xref: /linux/fs/affs/file.c (revision c532de5a67a70f8533d495f8f2aaa9a0491c3ad0)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  *  linux/fs/affs/file.c
4  *
5  *  (c) 1996  Hans-Joachim Widmaier - Rewritten
6  *
7  *  (C) 1993  Ray Burr - Modified for Amiga FFS filesystem.
8  *
9  *  (C) 1992  Eric Youngdale Modified for ISO 9660 filesystem.
10  *
11  *  (C) 1991  Linus Torvalds - minix filesystem
12  *
13  *  affs regular file handling primitives
14  */
15 
16 #include <linux/uio.h>
17 #include <linux/blkdev.h>
18 #include <linux/mpage.h>
19 #include "affs.h"
20 
21 static struct buffer_head *affs_get_extblock_slow(struct inode *inode, u32 ext);
22 
23 static int
24 affs_file_open(struct inode *inode, struct file *filp)
25 {
26 	pr_debug("open(%lu,%d)\n",
27 		 inode->i_ino, atomic_read(&AFFS_I(inode)->i_opencnt));
28 	atomic_inc(&AFFS_I(inode)->i_opencnt);
29 	return 0;
30 }
31 
32 static int
33 affs_file_release(struct inode *inode, struct file *filp)
34 {
35 	pr_debug("release(%lu, %d)\n",
36 		 inode->i_ino, atomic_read(&AFFS_I(inode)->i_opencnt));
37 
38 	if (atomic_dec_and_test(&AFFS_I(inode)->i_opencnt)) {
39 		inode_lock(inode);
40 		if (inode->i_size != AFFS_I(inode)->mmu_private)
41 			affs_truncate(inode);
42 		affs_free_prealloc(inode);
43 		inode_unlock(inode);
44 	}
45 
46 	return 0;
47 }
48 
49 static int
50 affs_grow_extcache(struct inode *inode, u32 lc_idx)
51 {
52 	struct super_block	*sb = inode->i_sb;
53 	struct buffer_head	*bh;
54 	u32 lc_max;
55 	int i, j, key;
56 
57 	if (!AFFS_I(inode)->i_lc) {
58 		char *ptr = (char *)get_zeroed_page(GFP_NOFS);
59 		if (!ptr)
60 			return -ENOMEM;
61 		AFFS_I(inode)->i_lc = (u32 *)ptr;
62 		AFFS_I(inode)->i_ac = (struct affs_ext_key *)(ptr + AFFS_CACHE_SIZE / 2);
63 	}
64 
65 	lc_max = AFFS_LC_SIZE << AFFS_I(inode)->i_lc_shift;
66 
67 	if (AFFS_I(inode)->i_extcnt > lc_max) {
68 		u32 lc_shift, lc_mask, tmp, off;
69 
70 		/* need to recalculate linear cache, start from old size */
71 		lc_shift = AFFS_I(inode)->i_lc_shift;
72 		tmp = (AFFS_I(inode)->i_extcnt / AFFS_LC_SIZE) >> lc_shift;
73 		for (; tmp; tmp >>= 1)
74 			lc_shift++;
75 		lc_mask = (1 << lc_shift) - 1;
76 
77 		/* fix idx and old size to new shift */
78 		lc_idx >>= (lc_shift - AFFS_I(inode)->i_lc_shift);
79 		AFFS_I(inode)->i_lc_size >>= (lc_shift - AFFS_I(inode)->i_lc_shift);
80 
81 		/* first shrink old cache to make more space */
82 		off = 1 << (lc_shift - AFFS_I(inode)->i_lc_shift);
83 		for (i = 1, j = off; j < AFFS_LC_SIZE; i++, j += off)
84 			AFFS_I(inode)->i_ac[i] = AFFS_I(inode)->i_ac[j];
85 
86 		AFFS_I(inode)->i_lc_shift = lc_shift;
87 		AFFS_I(inode)->i_lc_mask = lc_mask;
88 	}
89 
90 	/* fill cache to the needed index */
91 	i = AFFS_I(inode)->i_lc_size;
92 	AFFS_I(inode)->i_lc_size = lc_idx + 1;
93 	for (; i <= lc_idx; i++) {
94 		if (!i) {
95 			AFFS_I(inode)->i_lc[0] = inode->i_ino;
96 			continue;
97 		}
98 		key = AFFS_I(inode)->i_lc[i - 1];
99 		j = AFFS_I(inode)->i_lc_mask + 1;
100 		// unlock cache
101 		for (; j > 0; j--) {
102 			bh = affs_bread(sb, key);
103 			if (!bh)
104 				goto err;
105 			key = be32_to_cpu(AFFS_TAIL(sb, bh)->extension);
106 			affs_brelse(bh);
107 		}
108 		// lock cache
109 		AFFS_I(inode)->i_lc[i] = key;
110 	}
111 
112 	return 0;
113 
114 err:
115 	// lock cache
116 	return -EIO;
117 }
118 
119 static struct buffer_head *
120 affs_alloc_extblock(struct inode *inode, struct buffer_head *bh, u32 ext)
121 {
122 	struct super_block *sb = inode->i_sb;
123 	struct buffer_head *new_bh;
124 	u32 blocknr, tmp;
125 
126 	blocknr = affs_alloc_block(inode, bh->b_blocknr);
127 	if (!blocknr)
128 		return ERR_PTR(-ENOSPC);
129 
130 	new_bh = affs_getzeroblk(sb, blocknr);
131 	if (!new_bh) {
132 		affs_free_block(sb, blocknr);
133 		return ERR_PTR(-EIO);
134 	}
135 
136 	AFFS_HEAD(new_bh)->ptype = cpu_to_be32(T_LIST);
137 	AFFS_HEAD(new_bh)->key = cpu_to_be32(blocknr);
138 	AFFS_TAIL(sb, new_bh)->stype = cpu_to_be32(ST_FILE);
139 	AFFS_TAIL(sb, new_bh)->parent = cpu_to_be32(inode->i_ino);
140 	affs_fix_checksum(sb, new_bh);
141 
142 	mark_buffer_dirty_inode(new_bh, inode);
143 
144 	tmp = be32_to_cpu(AFFS_TAIL(sb, bh)->extension);
145 	if (tmp)
146 		affs_warning(sb, "alloc_ext", "previous extension set (%x)", tmp);
147 	AFFS_TAIL(sb, bh)->extension = cpu_to_be32(blocknr);
148 	affs_adjust_checksum(bh, blocknr - tmp);
149 	mark_buffer_dirty_inode(bh, inode);
150 
151 	AFFS_I(inode)->i_extcnt++;
152 	mark_inode_dirty(inode);
153 
154 	return new_bh;
155 }
156 
157 static inline struct buffer_head *
158 affs_get_extblock(struct inode *inode, u32 ext)
159 {
160 	/* inline the simplest case: same extended block as last time */
161 	struct buffer_head *bh = AFFS_I(inode)->i_ext_bh;
162 	if (ext == AFFS_I(inode)->i_ext_last)
163 		get_bh(bh);
164 	else
165 		/* we have to do more (not inlined) */
166 		bh = affs_get_extblock_slow(inode, ext);
167 
168 	return bh;
169 }
170 
171 static struct buffer_head *
172 affs_get_extblock_slow(struct inode *inode, u32 ext)
173 {
174 	struct super_block *sb = inode->i_sb;
175 	struct buffer_head *bh;
176 	u32 ext_key;
177 	u32 lc_idx, lc_off, ac_idx;
178 	u32 tmp, idx;
179 
180 	if (ext == AFFS_I(inode)->i_ext_last + 1) {
181 		/* read the next extended block from the current one */
182 		bh = AFFS_I(inode)->i_ext_bh;
183 		ext_key = be32_to_cpu(AFFS_TAIL(sb, bh)->extension);
184 		if (ext < AFFS_I(inode)->i_extcnt)
185 			goto read_ext;
186 		BUG_ON(ext > AFFS_I(inode)->i_extcnt);
187 		bh = affs_alloc_extblock(inode, bh, ext);
188 		if (IS_ERR(bh))
189 			return bh;
190 		goto store_ext;
191 	}
192 
193 	if (ext == 0) {
194 		/* we seek back to the file header block */
195 		ext_key = inode->i_ino;
196 		goto read_ext;
197 	}
198 
199 	if (ext >= AFFS_I(inode)->i_extcnt) {
200 		struct buffer_head *prev_bh;
201 
202 		/* allocate a new extended block */
203 		BUG_ON(ext > AFFS_I(inode)->i_extcnt);
204 
205 		/* get previous extended block */
206 		prev_bh = affs_get_extblock(inode, ext - 1);
207 		if (IS_ERR(prev_bh))
208 			return prev_bh;
209 		bh = affs_alloc_extblock(inode, prev_bh, ext);
210 		affs_brelse(prev_bh);
211 		if (IS_ERR(bh))
212 			return bh;
213 		goto store_ext;
214 	}
215 
216 again:
217 	/* check if there is an extended cache and whether it's large enough */
218 	lc_idx = ext >> AFFS_I(inode)->i_lc_shift;
219 	lc_off = ext & AFFS_I(inode)->i_lc_mask;
220 
221 	if (lc_idx >= AFFS_I(inode)->i_lc_size) {
222 		int err;
223 
224 		err = affs_grow_extcache(inode, lc_idx);
225 		if (err)
226 			return ERR_PTR(err);
227 		goto again;
228 	}
229 
230 	/* every n'th key we find in the linear cache */
231 	if (!lc_off) {
232 		ext_key = AFFS_I(inode)->i_lc[lc_idx];
233 		goto read_ext;
234 	}
235 
236 	/* maybe it's still in the associative cache */
237 	ac_idx = (ext - lc_idx - 1) & AFFS_AC_MASK;
238 	if (AFFS_I(inode)->i_ac[ac_idx].ext == ext) {
239 		ext_key = AFFS_I(inode)->i_ac[ac_idx].key;
240 		goto read_ext;
241 	}
242 
243 	/* try to find one of the previous extended blocks */
244 	tmp = ext;
245 	idx = ac_idx;
246 	while (--tmp, --lc_off > 0) {
247 		idx = (idx - 1) & AFFS_AC_MASK;
248 		if (AFFS_I(inode)->i_ac[idx].ext == tmp) {
249 			ext_key = AFFS_I(inode)->i_ac[idx].key;
250 			goto find_ext;
251 		}
252 	}
253 
254 	/* fall back to the linear cache */
255 	ext_key = AFFS_I(inode)->i_lc[lc_idx];
256 find_ext:
257 	/* read all extended blocks until we find the one we need */
258 	//unlock cache
259 	do {
260 		bh = affs_bread(sb, ext_key);
261 		if (!bh)
262 			goto err_bread;
263 		ext_key = be32_to_cpu(AFFS_TAIL(sb, bh)->extension);
264 		affs_brelse(bh);
265 		tmp++;
266 	} while (tmp < ext);
267 	//lock cache
268 
269 	/* store it in the associative cache */
270 	// recalculate ac_idx?
271 	AFFS_I(inode)->i_ac[ac_idx].ext = ext;
272 	AFFS_I(inode)->i_ac[ac_idx].key = ext_key;
273 
274 read_ext:
275 	/* finally read the right extended block */
276 	//unlock cache
277 	bh = affs_bread(sb, ext_key);
278 	if (!bh)
279 		goto err_bread;
280 	//lock cache
281 
282 store_ext:
283 	/* release old cached extended block and store the new one */
284 	affs_brelse(AFFS_I(inode)->i_ext_bh);
285 	AFFS_I(inode)->i_ext_last = ext;
286 	AFFS_I(inode)->i_ext_bh = bh;
287 	get_bh(bh);
288 
289 	return bh;
290 
291 err_bread:
292 	affs_brelse(bh);
293 	return ERR_PTR(-EIO);
294 }
295 
296 static int
297 affs_get_block(struct inode *inode, sector_t block, struct buffer_head *bh_result, int create)
298 {
299 	struct super_block	*sb = inode->i_sb;
300 	struct buffer_head	*ext_bh;
301 	u32			 ext;
302 
303 	pr_debug("%s(%lu, %llu)\n", __func__, inode->i_ino,
304 		 (unsigned long long)block);
305 
306 	BUG_ON(block > (sector_t)0x7fffffffUL);
307 
308 	if (block >= AFFS_I(inode)->i_blkcnt) {
309 		if (block > AFFS_I(inode)->i_blkcnt || !create)
310 			goto err_big;
311 	} else
312 		create = 0;
313 
314 	//lock cache
315 	affs_lock_ext(inode);
316 
317 	ext = (u32)block / AFFS_SB(sb)->s_hashsize;
318 	block -= ext * AFFS_SB(sb)->s_hashsize;
319 	ext_bh = affs_get_extblock(inode, ext);
320 	if (IS_ERR(ext_bh))
321 		goto err_ext;
322 	map_bh(bh_result, sb, (sector_t)be32_to_cpu(AFFS_BLOCK(sb, ext_bh, block)));
323 
324 	if (create) {
325 		u32 blocknr = affs_alloc_block(inode, ext_bh->b_blocknr);
326 		if (!blocknr)
327 			goto err_alloc;
328 		set_buffer_new(bh_result);
329 		AFFS_I(inode)->mmu_private += AFFS_SB(sb)->s_data_blksize;
330 		AFFS_I(inode)->i_blkcnt++;
331 
332 		/* store new block */
333 		if (bh_result->b_blocknr)
334 			affs_warning(sb, "get_block",
335 				     "block already set (%llx)",
336 				     (unsigned long long)bh_result->b_blocknr);
337 		AFFS_BLOCK(sb, ext_bh, block) = cpu_to_be32(blocknr);
338 		AFFS_HEAD(ext_bh)->block_count = cpu_to_be32(block + 1);
339 		affs_adjust_checksum(ext_bh, blocknr - bh_result->b_blocknr + 1);
340 		bh_result->b_blocknr = blocknr;
341 
342 		if (!block) {
343 			/* insert first block into header block */
344 			u32 tmp = be32_to_cpu(AFFS_HEAD(ext_bh)->first_data);
345 			if (tmp)
346 				affs_warning(sb, "get_block", "first block already set (%d)", tmp);
347 			AFFS_HEAD(ext_bh)->first_data = cpu_to_be32(blocknr);
348 			affs_adjust_checksum(ext_bh, blocknr - tmp);
349 		}
350 	}
351 
352 	affs_brelse(ext_bh);
353 	//unlock cache
354 	affs_unlock_ext(inode);
355 	return 0;
356 
357 err_big:
358 	affs_error(inode->i_sb, "get_block", "strange block request %llu",
359 		   (unsigned long long)block);
360 	return -EIO;
361 err_ext:
362 	// unlock cache
363 	affs_unlock_ext(inode);
364 	return PTR_ERR(ext_bh);
365 err_alloc:
366 	brelse(ext_bh);
367 	clear_buffer_mapped(bh_result);
368 	bh_result->b_bdev = NULL;
369 	// unlock cache
370 	affs_unlock_ext(inode);
371 	return -ENOSPC;
372 }
373 
374 static int affs_writepages(struct address_space *mapping,
375 			   struct writeback_control *wbc)
376 {
377 	return mpage_writepages(mapping, wbc, affs_get_block);
378 }
379 
380 static int affs_read_folio(struct file *file, struct folio *folio)
381 {
382 	return block_read_full_folio(folio, affs_get_block);
383 }
384 
385 static void affs_write_failed(struct address_space *mapping, loff_t to)
386 {
387 	struct inode *inode = mapping->host;
388 
389 	if (to > inode->i_size) {
390 		truncate_pagecache(inode, inode->i_size);
391 		affs_truncate(inode);
392 	}
393 }
394 
395 static ssize_t
396 affs_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
397 {
398 	struct file *file = iocb->ki_filp;
399 	struct address_space *mapping = file->f_mapping;
400 	struct inode *inode = mapping->host;
401 	size_t count = iov_iter_count(iter);
402 	loff_t offset = iocb->ki_pos;
403 	ssize_t ret;
404 
405 	if (iov_iter_rw(iter) == WRITE) {
406 		loff_t size = offset + count;
407 
408 		if (AFFS_I(inode)->mmu_private < size)
409 			return 0;
410 	}
411 
412 	ret = blockdev_direct_IO(iocb, inode, iter, affs_get_block);
413 	if (ret < 0 && iov_iter_rw(iter) == WRITE)
414 		affs_write_failed(mapping, offset + count);
415 	return ret;
416 }
417 
418 static int affs_write_begin(struct file *file, struct address_space *mapping,
419 			loff_t pos, unsigned len,
420 			struct folio **foliop, void **fsdata)
421 {
422 	int ret;
423 
424 	ret = cont_write_begin(file, mapping, pos, len, foliop, fsdata,
425 				affs_get_block,
426 				&AFFS_I(mapping->host)->mmu_private);
427 	if (unlikely(ret))
428 		affs_write_failed(mapping, pos + len);
429 
430 	return ret;
431 }
432 
433 static int affs_write_end(struct file *file, struct address_space *mapping,
434 			  loff_t pos, unsigned int len, unsigned int copied,
435 			  struct folio *folio, void *fsdata)
436 {
437 	struct inode *inode = mapping->host;
438 	int ret;
439 
440 	ret = generic_write_end(file, mapping, pos, len, copied, folio, fsdata);
441 
442 	/* Clear Archived bit on file writes, as AmigaOS would do */
443 	if (AFFS_I(inode)->i_protect & FIBF_ARCHIVED) {
444 		AFFS_I(inode)->i_protect &= ~FIBF_ARCHIVED;
445 		mark_inode_dirty(inode);
446 	}
447 
448 	return ret;
449 }
450 
451 static sector_t _affs_bmap(struct address_space *mapping, sector_t block)
452 {
453 	return generic_block_bmap(mapping,block,affs_get_block);
454 }
455 
456 const struct address_space_operations affs_aops = {
457 	.dirty_folio	= block_dirty_folio,
458 	.invalidate_folio = block_invalidate_folio,
459 	.read_folio = affs_read_folio,
460 	.writepages = affs_writepages,
461 	.write_begin = affs_write_begin,
462 	.write_end = affs_write_end,
463 	.direct_IO = affs_direct_IO,
464 	.migrate_folio = buffer_migrate_folio,
465 	.bmap = _affs_bmap
466 };
467 
468 static inline struct buffer_head *
469 affs_bread_ino(struct inode *inode, int block, int create)
470 {
471 	struct buffer_head *bh, tmp_bh;
472 	int err;
473 
474 	tmp_bh.b_state = 0;
475 	err = affs_get_block(inode, block, &tmp_bh, create);
476 	if (!err) {
477 		bh = affs_bread(inode->i_sb, tmp_bh.b_blocknr);
478 		if (bh) {
479 			bh->b_state |= tmp_bh.b_state;
480 			return bh;
481 		}
482 		err = -EIO;
483 	}
484 	return ERR_PTR(err);
485 }
486 
487 static inline struct buffer_head *
488 affs_getzeroblk_ino(struct inode *inode, int block)
489 {
490 	struct buffer_head *bh, tmp_bh;
491 	int err;
492 
493 	tmp_bh.b_state = 0;
494 	err = affs_get_block(inode, block, &tmp_bh, 1);
495 	if (!err) {
496 		bh = affs_getzeroblk(inode->i_sb, tmp_bh.b_blocknr);
497 		if (bh) {
498 			bh->b_state |= tmp_bh.b_state;
499 			return bh;
500 		}
501 		err = -EIO;
502 	}
503 	return ERR_PTR(err);
504 }
505 
506 static inline struct buffer_head *
507 affs_getemptyblk_ino(struct inode *inode, int block)
508 {
509 	struct buffer_head *bh, tmp_bh;
510 	int err;
511 
512 	tmp_bh.b_state = 0;
513 	err = affs_get_block(inode, block, &tmp_bh, 1);
514 	if (!err) {
515 		bh = affs_getemptyblk(inode->i_sb, tmp_bh.b_blocknr);
516 		if (bh) {
517 			bh->b_state |= tmp_bh.b_state;
518 			return bh;
519 		}
520 		err = -EIO;
521 	}
522 	return ERR_PTR(err);
523 }
524 
525 static int affs_do_read_folio_ofs(struct folio *folio, size_t to, int create)
526 {
527 	struct inode *inode = folio->mapping->host;
528 	struct super_block *sb = inode->i_sb;
529 	struct buffer_head *bh;
530 	size_t pos = 0;
531 	size_t bidx, boff, bsize;
532 	u32 tmp;
533 
534 	pr_debug("%s(%lu, %ld, 0, %zu)\n", __func__, inode->i_ino,
535 		 folio->index, to);
536 	BUG_ON(to > folio_size(folio));
537 	bsize = AFFS_SB(sb)->s_data_blksize;
538 	tmp = folio_pos(folio);
539 	bidx = tmp / bsize;
540 	boff = tmp % bsize;
541 
542 	while (pos < to) {
543 		bh = affs_bread_ino(inode, bidx, create);
544 		if (IS_ERR(bh))
545 			return PTR_ERR(bh);
546 		tmp = min(bsize - boff, to - pos);
547 		BUG_ON(pos + tmp > to || tmp > bsize);
548 		memcpy_to_folio(folio, pos, AFFS_DATA(bh) + boff, tmp);
549 		affs_brelse(bh);
550 		bidx++;
551 		pos += tmp;
552 		boff = 0;
553 	}
554 	return 0;
555 }
556 
557 static int
558 affs_extent_file_ofs(struct inode *inode, u32 newsize)
559 {
560 	struct super_block *sb = inode->i_sb;
561 	struct buffer_head *bh, *prev_bh;
562 	u32 bidx, boff;
563 	u32 size, bsize;
564 	u32 tmp;
565 
566 	pr_debug("%s(%lu, %d)\n", __func__, inode->i_ino, newsize);
567 	bsize = AFFS_SB(sb)->s_data_blksize;
568 	bh = NULL;
569 	size = AFFS_I(inode)->mmu_private;
570 	bidx = size / bsize;
571 	boff = size % bsize;
572 	if (boff) {
573 		bh = affs_bread_ino(inode, bidx, 0);
574 		if (IS_ERR(bh))
575 			return PTR_ERR(bh);
576 		tmp = min(bsize - boff, newsize - size);
577 		BUG_ON(boff + tmp > bsize || tmp > bsize);
578 		memset(AFFS_DATA(bh) + boff, 0, tmp);
579 		be32_add_cpu(&AFFS_DATA_HEAD(bh)->size, tmp);
580 		affs_fix_checksum(sb, bh);
581 		mark_buffer_dirty_inode(bh, inode);
582 		size += tmp;
583 		bidx++;
584 	} else if (bidx) {
585 		bh = affs_bread_ino(inode, bidx - 1, 0);
586 		if (IS_ERR(bh))
587 			return PTR_ERR(bh);
588 	}
589 
590 	while (size < newsize) {
591 		prev_bh = bh;
592 		bh = affs_getzeroblk_ino(inode, bidx);
593 		if (IS_ERR(bh))
594 			goto out;
595 		tmp = min(bsize, newsize - size);
596 		BUG_ON(tmp > bsize);
597 		AFFS_DATA_HEAD(bh)->ptype = cpu_to_be32(T_DATA);
598 		AFFS_DATA_HEAD(bh)->key = cpu_to_be32(inode->i_ino);
599 		AFFS_DATA_HEAD(bh)->sequence = cpu_to_be32(bidx);
600 		AFFS_DATA_HEAD(bh)->size = cpu_to_be32(tmp);
601 		affs_fix_checksum(sb, bh);
602 		bh->b_state &= ~(1UL << BH_New);
603 		mark_buffer_dirty_inode(bh, inode);
604 		if (prev_bh) {
605 			u32 tmp_next = be32_to_cpu(AFFS_DATA_HEAD(prev_bh)->next);
606 
607 			if (tmp_next)
608 				affs_warning(sb, "extent_file_ofs",
609 					     "next block already set for %d (%d)",
610 					     bidx, tmp_next);
611 			AFFS_DATA_HEAD(prev_bh)->next = cpu_to_be32(bh->b_blocknr);
612 			affs_adjust_checksum(prev_bh, bh->b_blocknr - tmp_next);
613 			mark_buffer_dirty_inode(prev_bh, inode);
614 			affs_brelse(prev_bh);
615 		}
616 		size += bsize;
617 		bidx++;
618 	}
619 	affs_brelse(bh);
620 	inode->i_size = AFFS_I(inode)->mmu_private = newsize;
621 	return 0;
622 
623 out:
624 	inode->i_size = AFFS_I(inode)->mmu_private = newsize;
625 	return PTR_ERR(bh);
626 }
627 
628 static int affs_read_folio_ofs(struct file *file, struct folio *folio)
629 {
630 	struct inode *inode = folio->mapping->host;
631 	size_t to;
632 	int err;
633 
634 	pr_debug("%s(%lu, %ld)\n", __func__, inode->i_ino, folio->index);
635 	to = folio_size(folio);
636 	if (folio_pos(folio) + to > inode->i_size) {
637 		to = inode->i_size - folio_pos(folio);
638 		folio_zero_segment(folio, to, folio_size(folio));
639 	}
640 
641 	err = affs_do_read_folio_ofs(folio, to, 0);
642 	if (!err)
643 		folio_mark_uptodate(folio);
644 	folio_unlock(folio);
645 	return err;
646 }
647 
648 static int affs_write_begin_ofs(struct file *file, struct address_space *mapping,
649 				loff_t pos, unsigned len,
650 				struct folio **foliop, void **fsdata)
651 {
652 	struct inode *inode = mapping->host;
653 	struct folio *folio;
654 	pgoff_t index;
655 	int err = 0;
656 
657 	pr_debug("%s(%lu, %llu, %llu)\n", __func__, inode->i_ino, pos,
658 		 pos + len);
659 	if (pos > AFFS_I(inode)->mmu_private) {
660 		/* XXX: this probably leaves a too-big i_size in case of
661 		 * failure. Should really be updating i_size at write_end time
662 		 */
663 		err = affs_extent_file_ofs(inode, pos);
664 		if (err)
665 			return err;
666 	}
667 
668 	index = pos >> PAGE_SHIFT;
669 	folio = __filemap_get_folio(mapping, index, FGP_WRITEBEGIN,
670 			mapping_gfp_mask(mapping));
671 	if (IS_ERR(folio))
672 		return PTR_ERR(folio);
673 	*foliop = folio;
674 
675 	if (folio_test_uptodate(folio))
676 		return 0;
677 
678 	/* XXX: inefficient but safe in the face of short writes */
679 	err = affs_do_read_folio_ofs(folio, folio_size(folio), 1);
680 	if (err) {
681 		folio_unlock(folio);
682 		folio_put(folio);
683 	}
684 	return err;
685 }
686 
687 static int affs_write_end_ofs(struct file *file, struct address_space *mapping,
688 				loff_t pos, unsigned len, unsigned copied,
689 				struct folio *folio, void *fsdata)
690 {
691 	struct inode *inode = mapping->host;
692 	struct super_block *sb = inode->i_sb;
693 	struct buffer_head *bh, *prev_bh;
694 	char *data;
695 	u32 bidx, boff, bsize;
696 	unsigned from, to;
697 	u32 tmp;
698 	int written;
699 
700 	from = pos & (PAGE_SIZE - 1);
701 	to = from + len;
702 	/*
703 	 * XXX: not sure if this can handle short copies (len < copied), but
704 	 * we don't have to, because the folio should always be uptodate here,
705 	 * due to write_begin.
706 	 */
707 
708 	pr_debug("%s(%lu, %llu, %llu)\n", __func__, inode->i_ino, pos,
709 		 pos + len);
710 	bsize = AFFS_SB(sb)->s_data_blksize;
711 	data = folio_address(folio);
712 
713 	bh = NULL;
714 	written = 0;
715 	tmp = (folio->index << PAGE_SHIFT) + from;
716 	bidx = tmp / bsize;
717 	boff = tmp % bsize;
718 	if (boff) {
719 		bh = affs_bread_ino(inode, bidx, 0);
720 		if (IS_ERR(bh)) {
721 			written = PTR_ERR(bh);
722 			goto err_first_bh;
723 		}
724 		tmp = min(bsize - boff, to - from);
725 		BUG_ON(boff + tmp > bsize || tmp > bsize);
726 		memcpy(AFFS_DATA(bh) + boff, data + from, tmp);
727 		be32_add_cpu(&AFFS_DATA_HEAD(bh)->size, tmp);
728 		affs_fix_checksum(sb, bh);
729 		mark_buffer_dirty_inode(bh, inode);
730 		written += tmp;
731 		from += tmp;
732 		bidx++;
733 	} else if (bidx) {
734 		bh = affs_bread_ino(inode, bidx - 1, 0);
735 		if (IS_ERR(bh)) {
736 			written = PTR_ERR(bh);
737 			goto err_first_bh;
738 		}
739 	}
740 	while (from + bsize <= to) {
741 		prev_bh = bh;
742 		bh = affs_getemptyblk_ino(inode, bidx);
743 		if (IS_ERR(bh))
744 			goto err_bh;
745 		memcpy(AFFS_DATA(bh), data + from, bsize);
746 		if (buffer_new(bh)) {
747 			AFFS_DATA_HEAD(bh)->ptype = cpu_to_be32(T_DATA);
748 			AFFS_DATA_HEAD(bh)->key = cpu_to_be32(inode->i_ino);
749 			AFFS_DATA_HEAD(bh)->sequence = cpu_to_be32(bidx);
750 			AFFS_DATA_HEAD(bh)->size = cpu_to_be32(bsize);
751 			AFFS_DATA_HEAD(bh)->next = 0;
752 			bh->b_state &= ~(1UL << BH_New);
753 			if (prev_bh) {
754 				u32 tmp_next = be32_to_cpu(AFFS_DATA_HEAD(prev_bh)->next);
755 
756 				if (tmp_next)
757 					affs_warning(sb, "commit_write_ofs",
758 						     "next block already set for %d (%d)",
759 						     bidx, tmp_next);
760 				AFFS_DATA_HEAD(prev_bh)->next = cpu_to_be32(bh->b_blocknr);
761 				affs_adjust_checksum(prev_bh, bh->b_blocknr - tmp_next);
762 				mark_buffer_dirty_inode(prev_bh, inode);
763 			}
764 		}
765 		affs_brelse(prev_bh);
766 		affs_fix_checksum(sb, bh);
767 		mark_buffer_dirty_inode(bh, inode);
768 		written += bsize;
769 		from += bsize;
770 		bidx++;
771 	}
772 	if (from < to) {
773 		prev_bh = bh;
774 		bh = affs_bread_ino(inode, bidx, 1);
775 		if (IS_ERR(bh))
776 			goto err_bh;
777 		tmp = min(bsize, to - from);
778 		BUG_ON(tmp > bsize);
779 		memcpy(AFFS_DATA(bh), data + from, tmp);
780 		if (buffer_new(bh)) {
781 			AFFS_DATA_HEAD(bh)->ptype = cpu_to_be32(T_DATA);
782 			AFFS_DATA_HEAD(bh)->key = cpu_to_be32(inode->i_ino);
783 			AFFS_DATA_HEAD(bh)->sequence = cpu_to_be32(bidx);
784 			AFFS_DATA_HEAD(bh)->size = cpu_to_be32(tmp);
785 			AFFS_DATA_HEAD(bh)->next = 0;
786 			bh->b_state &= ~(1UL << BH_New);
787 			if (prev_bh) {
788 				u32 tmp_next = be32_to_cpu(AFFS_DATA_HEAD(prev_bh)->next);
789 
790 				if (tmp_next)
791 					affs_warning(sb, "commit_write_ofs",
792 						     "next block already set for %d (%d)",
793 						     bidx, tmp_next);
794 				AFFS_DATA_HEAD(prev_bh)->next = cpu_to_be32(bh->b_blocknr);
795 				affs_adjust_checksum(prev_bh, bh->b_blocknr - tmp_next);
796 				mark_buffer_dirty_inode(prev_bh, inode);
797 			}
798 		} else if (be32_to_cpu(AFFS_DATA_HEAD(bh)->size) < tmp)
799 			AFFS_DATA_HEAD(bh)->size = cpu_to_be32(tmp);
800 		affs_brelse(prev_bh);
801 		affs_fix_checksum(sb, bh);
802 		mark_buffer_dirty_inode(bh, inode);
803 		written += tmp;
804 		from += tmp;
805 		bidx++;
806 	}
807 	folio_mark_uptodate(folio);
808 
809 done:
810 	affs_brelse(bh);
811 	tmp = (folio->index << PAGE_SHIFT) + from;
812 	if (tmp > inode->i_size)
813 		inode->i_size = AFFS_I(inode)->mmu_private = tmp;
814 
815 	/* Clear Archived bit on file writes, as AmigaOS would do */
816 	if (AFFS_I(inode)->i_protect & FIBF_ARCHIVED) {
817 		AFFS_I(inode)->i_protect &= ~FIBF_ARCHIVED;
818 		mark_inode_dirty(inode);
819 	}
820 
821 err_first_bh:
822 	folio_unlock(folio);
823 	folio_put(folio);
824 
825 	return written;
826 
827 err_bh:
828 	bh = prev_bh;
829 	if (!written)
830 		written = PTR_ERR(bh);
831 	goto done;
832 }
833 
834 const struct address_space_operations affs_aops_ofs = {
835 	.dirty_folio	= block_dirty_folio,
836 	.invalidate_folio = block_invalidate_folio,
837 	.read_folio = affs_read_folio_ofs,
838 	//.writepages = affs_writepages_ofs,
839 	.write_begin = affs_write_begin_ofs,
840 	.write_end = affs_write_end_ofs,
841 	.migrate_folio = filemap_migrate_folio,
842 };
843 
844 /* Free any preallocated blocks. */
845 
846 void
847 affs_free_prealloc(struct inode *inode)
848 {
849 	struct super_block *sb = inode->i_sb;
850 
851 	pr_debug("free_prealloc(ino=%lu)\n", inode->i_ino);
852 
853 	while (AFFS_I(inode)->i_pa_cnt) {
854 		AFFS_I(inode)->i_pa_cnt--;
855 		affs_free_block(sb, ++AFFS_I(inode)->i_lastalloc);
856 	}
857 }
858 
859 /* Truncate (or enlarge) a file to the requested size. */
860 
861 void
862 affs_truncate(struct inode *inode)
863 {
864 	struct super_block *sb = inode->i_sb;
865 	u32 ext, ext_key;
866 	u32 last_blk, blkcnt, blk;
867 	u32 size;
868 	struct buffer_head *ext_bh;
869 	int i;
870 
871 	pr_debug("truncate(inode=%lu, oldsize=%llu, newsize=%llu)\n",
872 		 inode->i_ino, AFFS_I(inode)->mmu_private, inode->i_size);
873 
874 	last_blk = 0;
875 	ext = 0;
876 	if (inode->i_size) {
877 		last_blk = ((u32)inode->i_size - 1) / AFFS_SB(sb)->s_data_blksize;
878 		ext = last_blk / AFFS_SB(sb)->s_hashsize;
879 	}
880 
881 	if (inode->i_size > AFFS_I(inode)->mmu_private) {
882 		struct address_space *mapping = inode->i_mapping;
883 		struct folio *folio;
884 		void *fsdata = NULL;
885 		loff_t isize = inode->i_size;
886 		int res;
887 
888 		res = mapping->a_ops->write_begin(NULL, mapping, isize, 0, &folio, &fsdata);
889 		if (!res)
890 			res = mapping->a_ops->write_end(NULL, mapping, isize, 0, 0, folio, fsdata);
891 		else
892 			inode->i_size = AFFS_I(inode)->mmu_private;
893 		mark_inode_dirty(inode);
894 		return;
895 	} else if (inode->i_size == AFFS_I(inode)->mmu_private)
896 		return;
897 
898 	// lock cache
899 	ext_bh = affs_get_extblock(inode, ext);
900 	if (IS_ERR(ext_bh)) {
901 		affs_warning(sb, "truncate",
902 			     "unexpected read error for ext block %u (%ld)",
903 			     ext, PTR_ERR(ext_bh));
904 		return;
905 	}
906 	if (AFFS_I(inode)->i_lc) {
907 		/* clear linear cache */
908 		i = (ext + 1) >> AFFS_I(inode)->i_lc_shift;
909 		if (AFFS_I(inode)->i_lc_size > i) {
910 			AFFS_I(inode)->i_lc_size = i;
911 			for (; i < AFFS_LC_SIZE; i++)
912 				AFFS_I(inode)->i_lc[i] = 0;
913 		}
914 		/* clear associative cache */
915 		for (i = 0; i < AFFS_AC_SIZE; i++)
916 			if (AFFS_I(inode)->i_ac[i].ext >= ext)
917 				AFFS_I(inode)->i_ac[i].ext = 0;
918 	}
919 	ext_key = be32_to_cpu(AFFS_TAIL(sb, ext_bh)->extension);
920 
921 	blkcnt = AFFS_I(inode)->i_blkcnt;
922 	i = 0;
923 	blk = last_blk;
924 	if (inode->i_size) {
925 		i = last_blk % AFFS_SB(sb)->s_hashsize + 1;
926 		blk++;
927 	} else
928 		AFFS_HEAD(ext_bh)->first_data = 0;
929 	AFFS_HEAD(ext_bh)->block_count = cpu_to_be32(i);
930 	size = AFFS_SB(sb)->s_hashsize;
931 	if (size > blkcnt - blk + i)
932 		size = blkcnt - blk + i;
933 	for (; i < size; i++, blk++) {
934 		affs_free_block(sb, be32_to_cpu(AFFS_BLOCK(sb, ext_bh, i)));
935 		AFFS_BLOCK(sb, ext_bh, i) = 0;
936 	}
937 	AFFS_TAIL(sb, ext_bh)->extension = 0;
938 	affs_fix_checksum(sb, ext_bh);
939 	mark_buffer_dirty_inode(ext_bh, inode);
940 	affs_brelse(ext_bh);
941 
942 	if (inode->i_size) {
943 		AFFS_I(inode)->i_blkcnt = last_blk + 1;
944 		AFFS_I(inode)->i_extcnt = ext + 1;
945 		if (affs_test_opt(AFFS_SB(sb)->s_flags, SF_OFS)) {
946 			struct buffer_head *bh = affs_bread_ino(inode, last_blk, 0);
947 			u32 tmp;
948 			if (IS_ERR(bh)) {
949 				affs_warning(sb, "truncate",
950 					     "unexpected read error for last block %u (%ld)",
951 					     ext, PTR_ERR(bh));
952 				return;
953 			}
954 			tmp = be32_to_cpu(AFFS_DATA_HEAD(bh)->next);
955 			AFFS_DATA_HEAD(bh)->next = 0;
956 			affs_adjust_checksum(bh, -tmp);
957 			affs_brelse(bh);
958 		}
959 	} else {
960 		AFFS_I(inode)->i_blkcnt = 0;
961 		AFFS_I(inode)->i_extcnt = 1;
962 	}
963 	AFFS_I(inode)->mmu_private = inode->i_size;
964 	// unlock cache
965 
966 	while (ext_key) {
967 		ext_bh = affs_bread(sb, ext_key);
968 		size = AFFS_SB(sb)->s_hashsize;
969 		if (size > blkcnt - blk)
970 			size = blkcnt - blk;
971 		for (i = 0; i < size; i++, blk++)
972 			affs_free_block(sb, be32_to_cpu(AFFS_BLOCK(sb, ext_bh, i)));
973 		affs_free_block(sb, ext_key);
974 		ext_key = be32_to_cpu(AFFS_TAIL(sb, ext_bh)->extension);
975 		affs_brelse(ext_bh);
976 	}
977 	affs_free_prealloc(inode);
978 }
979 
980 int affs_file_fsync(struct file *filp, loff_t start, loff_t end, int datasync)
981 {
982 	struct inode *inode = filp->f_mapping->host;
983 	int ret, err;
984 
985 	err = file_write_and_wait_range(filp, start, end);
986 	if (err)
987 		return err;
988 
989 	inode_lock(inode);
990 	ret = write_inode_now(inode, 0);
991 	err = sync_blockdev(inode->i_sb->s_bdev);
992 	if (!ret)
993 		ret = err;
994 	inode_unlock(inode);
995 	return ret;
996 }
997 const struct file_operations affs_file_operations = {
998 	.llseek		= generic_file_llseek,
999 	.read_iter	= generic_file_read_iter,
1000 	.write_iter	= generic_file_write_iter,
1001 	.mmap		= generic_file_mmap,
1002 	.open		= affs_file_open,
1003 	.release	= affs_file_release,
1004 	.fsync		= affs_file_fsync,
1005 	.splice_read	= filemap_splice_read,
1006 };
1007 
1008 const struct inode_operations affs_file_inode_operations = {
1009 	.setattr	= affs_notify_change,
1010 };
1011