xref: /linux/fs/affs/file.c (revision 73aea586d6c58f55799f6130e19321ff7b574c3d)
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 page **pagep, void **fsdata)
421 {
422 	int ret;
423 
424 	*pagep = NULL;
425 	ret = cont_write_begin(file, mapping, pos, len, pagep, fsdata,
426 				affs_get_block,
427 				&AFFS_I(mapping->host)->mmu_private);
428 	if (unlikely(ret))
429 		affs_write_failed(mapping, pos + len);
430 
431 	return ret;
432 }
433 
434 static int affs_write_end(struct file *file, struct address_space *mapping,
435 			  loff_t pos, unsigned int len, unsigned int copied,
436 			  struct page *page, void *fsdata)
437 {
438 	struct inode *inode = mapping->host;
439 	int ret;
440 
441 	ret = generic_write_end(file, mapping, pos, len, copied, page, fsdata);
442 
443 	/* Clear Archived bit on file writes, as AmigaOS would do */
444 	if (AFFS_I(inode)->i_protect & FIBF_ARCHIVED) {
445 		AFFS_I(inode)->i_protect &= ~FIBF_ARCHIVED;
446 		mark_inode_dirty(inode);
447 	}
448 
449 	return ret;
450 }
451 
452 static sector_t _affs_bmap(struct address_space *mapping, sector_t block)
453 {
454 	return generic_block_bmap(mapping,block,affs_get_block);
455 }
456 
457 const struct address_space_operations affs_aops = {
458 	.dirty_folio	= block_dirty_folio,
459 	.invalidate_folio = block_invalidate_folio,
460 	.read_folio = affs_read_folio,
461 	.writepages = affs_writepages,
462 	.write_begin = affs_write_begin,
463 	.write_end = affs_write_end,
464 	.direct_IO = affs_direct_IO,
465 	.migrate_folio = buffer_migrate_folio,
466 	.bmap = _affs_bmap
467 };
468 
469 static inline struct buffer_head *
470 affs_bread_ino(struct inode *inode, int block, int create)
471 {
472 	struct buffer_head *bh, tmp_bh;
473 	int err;
474 
475 	tmp_bh.b_state = 0;
476 	err = affs_get_block(inode, block, &tmp_bh, create);
477 	if (!err) {
478 		bh = affs_bread(inode->i_sb, tmp_bh.b_blocknr);
479 		if (bh) {
480 			bh->b_state |= tmp_bh.b_state;
481 			return bh;
482 		}
483 		err = -EIO;
484 	}
485 	return ERR_PTR(err);
486 }
487 
488 static inline struct buffer_head *
489 affs_getzeroblk_ino(struct inode *inode, int block)
490 {
491 	struct buffer_head *bh, tmp_bh;
492 	int err;
493 
494 	tmp_bh.b_state = 0;
495 	err = affs_get_block(inode, block, &tmp_bh, 1);
496 	if (!err) {
497 		bh = affs_getzeroblk(inode->i_sb, tmp_bh.b_blocknr);
498 		if (bh) {
499 			bh->b_state |= tmp_bh.b_state;
500 			return bh;
501 		}
502 		err = -EIO;
503 	}
504 	return ERR_PTR(err);
505 }
506 
507 static inline struct buffer_head *
508 affs_getemptyblk_ino(struct inode *inode, int block)
509 {
510 	struct buffer_head *bh, tmp_bh;
511 	int err;
512 
513 	tmp_bh.b_state = 0;
514 	err = affs_get_block(inode, block, &tmp_bh, 1);
515 	if (!err) {
516 		bh = affs_getemptyblk(inode->i_sb, tmp_bh.b_blocknr);
517 		if (bh) {
518 			bh->b_state |= tmp_bh.b_state;
519 			return bh;
520 		}
521 		err = -EIO;
522 	}
523 	return ERR_PTR(err);
524 }
525 
526 static int affs_do_read_folio_ofs(struct folio *folio, size_t to, int create)
527 {
528 	struct inode *inode = folio->mapping->host;
529 	struct super_block *sb = inode->i_sb;
530 	struct buffer_head *bh;
531 	size_t pos = 0;
532 	size_t bidx, boff, bsize;
533 	u32 tmp;
534 
535 	pr_debug("%s(%lu, %ld, 0, %zu)\n", __func__, inode->i_ino,
536 		 folio->index, to);
537 	BUG_ON(to > folio_size(folio));
538 	bsize = AFFS_SB(sb)->s_data_blksize;
539 	tmp = folio_pos(folio);
540 	bidx = tmp / bsize;
541 	boff = tmp % bsize;
542 
543 	while (pos < to) {
544 		bh = affs_bread_ino(inode, bidx, create);
545 		if (IS_ERR(bh))
546 			return PTR_ERR(bh);
547 		tmp = min(bsize - boff, to - pos);
548 		BUG_ON(pos + tmp > to || tmp > bsize);
549 		memcpy_to_folio(folio, pos, AFFS_DATA(bh) + boff, tmp);
550 		affs_brelse(bh);
551 		bidx++;
552 		pos += tmp;
553 		boff = 0;
554 	}
555 	return 0;
556 }
557 
558 static int
559 affs_extent_file_ofs(struct inode *inode, u32 newsize)
560 {
561 	struct super_block *sb = inode->i_sb;
562 	struct buffer_head *bh, *prev_bh;
563 	u32 bidx, boff;
564 	u32 size, bsize;
565 	u32 tmp;
566 
567 	pr_debug("%s(%lu, %d)\n", __func__, inode->i_ino, newsize);
568 	bsize = AFFS_SB(sb)->s_data_blksize;
569 	bh = NULL;
570 	size = AFFS_I(inode)->mmu_private;
571 	bidx = size / bsize;
572 	boff = size % bsize;
573 	if (boff) {
574 		bh = affs_bread_ino(inode, bidx, 0);
575 		if (IS_ERR(bh))
576 			return PTR_ERR(bh);
577 		tmp = min(bsize - boff, newsize - size);
578 		BUG_ON(boff + tmp > bsize || tmp > bsize);
579 		memset(AFFS_DATA(bh) + boff, 0, tmp);
580 		be32_add_cpu(&AFFS_DATA_HEAD(bh)->size, tmp);
581 		affs_fix_checksum(sb, bh);
582 		mark_buffer_dirty_inode(bh, inode);
583 		size += tmp;
584 		bidx++;
585 	} else if (bidx) {
586 		bh = affs_bread_ino(inode, bidx - 1, 0);
587 		if (IS_ERR(bh))
588 			return PTR_ERR(bh);
589 	}
590 
591 	while (size < newsize) {
592 		prev_bh = bh;
593 		bh = affs_getzeroblk_ino(inode, bidx);
594 		if (IS_ERR(bh))
595 			goto out;
596 		tmp = min(bsize, newsize - size);
597 		BUG_ON(tmp > bsize);
598 		AFFS_DATA_HEAD(bh)->ptype = cpu_to_be32(T_DATA);
599 		AFFS_DATA_HEAD(bh)->key = cpu_to_be32(inode->i_ino);
600 		AFFS_DATA_HEAD(bh)->sequence = cpu_to_be32(bidx);
601 		AFFS_DATA_HEAD(bh)->size = cpu_to_be32(tmp);
602 		affs_fix_checksum(sb, bh);
603 		bh->b_state &= ~(1UL << BH_New);
604 		mark_buffer_dirty_inode(bh, inode);
605 		if (prev_bh) {
606 			u32 tmp_next = be32_to_cpu(AFFS_DATA_HEAD(prev_bh)->next);
607 
608 			if (tmp_next)
609 				affs_warning(sb, "extent_file_ofs",
610 					     "next block already set for %d (%d)",
611 					     bidx, tmp_next);
612 			AFFS_DATA_HEAD(prev_bh)->next = cpu_to_be32(bh->b_blocknr);
613 			affs_adjust_checksum(prev_bh, bh->b_blocknr - tmp_next);
614 			mark_buffer_dirty_inode(prev_bh, inode);
615 			affs_brelse(prev_bh);
616 		}
617 		size += bsize;
618 		bidx++;
619 	}
620 	affs_brelse(bh);
621 	inode->i_size = AFFS_I(inode)->mmu_private = newsize;
622 	return 0;
623 
624 out:
625 	inode->i_size = AFFS_I(inode)->mmu_private = newsize;
626 	return PTR_ERR(bh);
627 }
628 
629 static int affs_read_folio_ofs(struct file *file, struct folio *folio)
630 {
631 	struct inode *inode = folio->mapping->host;
632 	size_t to;
633 	int err;
634 
635 	pr_debug("%s(%lu, %ld)\n", __func__, inode->i_ino, folio->index);
636 	to = folio_size(folio);
637 	if (folio_pos(folio) + to > inode->i_size) {
638 		to = inode->i_size - folio_pos(folio);
639 		folio_zero_segment(folio, to, folio_size(folio));
640 	}
641 
642 	err = affs_do_read_folio_ofs(folio, to, 0);
643 	if (!err)
644 		folio_mark_uptodate(folio);
645 	folio_unlock(folio);
646 	return err;
647 }
648 
649 static int affs_write_begin_ofs(struct file *file, struct address_space *mapping,
650 				loff_t pos, unsigned len,
651 				struct page **pagep, void **fsdata)
652 {
653 	struct inode *inode = mapping->host;
654 	struct folio *folio;
655 	pgoff_t index;
656 	int err = 0;
657 
658 	pr_debug("%s(%lu, %llu, %llu)\n", __func__, inode->i_ino, pos,
659 		 pos + len);
660 	if (pos > AFFS_I(inode)->mmu_private) {
661 		/* XXX: this probably leaves a too-big i_size in case of
662 		 * failure. Should really be updating i_size at write_end time
663 		 */
664 		err = affs_extent_file_ofs(inode, pos);
665 		if (err)
666 			return err;
667 	}
668 
669 	index = pos >> PAGE_SHIFT;
670 	folio = __filemap_get_folio(mapping, index, FGP_WRITEBEGIN,
671 			mapping_gfp_mask(mapping));
672 	if (IS_ERR(folio))
673 		return PTR_ERR(folio);
674 	*pagep = &folio->page;
675 
676 	if (folio_test_uptodate(folio))
677 		return 0;
678 
679 	/* XXX: inefficient but safe in the face of short writes */
680 	err = affs_do_read_folio_ofs(folio, folio_size(folio), 1);
681 	if (err) {
682 		folio_unlock(folio);
683 		folio_put(folio);
684 	}
685 	return err;
686 }
687 
688 static int affs_write_end_ofs(struct file *file, struct address_space *mapping,
689 				loff_t pos, unsigned len, unsigned copied,
690 				struct page *page, void *fsdata)
691 {
692 	struct folio *folio = page_folio(page);
693 	struct inode *inode = mapping->host;
694 	struct super_block *sb = inode->i_sb;
695 	struct buffer_head *bh, *prev_bh;
696 	char *data;
697 	u32 bidx, boff, bsize;
698 	unsigned from, to;
699 	u32 tmp;
700 	int written;
701 
702 	from = pos & (PAGE_SIZE - 1);
703 	to = from + len;
704 	/*
705 	 * XXX: not sure if this can handle short copies (len < copied), but
706 	 * we don't have to, because the folio should always be uptodate here,
707 	 * due to write_begin.
708 	 */
709 
710 	pr_debug("%s(%lu, %llu, %llu)\n", __func__, inode->i_ino, pos,
711 		 pos + len);
712 	bsize = AFFS_SB(sb)->s_data_blksize;
713 	data = folio_address(folio);
714 
715 	bh = NULL;
716 	written = 0;
717 	tmp = (folio->index << PAGE_SHIFT) + from;
718 	bidx = tmp / bsize;
719 	boff = tmp % bsize;
720 	if (boff) {
721 		bh = affs_bread_ino(inode, bidx, 0);
722 		if (IS_ERR(bh)) {
723 			written = PTR_ERR(bh);
724 			goto err_first_bh;
725 		}
726 		tmp = min(bsize - boff, to - from);
727 		BUG_ON(boff + tmp > bsize || tmp > bsize);
728 		memcpy(AFFS_DATA(bh) + boff, data + from, tmp);
729 		be32_add_cpu(&AFFS_DATA_HEAD(bh)->size, tmp);
730 		affs_fix_checksum(sb, bh);
731 		mark_buffer_dirty_inode(bh, inode);
732 		written += tmp;
733 		from += tmp;
734 		bidx++;
735 	} else if (bidx) {
736 		bh = affs_bread_ino(inode, bidx - 1, 0);
737 		if (IS_ERR(bh)) {
738 			written = PTR_ERR(bh);
739 			goto err_first_bh;
740 		}
741 	}
742 	while (from + bsize <= to) {
743 		prev_bh = bh;
744 		bh = affs_getemptyblk_ino(inode, bidx);
745 		if (IS_ERR(bh))
746 			goto err_bh;
747 		memcpy(AFFS_DATA(bh), data + from, bsize);
748 		if (buffer_new(bh)) {
749 			AFFS_DATA_HEAD(bh)->ptype = cpu_to_be32(T_DATA);
750 			AFFS_DATA_HEAD(bh)->key = cpu_to_be32(inode->i_ino);
751 			AFFS_DATA_HEAD(bh)->sequence = cpu_to_be32(bidx);
752 			AFFS_DATA_HEAD(bh)->size = cpu_to_be32(bsize);
753 			AFFS_DATA_HEAD(bh)->next = 0;
754 			bh->b_state &= ~(1UL << BH_New);
755 			if (prev_bh) {
756 				u32 tmp_next = be32_to_cpu(AFFS_DATA_HEAD(prev_bh)->next);
757 
758 				if (tmp_next)
759 					affs_warning(sb, "commit_write_ofs",
760 						     "next block already set for %d (%d)",
761 						     bidx, tmp_next);
762 				AFFS_DATA_HEAD(prev_bh)->next = cpu_to_be32(bh->b_blocknr);
763 				affs_adjust_checksum(prev_bh, bh->b_blocknr - tmp_next);
764 				mark_buffer_dirty_inode(prev_bh, inode);
765 			}
766 		}
767 		affs_brelse(prev_bh);
768 		affs_fix_checksum(sb, bh);
769 		mark_buffer_dirty_inode(bh, inode);
770 		written += bsize;
771 		from += bsize;
772 		bidx++;
773 	}
774 	if (from < to) {
775 		prev_bh = bh;
776 		bh = affs_bread_ino(inode, bidx, 1);
777 		if (IS_ERR(bh))
778 			goto err_bh;
779 		tmp = min(bsize, to - from);
780 		BUG_ON(tmp > bsize);
781 		memcpy(AFFS_DATA(bh), data + from, tmp);
782 		if (buffer_new(bh)) {
783 			AFFS_DATA_HEAD(bh)->ptype = cpu_to_be32(T_DATA);
784 			AFFS_DATA_HEAD(bh)->key = cpu_to_be32(inode->i_ino);
785 			AFFS_DATA_HEAD(bh)->sequence = cpu_to_be32(bidx);
786 			AFFS_DATA_HEAD(bh)->size = cpu_to_be32(tmp);
787 			AFFS_DATA_HEAD(bh)->next = 0;
788 			bh->b_state &= ~(1UL << BH_New);
789 			if (prev_bh) {
790 				u32 tmp_next = be32_to_cpu(AFFS_DATA_HEAD(prev_bh)->next);
791 
792 				if (tmp_next)
793 					affs_warning(sb, "commit_write_ofs",
794 						     "next block already set for %d (%d)",
795 						     bidx, tmp_next);
796 				AFFS_DATA_HEAD(prev_bh)->next = cpu_to_be32(bh->b_blocknr);
797 				affs_adjust_checksum(prev_bh, bh->b_blocknr - tmp_next);
798 				mark_buffer_dirty_inode(prev_bh, inode);
799 			}
800 		} else if (be32_to_cpu(AFFS_DATA_HEAD(bh)->size) < tmp)
801 			AFFS_DATA_HEAD(bh)->size = cpu_to_be32(tmp);
802 		affs_brelse(prev_bh);
803 		affs_fix_checksum(sb, bh);
804 		mark_buffer_dirty_inode(bh, inode);
805 		written += tmp;
806 		from += tmp;
807 		bidx++;
808 	}
809 	folio_mark_uptodate(folio);
810 
811 done:
812 	affs_brelse(bh);
813 	tmp = (folio->index << PAGE_SHIFT) + from;
814 	if (tmp > inode->i_size)
815 		inode->i_size = AFFS_I(inode)->mmu_private = tmp;
816 
817 	/* Clear Archived bit on file writes, as AmigaOS would do */
818 	if (AFFS_I(inode)->i_protect & FIBF_ARCHIVED) {
819 		AFFS_I(inode)->i_protect &= ~FIBF_ARCHIVED;
820 		mark_inode_dirty(inode);
821 	}
822 
823 err_first_bh:
824 	folio_unlock(folio);
825 	folio_put(folio);
826 
827 	return written;
828 
829 err_bh:
830 	bh = prev_bh;
831 	if (!written)
832 		written = PTR_ERR(bh);
833 	goto done;
834 }
835 
836 const struct address_space_operations affs_aops_ofs = {
837 	.dirty_folio	= block_dirty_folio,
838 	.invalidate_folio = block_invalidate_folio,
839 	.read_folio = affs_read_folio_ofs,
840 	//.writepages = affs_writepages_ofs,
841 	.write_begin = affs_write_begin_ofs,
842 	.write_end = affs_write_end_ofs,
843 	.migrate_folio = filemap_migrate_folio,
844 };
845 
846 /* Free any preallocated blocks. */
847 
848 void
849 affs_free_prealloc(struct inode *inode)
850 {
851 	struct super_block *sb = inode->i_sb;
852 
853 	pr_debug("free_prealloc(ino=%lu)\n", inode->i_ino);
854 
855 	while (AFFS_I(inode)->i_pa_cnt) {
856 		AFFS_I(inode)->i_pa_cnt--;
857 		affs_free_block(sb, ++AFFS_I(inode)->i_lastalloc);
858 	}
859 }
860 
861 /* Truncate (or enlarge) a file to the requested size. */
862 
863 void
864 affs_truncate(struct inode *inode)
865 {
866 	struct super_block *sb = inode->i_sb;
867 	u32 ext, ext_key;
868 	u32 last_blk, blkcnt, blk;
869 	u32 size;
870 	struct buffer_head *ext_bh;
871 	int i;
872 
873 	pr_debug("truncate(inode=%lu, oldsize=%llu, newsize=%llu)\n",
874 		 inode->i_ino, AFFS_I(inode)->mmu_private, inode->i_size);
875 
876 	last_blk = 0;
877 	ext = 0;
878 	if (inode->i_size) {
879 		last_blk = ((u32)inode->i_size - 1) / AFFS_SB(sb)->s_data_blksize;
880 		ext = last_blk / AFFS_SB(sb)->s_hashsize;
881 	}
882 
883 	if (inode->i_size > AFFS_I(inode)->mmu_private) {
884 		struct address_space *mapping = inode->i_mapping;
885 		struct page *page;
886 		void *fsdata = NULL;
887 		loff_t isize = inode->i_size;
888 		int res;
889 
890 		res = mapping->a_ops->write_begin(NULL, mapping, isize, 0, &page, &fsdata);
891 		if (!res)
892 			res = mapping->a_ops->write_end(NULL, mapping, isize, 0, 0, page, fsdata);
893 		else
894 			inode->i_size = AFFS_I(inode)->mmu_private;
895 		mark_inode_dirty(inode);
896 		return;
897 	} else if (inode->i_size == AFFS_I(inode)->mmu_private)
898 		return;
899 
900 	// lock cache
901 	ext_bh = affs_get_extblock(inode, ext);
902 	if (IS_ERR(ext_bh)) {
903 		affs_warning(sb, "truncate",
904 			     "unexpected read error for ext block %u (%ld)",
905 			     ext, PTR_ERR(ext_bh));
906 		return;
907 	}
908 	if (AFFS_I(inode)->i_lc) {
909 		/* clear linear cache */
910 		i = (ext + 1) >> AFFS_I(inode)->i_lc_shift;
911 		if (AFFS_I(inode)->i_lc_size > i) {
912 			AFFS_I(inode)->i_lc_size = i;
913 			for (; i < AFFS_LC_SIZE; i++)
914 				AFFS_I(inode)->i_lc[i] = 0;
915 		}
916 		/* clear associative cache */
917 		for (i = 0; i < AFFS_AC_SIZE; i++)
918 			if (AFFS_I(inode)->i_ac[i].ext >= ext)
919 				AFFS_I(inode)->i_ac[i].ext = 0;
920 	}
921 	ext_key = be32_to_cpu(AFFS_TAIL(sb, ext_bh)->extension);
922 
923 	blkcnt = AFFS_I(inode)->i_blkcnt;
924 	i = 0;
925 	blk = last_blk;
926 	if (inode->i_size) {
927 		i = last_blk % AFFS_SB(sb)->s_hashsize + 1;
928 		blk++;
929 	} else
930 		AFFS_HEAD(ext_bh)->first_data = 0;
931 	AFFS_HEAD(ext_bh)->block_count = cpu_to_be32(i);
932 	size = AFFS_SB(sb)->s_hashsize;
933 	if (size > blkcnt - blk + i)
934 		size = blkcnt - blk + i;
935 	for (; i < size; i++, blk++) {
936 		affs_free_block(sb, be32_to_cpu(AFFS_BLOCK(sb, ext_bh, i)));
937 		AFFS_BLOCK(sb, ext_bh, i) = 0;
938 	}
939 	AFFS_TAIL(sb, ext_bh)->extension = 0;
940 	affs_fix_checksum(sb, ext_bh);
941 	mark_buffer_dirty_inode(ext_bh, inode);
942 	affs_brelse(ext_bh);
943 
944 	if (inode->i_size) {
945 		AFFS_I(inode)->i_blkcnt = last_blk + 1;
946 		AFFS_I(inode)->i_extcnt = ext + 1;
947 		if (affs_test_opt(AFFS_SB(sb)->s_flags, SF_OFS)) {
948 			struct buffer_head *bh = affs_bread_ino(inode, last_blk, 0);
949 			u32 tmp;
950 			if (IS_ERR(bh)) {
951 				affs_warning(sb, "truncate",
952 					     "unexpected read error for last block %u (%ld)",
953 					     ext, PTR_ERR(bh));
954 				return;
955 			}
956 			tmp = be32_to_cpu(AFFS_DATA_HEAD(bh)->next);
957 			AFFS_DATA_HEAD(bh)->next = 0;
958 			affs_adjust_checksum(bh, -tmp);
959 			affs_brelse(bh);
960 		}
961 	} else {
962 		AFFS_I(inode)->i_blkcnt = 0;
963 		AFFS_I(inode)->i_extcnt = 1;
964 	}
965 	AFFS_I(inode)->mmu_private = inode->i_size;
966 	// unlock cache
967 
968 	while (ext_key) {
969 		ext_bh = affs_bread(sb, ext_key);
970 		size = AFFS_SB(sb)->s_hashsize;
971 		if (size > blkcnt - blk)
972 			size = blkcnt - blk;
973 		for (i = 0; i < size; i++, blk++)
974 			affs_free_block(sb, be32_to_cpu(AFFS_BLOCK(sb, ext_bh, i)));
975 		affs_free_block(sb, ext_key);
976 		ext_key = be32_to_cpu(AFFS_TAIL(sb, ext_bh)->extension);
977 		affs_brelse(ext_bh);
978 	}
979 	affs_free_prealloc(inode);
980 }
981 
982 int affs_file_fsync(struct file *filp, loff_t start, loff_t end, int datasync)
983 {
984 	struct inode *inode = filp->f_mapping->host;
985 	int ret, err;
986 
987 	err = file_write_and_wait_range(filp, start, end);
988 	if (err)
989 		return err;
990 
991 	inode_lock(inode);
992 	ret = write_inode_now(inode, 0);
993 	err = sync_blockdev(inode->i_sb->s_bdev);
994 	if (!ret)
995 		ret = err;
996 	inode_unlock(inode);
997 	return ret;
998 }
999 const struct file_operations affs_file_operations = {
1000 	.llseek		= generic_file_llseek,
1001 	.read_iter	= generic_file_read_iter,
1002 	.write_iter	= generic_file_write_iter,
1003 	.mmap		= generic_file_mmap,
1004 	.open		= affs_file_open,
1005 	.release	= affs_file_release,
1006 	.fsync		= affs_file_fsync,
1007 	.splice_read	= filemap_splice_read,
1008 };
1009 
1010 const struct inode_operations affs_file_inode_operations = {
1011 	.setattr	= affs_notify_change,
1012 };
1013