1/*
  2 *  linux/fs/affs/file.c
  3 *
  4 *  (c) 1996  Hans-Joachim Widmaier - Rewritten
  5 *
  6 *  (C) 1993  Ray Burr - Modified for Amiga FFS filesystem.
  7 *
  8 *  (C) 1992  Eric Youngdale Modified for ISO 9660 filesystem.
  9 *
 10 *  (C) 1991  Linus Torvalds - minix filesystem
 11 *
 12 *  affs regular file handling primitives
 13 */
 14
 15#include "affs.h"
 16
 17#if PAGE_SIZE < 4096
 18#error PAGE_SIZE must be at least 4096
 19#endif
 20
 21static int affs_grow_extcache(struct inode *inode, u32 lc_idx);
 22static struct buffer_head *affs_alloc_extblock(struct inode *inode, struct buffer_head *bh, u32 ext);
 23static inline struct buffer_head *affs_get_extblock(struct inode *inode, u32 ext);
 24static struct buffer_head *affs_get_extblock_slow(struct inode *inode, u32 ext);
 25static int affs_file_open(struct inode *inode, struct file *filp);
 26static int affs_file_release(struct inode *inode, struct file *filp);
 27
 28const struct file_operations affs_file_operations = {
 29	.llseek		= generic_file_llseek,
 30	.read		= do_sync_read,
 31	.aio_read	= generic_file_aio_read,
 32	.write		= do_sync_write,
 33	.aio_write	= generic_file_aio_write,
 34	.mmap		= generic_file_mmap,
 35	.open		= affs_file_open,
 36	.release	= affs_file_release,
 37	.fsync		= affs_file_fsync,
 38	.splice_read	= generic_file_splice_read,
 39};
 40
 41const struct inode_operations affs_file_inode_operations = {
 42	.truncate	= affs_truncate,
 43	.setattr	= affs_notify_change,
 44};
 45
 46static int
 47affs_file_open(struct inode *inode, struct file *filp)
 48{
 49	pr_debug("AFFS: open(%lu,%d)\n",
 50		 inode->i_ino, atomic_read(&AFFS_I(inode)->i_opencnt));
 51	atomic_inc(&AFFS_I(inode)->i_opencnt);
 52	return 0;
 53}
 54
 55static int
 56affs_file_release(struct inode *inode, struct file *filp)
 57{
 58	pr_debug("AFFS: release(%lu, %d)\n",
 59		 inode->i_ino, atomic_read(&AFFS_I(inode)->i_opencnt));
 60
 61	if (atomic_dec_and_test(&AFFS_I(inode)->i_opencnt)) {
 62		mutex_lock(&inode->i_mutex);
 63		if (inode->i_size != AFFS_I(inode)->mmu_private)
 64			affs_truncate(inode);
 65		affs_free_prealloc(inode);
 66		mutex_unlock(&inode->i_mutex);
 67	}
 68
 69	return 0;
 70}
 71
 72static int
 73affs_grow_extcache(struct inode *inode, u32 lc_idx)
 74{
 75	struct super_block	*sb = inode->i_sb;
 76	struct buffer_head	*bh;
 77	u32 lc_max;
 78	int i, j, key;
 79
 80	if (!AFFS_I(inode)->i_lc) {
 81		char *ptr = (char *)get_zeroed_page(GFP_NOFS);
 82		if (!ptr)
 83			return -ENOMEM;
 84		AFFS_I(inode)->i_lc = (u32 *)ptr;
 85		AFFS_I(inode)->i_ac = (struct affs_ext_key *)(ptr + AFFS_CACHE_SIZE / 2);
 86	}
 87
 88	lc_max = AFFS_LC_SIZE << AFFS_I(inode)->i_lc_shift;
 89
 90	if (AFFS_I(inode)->i_extcnt > lc_max) {
 91		u32 lc_shift, lc_mask, tmp, off;
 92
 93		/* need to recalculate linear cache, start from old size */
 94		lc_shift = AFFS_I(inode)->i_lc_shift;
 95		tmp = (AFFS_I(inode)->i_extcnt / AFFS_LC_SIZE) >> lc_shift;
 96		for (; tmp; tmp >>= 1)
 97			lc_shift++;
 98		lc_mask = (1 << lc_shift) - 1;
 99
100		/* fix idx and old size to new shift */
101		lc_idx >>= (lc_shift - AFFS_I(inode)->i_lc_shift);
102		AFFS_I(inode)->i_lc_size >>= (lc_shift - AFFS_I(inode)->i_lc_shift);
103
104		/* first shrink old cache to make more space */
105		off = 1 << (lc_shift - AFFS_I(inode)->i_lc_shift);
106		for (i = 1, j = off; j < AFFS_LC_SIZE; i++, j += off)
107			AFFS_I(inode)->i_ac[i] = AFFS_I(inode)->i_ac[j];
108
109		AFFS_I(inode)->i_lc_shift = lc_shift;
110		AFFS_I(inode)->i_lc_mask = lc_mask;
111	}
112
113	/* fill cache to the needed index */
114	i = AFFS_I(inode)->i_lc_size;
115	AFFS_I(inode)->i_lc_size = lc_idx + 1;
116	for (; i <= lc_idx; i++) {
117		if (!i) {
118			AFFS_I(inode)->i_lc[0] = inode->i_ino;
119			continue;
120		}
121		key = AFFS_I(inode)->i_lc[i - 1];
122		j = AFFS_I(inode)->i_lc_mask + 1;
123		// unlock cache
124		for (; j > 0; j--) {
125			bh = affs_bread(sb, key);
126			if (!bh)
127				goto err;
128			key = be32_to_cpu(AFFS_TAIL(sb, bh)->extension);
129			affs_brelse(bh);
130		}
131		// lock cache
132		AFFS_I(inode)->i_lc[i] = key;
133	}
134
135	return 0;
136
137err:
138	// lock cache
139	return -EIO;
140}
141
142static struct buffer_head *
143affs_alloc_extblock(struct inode *inode, struct buffer_head *bh, u32 ext)
144{
145	struct super_block *sb = inode->i_sb;
146	struct buffer_head *new_bh;
147	u32 blocknr, tmp;
148
149	blocknr = affs_alloc_block(inode, bh->b_blocknr);
150	if (!blocknr)
151		return ERR_PTR(-ENOSPC);
152
153	new_bh = affs_getzeroblk(sb, blocknr);
154	if (!new_bh) {
155		affs_free_block(sb, blocknr);
156		return ERR_PTR(-EIO);
157	}
158
159	AFFS_HEAD(new_bh)->ptype = cpu_to_be32(T_LIST);
160	AFFS_HEAD(new_bh)->key = cpu_to_be32(blocknr);
161	AFFS_TAIL(sb, new_bh)->stype = cpu_to_be32(ST_FILE);
162	AFFS_TAIL(sb, new_bh)->parent = cpu_to_be32(inode->i_ino);
163	affs_fix_checksum(sb, new_bh);
164
165	mark_buffer_dirty_inode(new_bh, inode);
166
167	tmp = be32_to_cpu(AFFS_TAIL(sb, bh)->extension);
168	if (tmp)
169		affs_warning(sb, "alloc_ext", "previous extension set (%x)", tmp);
170	AFFS_TAIL(sb, bh)->extension = cpu_to_be32(blocknr);
171	affs_adjust_checksum(bh, blocknr - tmp);
172	mark_buffer_dirty_inode(bh, inode);
173
174	AFFS_I(inode)->i_extcnt++;
175	mark_inode_dirty(inode);
176
177	return new_bh;
178}
179
180static inline struct buffer_head *
181affs_get_extblock(struct inode *inode, u32 ext)
182{
183	/* inline the simplest case: same extended block as last time */
184	struct buffer_head *bh = AFFS_I(inode)->i_ext_bh;
185	if (ext == AFFS_I(inode)->i_ext_last)
186		get_bh(bh);
187	else
188		/* we have to do more (not inlined) */
189		bh = affs_get_extblock_slow(inode, ext);
190
191	return bh;
192}
193
194static struct buffer_head *
195affs_get_extblock_slow(struct inode *inode, u32 ext)
196{
197	struct super_block *sb = inode->i_sb;
198	struct buffer_head *bh;
199	u32 ext_key;
200	u32 lc_idx, lc_off, ac_idx;
201	u32 tmp, idx;
202
203	if (ext == AFFS_I(inode)->i_ext_last + 1) {
204		/* read the next extended block from the current one */
205		bh = AFFS_I(inode)->i_ext_bh;
206		ext_key = be32_to_cpu(AFFS_TAIL(sb, bh)->extension);
207		if (ext < AFFS_I(inode)->i_extcnt)
208			goto read_ext;
209		if (ext > AFFS_I(inode)->i_extcnt)
210			BUG();
211		bh = affs_alloc_extblock(inode, bh, ext);
212		if (IS_ERR(bh))
213			return bh;
214		goto store_ext;
215	}
216
217	if (ext == 0) {
218		/* we seek back to the file header block */
219		ext_key = inode->i_ino;
220		goto read_ext;
221	}
222
223	if (ext >= AFFS_I(inode)->i_extcnt) {
224		struct buffer_head *prev_bh;
225
226		/* allocate a new extended block */
227		if (ext > AFFS_I(inode)->i_extcnt)
228			BUG();
229
230		/* get previous extended block */
231		prev_bh = affs_get_extblock(inode, ext - 1);
232		if (IS_ERR(prev_bh))
233			return prev_bh;
234		bh = affs_alloc_extblock(inode, prev_bh, ext);
235		affs_brelse(prev_bh);
236		if (IS_ERR(bh))
237			return bh;
238		goto store_ext;
239	}
240
241again:
242	/* check if there is an extended cache and whether it's large enough */
243	lc_idx = ext >> AFFS_I(inode)->i_lc_shift;
244	lc_off = ext & AFFS_I(inode)->i_lc_mask;
245
246	if (lc_idx >= AFFS_I(inode)->i_lc_size) {
247		int err;
248
249		err = affs_grow_extcache(inode, lc_idx);
250		if (err)
251			return ERR_PTR(err);
252		goto again;
253	}
254
255	/* every n'th key we find in the linear cache */
256	if (!lc_off) {
257		ext_key = AFFS_I(inode)->i_lc[lc_idx];
258		goto read_ext;
259	}
260
261	/* maybe it's still in the associative cache */
262	ac_idx = (ext - lc_idx - 1) & AFFS_AC_MASK;
263	if (AFFS_I(inode)->i_ac[ac_idx].ext == ext) {
264		ext_key = AFFS_I(inode)->i_ac[ac_idx].key;
265		goto read_ext;
266	}
267
268	/* try to find one of the previous extended blocks */
269	tmp = ext;
270	idx = ac_idx;
271	while (--tmp, --lc_off > 0) {
272		idx = (idx - 1) & AFFS_AC_MASK;
273		if (AFFS_I(inode)->i_ac[idx].ext == tmp) {
274			ext_key = AFFS_I(inode)->i_ac[idx].key;
275			goto find_ext;
276		}
277	}
278
279	/* fall back to the linear cache */
280	ext_key = AFFS_I(inode)->i_lc[lc_idx];
281find_ext:
282	/* read all extended blocks until we find the one we need */
283	//unlock cache
284	do {
285		bh = affs_bread(sb, ext_key);
286		if (!bh)
287			goto err_bread;
288		ext_key = be32_to_cpu(AFFS_TAIL(sb, bh)->extension);
289		affs_brelse(bh);
290		tmp++;
291	} while (tmp < ext);
292	//lock cache
293
294	/* store it in the associative cache */
295	// recalculate ac_idx?
296	AFFS_I(inode)->i_ac[ac_idx].ext = ext;
297	AFFS_I(inode)->i_ac[ac_idx].key = ext_key;
298
299read_ext:
300	/* finally read the right extended block */
301	//unlock cache
302	bh = affs_bread(sb, ext_key);
303	if (!bh)
304		goto err_bread;
305	//lock cache
306
307store_ext:
308	/* release old cached extended block and store the new one */
309	affs_brelse(AFFS_I(inode)->i_ext_bh);
310	AFFS_I(inode)->i_ext_last = ext;
311	AFFS_I(inode)->i_ext_bh = bh;
312	get_bh(bh);
313
314	return bh;
315
316err_bread:
317	affs_brelse(bh);
318	return ERR_PTR(-EIO);
319}
320
321static int
322affs_get_block(struct inode *inode, sector_t block, struct buffer_head *bh_result, int create)
323{
324	struct super_block	*sb = inode->i_sb;
325	struct buffer_head	*ext_bh;
326	u32			 ext;
327
328	pr_debug("AFFS: get_block(%u, %lu)\n", (u32)inode->i_ino, (unsigned long)block);
329
330	BUG_ON(block > (sector_t)0x7fffffffUL);
331
332	if (block >= AFFS_I(inode)->i_blkcnt) {
333		if (block > AFFS_I(inode)->i_blkcnt || !create)
334			goto err_big;
335	} else
336		create = 0;
337
338	//lock cache
339	affs_lock_ext(inode);
340
341	ext = (u32)block / AFFS_SB(sb)->s_hashsize;
342	block -= ext * AFFS_SB(sb)->s_hashsize;
343	ext_bh = affs_get_extblock(inode, ext);
344	if (IS_ERR(ext_bh))
345		goto err_ext;
346	map_bh(bh_result, sb, (sector_t)be32_to_cpu(AFFS_BLOCK(sb, ext_bh, block)));
347
348	if (create) {
349		u32 blocknr = affs_alloc_block(inode, ext_bh->b_blocknr);
350		if (!blocknr)
351			goto err_alloc;
352		set_buffer_new(bh_result);
353		AFFS_I(inode)->mmu_private += AFFS_SB(sb)->s_data_blksize;
354		AFFS_I(inode)->i_blkcnt++;
355
356		/* store new block */
357		if (bh_result->b_blocknr)
358			affs_warning(sb, "get_block", "block already set (%x)", bh_result->b_blocknr);
359		AFFS_BLOCK(sb, ext_bh, block) = cpu_to_be32(blocknr);
360		AFFS_HEAD(ext_bh)->block_count = cpu_to_be32(block + 1);
361		affs_adjust_checksum(ext_bh, blocknr - bh_result->b_blocknr + 1);
362		bh_result->b_blocknr = blocknr;
363
364		if (!block) {
365			/* insert first block into header block */
366			u32 tmp = be32_to_cpu(AFFS_HEAD(ext_bh)->first_data);
367			if (tmp)
368				affs_warning(sb, "get_block", "first block already set (%d)", tmp);
369			AFFS_HEAD(ext_bh)->first_data = cpu_to_be32(blocknr);
370			affs_adjust_checksum(ext_bh, blocknr - tmp);
371		}
372	}
373
374	affs_brelse(ext_bh);
375	//unlock cache
376	affs_unlock_ext(inode);
377	return 0;
378
379err_big:
380	affs_error(inode->i_sb,"get_block","strange block request %d", block);
381	return -EIO;
382err_ext:
383	// unlock cache
384	affs_unlock_ext(inode);
385	return PTR_ERR(ext_bh);
386err_alloc:
387	brelse(ext_bh);
388	clear_buffer_mapped(bh_result);
389	bh_result->b_bdev = NULL;
390	// unlock cache
391	affs_unlock_ext(inode);
392	return -ENOSPC;
393}
394
395static int affs_writepage(struct page *page, struct writeback_control *wbc)
396{
397	return block_write_full_page(page, affs_get_block, wbc);
398}
399
400static int affs_readpage(struct file *file, struct page *page)
401{
402	return block_read_full_page(page, affs_get_block);
403}
404
405static int affs_write_begin(struct file *file, struct address_space *mapping,
406			loff_t pos, unsigned len, unsigned flags,
407			struct page **pagep, void **fsdata)
408{
409	int ret;
410
411	*pagep = NULL;
412	ret = cont_write_begin(file, mapping, pos, len, flags, pagep, fsdata,
413				affs_get_block,
414				&AFFS_I(mapping->host)->mmu_private);
415	if (unlikely(ret)) {
416		loff_t isize = mapping->host->i_size;
417		if (pos + len > isize)
418			vmtruncate(mapping->host, isize);
419	}
420
421	return ret;
422}
423
424static sector_t _affs_bmap(struct address_space *mapping, sector_t block)
425{
426	return generic_block_bmap(mapping,block,affs_get_block);
427}
428
429const struct address_space_operations affs_aops = {
430	.readpage = affs_readpage,
431	.writepage = affs_writepage,
432	.write_begin = affs_write_begin,
433	.write_end = generic_write_end,
434	.bmap = _affs_bmap
435};
436
437static inline struct buffer_head *
438affs_bread_ino(struct inode *inode, int block, int create)
439{
440	struct buffer_head *bh, tmp_bh;
441	int err;
442
443	tmp_bh.b_state = 0;
444	err = affs_get_block(inode, block, &tmp_bh, create);
445	if (!err) {
446		bh = affs_bread(inode->i_sb, tmp_bh.b_blocknr);
447		if (bh) {
448			bh->b_state |= tmp_bh.b_state;
449			return bh;
450		}
451		err = -EIO;
452	}
453	return ERR_PTR(err);
454}
455
456static inline struct buffer_head *
457affs_getzeroblk_ino(struct inode *inode, int block)
458{
459	struct buffer_head *bh, tmp_bh;
460	int err;
461
462	tmp_bh.b_state = 0;
463	err = affs_get_block(inode, block, &tmp_bh, 1);
464	if (!err) {
465		bh = affs_getzeroblk(inode->i_sb, tmp_bh.b_blocknr);
466		if (bh) {
467			bh->b_state |= tmp_bh.b_state;
468			return bh;
469		}
470		err = -EIO;
471	}
472	return ERR_PTR(err);
473}
474
475static inline struct buffer_head *
476affs_getemptyblk_ino(struct inode *inode, int block)
477{
478	struct buffer_head *bh, tmp_bh;
479	int err;
480
481	tmp_bh.b_state = 0;
482	err = affs_get_block(inode, block, &tmp_bh, 1);
483	if (!err) {
484		bh = affs_getemptyblk(inode->i_sb, tmp_bh.b_blocknr);
485		if (bh) {
486			bh->b_state |= tmp_bh.b_state;
487			return bh;
488		}
489		err = -EIO;
490	}
491	return ERR_PTR(err);
492}
493
494static int
495affs_do_readpage_ofs(struct file *file, struct page *page, unsigned from, unsigned to)
496{
497	struct inode *inode = page->mapping->host;
498	struct super_block *sb = inode->i_sb;
499	struct buffer_head *bh;
500	char *data;
501	u32 bidx, boff, bsize;
502	u32 tmp;
503
504	pr_debug("AFFS: read_page(%u, %ld, %d, %d)\n", (u32)inode->i_ino, page->index, from, to);
505	BUG_ON(from > to || to > PAGE_CACHE_SIZE);
506	kmap(page);
507	data = page_address(page);
508	bsize = AFFS_SB(sb)->s_data_blksize;
509	tmp = (page->index << PAGE_CACHE_SHIFT) + from;
510	bidx = tmp / bsize;
511	boff = tmp % bsize;
512
513	while (from < to) {
514		bh = affs_bread_ino(inode, bidx, 0);
515		if (IS_ERR(bh))
516			return PTR_ERR(bh);
517		tmp = min(bsize - boff, to - from);
518		BUG_ON(from + tmp > to || tmp > bsize);
519		memcpy(data + from, AFFS_DATA(bh) + boff, tmp);
520		affs_brelse(bh);
521		bidx++;
522		from += tmp;
523		boff = 0;
524	}
525	flush_dcache_page(page);
526	kunmap(page);
527	return 0;
528}
529
530static int
531affs_extent_file_ofs(struct inode *inode, u32 newsize)
532{
533	struct super_block *sb = inode->i_sb;
534	struct buffer_head *bh, *prev_bh;
535	u32 bidx, boff;
536	u32 size, bsize;
537	u32 tmp;
538
539	pr_debug("AFFS: extent_file(%u, %d)\n", (u32)inode->i_ino, newsize);
540	bsize = AFFS_SB(sb)->s_data_blksize;
541	bh = NULL;
542	size = AFFS_I(inode)->mmu_private;
543	bidx = size / bsize;
544	boff = size % bsize;
545	if (boff) {
546		bh = affs_bread_ino(inode, bidx, 0);
547		if (IS_ERR(bh))
548			return PTR_ERR(bh);
549		tmp = min(bsize - boff, newsize - size);
550		BUG_ON(boff + tmp > bsize || tmp > bsize);
551		memset(AFFS_DATA(bh) + boff, 0, tmp);
552		be32_add_cpu(&AFFS_DATA_HEAD(bh)->size, tmp);
553		affs_fix_checksum(sb, bh);
554		mark_buffer_dirty_inode(bh, inode);
555		size += tmp;
556		bidx++;
557	} else if (bidx) {
558		bh = affs_bread_ino(inode, bidx - 1, 0);
559		if (IS_ERR(bh))
560			return PTR_ERR(bh);
561	}
562
563	while (size < newsize) {
564		prev_bh = bh;
565		bh = affs_getzeroblk_ino(inode, bidx);
566		if (IS_ERR(bh))
567			goto out;
568		tmp = min(bsize, newsize - size);
569		BUG_ON(tmp > bsize);
570		AFFS_DATA_HEAD(bh)->ptype = cpu_to_be32(T_DATA);
571		AFFS_DATA_HEAD(bh)->key = cpu_to_be32(inode->i_ino);
572		AFFS_DATA_HEAD(bh)->sequence = cpu_to_be32(bidx);
573		AFFS_DATA_HEAD(bh)->size = cpu_to_be32(tmp);
574		affs_fix_checksum(sb, bh);
575		bh->b_state &= ~(1UL << BH_New);
576		mark_buffer_dirty_inode(bh, inode);
577		if (prev_bh) {
578			u32 tmp = be32_to_cpu(AFFS_DATA_HEAD(prev_bh)->next);
579			if (tmp)
580				affs_warning(sb, "extent_file_ofs", "next block already set for %d (%d)", bidx, tmp);
581			AFFS_DATA_HEAD(prev_bh)->next = cpu_to_be32(bh->b_blocknr);
582			affs_adjust_checksum(prev_bh, bh->b_blocknr - tmp);
583			mark_buffer_dirty_inode(prev_bh, inode);
584			affs_brelse(prev_bh);
585		}
586		size += bsize;
587		bidx++;
588	}
589	affs_brelse(bh);
590	inode->i_size = AFFS_I(inode)->mmu_private = newsize;
591	return 0;
592
593out:
594	inode->i_size = AFFS_I(inode)->mmu_private = newsize;
595	return PTR_ERR(bh);
596}
597
598static int
599affs_readpage_ofs(struct file *file, struct page *page)
600{
601	struct inode *inode = page->mapping->host;
602	u32 to;
603	int err;
604
605	pr_debug("AFFS: read_page(%u, %ld)\n", (u32)inode->i_ino, page->index);
606	to = PAGE_CACHE_SIZE;
607	if (((page->index + 1) << PAGE_CACHE_SHIFT) > inode->i_size) {
608		to = inode->i_size & ~PAGE_CACHE_MASK;
609		memset(page_address(page) + to, 0, PAGE_CACHE_SIZE - to);
610	}
611
612	err = affs_do_readpage_ofs(file, page, 0, to);
613	if (!err)
614		SetPageUptodate(page);
615	unlock_page(page);
616	return err;
617}
618
619static int affs_write_begin_ofs(struct file *file, struct address_space *mapping,
620				loff_t pos, unsigned len, unsigned flags,
621				struct page **pagep, void **fsdata)
622{
623	struct inode *inode = mapping->host;
624	struct page *page;
625	pgoff_t index;
626	int err = 0;
627
628	pr_debug("AFFS: write_begin(%u, %llu, %llu)\n", (u32)inode->i_ino, (unsigned long long)pos, (unsigned long long)pos + len);
629	if (pos > AFFS_I(inode)->mmu_private) {
630		/* XXX: this probably leaves a too-big i_size in case of
631		 * failure. Should really be updating i_size at write_end time
632		 */
633		err = affs_extent_file_ofs(inode, pos);
634		if (err)
635			return err;
636	}
637
638	index = pos >> PAGE_CACHE_SHIFT;
639	page = grab_cache_page_write_begin(mapping, index, flags);
640	if (!page)
641		return -ENOMEM;
642	*pagep = page;
643
644	if (PageUptodate(page))
645		return 0;
646
647	/* XXX: inefficient but safe in the face of short writes */
648	err = affs_do_readpage_ofs(file, page, 0, PAGE_CACHE_SIZE);
649	if (err) {
650		unlock_page(page);
651		page_cache_release(page);
652	}
653	return err;
654}
655
656static int affs_write_end_ofs(struct file *file, struct address_space *mapping,
657				loff_t pos, unsigned len, unsigned copied,
658				struct page *page, void *fsdata)
659{
660	struct inode *inode = mapping->host;
661	struct super_block *sb = inode->i_sb;
662	struct buffer_head *bh, *prev_bh;
663	char *data;
664	u32 bidx, boff, bsize;
665	unsigned from, to;
666	u32 tmp;
667	int written;
668
669	from = pos & (PAGE_CACHE_SIZE - 1);
670	to = pos + len;
671	/*
672	 * XXX: not sure if this can handle short copies (len < copied), but
673	 * we don't have to, because the page should always be uptodate here,
674	 * due to write_begin.
675	 */
676
677	pr_debug("AFFS: write_begin(%u, %llu, %llu)\n", (u32)inode->i_ino, (unsigned long long)pos, (unsigned long long)pos + len);
678	bsize = AFFS_SB(sb)->s_data_blksize;
679	data = page_address(page);
680
681	bh = NULL;
682	written = 0;
683	tmp = (page->index << PAGE_CACHE_SHIFT) + from;
684	bidx = tmp / bsize;
685	boff = tmp % bsize;
686	if (boff) {
687		bh = affs_bread_ino(inode, bidx, 0);
688		if (IS_ERR(bh))
689			return PTR_ERR(bh);
690		tmp = min(bsize - boff, to - from);
691		BUG_ON(boff + tmp > bsize || tmp > bsize);
692		memcpy(AFFS_DATA(bh) + boff, data + from, tmp);
693		be32_add_cpu(&AFFS_DATA_HEAD(bh)->size, tmp);
694		affs_fix_checksum(sb, bh);
695		mark_buffer_dirty_inode(bh, inode);
696		written += tmp;
697		from += tmp;
698		bidx++;
699	} else if (bidx) {
700		bh = affs_bread_ino(inode, bidx - 1, 0);
701		if (IS_ERR(bh))
702			return PTR_ERR(bh);
703	}
704	while (from + bsize <= to) {
705		prev_bh = bh;
706		bh = affs_getemptyblk_ino(inode, bidx);
707		if (IS_ERR(bh))
708			goto out;
709		memcpy(AFFS_DATA(bh), data + from, bsize);
710		if (buffer_new(bh)) {
711			AFFS_DATA_HEAD(bh)->ptype = cpu_to_be32(T_DATA);
712			AFFS_DATA_HEAD(bh)->key = cpu_to_be32(inode->i_ino);
713			AFFS_DATA_HEAD(bh)->sequence = cpu_to_be32(bidx);
714			AFFS_DATA_HEAD(bh)->size = cpu_to_be32(bsize);
715			AFFS_DATA_HEAD(bh)->next = 0;
716			bh->b_state &= ~(1UL << BH_New);
717			if (prev_bh) {
718				u32 tmp = be32_to_cpu(AFFS_DATA_HEAD(prev_bh)->next);
719				if (tmp)
720					affs_warning(sb, "commit_write_ofs", "next block already set for %d (%d)", bidx, tmp);
721				AFFS_DATA_HEAD(prev_bh)->next = cpu_to_be32(bh->b_blocknr);
722				affs_adjust_checksum(prev_bh, bh->b_blocknr - tmp);
723				mark_buffer_dirty_inode(prev_bh, inode);
724			}
725		}
726		affs_brelse(prev_bh);
727		affs_fix_checksum(sb, bh);
728		mark_buffer_dirty_inode(bh, inode);
729		written += bsize;
730		from += bsize;
731		bidx++;
732	}
733	if (from < to) {
734		prev_bh = bh;
735		bh = affs_bread_ino(inode, bidx, 1);
736		if (IS_ERR(bh))
737			goto out;
738		tmp = min(bsize, to - from);
739		BUG_ON(tmp > bsize);
740		memcpy(AFFS_DATA(bh), data + from, tmp);
741		if (buffer_new(bh)) {
742			AFFS_DATA_HEAD(bh)->ptype = cpu_to_be32(T_DATA);
743			AFFS_DATA_HEAD(bh)->key = cpu_to_be32(inode->i_ino);
744			AFFS_DATA_HEAD(bh)->sequence = cpu_to_be32(bidx);
745			AFFS_DATA_HEAD(bh)->size = cpu_to_be32(tmp);
746			AFFS_DATA_HEAD(bh)->next = 0;
747			bh->b_state &= ~(1UL << BH_New);
748			if (prev_bh) {
749				u32 tmp = be32_to_cpu(AFFS_DATA_HEAD(prev_bh)->next);
750				if (tmp)
751					affs_warning(sb, "commit_write_ofs", "next block already set for %d (%d)", bidx, tmp);
752				AFFS_DATA_HEAD(prev_bh)->next = cpu_to_be32(bh->b_blocknr);
753				affs_adjust_checksum(prev_bh, bh->b_blocknr - tmp);
754				mark_buffer_dirty_inode(prev_bh, inode);
755			}
756		} else if (be32_to_cpu(AFFS_DATA_HEAD(bh)->size) < tmp)
757			AFFS_DATA_HEAD(bh)->size = cpu_to_be32(tmp);
758		affs_brelse(prev_bh);
759		affs_fix_checksum(sb, bh);
760		mark_buffer_dirty_inode(bh, inode);
761		written += tmp;
762		from += tmp;
763		bidx++;
764	}
765	SetPageUptodate(page);
766
767done:
768	affs_brelse(bh);
769	tmp = (page->index << PAGE_CACHE_SHIFT) + from;
770	if (tmp > inode->i_size)
771		inode->i_size = AFFS_I(inode)->mmu_private = tmp;
772
773	unlock_page(page);
774	page_cache_release(page);
775
776	return written;
777
778out:
779	bh = prev_bh;
780	if (!written)
781		written = PTR_ERR(bh);
782	goto done;
783}
784
785const struct address_space_operations affs_aops_ofs = {
786	.readpage = affs_readpage_ofs,
787	//.writepage = affs_writepage_ofs,
788	.write_begin = affs_write_begin_ofs,
789	.write_end = affs_write_end_ofs
790};
791
792/* Free any preallocated blocks. */
793
794void
795affs_free_prealloc(struct inode *inode)
796{
797	struct super_block *sb = inode->i_sb;
798
799	pr_debug("AFFS: free_prealloc(ino=%lu)\n", inode->i_ino);
800
801	while (AFFS_I(inode)->i_pa_cnt) {
802		AFFS_I(inode)->i_pa_cnt--;
803		affs_free_block(sb, ++AFFS_I(inode)->i_lastalloc);
804	}
805}
806
807/* Truncate (or enlarge) a file to the requested size. */
808
809void
810affs_truncate(struct inode *inode)
811{
812	struct super_block *sb = inode->i_sb;
813	u32 ext, ext_key;
814	u32 last_blk, blkcnt, blk;
815	u32 size;
816	struct buffer_head *ext_bh;
817	int i;
818
819	pr_debug("AFFS: truncate(inode=%d, oldsize=%u, newsize=%u)\n",
820		 (u32)inode->i_ino, (u32)AFFS_I(inode)->mmu_private, (u32)inode->i_size);
821
822	last_blk = 0;
823	ext = 0;
824	if (inode->i_size) {
825		last_blk = ((u32)inode->i_size - 1) / AFFS_SB(sb)->s_data_blksize;
826		ext = last_blk / AFFS_SB(sb)->s_hashsize;
827	}
828
829	if (inode->i_size > AFFS_I(inode)->mmu_private) {
830		struct address_space *mapping = inode->i_mapping;
831		struct page *page;
832		void *fsdata;
833		u32 size = inode->i_size;
834		int res;
835
836		res = mapping->a_ops->write_begin(NULL, mapping, size, 0, 0, &page, &fsdata);
837		if (!res)
838			res = mapping->a_ops->write_end(NULL, mapping, size, 0, 0, page, fsdata);
839		else
840			inode->i_size = AFFS_I(inode)->mmu_private;
841		mark_inode_dirty(inode);
842		return;
843	} else if (inode->i_size == AFFS_I(inode)->mmu_private)
844		return;
845
846	// lock cache
847	ext_bh = affs_get_extblock(inode, ext);
848	if (IS_ERR(ext_bh)) {
849		affs_warning(sb, "truncate", "unexpected read error for ext block %u (%d)",
850			     ext, PTR_ERR(ext_bh));
851		return;
852	}
853	if (AFFS_I(inode)->i_lc) {
854		/* clear linear cache */
855		i = (ext + 1) >> AFFS_I(inode)->i_lc_shift;
856		if (AFFS_I(inode)->i_lc_size > i) {
857			AFFS_I(inode)->i_lc_size = i;
858			for (; i < AFFS_LC_SIZE; i++)
859				AFFS_I(inode)->i_lc[i] = 0;
860		}
861		/* clear associative cache */
862		for (i = 0; i < AFFS_AC_SIZE; i++)
863			if (AFFS_I(inode)->i_ac[i].ext >= ext)
864				AFFS_I(inode)->i_ac[i].ext = 0;
865	}
866	ext_key = be32_to_cpu(AFFS_TAIL(sb, ext_bh)->extension);
867
868	blkcnt = AFFS_I(inode)->i_blkcnt;
869	i = 0;
870	blk = last_blk;
871	if (inode->i_size) {
872		i = last_blk % AFFS_SB(sb)->s_hashsize + 1;
873		blk++;
874	} else
875		AFFS_HEAD(ext_bh)->first_data = 0;
876	AFFS_HEAD(ext_bh)->block_count = cpu_to_be32(i);
877	size = AFFS_SB(sb)->s_hashsize;
878	if (size > blkcnt - blk + i)
879		size = blkcnt - blk + i;
880	for (; i < size; i++, blk++) {
881		affs_free_block(sb, be32_to_cpu(AFFS_BLOCK(sb, ext_bh, i)));
882		AFFS_BLOCK(sb, ext_bh, i) = 0;
883	}
884	AFFS_TAIL(sb, ext_bh)->extension = 0;
885	affs_fix_checksum(sb, ext_bh);
886	mark_buffer_dirty_inode(ext_bh, inode);
887	affs_brelse(ext_bh);
888
889	if (inode->i_size) {
890		AFFS_I(inode)->i_blkcnt = last_blk + 1;
891		AFFS_I(inode)->i_extcnt = ext + 1;
892		if (AFFS_SB(sb)->s_flags & SF_OFS) {
893			struct buffer_head *bh = affs_bread_ino(inode, last_blk, 0);
894			u32 tmp;
895			if (IS_ERR(bh)) {
896				affs_warning(sb, "truncate", "unexpected read error for last block %u (%d)",
897					     ext, PTR_ERR(bh));
898				return;
899			}
900			tmp = be32_to_cpu(AFFS_DATA_HEAD(bh)->next);
901			AFFS_DATA_HEAD(bh)->next = 0;
902			affs_adjust_checksum(bh, -tmp);
903			affs_brelse(bh);
904		}
905	} else {
906		AFFS_I(inode)->i_blkcnt = 0;
907		AFFS_I(inode)->i_extcnt = 1;
908	}
909	AFFS_I(inode)->mmu_private = inode->i_size;
910	// unlock cache
911
912	while (ext_key) {
913		ext_bh = affs_bread(sb, ext_key);
914		size = AFFS_SB(sb)->s_hashsize;
915		if (size > blkcnt - blk)
916			size = blkcnt - blk;
917		for (i = 0; i < size; i++, blk++)
918			affs_free_block(sb, be32_to_cpu(AFFS_BLOCK(sb, ext_bh, i)));
919		affs_free_block(sb, ext_key);
920		ext_key = be32_to_cpu(AFFS_TAIL(sb, ext_bh)->extension);
921		affs_brelse(ext_bh);
922	}
923	affs_free_prealloc(inode);
924}
925
926int affs_file_fsync(struct file *filp, loff_t start, loff_t end, int datasync)
927{
928	struct inode *inode = filp->f_mapping->host;
929	int ret, err;
930
931	err = filemap_write_and_wait_range(inode->i_mapping, start, end);
932	if (err)
933		return err;
934
935	mutex_lock(&inode->i_mutex);
936	ret = write_inode_now(inode, 0);
937	err = sync_blockdev(inode->i_sb->s_bdev);
938	if (!ret)
939		ret = err;
940	mutex_unlock(&inode->i_mutex);
941	return ret;
942}