xref: /openbmc/linux/fs/affs/file.c (revision f71a261a)
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 "affs.h"
19 
20 static struct buffer_head *affs_get_extblock_slow(struct inode *inode, u32 ext);
21 
22 static int
23 affs_file_open(struct inode *inode, struct file *filp)
24 {
25 	pr_debug("open(%lu,%d)\n",
26 		 inode->i_ino, atomic_read(&AFFS_I(inode)->i_opencnt));
27 	atomic_inc(&AFFS_I(inode)->i_opencnt);
28 	return 0;
29 }
30 
31 static int
32 affs_file_release(struct inode *inode, struct file *filp)
33 {
34 	pr_debug("release(%lu, %d)\n",
35 		 inode->i_ino, atomic_read(&AFFS_I(inode)->i_opencnt));
36 
37 	if (atomic_dec_and_test(&AFFS_I(inode)->i_opencnt)) {
38 		inode_lock(inode);
39 		if (inode->i_size != AFFS_I(inode)->mmu_private)
40 			affs_truncate(inode);
41 		affs_free_prealloc(inode);
42 		inode_unlock(inode);
43 	}
44 
45 	return 0;
46 }
47 
48 static int
49 affs_grow_extcache(struct inode *inode, u32 lc_idx)
50 {
51 	struct super_block	*sb = inode->i_sb;
52 	struct buffer_head	*bh;
53 	u32 lc_max;
54 	int i, j, key;
55 
56 	if (!AFFS_I(inode)->i_lc) {
57 		char *ptr = (char *)get_zeroed_page(GFP_NOFS);
58 		if (!ptr)
59 			return -ENOMEM;
60 		AFFS_I(inode)->i_lc = (u32 *)ptr;
61 		AFFS_I(inode)->i_ac = (struct affs_ext_key *)(ptr + AFFS_CACHE_SIZE / 2);
62 	}
63 
64 	lc_max = AFFS_LC_SIZE << AFFS_I(inode)->i_lc_shift;
65 
66 	if (AFFS_I(inode)->i_extcnt > lc_max) {
67 		u32 lc_shift, lc_mask, tmp, off;
68 
69 		/* need to recalculate linear cache, start from old size */
70 		lc_shift = AFFS_I(inode)->i_lc_shift;
71 		tmp = (AFFS_I(inode)->i_extcnt / AFFS_LC_SIZE) >> lc_shift;
72 		for (; tmp; tmp >>= 1)
73 			lc_shift++;
74 		lc_mask = (1 << lc_shift) - 1;
75 
76 		/* fix idx and old size to new shift */
77 		lc_idx >>= (lc_shift - AFFS_I(inode)->i_lc_shift);
78 		AFFS_I(inode)->i_lc_size >>= (lc_shift - AFFS_I(inode)->i_lc_shift);
79 
80 		/* first shrink old cache to make more space */
81 		off = 1 << (lc_shift - AFFS_I(inode)->i_lc_shift);
82 		for (i = 1, j = off; j < AFFS_LC_SIZE; i++, j += off)
83 			AFFS_I(inode)->i_ac[i] = AFFS_I(inode)->i_ac[j];
84 
85 		AFFS_I(inode)->i_lc_shift = lc_shift;
86 		AFFS_I(inode)->i_lc_mask = lc_mask;
87 	}
88 
89 	/* fill cache to the needed index */
90 	i = AFFS_I(inode)->i_lc_size;
91 	AFFS_I(inode)->i_lc_size = lc_idx + 1;
92 	for (; i <= lc_idx; i++) {
93 		if (!i) {
94 			AFFS_I(inode)->i_lc[0] = inode->i_ino;
95 			continue;
96 		}
97 		key = AFFS_I(inode)->i_lc[i - 1];
98 		j = AFFS_I(inode)->i_lc_mask + 1;
99 		// unlock cache
100 		for (; j > 0; j--) {
101 			bh = affs_bread(sb, key);
102 			if (!bh)
103 				goto err;
104 			key = be32_to_cpu(AFFS_TAIL(sb, bh)->extension);
105 			affs_brelse(bh);
106 		}
107 		// lock cache
108 		AFFS_I(inode)->i_lc[i] = key;
109 	}
110 
111 	return 0;
112 
113 err:
114 	// lock cache
115 	return -EIO;
116 }
117 
118 static struct buffer_head *
119 affs_alloc_extblock(struct inode *inode, struct buffer_head *bh, u32 ext)
120 {
121 	struct super_block *sb = inode->i_sb;
122 	struct buffer_head *new_bh;
123 	u32 blocknr, tmp;
124 
125 	blocknr = affs_alloc_block(inode, bh->b_blocknr);
126 	if (!blocknr)
127 		return ERR_PTR(-ENOSPC);
128 
129 	new_bh = affs_getzeroblk(sb, blocknr);
130 	if (!new_bh) {
131 		affs_free_block(sb, blocknr);
132 		return ERR_PTR(-EIO);
133 	}
134 
135 	AFFS_HEAD(new_bh)->ptype = cpu_to_be32(T_LIST);
136 	AFFS_HEAD(new_bh)->key = cpu_to_be32(blocknr);
137 	AFFS_TAIL(sb, new_bh)->stype = cpu_to_be32(ST_FILE);
138 	AFFS_TAIL(sb, new_bh)->parent = cpu_to_be32(inode->i_ino);
139 	affs_fix_checksum(sb, new_bh);
140 
141 	mark_buffer_dirty_inode(new_bh, inode);
142 
143 	tmp = be32_to_cpu(AFFS_TAIL(sb, bh)->extension);
144 	if (tmp)
145 		affs_warning(sb, "alloc_ext", "previous extension set (%x)", tmp);
146 	AFFS_TAIL(sb, bh)->extension = cpu_to_be32(blocknr);
147 	affs_adjust_checksum(bh, blocknr - tmp);
148 	mark_buffer_dirty_inode(bh, inode);
149 
150 	AFFS_I(inode)->i_extcnt++;
151 	mark_inode_dirty(inode);
152 
153 	return new_bh;
154 }
155 
156 static inline struct buffer_head *
157 affs_get_extblock(struct inode *inode, u32 ext)
158 {
159 	/* inline the simplest case: same extended block as last time */
160 	struct buffer_head *bh = AFFS_I(inode)->i_ext_bh;
161 	if (ext == AFFS_I(inode)->i_ext_last)
162 		get_bh(bh);
163 	else
164 		/* we have to do more (not inlined) */
165 		bh = affs_get_extblock_slow(inode, ext);
166 
167 	return bh;
168 }
169 
170 static struct buffer_head *
171 affs_get_extblock_slow(struct inode *inode, u32 ext)
172 {
173 	struct super_block *sb = inode->i_sb;
174 	struct buffer_head *bh;
175 	u32 ext_key;
176 	u32 lc_idx, lc_off, ac_idx;
177 	u32 tmp, idx;
178 
179 	if (ext == AFFS_I(inode)->i_ext_last + 1) {
180 		/* read the next extended block from the current one */
181 		bh = AFFS_I(inode)->i_ext_bh;
182 		ext_key = be32_to_cpu(AFFS_TAIL(sb, bh)->extension);
183 		if (ext < AFFS_I(inode)->i_extcnt)
184 			goto read_ext;
185 		BUG_ON(ext > AFFS_I(inode)->i_extcnt);
186 		bh = affs_alloc_extblock(inode, bh, ext);
187 		if (IS_ERR(bh))
188 			return bh;
189 		goto store_ext;
190 	}
191 
192 	if (ext == 0) {
193 		/* we seek back to the file header block */
194 		ext_key = inode->i_ino;
195 		goto read_ext;
196 	}
197 
198 	if (ext >= AFFS_I(inode)->i_extcnt) {
199 		struct buffer_head *prev_bh;
200 
201 		/* allocate a new extended block */
202 		BUG_ON(ext > AFFS_I(inode)->i_extcnt);
203 
204 		/* get previous extended block */
205 		prev_bh = affs_get_extblock(inode, ext - 1);
206 		if (IS_ERR(prev_bh))
207 			return prev_bh;
208 		bh = affs_alloc_extblock(inode, prev_bh, ext);
209 		affs_brelse(prev_bh);
210 		if (IS_ERR(bh))
211 			return bh;
212 		goto store_ext;
213 	}
214 
215 again:
216 	/* check if there is an extended cache and whether it's large enough */
217 	lc_idx = ext >> AFFS_I(inode)->i_lc_shift;
218 	lc_off = ext & AFFS_I(inode)->i_lc_mask;
219 
220 	if (lc_idx >= AFFS_I(inode)->i_lc_size) {
221 		int err;
222 
223 		err = affs_grow_extcache(inode, lc_idx);
224 		if (err)
225 			return ERR_PTR(err);
226 		goto again;
227 	}
228 
229 	/* every n'th key we find in the linear cache */
230 	if (!lc_off) {
231 		ext_key = AFFS_I(inode)->i_lc[lc_idx];
232 		goto read_ext;
233 	}
234 
235 	/* maybe it's still in the associative cache */
236 	ac_idx = (ext - lc_idx - 1) & AFFS_AC_MASK;
237 	if (AFFS_I(inode)->i_ac[ac_idx].ext == ext) {
238 		ext_key = AFFS_I(inode)->i_ac[ac_idx].key;
239 		goto read_ext;
240 	}
241 
242 	/* try to find one of the previous extended blocks */
243 	tmp = ext;
244 	idx = ac_idx;
245 	while (--tmp, --lc_off > 0) {
246 		idx = (idx - 1) & AFFS_AC_MASK;
247 		if (AFFS_I(inode)->i_ac[idx].ext == tmp) {
248 			ext_key = AFFS_I(inode)->i_ac[idx].key;
249 			goto find_ext;
250 		}
251 	}
252 
253 	/* fall back to the linear cache */
254 	ext_key = AFFS_I(inode)->i_lc[lc_idx];
255 find_ext:
256 	/* read all extended blocks until we find the one we need */
257 	//unlock cache
258 	do {
259 		bh = affs_bread(sb, ext_key);
260 		if (!bh)
261 			goto err_bread;
262 		ext_key = be32_to_cpu(AFFS_TAIL(sb, bh)->extension);
263 		affs_brelse(bh);
264 		tmp++;
265 	} while (tmp < ext);
266 	//lock cache
267 
268 	/* store it in the associative cache */
269 	// recalculate ac_idx?
270 	AFFS_I(inode)->i_ac[ac_idx].ext = ext;
271 	AFFS_I(inode)->i_ac[ac_idx].key = ext_key;
272 
273 read_ext:
274 	/* finally read the right extended block */
275 	//unlock cache
276 	bh = affs_bread(sb, ext_key);
277 	if (!bh)
278 		goto err_bread;
279 	//lock cache
280 
281 store_ext:
282 	/* release old cached extended block and store the new one */
283 	affs_brelse(AFFS_I(inode)->i_ext_bh);
284 	AFFS_I(inode)->i_ext_last = ext;
285 	AFFS_I(inode)->i_ext_bh = bh;
286 	get_bh(bh);
287 
288 	return bh;
289 
290 err_bread:
291 	affs_brelse(bh);
292 	return ERR_PTR(-EIO);
293 }
294 
295 static int
296 affs_get_block(struct inode *inode, sector_t block, struct buffer_head *bh_result, int create)
297 {
298 	struct super_block	*sb = inode->i_sb;
299 	struct buffer_head	*ext_bh;
300 	u32			 ext;
301 
302 	pr_debug("%s(%lu, %llu)\n", __func__, inode->i_ino,
303 		 (unsigned long long)block);
304 
305 	BUG_ON(block > (sector_t)0x7fffffffUL);
306 
307 	if (block >= AFFS_I(inode)->i_blkcnt) {
308 		if (block > AFFS_I(inode)->i_blkcnt || !create)
309 			goto err_big;
310 	} else
311 		create = 0;
312 
313 	//lock cache
314 	affs_lock_ext(inode);
315 
316 	ext = (u32)block / AFFS_SB(sb)->s_hashsize;
317 	block -= ext * AFFS_SB(sb)->s_hashsize;
318 	ext_bh = affs_get_extblock(inode, ext);
319 	if (IS_ERR(ext_bh))
320 		goto err_ext;
321 	map_bh(bh_result, sb, (sector_t)be32_to_cpu(AFFS_BLOCK(sb, ext_bh, block)));
322 
323 	if (create) {
324 		u32 blocknr = affs_alloc_block(inode, ext_bh->b_blocknr);
325 		if (!blocknr)
326 			goto err_alloc;
327 		set_buffer_new(bh_result);
328 		AFFS_I(inode)->mmu_private += AFFS_SB(sb)->s_data_blksize;
329 		AFFS_I(inode)->i_blkcnt++;
330 
331 		/* store new block */
332 		if (bh_result->b_blocknr)
333 			affs_warning(sb, "get_block",
334 				     "block already set (%llx)",
335 				     (unsigned long long)bh_result->b_blocknr);
336 		AFFS_BLOCK(sb, ext_bh, block) = cpu_to_be32(blocknr);
337 		AFFS_HEAD(ext_bh)->block_count = cpu_to_be32(block + 1);
338 		affs_adjust_checksum(ext_bh, blocknr - bh_result->b_blocknr + 1);
339 		bh_result->b_blocknr = blocknr;
340 
341 		if (!block) {
342 			/* insert first block into header block */
343 			u32 tmp = be32_to_cpu(AFFS_HEAD(ext_bh)->first_data);
344 			if (tmp)
345 				affs_warning(sb, "get_block", "first block already set (%d)", tmp);
346 			AFFS_HEAD(ext_bh)->first_data = cpu_to_be32(blocknr);
347 			affs_adjust_checksum(ext_bh, blocknr - tmp);
348 		}
349 	}
350 
351 	affs_brelse(ext_bh);
352 	//unlock cache
353 	affs_unlock_ext(inode);
354 	return 0;
355 
356 err_big:
357 	affs_error(inode->i_sb, "get_block", "strange block request %llu",
358 		   (unsigned long long)block);
359 	return -EIO;
360 err_ext:
361 	// unlock cache
362 	affs_unlock_ext(inode);
363 	return PTR_ERR(ext_bh);
364 err_alloc:
365 	brelse(ext_bh);
366 	clear_buffer_mapped(bh_result);
367 	bh_result->b_bdev = NULL;
368 	// unlock cache
369 	affs_unlock_ext(inode);
370 	return -ENOSPC;
371 }
372 
373 static int affs_writepage(struct page *page, struct writeback_control *wbc)
374 {
375 	return block_write_full_page(page, affs_get_block, wbc);
376 }
377 
378 static int affs_read_folio(struct file *file, struct folio *folio)
379 {
380 	return block_read_full_folio(folio, affs_get_block);
381 }
382 
383 static void affs_write_failed(struct address_space *mapping, loff_t to)
384 {
385 	struct inode *inode = mapping->host;
386 
387 	if (to > inode->i_size) {
388 		truncate_pagecache(inode, inode->i_size);
389 		affs_truncate(inode);
390 	}
391 }
392 
393 static ssize_t
394 affs_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
395 {
396 	struct file *file = iocb->ki_filp;
397 	struct address_space *mapping = file->f_mapping;
398 	struct inode *inode = mapping->host;
399 	size_t count = iov_iter_count(iter);
400 	loff_t offset = iocb->ki_pos;
401 	ssize_t ret;
402 
403 	if (iov_iter_rw(iter) == WRITE) {
404 		loff_t size = offset + count;
405 
406 		if (AFFS_I(inode)->mmu_private < size)
407 			return 0;
408 	}
409 
410 	ret = blockdev_direct_IO(iocb, inode, iter, affs_get_block);
411 	if (ret < 0 && iov_iter_rw(iter) == WRITE)
412 		affs_write_failed(mapping, offset + count);
413 	return ret;
414 }
415 
416 static int affs_write_begin(struct file *file, struct address_space *mapping,
417 			loff_t pos, unsigned len,
418 			struct page **pagep, void **fsdata)
419 {
420 	int ret;
421 
422 	*pagep = NULL;
423 	ret = cont_write_begin(file, mapping, pos, len, pagep, fsdata,
424 				affs_get_block,
425 				&AFFS_I(mapping->host)->mmu_private);
426 	if (unlikely(ret))
427 		affs_write_failed(mapping, pos + len);
428 
429 	return ret;
430 }
431 
432 static int affs_write_end(struct file *file, struct address_space *mapping,
433 			  loff_t pos, unsigned int len, unsigned int copied,
434 			  struct page *page, void *fsdata)
435 {
436 	struct inode *inode = mapping->host;
437 	int ret;
438 
439 	ret = generic_write_end(file, mapping, pos, len, copied, page, fsdata);
440 
441 	/* Clear Archived bit on file writes, as AmigaOS would do */
442 	if (AFFS_I(inode)->i_protect & FIBF_ARCHIVED) {
443 		AFFS_I(inode)->i_protect &= ~FIBF_ARCHIVED;
444 		mark_inode_dirty(inode);
445 	}
446 
447 	return ret;
448 }
449 
450 static sector_t _affs_bmap(struct address_space *mapping, sector_t block)
451 {
452 	return generic_block_bmap(mapping,block,affs_get_block);
453 }
454 
455 const struct address_space_operations affs_aops = {
456 	.dirty_folio	= block_dirty_folio,
457 	.invalidate_folio = block_invalidate_folio,
458 	.read_folio = affs_read_folio,
459 	.writepage = affs_writepage,
460 	.write_begin = affs_write_begin,
461 	.write_end = affs_write_end,
462 	.direct_IO = affs_direct_IO,
463 	.bmap = _affs_bmap
464 };
465 
466 static inline struct buffer_head *
467 affs_bread_ino(struct inode *inode, int block, int create)
468 {
469 	struct buffer_head *bh, tmp_bh;
470 	int err;
471 
472 	tmp_bh.b_state = 0;
473 	err = affs_get_block(inode, block, &tmp_bh, create);
474 	if (!err) {
475 		bh = affs_bread(inode->i_sb, tmp_bh.b_blocknr);
476 		if (bh) {
477 			bh->b_state |= tmp_bh.b_state;
478 			return bh;
479 		}
480 		err = -EIO;
481 	}
482 	return ERR_PTR(err);
483 }
484 
485 static inline struct buffer_head *
486 affs_getzeroblk_ino(struct inode *inode, int block)
487 {
488 	struct buffer_head *bh, tmp_bh;
489 	int err;
490 
491 	tmp_bh.b_state = 0;
492 	err = affs_get_block(inode, block, &tmp_bh, 1);
493 	if (!err) {
494 		bh = affs_getzeroblk(inode->i_sb, tmp_bh.b_blocknr);
495 		if (bh) {
496 			bh->b_state |= tmp_bh.b_state;
497 			return bh;
498 		}
499 		err = -EIO;
500 	}
501 	return ERR_PTR(err);
502 }
503 
504 static inline struct buffer_head *
505 affs_getemptyblk_ino(struct inode *inode, int block)
506 {
507 	struct buffer_head *bh, tmp_bh;
508 	int err;
509 
510 	tmp_bh.b_state = 0;
511 	err = affs_get_block(inode, block, &tmp_bh, 1);
512 	if (!err) {
513 		bh = affs_getemptyblk(inode->i_sb, tmp_bh.b_blocknr);
514 		if (bh) {
515 			bh->b_state |= tmp_bh.b_state;
516 			return bh;
517 		}
518 		err = -EIO;
519 	}
520 	return ERR_PTR(err);
521 }
522 
523 static int
524 affs_do_readpage_ofs(struct page *page, unsigned to, int create)
525 {
526 	struct inode *inode = page->mapping->host;
527 	struct super_block *sb = inode->i_sb;
528 	struct buffer_head *bh;
529 	char *data;
530 	unsigned pos = 0;
531 	u32 bidx, boff, bsize;
532 	u32 tmp;
533 
534 	pr_debug("%s(%lu, %ld, 0, %d)\n", __func__, inode->i_ino,
535 		 page->index, to);
536 	BUG_ON(to > PAGE_SIZE);
537 	bsize = AFFS_SB(sb)->s_data_blksize;
538 	tmp = page->index << PAGE_SHIFT;
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 		data = kmap_atomic(page);
549 		memcpy(data + pos, AFFS_DATA(bh) + boff, tmp);
550 		kunmap_atomic(data);
551 		affs_brelse(bh);
552 		bidx++;
553 		pos += tmp;
554 		boff = 0;
555 	}
556 	flush_dcache_page(page);
557 	return 0;
558 }
559 
560 static int
561 affs_extent_file_ofs(struct inode *inode, u32 newsize)
562 {
563 	struct super_block *sb = inode->i_sb;
564 	struct buffer_head *bh, *prev_bh;
565 	u32 bidx, boff;
566 	u32 size, bsize;
567 	u32 tmp;
568 
569 	pr_debug("%s(%lu, %d)\n", __func__, inode->i_ino, newsize);
570 	bsize = AFFS_SB(sb)->s_data_blksize;
571 	bh = NULL;
572 	size = AFFS_I(inode)->mmu_private;
573 	bidx = size / bsize;
574 	boff = size % bsize;
575 	if (boff) {
576 		bh = affs_bread_ino(inode, bidx, 0);
577 		if (IS_ERR(bh))
578 			return PTR_ERR(bh);
579 		tmp = min(bsize - boff, newsize - size);
580 		BUG_ON(boff + tmp > bsize || tmp > bsize);
581 		memset(AFFS_DATA(bh) + boff, 0, tmp);
582 		be32_add_cpu(&AFFS_DATA_HEAD(bh)->size, tmp);
583 		affs_fix_checksum(sb, bh);
584 		mark_buffer_dirty_inode(bh, inode);
585 		size += tmp;
586 		bidx++;
587 	} else if (bidx) {
588 		bh = affs_bread_ino(inode, bidx - 1, 0);
589 		if (IS_ERR(bh))
590 			return PTR_ERR(bh);
591 	}
592 
593 	while (size < newsize) {
594 		prev_bh = bh;
595 		bh = affs_getzeroblk_ino(inode, bidx);
596 		if (IS_ERR(bh))
597 			goto out;
598 		tmp = min(bsize, newsize - size);
599 		BUG_ON(tmp > bsize);
600 		AFFS_DATA_HEAD(bh)->ptype = cpu_to_be32(T_DATA);
601 		AFFS_DATA_HEAD(bh)->key = cpu_to_be32(inode->i_ino);
602 		AFFS_DATA_HEAD(bh)->sequence = cpu_to_be32(bidx);
603 		AFFS_DATA_HEAD(bh)->size = cpu_to_be32(tmp);
604 		affs_fix_checksum(sb, bh);
605 		bh->b_state &= ~(1UL << BH_New);
606 		mark_buffer_dirty_inode(bh, inode);
607 		if (prev_bh) {
608 			u32 tmp_next = be32_to_cpu(AFFS_DATA_HEAD(prev_bh)->next);
609 
610 			if (tmp_next)
611 				affs_warning(sb, "extent_file_ofs",
612 					     "next block already set for %d (%d)",
613 					     bidx, tmp_next);
614 			AFFS_DATA_HEAD(prev_bh)->next = cpu_to_be32(bh->b_blocknr);
615 			affs_adjust_checksum(prev_bh, bh->b_blocknr - tmp_next);
616 			mark_buffer_dirty_inode(prev_bh, inode);
617 			affs_brelse(prev_bh);
618 		}
619 		size += bsize;
620 		bidx++;
621 	}
622 	affs_brelse(bh);
623 	inode->i_size = AFFS_I(inode)->mmu_private = newsize;
624 	return 0;
625 
626 out:
627 	inode->i_size = AFFS_I(inode)->mmu_private = newsize;
628 	return PTR_ERR(bh);
629 }
630 
631 static int
632 affs_read_folio_ofs(struct file *file, struct folio *folio)
633 {
634 	struct page *page = &folio->page;
635 	struct inode *inode = page->mapping->host;
636 	u32 to;
637 	int err;
638 
639 	pr_debug("%s(%lu, %ld)\n", __func__, inode->i_ino, page->index);
640 	to = PAGE_SIZE;
641 	if (((page->index + 1) << PAGE_SHIFT) > inode->i_size) {
642 		to = inode->i_size & ~PAGE_MASK;
643 		memset(page_address(page) + to, 0, PAGE_SIZE - to);
644 	}
645 
646 	err = affs_do_readpage_ofs(page, to, 0);
647 	if (!err)
648 		SetPageUptodate(page);
649 	unlock_page(page);
650 	return err;
651 }
652 
653 static int affs_write_begin_ofs(struct file *file, struct address_space *mapping,
654 				loff_t pos, unsigned len,
655 				struct page **pagep, void **fsdata)
656 {
657 	struct inode *inode = mapping->host;
658 	struct page *page;
659 	pgoff_t index;
660 	int err = 0;
661 
662 	pr_debug("%s(%lu, %llu, %llu)\n", __func__, inode->i_ino, pos,
663 		 pos + len);
664 	if (pos > AFFS_I(inode)->mmu_private) {
665 		/* XXX: this probably leaves a too-big i_size in case of
666 		 * failure. Should really be updating i_size at write_end time
667 		 */
668 		err = affs_extent_file_ofs(inode, pos);
669 		if (err)
670 			return err;
671 	}
672 
673 	index = pos >> PAGE_SHIFT;
674 	page = grab_cache_page_write_begin(mapping, index);
675 	if (!page)
676 		return -ENOMEM;
677 	*pagep = page;
678 
679 	if (PageUptodate(page))
680 		return 0;
681 
682 	/* XXX: inefficient but safe in the face of short writes */
683 	err = affs_do_readpage_ofs(page, PAGE_SIZE, 1);
684 	if (err) {
685 		unlock_page(page);
686 		put_page(page);
687 	}
688 	return err;
689 }
690 
691 static int affs_write_end_ofs(struct file *file, struct address_space *mapping,
692 				loff_t pos, unsigned len, unsigned copied,
693 				struct page *page, void *fsdata)
694 {
695 	struct inode *inode = mapping->host;
696 	struct super_block *sb = inode->i_sb;
697 	struct buffer_head *bh, *prev_bh;
698 	char *data;
699 	u32 bidx, boff, bsize;
700 	unsigned from, to;
701 	u32 tmp;
702 	int written;
703 
704 	from = pos & (PAGE_SIZE - 1);
705 	to = from + len;
706 	/*
707 	 * XXX: not sure if this can handle short copies (len < copied), but
708 	 * we don't have to, because the page should always be uptodate here,
709 	 * due to write_begin.
710 	 */
711 
712 	pr_debug("%s(%lu, %llu, %llu)\n", __func__, inode->i_ino, pos,
713 		 pos + len);
714 	bsize = AFFS_SB(sb)->s_data_blksize;
715 	data = page_address(page);
716 
717 	bh = NULL;
718 	written = 0;
719 	tmp = (page->index << PAGE_SHIFT) + from;
720 	bidx = tmp / bsize;
721 	boff = tmp % bsize;
722 	if (boff) {
723 		bh = affs_bread_ino(inode, bidx, 0);
724 		if (IS_ERR(bh)) {
725 			written = PTR_ERR(bh);
726 			goto err_first_bh;
727 		}
728 		tmp = min(bsize - boff, to - from);
729 		BUG_ON(boff + tmp > bsize || tmp > bsize);
730 		memcpy(AFFS_DATA(bh) + boff, data + from, tmp);
731 		be32_add_cpu(&AFFS_DATA_HEAD(bh)->size, tmp);
732 		affs_fix_checksum(sb, bh);
733 		mark_buffer_dirty_inode(bh, inode);
734 		written += tmp;
735 		from += tmp;
736 		bidx++;
737 	} else if (bidx) {
738 		bh = affs_bread_ino(inode, bidx - 1, 0);
739 		if (IS_ERR(bh)) {
740 			written = PTR_ERR(bh);
741 			goto err_first_bh;
742 		}
743 	}
744 	while (from + bsize <= to) {
745 		prev_bh = bh;
746 		bh = affs_getemptyblk_ino(inode, bidx);
747 		if (IS_ERR(bh))
748 			goto err_bh;
749 		memcpy(AFFS_DATA(bh), data + from, bsize);
750 		if (buffer_new(bh)) {
751 			AFFS_DATA_HEAD(bh)->ptype = cpu_to_be32(T_DATA);
752 			AFFS_DATA_HEAD(bh)->key = cpu_to_be32(inode->i_ino);
753 			AFFS_DATA_HEAD(bh)->sequence = cpu_to_be32(bidx);
754 			AFFS_DATA_HEAD(bh)->size = cpu_to_be32(bsize);
755 			AFFS_DATA_HEAD(bh)->next = 0;
756 			bh->b_state &= ~(1UL << BH_New);
757 			if (prev_bh) {
758 				u32 tmp_next = be32_to_cpu(AFFS_DATA_HEAD(prev_bh)->next);
759 
760 				if (tmp_next)
761 					affs_warning(sb, "commit_write_ofs",
762 						     "next block already set for %d (%d)",
763 						     bidx, tmp_next);
764 				AFFS_DATA_HEAD(prev_bh)->next = cpu_to_be32(bh->b_blocknr);
765 				affs_adjust_checksum(prev_bh, bh->b_blocknr - tmp_next);
766 				mark_buffer_dirty_inode(prev_bh, inode);
767 			}
768 		}
769 		affs_brelse(prev_bh);
770 		affs_fix_checksum(sb, bh);
771 		mark_buffer_dirty_inode(bh, inode);
772 		written += bsize;
773 		from += bsize;
774 		bidx++;
775 	}
776 	if (from < to) {
777 		prev_bh = bh;
778 		bh = affs_bread_ino(inode, bidx, 1);
779 		if (IS_ERR(bh))
780 			goto err_bh;
781 		tmp = min(bsize, to - from);
782 		BUG_ON(tmp > bsize);
783 		memcpy(AFFS_DATA(bh), data + from, tmp);
784 		if (buffer_new(bh)) {
785 			AFFS_DATA_HEAD(bh)->ptype = cpu_to_be32(T_DATA);
786 			AFFS_DATA_HEAD(bh)->key = cpu_to_be32(inode->i_ino);
787 			AFFS_DATA_HEAD(bh)->sequence = cpu_to_be32(bidx);
788 			AFFS_DATA_HEAD(bh)->size = cpu_to_be32(tmp);
789 			AFFS_DATA_HEAD(bh)->next = 0;
790 			bh->b_state &= ~(1UL << BH_New);
791 			if (prev_bh) {
792 				u32 tmp_next = be32_to_cpu(AFFS_DATA_HEAD(prev_bh)->next);
793 
794 				if (tmp_next)
795 					affs_warning(sb, "commit_write_ofs",
796 						     "next block already set for %d (%d)",
797 						     bidx, tmp_next);
798 				AFFS_DATA_HEAD(prev_bh)->next = cpu_to_be32(bh->b_blocknr);
799 				affs_adjust_checksum(prev_bh, bh->b_blocknr - tmp_next);
800 				mark_buffer_dirty_inode(prev_bh, inode);
801 			}
802 		} else if (be32_to_cpu(AFFS_DATA_HEAD(bh)->size) < tmp)
803 			AFFS_DATA_HEAD(bh)->size = cpu_to_be32(tmp);
804 		affs_brelse(prev_bh);
805 		affs_fix_checksum(sb, bh);
806 		mark_buffer_dirty_inode(bh, inode);
807 		written += tmp;
808 		from += tmp;
809 		bidx++;
810 	}
811 	SetPageUptodate(page);
812 
813 done:
814 	affs_brelse(bh);
815 	tmp = (page->index << PAGE_SHIFT) + from;
816 	if (tmp > inode->i_size)
817 		inode->i_size = AFFS_I(inode)->mmu_private = tmp;
818 
819 	/* Clear Archived bit on file writes, as AmigaOS would do */
820 	if (AFFS_I(inode)->i_protect & FIBF_ARCHIVED) {
821 		AFFS_I(inode)->i_protect &= ~FIBF_ARCHIVED;
822 		mark_inode_dirty(inode);
823 	}
824 
825 err_first_bh:
826 	unlock_page(page);
827 	put_page(page);
828 
829 	return written;
830 
831 err_bh:
832 	bh = prev_bh;
833 	if (!written)
834 		written = PTR_ERR(bh);
835 	goto done;
836 }
837 
838 const struct address_space_operations affs_aops_ofs = {
839 	.dirty_folio	= block_dirty_folio,
840 	.invalidate_folio = block_invalidate_folio,
841 	.read_folio = affs_read_folio_ofs,
842 	//.writepage = affs_writepage_ofs,
843 	.write_begin = affs_write_begin_ofs,
844 	.write_end = affs_write_end_ofs
845 };
846 
847 /* Free any preallocated blocks. */
848 
849 void
850 affs_free_prealloc(struct inode *inode)
851 {
852 	struct super_block *sb = inode->i_sb;
853 
854 	pr_debug("free_prealloc(ino=%lu)\n", inode->i_ino);
855 
856 	while (AFFS_I(inode)->i_pa_cnt) {
857 		AFFS_I(inode)->i_pa_cnt--;
858 		affs_free_block(sb, ++AFFS_I(inode)->i_lastalloc);
859 	}
860 }
861 
862 /* Truncate (or enlarge) a file to the requested size. */
863 
864 void
865 affs_truncate(struct inode *inode)
866 {
867 	struct super_block *sb = inode->i_sb;
868 	u32 ext, ext_key;
869 	u32 last_blk, blkcnt, blk;
870 	u32 size;
871 	struct buffer_head *ext_bh;
872 	int i;
873 
874 	pr_debug("truncate(inode=%lu, oldsize=%llu, newsize=%llu)\n",
875 		 inode->i_ino, AFFS_I(inode)->mmu_private, inode->i_size);
876 
877 	last_blk = 0;
878 	ext = 0;
879 	if (inode->i_size) {
880 		last_blk = ((u32)inode->i_size - 1) / AFFS_SB(sb)->s_data_blksize;
881 		ext = last_blk / AFFS_SB(sb)->s_hashsize;
882 	}
883 
884 	if (inode->i_size > AFFS_I(inode)->mmu_private) {
885 		struct address_space *mapping = inode->i_mapping;
886 		struct page *page;
887 		void *fsdata;
888 		loff_t isize = inode->i_size;
889 		int res;
890 
891 		res = mapping->a_ops->write_begin(NULL, mapping, isize, 0, &page, &fsdata);
892 		if (!res)
893 			res = mapping->a_ops->write_end(NULL, mapping, isize, 0, 0, page, fsdata);
894 		else
895 			inode->i_size = AFFS_I(inode)->mmu_private;
896 		mark_inode_dirty(inode);
897 		return;
898 	} else if (inode->i_size == AFFS_I(inode)->mmu_private)
899 		return;
900 
901 	// lock cache
902 	ext_bh = affs_get_extblock(inode, ext);
903 	if (IS_ERR(ext_bh)) {
904 		affs_warning(sb, "truncate",
905 			     "unexpected read error for ext block %u (%ld)",
906 			     ext, PTR_ERR(ext_bh));
907 		return;
908 	}
909 	if (AFFS_I(inode)->i_lc) {
910 		/* clear linear cache */
911 		i = (ext + 1) >> AFFS_I(inode)->i_lc_shift;
912 		if (AFFS_I(inode)->i_lc_size > i) {
913 			AFFS_I(inode)->i_lc_size = i;
914 			for (; i < AFFS_LC_SIZE; i++)
915 				AFFS_I(inode)->i_lc[i] = 0;
916 		}
917 		/* clear associative cache */
918 		for (i = 0; i < AFFS_AC_SIZE; i++)
919 			if (AFFS_I(inode)->i_ac[i].ext >= ext)
920 				AFFS_I(inode)->i_ac[i].ext = 0;
921 	}
922 	ext_key = be32_to_cpu(AFFS_TAIL(sb, ext_bh)->extension);
923 
924 	blkcnt = AFFS_I(inode)->i_blkcnt;
925 	i = 0;
926 	blk = last_blk;
927 	if (inode->i_size) {
928 		i = last_blk % AFFS_SB(sb)->s_hashsize + 1;
929 		blk++;
930 	} else
931 		AFFS_HEAD(ext_bh)->first_data = 0;
932 	AFFS_HEAD(ext_bh)->block_count = cpu_to_be32(i);
933 	size = AFFS_SB(sb)->s_hashsize;
934 	if (size > blkcnt - blk + i)
935 		size = blkcnt - blk + i;
936 	for (; i < size; i++, blk++) {
937 		affs_free_block(sb, be32_to_cpu(AFFS_BLOCK(sb, ext_bh, i)));
938 		AFFS_BLOCK(sb, ext_bh, i) = 0;
939 	}
940 	AFFS_TAIL(sb, ext_bh)->extension = 0;
941 	affs_fix_checksum(sb, ext_bh);
942 	mark_buffer_dirty_inode(ext_bh, inode);
943 	affs_brelse(ext_bh);
944 
945 	if (inode->i_size) {
946 		AFFS_I(inode)->i_blkcnt = last_blk + 1;
947 		AFFS_I(inode)->i_extcnt = ext + 1;
948 		if (affs_test_opt(AFFS_SB(sb)->s_flags, SF_OFS)) {
949 			struct buffer_head *bh = affs_bread_ino(inode, last_blk, 0);
950 			u32 tmp;
951 			if (IS_ERR(bh)) {
952 				affs_warning(sb, "truncate",
953 					     "unexpected read error for last block %u (%ld)",
954 					     ext, PTR_ERR(bh));
955 				return;
956 			}
957 			tmp = be32_to_cpu(AFFS_DATA_HEAD(bh)->next);
958 			AFFS_DATA_HEAD(bh)->next = 0;
959 			affs_adjust_checksum(bh, -tmp);
960 			affs_brelse(bh);
961 		}
962 	} else {
963 		AFFS_I(inode)->i_blkcnt = 0;
964 		AFFS_I(inode)->i_extcnt = 1;
965 	}
966 	AFFS_I(inode)->mmu_private = inode->i_size;
967 	// unlock cache
968 
969 	while (ext_key) {
970 		ext_bh = affs_bread(sb, ext_key);
971 		size = AFFS_SB(sb)->s_hashsize;
972 		if (size > blkcnt - blk)
973 			size = blkcnt - blk;
974 		for (i = 0; i < size; i++, blk++)
975 			affs_free_block(sb, be32_to_cpu(AFFS_BLOCK(sb, ext_bh, i)));
976 		affs_free_block(sb, ext_key);
977 		ext_key = be32_to_cpu(AFFS_TAIL(sb, ext_bh)->extension);
978 		affs_brelse(ext_bh);
979 	}
980 	affs_free_prealloc(inode);
981 }
982 
983 int affs_file_fsync(struct file *filp, loff_t start, loff_t end, int datasync)
984 {
985 	struct inode *inode = filp->f_mapping->host;
986 	int ret, err;
987 
988 	err = file_write_and_wait_range(filp, start, end);
989 	if (err)
990 		return err;
991 
992 	inode_lock(inode);
993 	ret = write_inode_now(inode, 0);
994 	err = sync_blockdev(inode->i_sb->s_bdev);
995 	if (!ret)
996 		ret = err;
997 	inode_unlock(inode);
998 	return ret;
999 }
1000 const struct file_operations affs_file_operations = {
1001 	.llseek		= generic_file_llseek,
1002 	.read_iter	= generic_file_read_iter,
1003 	.write_iter	= generic_file_write_iter,
1004 	.mmap		= generic_file_mmap,
1005 	.open		= affs_file_open,
1006 	.release	= affs_file_release,
1007 	.fsync		= affs_file_fsync,
1008 	.splice_read	= generic_file_splice_read,
1009 };
1010 
1011 const struct inode_operations affs_file_inode_operations = {
1012 	.setattr	= affs_notify_change,
1013 };
1014