xref: /openbmc/linux/fs/affs/file.c (revision 01cc2ec6)
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_readpage(struct file *file, struct page *page)
379 {
380 	return block_read_full_page(page, 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, unsigned flags,
418 			struct page **pagep, void **fsdata)
419 {
420 	int ret;
421 
422 	*pagep = NULL;
423 	ret = cont_write_begin(file, mapping, pos, len, flags, 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 	.readpage = affs_readpage,
457 	.writepage = affs_writepage,
458 	.write_begin = affs_write_begin,
459 	.write_end = affs_write_end,
460 	.direct_IO = affs_direct_IO,
461 	.bmap = _affs_bmap
462 };
463 
464 static inline struct buffer_head *
465 affs_bread_ino(struct inode *inode, int block, int create)
466 {
467 	struct buffer_head *bh, tmp_bh;
468 	int err;
469 
470 	tmp_bh.b_state = 0;
471 	err = affs_get_block(inode, block, &tmp_bh, create);
472 	if (!err) {
473 		bh = affs_bread(inode->i_sb, tmp_bh.b_blocknr);
474 		if (bh) {
475 			bh->b_state |= tmp_bh.b_state;
476 			return bh;
477 		}
478 		err = -EIO;
479 	}
480 	return ERR_PTR(err);
481 }
482 
483 static inline struct buffer_head *
484 affs_getzeroblk_ino(struct inode *inode, int block)
485 {
486 	struct buffer_head *bh, tmp_bh;
487 	int err;
488 
489 	tmp_bh.b_state = 0;
490 	err = affs_get_block(inode, block, &tmp_bh, 1);
491 	if (!err) {
492 		bh = affs_getzeroblk(inode->i_sb, tmp_bh.b_blocknr);
493 		if (bh) {
494 			bh->b_state |= tmp_bh.b_state;
495 			return bh;
496 		}
497 		err = -EIO;
498 	}
499 	return ERR_PTR(err);
500 }
501 
502 static inline struct buffer_head *
503 affs_getemptyblk_ino(struct inode *inode, int block)
504 {
505 	struct buffer_head *bh, tmp_bh;
506 	int err;
507 
508 	tmp_bh.b_state = 0;
509 	err = affs_get_block(inode, block, &tmp_bh, 1);
510 	if (!err) {
511 		bh = affs_getemptyblk(inode->i_sb, tmp_bh.b_blocknr);
512 		if (bh) {
513 			bh->b_state |= tmp_bh.b_state;
514 			return bh;
515 		}
516 		err = -EIO;
517 	}
518 	return ERR_PTR(err);
519 }
520 
521 static int
522 affs_do_readpage_ofs(struct page *page, unsigned to, int create)
523 {
524 	struct inode *inode = page->mapping->host;
525 	struct super_block *sb = inode->i_sb;
526 	struct buffer_head *bh;
527 	char *data;
528 	unsigned pos = 0;
529 	u32 bidx, boff, bsize;
530 	u32 tmp;
531 
532 	pr_debug("%s(%lu, %ld, 0, %d)\n", __func__, inode->i_ino,
533 		 page->index, to);
534 	BUG_ON(to > PAGE_SIZE);
535 	bsize = AFFS_SB(sb)->s_data_blksize;
536 	tmp = page->index << PAGE_SHIFT;
537 	bidx = tmp / bsize;
538 	boff = tmp % bsize;
539 
540 	while (pos < to) {
541 		bh = affs_bread_ino(inode, bidx, create);
542 		if (IS_ERR(bh))
543 			return PTR_ERR(bh);
544 		tmp = min(bsize - boff, to - pos);
545 		BUG_ON(pos + tmp > to || tmp > bsize);
546 		data = kmap_atomic(page);
547 		memcpy(data + pos, AFFS_DATA(bh) + boff, tmp);
548 		kunmap_atomic(data);
549 		affs_brelse(bh);
550 		bidx++;
551 		pos += tmp;
552 		boff = 0;
553 	}
554 	flush_dcache_page(page);
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
630 affs_readpage_ofs(struct file *file, struct page *page)
631 {
632 	struct inode *inode = page->mapping->host;
633 	u32 to;
634 	int err;
635 
636 	pr_debug("%s(%lu, %ld)\n", __func__, inode->i_ino, page->index);
637 	to = PAGE_SIZE;
638 	if (((page->index + 1) << PAGE_SHIFT) > inode->i_size) {
639 		to = inode->i_size & ~PAGE_MASK;
640 		memset(page_address(page) + to, 0, PAGE_SIZE - to);
641 	}
642 
643 	err = affs_do_readpage_ofs(page, to, 0);
644 	if (!err)
645 		SetPageUptodate(page);
646 	unlock_page(page);
647 	return err;
648 }
649 
650 static int affs_write_begin_ofs(struct file *file, struct address_space *mapping,
651 				loff_t pos, unsigned len, unsigned flags,
652 				struct page **pagep, void **fsdata)
653 {
654 	struct inode *inode = mapping->host;
655 	struct page *page;
656 	pgoff_t index;
657 	int err = 0;
658 
659 	pr_debug("%s(%lu, %llu, %llu)\n", __func__, inode->i_ino, pos,
660 		 pos + len);
661 	if (pos > AFFS_I(inode)->mmu_private) {
662 		/* XXX: this probably leaves a too-big i_size in case of
663 		 * failure. Should really be updating i_size at write_end time
664 		 */
665 		err = affs_extent_file_ofs(inode, pos);
666 		if (err)
667 			return err;
668 	}
669 
670 	index = pos >> PAGE_SHIFT;
671 	page = grab_cache_page_write_begin(mapping, index, flags);
672 	if (!page)
673 		return -ENOMEM;
674 	*pagep = page;
675 
676 	if (PageUptodate(page))
677 		return 0;
678 
679 	/* XXX: inefficient but safe in the face of short writes */
680 	err = affs_do_readpage_ofs(page, PAGE_SIZE, 1);
681 	if (err) {
682 		unlock_page(page);
683 		put_page(page);
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 inode *inode = mapping->host;
693 	struct super_block *sb = inode->i_sb;
694 	struct buffer_head *bh, *prev_bh;
695 	char *data;
696 	u32 bidx, boff, bsize;
697 	unsigned from, to;
698 	u32 tmp;
699 	int written;
700 
701 	from = pos & (PAGE_SIZE - 1);
702 	to = from + len;
703 	/*
704 	 * XXX: not sure if this can handle short copies (len < copied), but
705 	 * we don't have to, because the page should always be uptodate here,
706 	 * due to write_begin.
707 	 */
708 
709 	pr_debug("%s(%lu, %llu, %llu)\n", __func__, inode->i_ino, pos,
710 		 pos + len);
711 	bsize = AFFS_SB(sb)->s_data_blksize;
712 	data = page_address(page);
713 
714 	bh = NULL;
715 	written = 0;
716 	tmp = (page->index << PAGE_SHIFT) + from;
717 	bidx = tmp / bsize;
718 	boff = tmp % bsize;
719 	if (boff) {
720 		bh = affs_bread_ino(inode, bidx, 0);
721 		if (IS_ERR(bh)) {
722 			written = PTR_ERR(bh);
723 			goto err_first_bh;
724 		}
725 		tmp = min(bsize - boff, to - from);
726 		BUG_ON(boff + tmp > bsize || tmp > bsize);
727 		memcpy(AFFS_DATA(bh) + boff, data + from, tmp);
728 		be32_add_cpu(&AFFS_DATA_HEAD(bh)->size, tmp);
729 		affs_fix_checksum(sb, bh);
730 		mark_buffer_dirty_inode(bh, inode);
731 		written += tmp;
732 		from += tmp;
733 		bidx++;
734 	} else if (bidx) {
735 		bh = affs_bread_ino(inode, bidx - 1, 0);
736 		if (IS_ERR(bh)) {
737 			written = PTR_ERR(bh);
738 			goto err_first_bh;
739 		}
740 	}
741 	while (from + bsize <= to) {
742 		prev_bh = bh;
743 		bh = affs_getemptyblk_ino(inode, bidx);
744 		if (IS_ERR(bh))
745 			goto err_bh;
746 		memcpy(AFFS_DATA(bh), data + from, bsize);
747 		if (buffer_new(bh)) {
748 			AFFS_DATA_HEAD(bh)->ptype = cpu_to_be32(T_DATA);
749 			AFFS_DATA_HEAD(bh)->key = cpu_to_be32(inode->i_ino);
750 			AFFS_DATA_HEAD(bh)->sequence = cpu_to_be32(bidx);
751 			AFFS_DATA_HEAD(bh)->size = cpu_to_be32(bsize);
752 			AFFS_DATA_HEAD(bh)->next = 0;
753 			bh->b_state &= ~(1UL << BH_New);
754 			if (prev_bh) {
755 				u32 tmp_next = be32_to_cpu(AFFS_DATA_HEAD(prev_bh)->next);
756 
757 				if (tmp_next)
758 					affs_warning(sb, "commit_write_ofs",
759 						     "next block already set for %d (%d)",
760 						     bidx, tmp_next);
761 				AFFS_DATA_HEAD(prev_bh)->next = cpu_to_be32(bh->b_blocknr);
762 				affs_adjust_checksum(prev_bh, bh->b_blocknr - tmp_next);
763 				mark_buffer_dirty_inode(prev_bh, inode);
764 			}
765 		}
766 		affs_brelse(prev_bh);
767 		affs_fix_checksum(sb, bh);
768 		mark_buffer_dirty_inode(bh, inode);
769 		written += bsize;
770 		from += bsize;
771 		bidx++;
772 	}
773 	if (from < to) {
774 		prev_bh = bh;
775 		bh = affs_bread_ino(inode, bidx, 1);
776 		if (IS_ERR(bh))
777 			goto err_bh;
778 		tmp = min(bsize, to - from);
779 		BUG_ON(tmp > bsize);
780 		memcpy(AFFS_DATA(bh), data + from, tmp);
781 		if (buffer_new(bh)) {
782 			AFFS_DATA_HEAD(bh)->ptype = cpu_to_be32(T_DATA);
783 			AFFS_DATA_HEAD(bh)->key = cpu_to_be32(inode->i_ino);
784 			AFFS_DATA_HEAD(bh)->sequence = cpu_to_be32(bidx);
785 			AFFS_DATA_HEAD(bh)->size = cpu_to_be32(tmp);
786 			AFFS_DATA_HEAD(bh)->next = 0;
787 			bh->b_state &= ~(1UL << BH_New);
788 			if (prev_bh) {
789 				u32 tmp_next = be32_to_cpu(AFFS_DATA_HEAD(prev_bh)->next);
790 
791 				if (tmp_next)
792 					affs_warning(sb, "commit_write_ofs",
793 						     "next block already set for %d (%d)",
794 						     bidx, tmp_next);
795 				AFFS_DATA_HEAD(prev_bh)->next = cpu_to_be32(bh->b_blocknr);
796 				affs_adjust_checksum(prev_bh, bh->b_blocknr - tmp_next);
797 				mark_buffer_dirty_inode(prev_bh, inode);
798 			}
799 		} else if (be32_to_cpu(AFFS_DATA_HEAD(bh)->size) < tmp)
800 			AFFS_DATA_HEAD(bh)->size = cpu_to_be32(tmp);
801 		affs_brelse(prev_bh);
802 		affs_fix_checksum(sb, bh);
803 		mark_buffer_dirty_inode(bh, inode);
804 		written += tmp;
805 		from += tmp;
806 		bidx++;
807 	}
808 	SetPageUptodate(page);
809 
810 done:
811 	affs_brelse(bh);
812 	tmp = (page->index << PAGE_SHIFT) + from;
813 	if (tmp > inode->i_size)
814 		inode->i_size = AFFS_I(inode)->mmu_private = tmp;
815 
816 	/* Clear Archived bit on file writes, as AmigaOS would do */
817 	if (AFFS_I(inode)->i_protect & FIBF_ARCHIVED) {
818 		AFFS_I(inode)->i_protect &= ~FIBF_ARCHIVED;
819 		mark_inode_dirty(inode);
820 	}
821 
822 err_first_bh:
823 	unlock_page(page);
824 	put_page(page);
825 
826 	return written;
827 
828 err_bh:
829 	bh = prev_bh;
830 	if (!written)
831 		written = PTR_ERR(bh);
832 	goto done;
833 }
834 
835 const struct address_space_operations affs_aops_ofs = {
836 	.readpage = affs_readpage_ofs,
837 	//.writepage = affs_writepage_ofs,
838 	.write_begin = affs_write_begin_ofs,
839 	.write_end = affs_write_end_ofs
840 };
841 
842 /* Free any preallocated blocks. */
843 
844 void
845 affs_free_prealloc(struct inode *inode)
846 {
847 	struct super_block *sb = inode->i_sb;
848 
849 	pr_debug("free_prealloc(ino=%lu)\n", inode->i_ino);
850 
851 	while (AFFS_I(inode)->i_pa_cnt) {
852 		AFFS_I(inode)->i_pa_cnt--;
853 		affs_free_block(sb, ++AFFS_I(inode)->i_lastalloc);
854 	}
855 }
856 
857 /* Truncate (or enlarge) a file to the requested size. */
858 
859 void
860 affs_truncate(struct inode *inode)
861 {
862 	struct super_block *sb = inode->i_sb;
863 	u32 ext, ext_key;
864 	u32 last_blk, blkcnt, blk;
865 	u32 size;
866 	struct buffer_head *ext_bh;
867 	int i;
868 
869 	pr_debug("truncate(inode=%lu, oldsize=%llu, newsize=%llu)\n",
870 		 inode->i_ino, AFFS_I(inode)->mmu_private, inode->i_size);
871 
872 	last_blk = 0;
873 	ext = 0;
874 	if (inode->i_size) {
875 		last_blk = ((u32)inode->i_size - 1) / AFFS_SB(sb)->s_data_blksize;
876 		ext = last_blk / AFFS_SB(sb)->s_hashsize;
877 	}
878 
879 	if (inode->i_size > AFFS_I(inode)->mmu_private) {
880 		struct address_space *mapping = inode->i_mapping;
881 		struct page *page;
882 		void *fsdata;
883 		loff_t isize = inode->i_size;
884 		int res;
885 
886 		res = mapping->a_ops->write_begin(NULL, mapping, isize, 0, 0, &page, &fsdata);
887 		if (!res)
888 			res = mapping->a_ops->write_end(NULL, mapping, isize, 0, 0, page, fsdata);
889 		else
890 			inode->i_size = AFFS_I(inode)->mmu_private;
891 		mark_inode_dirty(inode);
892 		return;
893 	} else if (inode->i_size == AFFS_I(inode)->mmu_private)
894 		return;
895 
896 	// lock cache
897 	ext_bh = affs_get_extblock(inode, ext);
898 	if (IS_ERR(ext_bh)) {
899 		affs_warning(sb, "truncate",
900 			     "unexpected read error for ext block %u (%ld)",
901 			     ext, PTR_ERR(ext_bh));
902 		return;
903 	}
904 	if (AFFS_I(inode)->i_lc) {
905 		/* clear linear cache */
906 		i = (ext + 1) >> AFFS_I(inode)->i_lc_shift;
907 		if (AFFS_I(inode)->i_lc_size > i) {
908 			AFFS_I(inode)->i_lc_size = i;
909 			for (; i < AFFS_LC_SIZE; i++)
910 				AFFS_I(inode)->i_lc[i] = 0;
911 		}
912 		/* clear associative cache */
913 		for (i = 0; i < AFFS_AC_SIZE; i++)
914 			if (AFFS_I(inode)->i_ac[i].ext >= ext)
915 				AFFS_I(inode)->i_ac[i].ext = 0;
916 	}
917 	ext_key = be32_to_cpu(AFFS_TAIL(sb, ext_bh)->extension);
918 
919 	blkcnt = AFFS_I(inode)->i_blkcnt;
920 	i = 0;
921 	blk = last_blk;
922 	if (inode->i_size) {
923 		i = last_blk % AFFS_SB(sb)->s_hashsize + 1;
924 		blk++;
925 	} else
926 		AFFS_HEAD(ext_bh)->first_data = 0;
927 	AFFS_HEAD(ext_bh)->block_count = cpu_to_be32(i);
928 	size = AFFS_SB(sb)->s_hashsize;
929 	if (size > blkcnt - blk + i)
930 		size = blkcnt - blk + i;
931 	for (; i < size; i++, blk++) {
932 		affs_free_block(sb, be32_to_cpu(AFFS_BLOCK(sb, ext_bh, i)));
933 		AFFS_BLOCK(sb, ext_bh, i) = 0;
934 	}
935 	AFFS_TAIL(sb, ext_bh)->extension = 0;
936 	affs_fix_checksum(sb, ext_bh);
937 	mark_buffer_dirty_inode(ext_bh, inode);
938 	affs_brelse(ext_bh);
939 
940 	if (inode->i_size) {
941 		AFFS_I(inode)->i_blkcnt = last_blk + 1;
942 		AFFS_I(inode)->i_extcnt = ext + 1;
943 		if (affs_test_opt(AFFS_SB(sb)->s_flags, SF_OFS)) {
944 			struct buffer_head *bh = affs_bread_ino(inode, last_blk, 0);
945 			u32 tmp;
946 			if (IS_ERR(bh)) {
947 				affs_warning(sb, "truncate",
948 					     "unexpected read error for last block %u (%ld)",
949 					     ext, PTR_ERR(bh));
950 				return;
951 			}
952 			tmp = be32_to_cpu(AFFS_DATA_HEAD(bh)->next);
953 			AFFS_DATA_HEAD(bh)->next = 0;
954 			affs_adjust_checksum(bh, -tmp);
955 			affs_brelse(bh);
956 		}
957 	} else {
958 		AFFS_I(inode)->i_blkcnt = 0;
959 		AFFS_I(inode)->i_extcnt = 1;
960 	}
961 	AFFS_I(inode)->mmu_private = inode->i_size;
962 	// unlock cache
963 
964 	while (ext_key) {
965 		ext_bh = affs_bread(sb, ext_key);
966 		size = AFFS_SB(sb)->s_hashsize;
967 		if (size > blkcnt - blk)
968 			size = blkcnt - blk;
969 		for (i = 0; i < size; i++, blk++)
970 			affs_free_block(sb, be32_to_cpu(AFFS_BLOCK(sb, ext_bh, i)));
971 		affs_free_block(sb, ext_key);
972 		ext_key = be32_to_cpu(AFFS_TAIL(sb, ext_bh)->extension);
973 		affs_brelse(ext_bh);
974 	}
975 	affs_free_prealloc(inode);
976 }
977 
978 int affs_file_fsync(struct file *filp, loff_t start, loff_t end, int datasync)
979 {
980 	struct inode *inode = filp->f_mapping->host;
981 	int ret, err;
982 
983 	err = file_write_and_wait_range(filp, start, end);
984 	if (err)
985 		return err;
986 
987 	inode_lock(inode);
988 	ret = write_inode_now(inode, 0);
989 	err = sync_blockdev(inode->i_sb->s_bdev);
990 	if (!ret)
991 		ret = err;
992 	inode_unlock(inode);
993 	return ret;
994 }
995 const struct file_operations affs_file_operations = {
996 	.llseek		= generic_file_llseek,
997 	.read_iter	= generic_file_read_iter,
998 	.write_iter	= generic_file_write_iter,
999 	.mmap		= generic_file_mmap,
1000 	.open		= affs_file_open,
1001 	.release	= affs_file_release,
1002 	.fsync		= affs_file_fsync,
1003 	.splice_read	= generic_file_splice_read,
1004 };
1005 
1006 const struct inode_operations affs_file_inode_operations = {
1007 	.setattr	= affs_notify_change,
1008 };
1009