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      1 /*	$NetBSD: v7fs_datablock.c,v 1.5 2011/08/14 09:02:07 apb Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 2011 The NetBSD Foundation, Inc.
      5  * All rights reserved.
      6  *
      7  * This code is derived from software contributed to The NetBSD Foundation
      8  * by UCHIYAMA Yasushi.
      9  *
     10  * Redistribution and use in source and binary forms, with or without
     11  * modification, are permitted provided that the following conditions
     12  * are met:
     13  * 1. Redistributions of source code must retain the above copyright
     14  *    notice, this list of conditions and the following disclaimer.
     15  * 2. Redistributions in binary form must reproduce the above copyright
     16  *    notice, this list of conditions and the following disclaimer in the
     17  *    documentation and/or other materials provided with the distribution.
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     23  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     29  * POSSIBILITY OF SUCH DAMAGE.
     30  */
     31 
     32 #if HAVE_NBTOOL_CONFIG_H
     33 #include "nbtool_config.h"
     34 #endif
     35 
     36 #include <sys/cdefs.h>
     37 __KERNEL_RCSID(0, "$NetBSD: v7fs_datablock.c,v 1.5 2011/08/14 09:02:07 apb Exp $");
     38 #if defined _KERNEL_OPT
     39 #include "opt_v7fs.h"
     40 #endif
     41 
     42 #include <sys/types.h>
     43 #ifdef _KERNEL
     44 #include <sys/systm.h>
     45 #include <sys/param.h>
     46 #else
     47 #include <stdio.h>
     48 #include <string.h>
     49 #include <errno.h>
     50 #endif
     51 
     52 #include "v7fs.h"
     53 #include "v7fs_impl.h"
     54 #include "v7fs_endian.h"
     55 #include "v7fs_inode.h"
     56 #include "v7fs_datablock.h"
     57 #include "v7fs_superblock.h"
     58 
     59 #ifdef V7FS_DATABLOCK_DEBUG
     60 #define	DPRINTF(fmt, args...)	printf("%s: " fmt, __func__, ##args)
     61 #else
     62 #define	DPRINTF(fmt, args...)	((void)0)
     63 #endif
     64 
     65 static int v7fs_datablock_deallocate(struct v7fs_self *, v7fs_daddr_t);
     66 static int v7fs_loop1(struct v7fs_self *, v7fs_daddr_t, size_t *,
     67     int (*)(struct v7fs_self *, void *, v7fs_daddr_t, size_t), void *);
     68 static int v7fs_loop2(struct v7fs_self *, v7fs_daddr_t, size_t *,
     69     int (*)(struct v7fs_self *, void *, v7fs_daddr_t, size_t), void *);
     70 static v7fs_daddr_t v7fs_link(struct v7fs_self *, v7fs_daddr_t, int);
     71 static v7fs_daddr_t v7fs_add_leaf(struct v7fs_self *, v7fs_daddr_t, int);
     72 static v7fs_daddr_t v7fs_unlink(struct v7fs_self *, v7fs_daddr_t, int);
     73 static v7fs_daddr_t v7fs_remove_leaf(struct v7fs_self *, v7fs_daddr_t, int);
     74 static v7fs_daddr_t v7fs_remove_self(struct v7fs_self *, v7fs_daddr_t);
     75 
     76 #ifdef V7FS_DATABLOCK_DEBUG
     77 void daddr_map_dump(const struct v7fs_daddr_map *);
     78 #else
     79 #define	daddr_map_dump(x)	((void)0)
     80 #endif
     81 
     82 bool
     83 datablock_number_sanity(const struct v7fs_self *fs, v7fs_daddr_t blk)
     84 {
     85 	const struct v7fs_superblock *sb = &fs->superblock;
     86 	bool ok = (blk >= sb->datablock_start_sector) &&
     87 	    (blk < sb->volume_size);
     88 
     89 #ifdef V7FS_DATABLOCK_DEBUG
     90 	if (!ok) {
     91 		DPRINTF("Bad data block #%d\n", blk);
     92 	}
     93 #endif
     94 
     95 	return ok;
     96 }
     97 
     98 int
     99 v7fs_datablock_allocate(struct v7fs_self *fs, v7fs_daddr_t *block_number)
    100 {
    101 	struct v7fs_superblock *sb = &fs->superblock;
    102 	v7fs_daddr_t blk;
    103 	int error = 0;
    104 
    105 	*block_number = 0;
    106 	SUPERB_LOCK(fs);
    107 	do {
    108 		if (!sb->total_freeblock) {
    109 			DPRINTF("free block exhausted!!!\n");
    110 			SUPERB_UNLOCK(fs);
    111 			return ENOSPC;
    112 		}
    113 
    114 		/* Get free block from superblock cache. */
    115 		blk = sb->freeblock[--sb->nfreeblock];
    116 		sb->total_freeblock--;
    117 		sb->modified = 1;
    118 
    119 		/* If nfreeblock is zero, it block is next freeblock link. */
    120 		if (sb->nfreeblock == 0) {
    121 			if ((error = v7fs_freeblock_update(fs, blk))) {
    122 				DPRINTF("no freeblock!!!\n");
    123 				SUPERB_UNLOCK(fs);
    124 				return error;
    125 			}
    126 			/* This freeblock link is no longer required. */
    127 			/* use as data block. */
    128 		}
    129 	} while (!datablock_number_sanity(fs, blk)); /* skip bogus block. */
    130 	SUPERB_UNLOCK(fs);
    131 
    132 	DPRINTF("Get freeblock %d\n", blk);
    133 	/* Zero clear datablock. */
    134 	void *buf;
    135 	if (!(buf = scratch_read(fs, blk)))
    136 		return EIO;
    137 	memset(buf, 0, V7FS_BSIZE);
    138 	if (!fs->io.write(fs->io.cookie, buf, blk))
    139 		error = EIO;
    140 	scratch_free(fs, buf);
    141 
    142 	if (error == 0)
    143 		*block_number = blk;
    144 
    145 	return error;
    146 }
    147 
    148 static int
    149 v7fs_datablock_deallocate(struct v7fs_self *fs, v7fs_daddr_t blk)
    150 {
    151 	struct v7fs_superblock *sb = &fs->superblock;
    152 	void *buf;
    153 	int error = 0;
    154 
    155 	if (!datablock_number_sanity(fs, blk))
    156 		return EIO;
    157 
    158 	/* Add to in-core freelist. */
    159 	SUPERB_LOCK(fs);
    160 	if (sb->nfreeblock < V7FS_MAX_FREEBLOCK) {
    161 		sb->freeblock[sb->nfreeblock++] = blk;
    162 		sb->total_freeblock++;
    163 		sb->modified = 1;
    164 		DPRINTF("n_freeblock=%d\n", sb->total_freeblock);
    165 		SUPERB_UNLOCK(fs);
    166 		return 0;
    167 	}
    168 
    169 	/* No space to push. */
    170 	/* Make this block to freeblock list.and current cache moved to this. */
    171 	if (!(buf = scratch_read(fs, blk))) {
    172 		SUPERB_UNLOCK(fs);
    173 		return EIO;	/* Fatal */
    174 	}
    175 
    176 	struct v7fs_freeblock *fb = (struct v7fs_freeblock *)buf;
    177 	fb->nfreeblock = V7FS_MAX_FREEBLOCK;
    178 	int i;
    179 	for (i = 0; i < V7FS_MAX_FREEBLOCK; i++)
    180 		fb->freeblock[i] = V7FS_VAL32(fs, sb->freeblock[i]);
    181 
    182 	if (!fs->io.write(fs->io.cookie, (uint8_t *)fb, blk)) {
    183 		error =  EIO;	/* Fatal */
    184 	} else {
    185 		/* Link. on next allocate, this block is used as datablock, */
    186 		/* and swap outed freeblock list is restored. */
    187 		sb->freeblock[0] = blk;
    188 		sb->nfreeblock = 1;
    189 		sb->total_freeblock++;
    190 		sb->modified = 1;
    191 		DPRINTF("n_freeblock=%d\n", sb->total_freeblock);
    192 	}
    193 	SUPERB_UNLOCK(fs);
    194 	scratch_free(fs, buf);
    195 
    196 	return error;
    197 }
    198 
    199 int
    200 v7fs_datablock_addr(size_t sz, struct v7fs_daddr_map *map)
    201 {
    202 #define	NIDX		V7FS_DADDR_PER_BLOCK
    203 #define	DIRECT_SZ	(V7FS_NADDR_DIRECT * V7FS_BSIZE)
    204 #define	IDX1_SZ		(NIDX * V7FS_BSIZE)
    205 #define	IDX2_SZ		(NIDX * NIDX * V7FS_BSIZE)
    206 #define	ROUND(x, a)	((((x) + ((a) - 1)) & ~((a) - 1)))
    207 	if (!sz) {
    208 		map->level = 0;
    209 		map->index[0] = 0;
    210 		return 0;
    211 	}
    212 
    213 	sz = V7FS_ROUND_BSIZE(sz);
    214 
    215 	/* Direct */
    216 	if (sz <= DIRECT_SZ) {
    217 		map->level = 0;
    218 		map->index[0] = (sz >> V7FS_BSHIFT) - 1;
    219 		return 0;
    220 	}
    221 	/* Index 1 */
    222 	sz -= DIRECT_SZ;
    223 
    224 	if (sz <= IDX1_SZ) {
    225 		map->level = 1;
    226 		map->index[0] = (sz >> V7FS_BSHIFT) - 1;
    227 		return 0;
    228 	}
    229 	sz -= IDX1_SZ;
    230 
    231 	/* Index 2 */
    232 	if (sz <= IDX2_SZ) {
    233 		map->level = 2;
    234 		map->index[0] = ROUND(sz, IDX1_SZ) / IDX1_SZ - 1;
    235 		map->index[1] = ((sz - (map->index[0] * IDX1_SZ)) >>
    236 		    V7FS_BSHIFT) - 1;
    237 		return 0;
    238 	}
    239 	sz -= IDX2_SZ;
    240 
    241 	/* Index 3 */
    242 	map->level = 3;
    243 	map->index[0] = ROUND(sz, IDX2_SZ) / IDX2_SZ - 1;
    244 	sz -= map->index[0] * IDX2_SZ;
    245 	map->index[1] = ROUND(sz, IDX1_SZ) / IDX1_SZ - 1;
    246 	sz -= map->index[1] * IDX1_SZ;
    247 	map->index[2] = (sz >> V7FS_BSHIFT) - 1;
    248 
    249 	return map->index[2] >= NIDX ? ENOSPC : 0;
    250 }
    251 
    252 int
    253 v7fs_datablock_foreach(struct v7fs_self *fs, struct v7fs_inode *p,
    254     int (*func)(struct v7fs_self *, void *, v7fs_daddr_t, size_t), void *ctx)
    255 {
    256 	size_t i;
    257 	v7fs_daddr_t blk, blk2;
    258 	size_t filesize;
    259 	bool last;
    260 	int ret;
    261 
    262 	if (!(filesize = v7fs_inode_filesize(p)))
    263 		return V7FS_ITERATOR_END;
    264 #ifdef V7FS_DATABLOCK_DEBUG
    265 	size_t sz = filesize;
    266 #endif
    267 
    268 	/* Direct */
    269 	for (i = 0; i < V7FS_NADDR_DIRECT; i++, filesize -= V7FS_BSIZE) {
    270 		blk = p->addr[i];
    271 		if (!datablock_number_sanity(fs, blk)) {
    272 			DPRINTF("inode#%d direct=%zu filesize=%zu\n",
    273 			    p->inode_number, i, sz);
    274 			return EIO;
    275 		}
    276 
    277 		last = filesize <= V7FS_BSIZE;
    278 		if ((ret = func(fs, ctx, blk, last ? filesize : V7FS_BSIZE)))
    279 			return ret;
    280 		if (last)
    281 			return V7FS_ITERATOR_END;
    282 	}
    283 
    284 	/* Index 1 */
    285 	blk = p->addr[V7FS_NADDR_INDEX1];
    286 	if (!datablock_number_sanity(fs, blk))
    287 		return EIO;
    288 
    289 	if ((ret = v7fs_loop1(fs, blk, &filesize, func, ctx)))
    290 		return ret;
    291 
    292 	/* Index 2 */
    293 	blk = p->addr[V7FS_NADDR_INDEX2];
    294 	if (!datablock_number_sanity(fs, blk))
    295 		return EIO;
    296 
    297 	if ((ret = v7fs_loop2(fs, blk, &filesize, func, ctx)))
    298 		return ret;
    299 
    300 	/* Index 3 */
    301 	blk = p->addr[V7FS_NADDR_INDEX3];
    302 	if (!datablock_number_sanity(fs, blk))
    303 		return EIO;
    304 
    305 	for (i = 0; i < V7FS_DADDR_PER_BLOCK; i++) {
    306 		blk2 = v7fs_link(fs, blk, i);
    307 		if (!datablock_number_sanity(fs, blk))
    308 			return EIO;
    309 
    310 		if ((ret = v7fs_loop2(fs, blk2, &filesize, func, ctx)))
    311 			return ret;
    312 	}
    313 
    314 	return EFBIG;
    315 }
    316 
    317 static int
    318 v7fs_loop2(struct v7fs_self *fs, v7fs_daddr_t listblk, size_t *filesize,
    319     int (*func)(struct v7fs_self *, void *, v7fs_daddr_t, size_t), void *ctx)
    320 {
    321 	v7fs_daddr_t blk;
    322 	int ret;
    323 	size_t j;
    324 
    325 	for (j = 0; j < V7FS_DADDR_PER_BLOCK; j++) {
    326 		blk = v7fs_link(fs, listblk, j);
    327 		if (!datablock_number_sanity(fs, blk))
    328 			return EIO;
    329 		if ((ret = v7fs_loop1(fs, blk, filesize, func, ctx)))
    330 			return ret;
    331 	}
    332 
    333 	return 0;
    334 }
    335 
    336 static int
    337 v7fs_loop1(struct v7fs_self *fs, v7fs_daddr_t listblk, size_t *filesize,
    338     int (*func)(struct v7fs_self *, void *, v7fs_daddr_t, size_t), void *ctx)
    339 {
    340 	v7fs_daddr_t blk;
    341 	bool last;
    342 	int ret;
    343 	size_t k;
    344 
    345 	for (k = 0; k < V7FS_DADDR_PER_BLOCK; k++, *filesize -= V7FS_BSIZE) {
    346 		blk = v7fs_link(fs, listblk, k);
    347 		if (!datablock_number_sanity(fs, blk))
    348 			return EIO;
    349 		last = *filesize <= V7FS_BSIZE;
    350 		if ((ret = func(fs, ctx, blk, last ? *filesize : V7FS_BSIZE)))
    351 			return ret;
    352 		if (last)
    353 			return V7FS_ITERATOR_END;
    354 	}
    355 
    356 	return 0;
    357 }
    358 
    359 v7fs_daddr_t
    360 v7fs_datablock_last(struct v7fs_self *fs, struct v7fs_inode *inode,
    361     v7fs_off_t ofs)
    362 {
    363 	struct v7fs_daddr_map map;
    364 	v7fs_daddr_t blk = 0;
    365 	v7fs_daddr_t *addr = inode->addr;
    366 
    367 	/* Inquire last data block location. */
    368 	if (v7fs_datablock_addr(ofs, &map) != 0)
    369 		return 0;
    370 
    371 	switch (map.level)
    372 	{
    373 	case 0: /*Direct */
    374 		blk = inode->addr[map.index[0]];
    375 		break;
    376 	case 1: /*Index1 */
    377 		blk = v7fs_link(fs, addr[V7FS_NADDR_INDEX1], map.index[0]);
    378 		break;
    379 	case 2: /*Index2 */
    380 		blk = v7fs_link(fs, v7fs_link(fs,
    381 		    addr[V7FS_NADDR_INDEX2], map.index[0]), map.index[1]);
    382 		break;
    383 	case 3: /*Index3 */
    384 		blk = v7fs_link(fs, v7fs_link(fs, v7fs_link(fs,
    385 		    addr[V7FS_NADDR_INDEX3], map.index[0]), map.index[1]),
    386 		    map.index[2]);
    387 		break;
    388 	}
    389 
    390 	return blk;
    391 }
    392 
    393 int
    394 v7fs_datablock_expand(struct v7fs_self *fs, struct v7fs_inode *inode, size_t sz)
    395 {
    396 	size_t old_filesize = inode->filesize;
    397 	size_t new_filesize = old_filesize + sz;
    398 	struct v7fs_daddr_map oldmap, newmap;
    399 	v7fs_daddr_t blk, idxblk;
    400 	int error;
    401 	v7fs_daddr_t old_nblk = V7FS_ROUND_BSIZE(old_filesize) >> V7FS_BSHIFT;
    402 	v7fs_daddr_t new_nblk = V7FS_ROUND_BSIZE(new_filesize) >> V7FS_BSHIFT;
    403 
    404 	if (old_nblk == new_nblk) {
    405 		inode->filesize += sz;
    406 		v7fs_inode_writeback(fs, inode);
    407 		return 0; /* no need to expand. */
    408 	}
    409 	struct v7fs_inode backup = *inode;
    410 	v7fs_daddr_t required_blk = new_nblk - old_nblk;
    411 
    412 	DPRINTF("%zu->%zu, required block=%d\n", old_filesize, new_filesize,
    413 	    required_blk);
    414 
    415 	v7fs_datablock_addr(old_filesize, &oldmap);
    416 	v7fs_daddr_t i;
    417 	for (i = 0; i < required_blk; i++) {
    418 		v7fs_datablock_addr(old_filesize + (i+1) * V7FS_BSIZE, &newmap);
    419 		daddr_map_dump(&oldmap);
    420 		daddr_map_dump(&newmap);
    421 
    422 		if (oldmap.level != newmap.level) {
    423 			/* Allocate index area */
    424 			if ((error = v7fs_datablock_allocate(fs, &idxblk)))
    425 				return error;
    426 
    427 			switch (newmap.level) {
    428 			case 1:
    429 				DPRINTF("0->1\n");
    430 				inode->addr[V7FS_NADDR_INDEX1] = idxblk;
    431 				blk = v7fs_add_leaf(fs, idxblk, 0);
    432 				break;
    433 			case 2:
    434 				DPRINTF("1->2\n");
    435 				inode->addr[V7FS_NADDR_INDEX2] = idxblk;
    436 				blk = v7fs_add_leaf(fs, v7fs_add_leaf(fs,
    437 				    idxblk, 0), 0);
    438 				break;
    439 			case 3:
    440 				DPRINTF("2->3\n");
    441 				inode->addr[V7FS_NADDR_INDEX3] = idxblk;
    442 				blk = v7fs_add_leaf(fs, v7fs_add_leaf(fs,
    443 				    v7fs_add_leaf(fs, idxblk, 0), 0), 0);
    444 				break;
    445 			}
    446 		} else {
    447 			switch (newmap.level) {
    448 			case 0:
    449 				if ((error = v7fs_datablock_allocate(fs, &blk)))
    450 					return error;
    451 				inode->addr[newmap.index[0]] = blk;
    452 				DPRINTF("direct index %d = blk%d\n",
    453 				    newmap.index[0], blk);
    454 				break;
    455 			case 1:
    456 				idxblk = inode->addr[V7FS_NADDR_INDEX1];
    457 				blk = v7fs_add_leaf(fs, idxblk,
    458 				    newmap.index[0]);
    459 				break;
    460 			case 2:
    461 				idxblk = inode->addr[V7FS_NADDR_INDEX2];
    462 				if (oldmap.index[0] != newmap.index[0]) {
    463 					v7fs_add_leaf(fs, idxblk,
    464 					    newmap.index[0]);
    465 				}
    466 				blk = v7fs_add_leaf(fs, v7fs_link(fs,idxblk,
    467 				    newmap.index[0]), newmap.index[1]);
    468 				break;
    469 			case 3:
    470 				idxblk = inode->addr[V7FS_NADDR_INDEX3];
    471 
    472 				if (oldmap.index[0] != newmap.index[0]) {
    473 					v7fs_add_leaf(fs, idxblk,
    474 					    newmap.index[0]);
    475 				}
    476 
    477 				if (oldmap.index[1] != newmap.index[1]) {
    478 					v7fs_add_leaf(fs, v7fs_link(fs, idxblk,
    479 					    newmap.index[0]), newmap.index[1]);
    480 				}
    481 				blk = v7fs_add_leaf(fs, v7fs_link(fs,
    482 				    v7fs_link(fs, idxblk, newmap.index[0]),
    483 				    newmap.index[1]), newmap.index[2]);
    484 				break;
    485 			}
    486 		}
    487 		if (!blk) {
    488 			*inode = backup; /* structure copy; */
    489 			return ENOSPC;
    490 		}
    491 		oldmap = newmap;
    492 	}
    493 	inode->filesize += sz;
    494 	v7fs_inode_writeback(fs, inode);
    495 
    496 	return 0;
    497 }
    498 
    499 static v7fs_daddr_t
    500 v7fs_link(struct v7fs_self *fs, v7fs_daddr_t listblk, int n)
    501 {
    502 	v7fs_daddr_t *list;
    503 	v7fs_daddr_t blk;
    504 	void *buf;
    505 
    506 	if (!datablock_number_sanity(fs, listblk))
    507 		return 0;
    508 	if (!(buf = scratch_read(fs, listblk)))
    509 		return 0;
    510 	list = (v7fs_daddr_t *)buf;
    511 	blk = V7FS_VAL32(fs, list[n]);
    512 	scratch_free(fs, buf);
    513 
    514 	if (!datablock_number_sanity(fs, blk))
    515 		return 0;
    516 
    517 	return blk;
    518 }
    519 
    520 static v7fs_daddr_t
    521 v7fs_add_leaf(struct v7fs_self *fs, v7fs_daddr_t up, int idx)
    522 {
    523 	v7fs_daddr_t newblk;
    524 	v7fs_daddr_t *daddr_list;
    525 	int error = 0;
    526 	void *buf;
    527 
    528 	if (!up)
    529 		return 0;
    530 	if (!datablock_number_sanity(fs, up))
    531 		return 0;
    532 
    533 	if ((error = v7fs_datablock_allocate(fs, &newblk)))
    534 		return 0;
    535 	if (!(buf = scratch_read(fs, up)))
    536 		return 0;
    537 	daddr_list = (v7fs_daddr_t *)buf;
    538 	daddr_list[idx] = V7FS_VAL32(fs, newblk);
    539 	if (!fs->io.write(fs->io.cookie, buf, up))
    540 		newblk = 0;
    541 	scratch_free(fs, buf);
    542 
    543 	return newblk;
    544 }
    545 
    546 int
    547 v7fs_datablock_contract(struct v7fs_self *fs, struct v7fs_inode *inode,
    548     size_t sz)
    549 {
    550 	size_t old_filesize = inode->filesize;
    551 	size_t new_filesize = old_filesize - sz;
    552 	struct v7fs_daddr_map oldmap, newmap;
    553 	v7fs_daddr_t blk, idxblk;
    554 	int error = 0;
    555 	v7fs_daddr_t old_nblk = V7FS_ROUND_BSIZE(old_filesize) >> V7FS_BSHIFT;
    556 	v7fs_daddr_t new_nblk = V7FS_ROUND_BSIZE(new_filesize) >> V7FS_BSHIFT;
    557 
    558 	if (old_nblk == new_nblk) {
    559 		inode->filesize -= sz;
    560 		v7fs_inode_writeback(fs, inode);
    561 		return 0; /* no need to contract; */
    562 	}
    563 	v7fs_daddr_t erase_blk = old_nblk - new_nblk;
    564 
    565 	DPRINTF("%zu->%zu # of erased block=%d\n", old_filesize, new_filesize,
    566 	    erase_blk);
    567 
    568 	v7fs_datablock_addr(old_filesize, &oldmap);
    569 	v7fs_daddr_t i;
    570 	for (i = 0; i < erase_blk; i++) {
    571 		v7fs_datablock_addr(old_filesize - (i+1) * V7FS_BSIZE, &newmap);
    572 
    573 		if (oldmap.level != newmap.level) {
    574 			switch (newmap.level) {
    575 			case 0: /*1->0 */
    576 				DPRINTF("1->0\n");
    577 				idxblk = inode->addr[V7FS_NADDR_INDEX1];
    578 				inode->addr[V7FS_NADDR_INDEX1] = 0;
    579 				error = v7fs_datablock_deallocate(fs,
    580 				    v7fs_remove_self(fs, idxblk));
    581 				break;
    582 			case 1: /*2->1 */
    583 				DPRINTF("2->1\n");
    584 				idxblk = inode->addr[V7FS_NADDR_INDEX2];
    585 				inode->addr[V7FS_NADDR_INDEX2] = 0;
    586 				error = v7fs_datablock_deallocate(fs,
    587 				    v7fs_remove_self(fs, v7fs_remove_self(fs,
    588 				    idxblk)));
    589 				break;
    590 			case 2:/*3->2 */
    591 				DPRINTF("3->2\n");
    592 				idxblk = inode->addr[V7FS_NADDR_INDEX3];
    593 				inode->addr[V7FS_NADDR_INDEX3] = 0;
    594 				error = v7fs_datablock_deallocate(fs,
    595 				    v7fs_remove_self(fs, v7fs_remove_self(fs,
    596 					v7fs_remove_self(fs, idxblk))));
    597 				break;
    598 			}
    599 		} else {
    600 			switch (newmap.level) {
    601 			case 0:
    602 				DPRINTF("[0] %d\n", oldmap.index[0]);
    603 				blk = inode->addr[oldmap.index[0]];
    604 				error = v7fs_datablock_deallocate(fs, blk);
    605 				break;
    606 			case 1:
    607 				DPRINTF("[1] %d\n", oldmap.index[0]);
    608 				idxblk = inode->addr[V7FS_NADDR_INDEX1];
    609 				v7fs_remove_leaf(fs, idxblk, oldmap.index[0]);
    610 
    611 				break;
    612 			case 2:
    613 				DPRINTF("[2] %d %d\n", oldmap.index[0],
    614 				    oldmap.index[1]);
    615 				idxblk = inode->addr[V7FS_NADDR_INDEX2];
    616 				v7fs_remove_leaf(fs, v7fs_link(fs, idxblk,
    617 				    oldmap.index[0]), oldmap.index[1]);
    618 				if (oldmap.index[0] != newmap.index[0]) {
    619 					v7fs_remove_leaf(fs, idxblk,
    620 					    oldmap.index[0]);
    621 				}
    622 				break;
    623 			case 3:
    624 				DPRINTF("[2] %d %d %d\n", oldmap.index[0],
    625 				    oldmap.index[1], oldmap.index[2]);
    626 				idxblk = inode->addr[V7FS_NADDR_INDEX3];
    627 				v7fs_remove_leaf(fs, v7fs_link(fs,
    628 				    v7fs_link(fs, idxblk, oldmap.index[0]),
    629 				    oldmap.index[1]), oldmap.index[2]);
    630 
    631 				if (oldmap.index[1] != newmap.index[1])	{
    632 					v7fs_remove_leaf(fs, v7fs_link(fs,
    633 					    idxblk, oldmap.index[0]),
    634 					    oldmap.index[1]);
    635 				}
    636 				if (oldmap.index[0] != newmap.index[0]) {
    637 					v7fs_remove_leaf(fs, idxblk,
    638 					    oldmap.index[0]);
    639 				}
    640 				break;
    641 			}
    642 		}
    643 		oldmap = newmap;
    644 	}
    645 	inode->filesize -= sz;
    646 	v7fs_inode_writeback(fs, inode);
    647 
    648 	return error;
    649 }
    650 
    651 static v7fs_daddr_t
    652 v7fs_unlink(struct v7fs_self *fs, v7fs_daddr_t idxblk, int n)
    653 {
    654 	v7fs_daddr_t *daddr_list;
    655 	v7fs_daddr_t blk;
    656 	void *buf;
    657 
    658 	if (!(buf = scratch_read(fs, idxblk)))
    659 		return 0;
    660 	daddr_list = (v7fs_daddr_t *)buf;
    661 	blk = V7FS_VAL32(fs, daddr_list[n]);
    662 	daddr_list[n] = 0;
    663 	fs->io.write(fs->io.cookie, buf, idxblk);
    664 	scratch_free(fs, buf);
    665 
    666 	return blk; /* unlinked block. */
    667 }
    668 
    669 static v7fs_daddr_t
    670 v7fs_remove_self(struct v7fs_self *fs, v7fs_daddr_t up)
    671 {
    672 	v7fs_daddr_t down;
    673 
    674 	if (!datablock_number_sanity(fs, up))
    675 		return 0;
    676 
    677 	/* At 1st, remove from datablock list. */
    678 	down = v7fs_unlink(fs, up, 0);
    679 
    680 	/* link self to freelist. */
    681 	v7fs_datablock_deallocate(fs, up);
    682 
    683 	return down;
    684 }
    685 
    686 static v7fs_daddr_t
    687 v7fs_remove_leaf(struct v7fs_self *fs, v7fs_daddr_t up, int n)
    688 {
    689 	v7fs_daddr_t down;
    690 
    691 	if (!datablock_number_sanity(fs, up))
    692 		return 0;
    693 
    694 	/* At 1st, remove from datablock list. */
    695 	down = v7fs_unlink(fs, up, n);
    696 
    697 	/* link leaf to freelist. */
    698 	v7fs_datablock_deallocate(fs, down);
    699 
    700 	return down;
    701 }
    702 
    703 int
    704 v7fs_datablock_size_change(struct v7fs_self *fs, size_t newsz,
    705     struct v7fs_inode *inode)
    706 {
    707 	ssize_t diff = newsz - v7fs_inode_filesize(inode);
    708 	int error = 0;
    709 
    710 	if (diff > 0)
    711 		error = v7fs_datablock_expand(fs, inode, diff);
    712 	else if (diff < 0)
    713 		error = v7fs_datablock_contract(fs, inode, -diff);
    714 
    715 	return error;
    716 }
    717 
    718 #ifdef V7FS_DATABLOCK_DEBUG
    719 void
    720 daddr_map_dump(const struct v7fs_daddr_map *map)
    721 {
    722 
    723 	DPRINTF("level %d ", map->level);
    724 	int m, n = !map->level ? 1 : map->level;
    725 	for (m = 0; m < n; m++)
    726 		printf("[%d]", map->index[m]);
    727 	printf("\n");
    728 }
    729 #endif
    730