq_printf(m, ",gid=%u",
307 			   from_kgid_munged(&init_user_ns, sbi->s_gid));
308 
309 	if (sbi->s_dmask == sbi->s_fmask) {
310 		if (sbi->s_fmask != cur_umask)
311 			seq_printf(m, ",umask=%o", sbi->s_fmask);
312 	} else {
313 		if (sbi->s_dmask != cur_umask)
314 			seq_printf(m, ",dmask=%o", sbi->s_dmask);
315 		if (sbi->s_fmask != cur_umask)
316 			seq_printf(m, ",fmask=%o", sbi->s_fmask);
317 	}
318 
319 	return 0;
320 }
321 
322 static const struct super_operations omfs_sops = {
323 	.write_inode	= omfs_write_inode,
324 	.evict_inode	= omfs_evict_inode,
325 	.put_super	= omfs_put_super,
326 	.statfs		= omfs_statfs,
327 	.show_options	= omfs_show_options,
328 };
329 
330 /*
331  * For Rio Karma, there is an on-disk free bitmap whose location is
332  * stored in the root block.  For ReplayTV, there is no such free bitmap
333  * so we have to walk the tree.  Both inodes and file data are allocated
334  * from the same map.  This array can be big (300k) so we allocate
335  * in units of the blocksize.
336  */
omfs_get_imap(struct super_block * sb)337 static int omfs_get_imap(struct super_block *sb)
338 {
339 	unsigned int bitmap_size, array_size;
340 	int count;
341 	struct omfs_sb_info *sbi = OMFS_SB(sb);
342 	struct buffer_head *bh;
343 	unsigned long **ptr;
344 	sector_t block;
345 
346 	bitmap_size = DIV_ROUND_UP(sbi->s_num_blocks, 8);
347 	array_size = DIV_ROUND_UP(bitmap_size, sb->s_blocksize);
348 
349 	if (sbi->s_bitmap_ino == ~0ULL)
350 		goto out;
351 
352 	sbi->s_imap_size = array_size;
353 	sbi->s_imap = kcalloc(array_size, sizeof(unsigned long *), GFP_KERNEL);
354 	if (!sbi->s_imap)
355 		goto nomem;
356 
357 	block = clus_to_blk(sbi, sbi->s_bitmap_ino);
358 	if (block >= sbi->s_num_blocks)
359 		goto nomem;
360 
361 	ptr = sbi->s_imap;
362 	for (count = bitmap_size; count > 0; count -= sb->s_blocksize) {
363 		bh = sb_bread(sb, block++);
364 		if (!bh)
365 			goto nomem_free;
366 		*ptr = kmemdup(bh->b_data, sb->s_blocksize, GFP_KERNEL);
367 		if (!*ptr) {
368 			brelse(bh);
369 			goto nomem_free;
370 		}
371 		if (count < sb->s_blocksize)
372 			memset((void *)*ptr + count, 0xff,
373 				sb->s_blocksize - count);
374 		brelse(bh);
375 		ptr++;
376 	}
377 out:
378 	return 0;
379 
380 nomem_free:
381 	for (count = 0; count < array_size; count++)
382 		kfree(sbi->s_imap[count]);
383 
384 	kfree(sbi->s_imap);
385 nomem:
386 	sbi->s_imap = NULL;
387 	sbi->s_imap_size = 0;
388 	return -ENOMEM;
389 }
390 
391 enum {
392 	Opt_uid, Opt_gid, Opt_umask, Opt_dmask, Opt_fmask, Opt_err
393 };
394 
395 static const match_table_t tokens = {
396 	{Opt_uid, "uid=%u"},
397 	{Opt_gid, "gid=%u"},
398 	{Opt_umask, "umask=%o"},
399 	{Opt_dmask, "dmask=%o"},
400 	{Opt_fmask, "fmask=%o"},
401 	{Opt_err, NULL},
402 };
403 
parse_options(char * options,struct omfs_sb_info * sbi)404 static int parse_options(char *options, struct omfs_sb_info *sbi)
405 {
406 	char *p;
407 	substring_t args[MAX_OPT_ARGS];
408 	int option;
409 
410 	if (!options)
411 		return 1;
412 
413 	while ((p = strsep(&options, ",")) != NULL) {
414 		int token;
415 		if (!*p)
416 			continue;
417 
418 		token = match_token(p, tokens, args);
419 		switch (token) {
420 		case Opt_uid:
421 			if (match_int(&args[0], &option))
422 				return 0;
423 			sbi->s_uid = make_kuid(current_user_ns(), option);
424 			if (!uid_valid(sbi->s_uid))
425 				return 0;
426 			break;
427 		case Opt_gid:
428 			if (match_int(&args[0], &option))
429 				return 0;
430 			sbi->s_gid = make_kgid(current_user_ns(), option);
431 			if (!gid_valid(sbi->s_gid))
432 				return 0;
433 			break;
434 		case Opt_umask:
435 			if (match_octal(&args[0], &option))
436 				return 0;
437 			sbi->s_fmask = sbi->s_dmask = option;
438 			break;
439 		case Opt_dmask:
440 			if (match_octal(&args[0], &option))
441 				return 0;
442 			sbi->s_dmask = option;
443 			break;
444 		case Opt_fmask:
445 			if (match_octal(&args[0], &option))
446 				return 0;
447 			sbi->s_fmask = option;
448 			break;
449 		default:
450 			return 0;
451 		}
452 	}
453 	return 1;
454 }
455 
omfs_fill_super(struct super_block * sb,void * data,int silent)456 static int omfs_fill_super(struct super_block *sb, void *data, int silent)
457 {
458 	struct buffer_head *bh, *bh2;
459 	struct omfs_super_block *omfs_sb;
460 	struct omfs_root_block *omfs_rb;
461 	struct omfs_sb_info *sbi;
462 	struct inode *root;
463 	int ret = -EINVAL;
464 
465 	sbi = kzalloc(sizeof(struct omfs_sb_info), GFP_KERNEL);
466 	if (!sbi)
467 		return -ENOMEM;
468 
469 	sb->s_fs_info = sbi;
470 
471 	sbi->s_uid = current_uid();
472 	sbi->s_gid = current_gid();
473 	sbi->s_dmask = sbi->s_fmask = current_umask();
474 
475 	if (!parse_options((char *) data, sbi))
476 		goto end;
477 
478 	sb->s_maxbytes = 0xffffffff;
479 
480 	sb->s_time_gran = NSEC_PER_MSEC;
481 	sb->s_time_min = 0;
482 	sb->s_time_max = U64_MAX / MSEC_PER_SEC;
483 
484 	sb_set_blocksize(sb, 0x200);
485 
486 	bh = sb_bread(sb, 0);
487 	if (!bh)
488 		goto end;
489 
490 	omfs_sb = (struct omfs_super_block *)bh->b_data;
491 
492 	if (omfs_sb->s_magic != cpu_to_be32(OMFS_MAGIC)) {
493 		if (!silent)
494 			printk(KERN_ERR "omfs: Invalid superblock (%x)\n",
495 				   omfs_sb->s_magic);
496 		goto out_brelse_bh;
497 	}
498 	sb->s_magic = OMFS_MAGIC;
499 
500 	sbi->s_num_blocks = be64_to_cpu(omfs_sb->s_num_blocks);
501 	sbi->s_blocksize = be32_to_cpu(omfs_sb->s_blocksize);
502 	sbi->s_mirrors = be32_to_cpu(omfs_sb->s_mirrors);
503 	sbi->s_root_ino = be64_to_cpu(omfs_sb->s_root_block);
504 	sbi->s_sys_blocksize = be32_to_cpu(omfs_sb->s_sys_blocksize);
505 	mutex_init(&sbi->s_bitmap_lock);
506 
507 	if (sbi->s_num_blocks > OMFS_MAX_BLOCKS) {
508 		printk(KERN_ERR "omfs: sysblock number (%llx) is out of range\n",
509 		       (unsigned long long)sbi->s_num_blocks);
510 		goto out_brelse_bh;
511 	}
512 
513 	if (sbi->s_sys_blocksize > PAGE_SIZE) {
514 		printk(KERN_ERR "omfs: sysblock size (%d) is out of range\n",
515 			sbi->s_sys_blocksize);
516 		goto out_brelse_bh;
517 	}
518 
519 	if (sbi->s_blocksize < sbi->s_sys_blocksize ||
520 	    sbi->s_blocksize > OMFS_MAX_BLOCK_SIZE) {
521 		printk(KERN_ERR "omfs: block size (%d) is out of range\n",
522 			sbi->s_blocksize);
523 		goto out_brelse_bh;
524 	}
525 
526 	/*
527 	 * Use sys_blocksize as the fs block since it is smaller than a
528 	 * page while the fs blocksize can be larger.
529 	 */
530 	sb_set_blocksize(sb, sbi->s_sys_blocksize);
531 
532 	/*
533 	 * ...and the difference goes into a shift.  sys_blocksize is always
534 	 * a power of two factor of blocksize.
535 	 */
536 	sbi->s_block_shift = get_bitmask_order(sbi->s_blocksize) -
537 		get_bitmask_order(sbi->s_sys_blocksize);
538 
539 	bh2 = omfs_bread(sb, be64_to_cpu(omfs_sb->s_root_block));
540 	if (!bh2)
541 		goto out_brelse_bh;
542 
543 	omfs_rb = (struct omfs_root_block *)bh2->b_data;
544 
545 	sbi->s_bitmap_ino = be64_to_cpu(omfs_rb->r_bitmap);
546 	sbi->s_clustersize = be32_to_cpu(omfs_rb->r_clustersize);
547 
548 	if (sbi->s_num_blocks != be64_to_cpu(omfs_rb->r_num_blocks)) {
549 		printk(KERN_ERR "omfs: block count discrepancy between "
550 			"super and root blocks (%llx, %llx)\n",
551 			(unsigned long long)sbi->s_num_blocks,
552 			(unsigned long long)be64_to_cpu(omfs_rb->r_num_blocks));
553 		goto out_brelse_bh2;
554 	}
555 
556 	if (sbi->s_bitmap_ino != ~0ULL &&
557 	    sbi->s_bitmap_ino > sbi->s_num_blocks) {
558 		printk(KERN_ERR "omfs: free space bitmap location is corrupt "
559 			"(%llx, total blocks %llx)\n",
560 			(unsigned long long) sbi->s_bitmap_ino,
561 			(unsigned long long) sbi->s_num_blocks);
562 		goto out_brelse_bh2;
563 	}
564 	if (sbi->s_clustersize < 1 ||
565 	    sbi->s_clustersize > OMFS_MAX_CLUSTER_SIZE) {
566 		printk(KERN_ERR "omfs: cluster size out of range (%d)",
567 			sbi->s_clustersize);
568 		goto out_brelse_bh2;
569 	}
570 
571 	ret = omfs_get_imap(sb);
572 	if (ret)
573 		goto out_brelse_bh2;
574 
575 	sb->s_op = &omfs_sops;
576 
577 	root = omfs_iget(sb, be64_to_cpu(omfs_rb->r_root_dir));
578 	if (IS_ERR(root)) {
579 		ret = PTR_ERR(root);
580 		goto out_brelse_bh2;
581 	}
582 
583 	sb->s_root = d_make_root(root);
584 	if (!sb->s_root) {
585 		ret = -ENOMEM;
586 		goto out_brelse_bh2;
587 	}
588 	printk(KERN_DEBUG "omfs: Mounted volume %s\n", omfs_rb->r_name);
589 
590 	ret = 0;
591 out_brelse_bh2:
592 	brelse(bh2);
593 out_brelse_bh:
594 	brelse(bh);
595 end:
596 	if (ret)
597 		kfree(sbi);
598 	return ret;
599 }
600 
omfs_mount(struct file_system_type * fs_type,int flags,const char * dev_name,void * data)601 static struct dentry *omfs_mount(struct file_system_type *fs_type,
602 			int flags, const char *dev_name, void *data)
603 {
604 	return mount_bdev(fs_type, flags, dev_name, data, omfs_fill_super);
605 }
606 
607 static struct file_system_type omfs_fs_type = {
608 	.owner = THIS_MODULE,
609 	.name = "omfs",
610 	.mount = omfs_mount,
611 	.kill_sb = kill_block_super,
612 	.fs_flags = FS_REQUIRES_DEV,
613 };
614 MODULE_ALIAS_FS("omfs");
615 
init_omfs_fs(void)616 static int __init init_omfs_fs(void)
617 {
618 	return register_filesystem(&omfs_fs_type);
619 }
620 
exit_omfs_fs(void)621 static void __exit exit_omfs_fs(void)
622 {
623 	unregister_filesystem(&omfs_fs_type);
624 }
625 
626 module_init(init_omfs_fs);
627 module_exit(exit_omfs_fs);
628