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linux-6.19.14/fs/affs/file.c C 
   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
  21static struct buffer_head *affs_get_extblock_slow(struct inode *inode, u32 ext);
  22
  23static int
  24affs_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
  32static int
  33affs_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
  49static int
  50affs_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
 114err:
 115	// lock cache
 116	return -EIO;
 117}
 118
 119static struct buffer_head *
 120affs_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
 157static inline struct buffer_head *
 158affs_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
 171static struct buffer_head *
 172affs_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
 216again:
 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];
 256find_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
 274read_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
 282store_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
 291err_bread:
 292	affs_brelse(bh);
 293	return ERR_PTR(-EIO);
 294}
 295
 296static int
 297affs_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
 357err_big:
 358	affs_error(inode->i_sb, "get_block", "strange block request %llu",
 359		   (unsigned long long)block);
 360	return -EIO;
 361err_ext:
 362	// unlock cache
 363	affs_unlock_ext(inode);
 364	return PTR_ERR(ext_bh);
 365err_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
 374static int affs_writepages(struct address_space *mapping,
 375			   struct writeback_control *wbc)
 376{
 377	return mpage_writepages(mapping, wbc, affs_get_block);
 378}
 379
 380static int affs_read_folio(struct file *file, struct folio *folio)
 381{
 382	return block_read_full_folio(folio, affs_get_block);
 383}
 384
 385static 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
 395static ssize_t
 396affs_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
 418static int affs_write_begin(const struct kiocb *iocb,
 419			    struct address_space *mapping,
 420			    loff_t pos, unsigned len,
 421			    struct folio **foliop, void **fsdata)
 422{
 423	int ret;
 424
 425	ret = cont_write_begin(iocb, mapping, pos, len, foliop, 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
 434static int affs_write_end(const struct kiocb *iocb,
 435			  struct address_space *mapping, loff_t pos,
 436			  unsigned int len, unsigned int copied,
 437			  struct folio *folio, void *fsdata)
 438{
 439	struct inode *inode = mapping->host;
 440	int ret;
 441
 442	ret = generic_write_end(iocb, mapping, pos, len, copied, folio, fsdata);
 443
 444	/* Clear Archived bit on file writes, as AmigaOS would do */
 445	if (AFFS_I(inode)->i_protect & FIBF_ARCHIVED) {
 446		AFFS_I(inode)->i_protect &= ~FIBF_ARCHIVED;
 447		mark_inode_dirty(inode);
 448	}
 449
 450	return ret;
 451}
 452
 453static sector_t _affs_bmap(struct address_space *mapping, sector_t block)
 454{
 455	return generic_block_bmap(mapping,block,affs_get_block);
 456}
 457
 458const struct address_space_operations affs_aops = {
 459	.dirty_folio	= block_dirty_folio,
 460	.invalidate_folio = block_invalidate_folio,
 461	.read_folio = affs_read_folio,
 462	.writepages = affs_writepages,
 463	.write_begin = affs_write_begin,
 464	.write_end = affs_write_end,
 465	.direct_IO = affs_direct_IO,
 466	.migrate_folio = buffer_migrate_folio,
 467	.bmap = _affs_bmap
 468};
 469
 470static inline struct buffer_head *
 471affs_bread_ino(struct inode *inode, int block, int create)
 472{
 473	struct buffer_head *bh, tmp_bh;
 474	int err;
 475
 476	tmp_bh.b_state = 0;
 477	err = affs_get_block(inode, block, &tmp_bh, create);
 478	if (!err) {
 479		bh = affs_bread(inode->i_sb, tmp_bh.b_blocknr);
 480		if (bh) {
 481			bh->b_state |= tmp_bh.b_state;
 482			return bh;
 483		}
 484		err = -EIO;
 485	}
 486	return ERR_PTR(err);
 487}
 488
 489static inline struct buffer_head *
 490affs_getzeroblk_ino(struct inode *inode, int block)
 491{
 492	struct buffer_head *bh, tmp_bh;
 493	int err;
 494
 495	tmp_bh.b_state = 0;
 496	err = affs_get_block(inode, block, &tmp_bh, 1);
 497	if (!err) {
 498		bh = affs_getzeroblk(inode->i_sb, tmp_bh.b_blocknr);
 499		if (bh) {
 500			bh->b_state |= tmp_bh.b_state;
 501			return bh;
 502		}
 503		err = -EIO;
 504	}
 505	return ERR_PTR(err);
 506}
 507
 508static inline struct buffer_head *
 509affs_getemptyblk_ino(struct inode *inode, int block)
 510{
 511	struct buffer_head *bh, tmp_bh;
 512	int err;
 513
 514	tmp_bh.b_state = 0;
 515	err = affs_get_block(inode, block, &tmp_bh, 1);
 516	if (!err) {
 517		bh = affs_getemptyblk(inode->i_sb, tmp_bh.b_blocknr);
 518		if (bh) {
 519			bh->b_state |= tmp_bh.b_state;
 520			return bh;
 521		}
 522		err = -EIO;
 523	}
 524	return ERR_PTR(err);
 525}
 526
 527static int affs_do_read_folio_ofs(struct folio *folio, size_t to, int create)
 528{
 529	struct inode *inode = folio->mapping->host;
 530	struct super_block *sb = inode->i_sb;
 531	struct buffer_head *bh;
 532	size_t pos = 0;
 533	size_t bidx, boff, bsize;
 534	u32 tmp;
 535
 536	pr_debug("%s(%lu, %ld, 0, %zu)\n", __func__, inode->i_ino,
 537		 folio->index, to);
 538	BUG_ON(to > folio_size(folio));
 539	bsize = AFFS_SB(sb)->s_data_blksize;
 540	tmp = folio_pos(folio);
 541	bidx = tmp / bsize;
 542	boff = tmp % bsize;
 543
 544	while (pos < to) {
 545		bh = affs_bread_ino(inode, bidx, create);
 546		if (IS_ERR(bh))
 547			return PTR_ERR(bh);
 548		tmp = min(bsize - boff, to - pos);
 549		BUG_ON(pos + tmp > to || tmp > bsize);
 550		memcpy_to_folio(folio, pos, AFFS_DATA(bh) + boff, tmp);
 551		affs_brelse(bh);
 552		bidx++;
 553		pos += tmp;
 554		boff = 0;
 555	}
 556	return 0;
 557}
 558
 559static int
 560affs_extent_file_ofs(struct inode *inode, u32 newsize)
 561{
 562	struct super_block *sb = inode->i_sb;
 563	struct buffer_head *bh, *prev_bh;
 564	u32 bidx, boff;
 565	u32 size, bsize;
 566	u32 tmp;
 567
 568	pr_debug("%s(%lu, %d)\n", __func__, inode->i_ino, newsize);
 569	bsize = AFFS_SB(sb)->s_data_blksize;
 570	bh = NULL;
 571	size = AFFS_I(inode)->mmu_private;
 572	bidx = size / bsize;
 573	boff = size % bsize;
 574	if (boff) {
 575		bh = affs_bread_ino(inode, bidx, 0);
 576		if (IS_ERR(bh))
 577			return PTR_ERR(bh);
 578		tmp = min(bsize - boff, newsize - size);
 579		BUG_ON(boff + tmp > bsize || tmp > bsize);
 580		memset(AFFS_DATA(bh) + boff, 0, tmp);
 581		be32_add_cpu(&AFFS_DATA_HEAD(bh)->size, tmp);
 582		affs_fix_checksum(sb, bh);
 583		mark_buffer_dirty_inode(bh, inode);
 584		size += tmp;
 585		bidx++;
 586	} else if (bidx) {
 587		bh = affs_bread_ino(inode, bidx - 1, 0);
 588		if (IS_ERR(bh))
 589			return PTR_ERR(bh);
 590	}
 591
 592	while (size < newsize) {
 593		prev_bh = bh;
 594		bh = affs_getzeroblk_ino(inode, bidx);
 595		if (IS_ERR(bh))
 596			goto out;
 597		tmp = min(bsize, newsize - size);
 598		BUG_ON(tmp > bsize);
 599		AFFS_DATA_HEAD(bh)->ptype = cpu_to_be32(T_DATA);
 600		AFFS_DATA_HEAD(bh)->key = cpu_to_be32(inode->i_ino);
 601		AFFS_DATA_HEAD(bh)->sequence = cpu_to_be32(bidx + 1);
 602		AFFS_DATA_HEAD(bh)->size = cpu_to_be32(tmp);
 603		affs_fix_checksum(sb, bh);
 604		bh->b_state &= ~(1UL << BH_New);
 605		mark_buffer_dirty_inode(bh, inode);
 606		if (prev_bh) {
 607			u32 tmp_next = be32_to_cpu(AFFS_DATA_HEAD(prev_bh)->next);
 608
 609			if (tmp_next)
 610				affs_warning(sb, "extent_file_ofs",
 611					     "next block already set for %d (%d)",
 612					     bidx, tmp_next);
 613			AFFS_DATA_HEAD(prev_bh)->next = cpu_to_be32(bh->b_blocknr);
 614			affs_adjust_checksum(prev_bh, bh->b_blocknr - tmp_next);
 615			mark_buffer_dirty_inode(prev_bh, inode);
 616			affs_brelse(prev_bh);
 617		}
 618		size += bsize;
 619		bidx++;
 620	}
 621	affs_brelse(bh);
 622	inode->i_size = AFFS_I(inode)->mmu_private = newsize;
 623	return 0;
 624
 625out:
 626	inode->i_size = AFFS_I(inode)->mmu_private = newsize;
 627	return PTR_ERR(bh);
 628}
 629
 630static int affs_read_folio_ofs(struct file *file, struct folio *folio)
 631{
 632	struct inode *inode = folio->mapping->host;
 633	size_t to;
 634	int err;
 635
 636	pr_debug("%s(%lu, %ld)\n", __func__, inode->i_ino, folio->index);
 637	to = folio_size(folio);
 638	if (folio_pos(folio) + to > inode->i_size) {
 639		to = inode->i_size - folio_pos(folio);
 640		folio_zero_segment(folio, to, folio_size(folio));
 641	}
 642
 643	err = affs_do_read_folio_ofs(folio, to, 0);
 644	if (!err)
 645		folio_mark_uptodate(folio);
 646	folio_unlock(folio);
 647	return err;
 648}
 649
 650static int affs_write_begin_ofs(const struct kiocb *iocb,
 651				struct address_space *mapping,
 652				loff_t pos, unsigned len,
 653				struct folio **foliop, void **fsdata)
 654{
 655	struct inode *inode = mapping->host;
 656	struct folio *folio;
 657	pgoff_t index;
 658	int err = 0;
 659
 660	pr_debug("%s(%lu, %llu, %llu)\n", __func__, inode->i_ino, pos,
 661		 pos + len);
 662	if (pos > AFFS_I(inode)->mmu_private) {
 663		/* XXX: this probably leaves a too-big i_size in case of
 664		 * failure. Should really be updating i_size at write_end time
 665		 */
 666		err = affs_extent_file_ofs(inode, pos);
 667		if (err)
 668			return err;
 669	}
 670
 671	index = pos >> PAGE_SHIFT;
 672	folio = __filemap_get_folio(mapping, index, FGP_WRITEBEGIN,
 673			mapping_gfp_mask(mapping));
 674	if (IS_ERR(folio))
 675		return PTR_ERR(folio);
 676	*foliop = folio;
 677
 678	if (folio_test_uptodate(folio))
 679		return 0;
 680
 681	/* XXX: inefficient but safe in the face of short writes */
 682	err = affs_do_read_folio_ofs(folio, folio_size(folio), 1);
 683	if (err) {
 684		folio_unlock(folio);
 685		folio_put(folio);
 686	}
 687	return err;
 688}
 689
 690static int affs_write_end_ofs(const struct kiocb *iocb,
 691			      struct address_space *mapping,
 692			      loff_t pos, unsigned len, unsigned copied,
 693			      struct folio *folio, 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 folio 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 = folio_address(folio);
 716
 717	bh = NULL;
 718	written = 0;
 719	tmp = (folio->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		AFFS_DATA_HEAD(bh)->size = cpu_to_be32(
 732			max(boff + tmp, be32_to_cpu(AFFS_DATA_HEAD(bh)->size)));
 733		affs_fix_checksum(sb, bh);
 734		mark_buffer_dirty_inode(bh, inode);
 735		written += tmp;
 736		from += tmp;
 737		bidx++;
 738	} else if (bidx) {
 739		bh = affs_bread_ino(inode, bidx - 1, 0);
 740		if (IS_ERR(bh)) {
 741			written = PTR_ERR(bh);
 742			goto err_first_bh;
 743		}
 744	}
 745	while (from + bsize <= to) {
 746		prev_bh = bh;
 747		bh = affs_getemptyblk_ino(inode, bidx);
 748		if (IS_ERR(bh))
 749			goto err_bh;
 750		memcpy(AFFS_DATA(bh), data + from, bsize);
 751		if (buffer_new(bh)) {
 752			AFFS_DATA_HEAD(bh)->ptype = cpu_to_be32(T_DATA);
 753			AFFS_DATA_HEAD(bh)->key = cpu_to_be32(inode->i_ino);
 754			AFFS_DATA_HEAD(bh)->sequence = cpu_to_be32(bidx + 1);
 755			AFFS_DATA_HEAD(bh)->size = cpu_to_be32(bsize);
 756			AFFS_DATA_HEAD(bh)->next = 0;
 757			bh->b_state &= ~(1UL << BH_New);
 758			if (prev_bh) {
 759				u32 tmp_next = be32_to_cpu(AFFS_DATA_HEAD(prev_bh)->next);
 760
 761				if (tmp_next)
 762					affs_warning(sb, "commit_write_ofs",
 763						     "next block already set for %d (%d)",
 764						     bidx, tmp_next);
 765				AFFS_DATA_HEAD(prev_bh)->next = cpu_to_be32(bh->b_blocknr);
 766				affs_adjust_checksum(prev_bh, bh->b_blocknr - tmp_next);
 767				mark_buffer_dirty_inode(prev_bh, inode);
 768			}
 769		}
 770		affs_brelse(prev_bh);
 771		affs_fix_checksum(sb, bh);
 772		mark_buffer_dirty_inode(bh, inode);
 773		written += bsize;
 774		from += bsize;
 775		bidx++;
 776	}
 777	if (from < to) {
 778		prev_bh = bh;
 779		bh = affs_bread_ino(inode, bidx, 1);
 780		if (IS_ERR(bh))
 781			goto err_bh;
 782		tmp = min(bsize, to - from);
 783		BUG_ON(tmp > bsize);
 784		memcpy(AFFS_DATA(bh), data + from, tmp);
 785		if (buffer_new(bh)) {
 786			AFFS_DATA_HEAD(bh)->ptype = cpu_to_be32(T_DATA);
 787			AFFS_DATA_HEAD(bh)->key = cpu_to_be32(inode->i_ino);
 788			AFFS_DATA_HEAD(bh)->sequence = cpu_to_be32(bidx + 1);
 789			AFFS_DATA_HEAD(bh)->size = cpu_to_be32(tmp);
 790			AFFS_DATA_HEAD(bh)->next = 0;
 791			bh->b_state &= ~(1UL << BH_New);
 792			if (prev_bh) {
 793				u32 tmp_next = be32_to_cpu(AFFS_DATA_HEAD(prev_bh)->next);
 794
 795				if (tmp_next)
 796					affs_warning(sb, "commit_write_ofs",
 797						     "next block already set for %d (%d)",
 798						     bidx, tmp_next);
 799				AFFS_DATA_HEAD(prev_bh)->next = cpu_to_be32(bh->b_blocknr);
 800				affs_adjust_checksum(prev_bh, bh->b_blocknr - tmp_next);
 801				mark_buffer_dirty_inode(prev_bh, inode);
 802			}
 803		} else if (be32_to_cpu(AFFS_DATA_HEAD(bh)->size) < tmp)
 804			AFFS_DATA_HEAD(bh)->size = cpu_to_be32(tmp);
 805		affs_brelse(prev_bh);
 806		affs_fix_checksum(sb, bh);
 807		mark_buffer_dirty_inode(bh, inode);
 808		written += tmp;
 809		from += tmp;
 810		bidx++;
 811	}
 812	folio_mark_uptodate(folio);
 813
 814done:
 815	affs_brelse(bh);
 816	tmp = (folio->index << PAGE_SHIFT) + from;
 817	if (tmp > inode->i_size)
 818		inode->i_size = AFFS_I(inode)->mmu_private = tmp;
 819
 820	/* Clear Archived bit on file writes, as AmigaOS would do */
 821	if (AFFS_I(inode)->i_protect & FIBF_ARCHIVED) {
 822		AFFS_I(inode)->i_protect &= ~FIBF_ARCHIVED;
 823		mark_inode_dirty(inode);
 824	}
 825
 826err_first_bh:
 827	folio_unlock(folio);
 828	folio_put(folio);
 829
 830	return written;
 831
 832err_bh:
 833	bh = prev_bh;
 834	if (!written)
 835		written = PTR_ERR(bh);
 836	goto done;
 837}
 838
 839const struct address_space_operations affs_aops_ofs = {
 840	.dirty_folio	= block_dirty_folio,
 841	.invalidate_folio = block_invalidate_folio,
 842	.read_folio = affs_read_folio_ofs,
 843	//.writepages = affs_writepages_ofs,
 844	.write_begin = affs_write_begin_ofs,
 845	.write_end = affs_write_end_ofs,
 846	.migrate_folio = filemap_migrate_folio,
 847};
 848
 849/* Free any preallocated blocks. */
 850
 851void
 852affs_free_prealloc(struct inode *inode)
 853{
 854	struct super_block *sb = inode->i_sb;
 855
 856	pr_debug("free_prealloc(ino=%lu)\n", inode->i_ino);
 857
 858	while (AFFS_I(inode)->i_pa_cnt) {
 859		AFFS_I(inode)->i_pa_cnt--;
 860		affs_free_block(sb, ++AFFS_I(inode)->i_lastalloc);
 861	}
 862}
 863
 864/* Truncate (or enlarge) a file to the requested size. */
 865
 866void
 867affs_truncate(struct inode *inode)
 868{
 869	struct super_block *sb = inode->i_sb;
 870	u32 ext, ext_key;
 871	u32 last_blk, blkcnt, blk;
 872	u32 size;
 873	struct buffer_head *ext_bh;
 874	int i;
 875
 876	pr_debug("truncate(inode=%lu, oldsize=%llu, newsize=%llu)\n",
 877		 inode->i_ino, AFFS_I(inode)->mmu_private, inode->i_size);
 878
 879	last_blk = 0;
 880	ext = 0;
 881	if (inode->i_size) {
 882		last_blk = ((u32)inode->i_size - 1) / AFFS_SB(sb)->s_data_blksize;
 883		ext = last_blk / AFFS_SB(sb)->s_hashsize;
 884	}
 885
 886	if (inode->i_size > AFFS_I(inode)->mmu_private) {
 887		struct address_space *mapping = inode->i_mapping;
 888		struct folio *folio;
 889		void *fsdata = NULL;
 890		loff_t isize = inode->i_size;
 891		int res;
 892
 893		res = mapping->a_ops->write_begin(NULL, mapping, isize, 0, &folio, &fsdata);
 894		if (!res)
 895			res = mapping->a_ops->write_end(NULL, mapping, isize, 0, 0, folio, fsdata);
 896		else
 897			inode->i_size = AFFS_I(inode)->mmu_private;
 898		mark_inode_dirty(inode);
 899		return;
 900	} else if (inode->i_size == AFFS_I(inode)->mmu_private)
 901		return;
 902
 903	// lock cache
 904	ext_bh = affs_get_extblock(inode, ext);
 905	if (IS_ERR(ext_bh)) {
 906		affs_warning(sb, "truncate",
 907			     "unexpected read error for ext block %u (%ld)",
 908			     ext, PTR_ERR(ext_bh));
 909		return;
 910	}
 911	if (AFFS_I(inode)->i_lc) {
 912		/* clear linear cache */
 913		i = (ext + 1) >> AFFS_I(inode)->i_lc_shift;
 914		if (AFFS_I(inode)->i_lc_size > i) {
 915			AFFS_I(inode)->i_lc_size = i;
 916			for (; i < AFFS_LC_SIZE; i++)
 917				AFFS_I(inode)->i_lc[i] = 0;
 918		}
 919		/* clear associative cache */
 920		for (i = 0; i < AFFS_AC_SIZE; i++)
 921			if (AFFS_I(inode)->i_ac[i].ext >= ext)
 922				AFFS_I(inode)->i_ac[i].ext = 0;
 923	}
 924	ext_key = be32_to_cpu(AFFS_TAIL(sb, ext_bh)->extension);
 925
 926	blkcnt = AFFS_I(inode)->i_blkcnt;
 927	i = 0;
 928	blk = last_blk;
 929	if (inode->i_size) {
 930		i = last_blk % AFFS_SB(sb)->s_hashsize + 1;
 931		blk++;
 932	} else
 933		AFFS_HEAD(ext_bh)->first_data = 0;
 934	AFFS_HEAD(ext_bh)->block_count = cpu_to_be32(i);
 935	size = AFFS_SB(sb)->s_hashsize;
 936	if (size > blkcnt - blk + i)
 937		size = blkcnt - blk + i;
 938	for (; i < size; i++, blk++) {
 939		affs_free_block(sb, be32_to_cpu(AFFS_BLOCK(sb, ext_bh, i)));
 940		AFFS_BLOCK(sb, ext_bh, i) = 0;
 941	}
 942	AFFS_TAIL(sb, ext_bh)->extension = 0;
 943	affs_fix_checksum(sb, ext_bh);
 944	mark_buffer_dirty_inode(ext_bh, inode);
 945	affs_brelse(ext_bh);
 946
 947	if (inode->i_size) {
 948		AFFS_I(inode)->i_blkcnt = last_blk + 1;
 949		AFFS_I(inode)->i_extcnt = ext + 1;
 950		if (affs_test_opt(AFFS_SB(sb)->s_flags, SF_OFS)) {
 951			struct buffer_head *bh = affs_bread_ino(inode, last_blk, 0);
 952			u32 tmp;
 953			if (IS_ERR(bh)) {
 954				affs_warning(sb, "truncate",
 955					     "unexpected read error for last block %u (%ld)",
 956					     ext, PTR_ERR(bh));
 957				return;
 958			}
 959			tmp = be32_to_cpu(AFFS_DATA_HEAD(bh)->next);
 960			AFFS_DATA_HEAD(bh)->next = 0;
 961			affs_adjust_checksum(bh, -tmp);
 962			affs_brelse(bh);
 963		}
 964	} else {
 965		AFFS_I(inode)->i_blkcnt = 0;
 966		AFFS_I(inode)->i_extcnt = 1;
 967	}
 968	AFFS_I(inode)->mmu_private = inode->i_size;
 969	// unlock cache
 970
 971	while (ext_key) {
 972		ext_bh = affs_bread(sb, ext_key);
 973		size = AFFS_SB(sb)->s_hashsize;
 974		if (size > blkcnt - blk)
 975			size = blkcnt - blk;
 976		for (i = 0; i < size; i++, blk++)
 977			affs_free_block(sb, be32_to_cpu(AFFS_BLOCK(sb, ext_bh, i)));
 978		affs_free_block(sb, ext_key);
 979		ext_key = be32_to_cpu(AFFS_TAIL(sb, ext_bh)->extension);
 980		affs_brelse(ext_bh);
 981	}
 982	affs_free_prealloc(inode);
 983}
 984
 985int affs_file_fsync(struct file *filp, loff_t start, loff_t end, int datasync)
 986{
 987	struct inode *inode = filp->f_mapping->host;
 988	int ret, err;
 989
 990	err = file_write_and_wait_range(filp, start, end);
 991	if (err)
 992		return err;
 993
 994	inode_lock(inode);
 995	ret = write_inode_now(inode, 0);
 996	err = sync_blockdev(inode->i_sb->s_bdev);
 997	if (!ret)
 998		ret = err;
 999	inode_unlock(inode);
1000	return ret;
1001}
1002const struct file_operations affs_file_operations = {
1003	.llseek		= generic_file_llseek,
1004	.read_iter	= generic_file_read_iter,
1005	.write_iter	= generic_file_write_iter,
1006	.mmap_prepare	= generic_file_mmap_prepare,
1007	.open		= affs_file_open,
1008	.release	= affs_file_release,
1009	.fsync		= affs_file_fsync,
1010	.splice_read	= filemap_splice_read,
1011};
1012
1013const struct inode_operations affs_file_inode_operations = {
1014	.setattr	= affs_notify_change,
1015};
~/ Read-only file preview.