[linux.git] / fs / affs / bitmap.c

/*
 *  linux/fs/affs/bitmap.c
 *
 *  (c) 1996 Hans-Joachim Widmaier
 *
 *  bitmap.c contains the code that handles all bitmap related stuff -
 *  block allocation, deallocation, calculation of free space.
 */

#include <linux/slab.h>
#include "affs.h"

/* This is, of course, shamelessly stolen from fs/minix */

static const int nibblemap[] = { 0,1,1,2,1,2,2,3,1,2,2,3,2,3,3,4 };

static u32
affs_count_free_bits(u32 blocksize, const void *data)
{
	const u32 *map;
	u32 free;
	u32 tmp;

	map = data;
	free = 0;
	for (blocksize /= 4; blocksize > 0; blocksize--) {
		tmp = *map++;
		while (tmp) {
			free += nibblemap[tmp & 0xf];
			tmp >>= 4;
		}
	}

	return free;
}

u32
affs_count_free_blocks(struct super_block *sb)
{
	struct affs_bm_info *bm;
	u32 free;
	int i;

	pr_debug("AFFS: count_free_blocks()\n");

	if (sb->s_flags & MS_RDONLY)
		return 0;

	mutex_lock(&AFFS_SB(sb)->s_bmlock);

	bm = AFFS_SB(sb)->s_bitmap;
	free = 0;
	for (i = AFFS_SB(sb)->s_bmap_count; i > 0; bm++, i--)
		free += bm->bm_free;

	mutex_unlock(&AFFS_SB(sb)->s_bmlock);

	return free;
}

void
affs_free_block(struct super_block *sb, u32 block)
{
	struct affs_sb_info *sbi = AFFS_SB(sb);
	struct affs_bm_info *bm;
	struct buffer_head *bh;
	u32 blk, bmap, bit, mask, tmp;
	__be32 *data;

	pr_debug("AFFS: free_block(%u)\n", block);

	if (block > sbi->s_partition_size)
		goto err_range;

	blk     = block - sbi->s_reserved;
	bmap    = blk / sbi->s_bmap_bits;
	bit     = blk % sbi->s_bmap_bits;
	bm      = &sbi->s_bitmap[bmap];

	mutex_lock(&sbi->s_bmlock);

	bh = sbi->s_bmap_bh;
	if (sbi->s_last_bmap != bmap) {
		affs_brelse(bh);
		bh = affs_bread(sb, bm->bm_key);
		if (!bh)
			goto err_bh_read;
		sbi->s_bmap_bh = bh;
		sbi->s_last_bmap = bmap;
	}

	mask = 1 << (bit & 31);
	data = (__be32 *)bh->b_data + bit / 32 + 1;

	/* mark block free */
	tmp = be32_to_cpu(*data);
	if (tmp & mask)
		goto err_free;
	*data = cpu_to_be32(tmp | mask);

	/* fix checksum */
	tmp = be32_to_cpu(*(__be32 *)bh->b_data);
	*(__be32 *)bh->b_data = cpu_to_be32(tmp - mask);

	mark_buffer_dirty(bh);
	sb->s_dirt = 1;
	bm->bm_free++;

	mutex_unlock(&sbi->s_bmlock);
	return;

err_free:
	affs_warning(sb,"affs_free_block","Trying to free block %u which is already free", block);
	mutex_unlock(&sbi->s_bmlock);
	return;

err_bh_read:
	affs_error(sb,"affs_free_block","Cannot read bitmap block %u", bm->bm_key);
	sbi->s_bmap_bh = NULL;
	sbi->s_last_bmap = ~0;
	mutex_unlock(&sbi->s_bmlock);
	return;

err_range:
	affs_error(sb, "affs_free_block","Block %u outside partition", block);
	return;
}

/*
 * Allocate a block in the given allocation zone.
 * Since we have to byte-swap the bitmap on little-endian
 * machines, this is rather expensive. Therefore we will
 * preallocate up to 16 blocks from the same word, if
 * possible. We are not doing preallocations in the
 * header zone, though.
 */

u32
affs_alloc_block(struct inode *inode, u32 goal)
{
	struct super_block *sb;
	struct affs_sb_info *sbi;
	struct affs_bm_info *bm;
	struct buffer_head *bh;
	__be32 *data, *enddata;
	u32 blk, bmap, bit, mask, mask2, tmp;
	int i;

	sb = inode->i_sb;
	sbi = AFFS_SB(sb);

	pr_debug("AFFS: balloc(inode=%lu,goal=%u): ", inode->i_ino, goal);

	if (AFFS_I(inode)->i_pa_cnt) {
		pr_debug("%d\n", AFFS_I(inode)->i_lastalloc+1);
		AFFS_I(inode)->i_pa_cnt--;
		return ++AFFS_I(inode)->i_lastalloc;
	}

	if (!goal || goal > sbi->s_partition_size) {
		if (goal)
			affs_warning(sb, "affs_balloc", "invalid goal %d", goal);
		//if (!AFFS_I(inode)->i_last_block)
		//	affs_warning(sb, "affs_balloc", "no last alloc block");
		goal = sbi->s_reserved;
	}

	blk = goal - sbi->s_reserved;
	bmap = blk / sbi->s_bmap_bits;
	bm = &sbi->s_bitmap[bmap];

	mutex_lock(&sbi->s_bmlock);

	if (bm->bm_free)
		goto find_bmap_bit;

find_bmap:
	/* search for the next bmap buffer with free bits */
	i = sbi->s_bmap_count;
	do {
		if (--i < 0)
			goto err_full;
		bmap++;
		bm++;
		if (bmap < sbi->s_bmap_count)
			continue;
		/* restart search at zero */
		bmap = 0;
		bm = sbi->s_bitmap;
	} while (!bm->bm_free);
	blk = bmap * sbi->s_bmap_bits;

find_bmap_bit:

	bh = sbi->s_bmap_bh;
	if (sbi->s_last_bmap != bmap) {
		affs_brelse(bh);
		bh = affs_bread(sb, bm->bm_key);
		if (!bh)
			goto err_bh_read;
		sbi->s_bmap_bh = bh;
		sbi->s_last_bmap = bmap;
	}

	/* find an unused block in this bitmap block */
	bit = blk % sbi->s_bmap_bits;
	data = (__be32 *)bh->b_data + bit / 32 + 1;
	enddata = (__be32 *)((u8 *)bh->b_data + sb->s_blocksize);
	mask = ~0UL << (bit & 31);
	blk &= ~31UL;

	tmp = be32_to_cpu(*data);
	if (tmp & mask)
		goto find_bit;

	/* scan the rest of the buffer */
	do {
		blk += 32;
		if (++data >= enddata)
			/* didn't find something, can only happen
			 * if scan didn't start at 0, try next bmap
			 */
			goto find_bmap;
	} while (!*data);
	tmp = be32_to_cpu(*data);
	mask = ~0;

find_bit:
	/* finally look for a free bit in the word */
	bit = ffs(tmp & mask) - 1;
	blk += bit + sbi->s_reserved;
	mask2 = mask = 1 << (bit & 31);
	AFFS_I(inode)->i_lastalloc = blk;

	/* prealloc as much as possible within this word */
	while ((mask2 <<= 1)) {
		if (!(tmp & mask2))
			break;
		AFFS_I(inode)->i_pa_cnt++;
		mask |= mask2;
	}
	bm->bm_free -= AFFS_I(inode)->i_pa_cnt + 1;

	*data = cpu_to_be32(tmp & ~mask);

	/* fix checksum */
	tmp = be32_to_cpu(*(__be32 *)bh->b_data);
	*(__be32 *)bh->b_data = cpu_to_be32(tmp + mask);

	mark_buffer_dirty(bh);
	sb->s_dirt = 1;

	mutex_unlock(&sbi->s_bmlock);

	pr_debug("%d\n", blk);
	return blk;

err_bh_read:
	affs_error(sb,"affs_read_block","Cannot read bitmap block %u", bm->bm_key);
	sbi->s_bmap_bh = NULL;
	sbi->s_last_bmap = ~0;
err_full:
	mutex_unlock(&sbi->s_bmlock);
	pr_debug("failed\n");
	return 0;
}

int affs_init_bitmap(struct super_block *sb, int *flags)
{
	struct affs_bm_info *bm;
	struct buffer_head *bmap_bh = NULL, *bh = NULL;
	__be32 *bmap_blk;
	u32 size, blk, end, offset, mask;
	int i, res = 0;
	struct affs_sb_info *sbi = AFFS_SB(sb);

	if (*flags & MS_RDONLY)
		return 0;

	if (!AFFS_ROOT_TAIL(sb, sbi->s_root_bh)->bm_flag) {
		printk(KERN_NOTICE "AFFS: Bitmap invalid - mounting %s read only\n",
			sb->s_id);
		*flags |= MS_RDONLY;
		return 0;
	}

	sbi->s_last_bmap = ~0;
	sbi->s_bmap_bh = NULL;
	sbi->s_bmap_bits = sb->s_blocksize * 8 - 32;
	sbi->s_bmap_count = (sbi->s_partition_size - sbi->s_reserved +
				 sbi->s_bmap_bits - 1) / sbi->s_bmap_bits;
	size = sbi->s_bmap_count * sizeof(*bm);
	bm = sbi->s_bitmap = kzalloc(size, GFP_KERNEL);
	if (!sbi->s_bitmap) {
		printk(KERN_ERR "AFFS: Bitmap allocation failed\n");
		return -ENOMEM;
	}

	bmap_blk = (__be32 *)sbi->s_root_bh->b_data;
	blk = sb->s_blocksize / 4 - 49;
	end = blk + 25;

	for (i = sbi->s_bmap_count; i > 0; bm++, i--) {
		affs_brelse(bh);

		bm->bm_key = be32_to_cpu(bmap_blk[blk]);
		bh = affs_bread(sb, bm->bm_key);
		if (!bh) {
			printk(KERN_ERR "AFFS: Cannot read bitmap\n");
			res = -EIO;
			goto out;
		}
		if (affs_checksum_block(sb, bh)) {
			printk(KERN_WARNING "AFFS: Bitmap %u invalid - mounting %s read only.\n",
			       bm->bm_key, sb->s_id);
			*flags |= MS_RDONLY;
			goto out;
		}
		pr_debug("AFFS: read bitmap block %d: %d\n", blk, bm->bm_key);
		bm->bm_free = affs_count_free_bits(sb->s_blocksize - 4, bh->b_data + 4);

		/* Don't try read the extension if this is the last block,
		 * but we also need the right bm pointer below
		 */
		if (++blk < end || i == 1)
			continue;
		if (bmap_bh)
			affs_brelse(bmap_bh);
		bmap_bh = affs_bread(sb, be32_to_cpu(bmap_blk[blk]));
		if (!bmap_bh) {
			printk(KERN_ERR "AFFS: Cannot read bitmap extension\n");
			res = -EIO;
			goto out;
		}
		bmap_blk = (__be32 *)bmap_bh->b_data;
		blk = 0;
		end = sb->s_blocksize / 4 - 1;
	}

	offset = (sbi->s_partition_size - sbi->s_reserved) % sbi->s_bmap_bits;
	mask = ~(0xFFFFFFFFU << (offset & 31));
	pr_debug("last word: %d %d %d\n", offset, offset / 32 + 1, mask);
	offset = offset / 32 + 1;

	if (mask) {
		u32 old, new;

		/* Mark unused bits in the last word as allocated */
		old = be32_to_cpu(((__be32 *)bh->b_data)[offset]);
		new = old & mask;
		//if (old != new) {
			((__be32 *)bh->b_data)[offset] = cpu_to_be32(new);
			/* fix checksum */
			//new -= old;
			//old = be32_to_cpu(*(__be32 *)bh->b_data);
			//*(__be32 *)bh->b_data = cpu_to_be32(old - new);
			//mark_buffer_dirty(bh);
		//}
		/* correct offset for the bitmap count below */
		//offset++;
	}
	while (++offset < sb->s_blocksize / 4)
		((__be32 *)bh->b_data)[offset] = 0;
	((__be32 *)bh->b_data)[0] = 0;
	((__be32 *)bh->b_data)[0] = cpu_to_be32(-affs_checksum_block(sb, bh));
	mark_buffer_dirty(bh);

	/* recalculate bitmap count for last block */
	bm--;
	bm->bm_free = affs_count_free_bits(sb->s_blocksize - 4, bh->b_data + 4);

out:
	affs_brelse(bh);
	affs_brelse(bmap_bh);
	return res;
}

void affs_free_bitmap(struct super_block *sb)
{
	struct affs_sb_info *sbi = AFFS_SB(sb);

	if (!sbi->s_bitmap)
		return;

	affs_brelse(sbi->s_bmap_bh);
	sbi->s_bmap_bh = NULL;
	sbi->s_last_bmap = ~0;
	kfree(sbi->s_bitmap);
	sbi->s_bitmap = NULL;
}
Commit	Line	Data
1da177e4 LT	1	/*
	2	* linux/fs/affs/bitmap.c
	3	*
	4	* (c) 1996 Hans-Joachim Widmaier
	5	*
	6	* bitmap.c contains the code that handles all bitmap related stuff -
	7	* block allocation, deallocation, calculation of free space.
	8	*/
	9
5a0e3ad6	10	#include <linux/slab.h>
1da177e4 LT	11	#include "affs.h"
	12
	13	/* This is, of course, shamelessly stolen from fs/minix */
	14
febfcf91	15	static const int nibblemap[] = { 0,1,1,2,1,2,2,3,1,2,2,3,2,3,3,4 };
1da177e4 LT	16
	17	static u32
	18	affs_count_free_bits(u32 blocksize, const void *data)
	19	{
	20	const u32 *map;
	21	u32 free;
	22	u32 tmp;
	23
	24	map = data;
	25	free = 0;
	26	for (blocksize /= 4; blocksize > 0; blocksize--) {
	27	tmp = *map++;
	28	while (tmp) {
	29	free += nibblemap[tmp & 0xf];
	30	tmp >>= 4;
	31	}
	32	}
	33
	34	return free;
	35	}
	36
	37	u32
	38	affs_count_free_blocks(struct super_block *sb)
	39	{
	40	struct affs_bm_info *bm;
	41	u32 free;
	42	int i;
	43
	44	pr_debug("AFFS: count_free_blocks()\n");
	45
	46	if (sb->s_flags & MS_RDONLY)
	47	return 0;
	48
7d135a5d	49	mutex_lock(&AFFS_SB(sb)->s_bmlock);
1da177e4 LT	50
	51	bm = AFFS_SB(sb)->s_bitmap;
	52	free = 0;
	53	for (i = AFFS_SB(sb)->s_bmap_count; i > 0; bm++, i--)
	54	free += bm->bm_free;
	55
7d135a5d	56	mutex_unlock(&AFFS_SB(sb)->s_bmlock);
1da177e4 LT	57
	58	return free;
	59	}
	60
	61	void
	62	affs_free_block(struct super_block *sb, u32 block)
	63	{
	64	struct affs_sb_info *sbi = AFFS_SB(sb);
	65	struct affs_bm_info *bm;
	66	struct buffer_head *bh;
	67	u32 blk, bmap, bit, mask, tmp;
	68	__be32 *data;
	69
	70	pr_debug("AFFS: free_block(%u)\n", block);
	71
	72	if (block > sbi->s_partition_size)
	73	goto err_range;
	74
	75	blk = block - sbi->s_reserved;
	76	bmap = blk / sbi->s_bmap_bits;
	77	bit = blk % sbi->s_bmap_bits;
	78	bm = &sbi->s_bitmap[bmap];
	79
7d135a5d	80	mutex_lock(&sbi->s_bmlock);
1da177e4 LT	81
	82	bh = sbi->s_bmap_bh;
	83	if (sbi->s_last_bmap != bmap) {
	84	affs_brelse(bh);
	85	bh = affs_bread(sb, bm->bm_key);
	86	if (!bh)
	87	goto err_bh_read;
	88	sbi->s_bmap_bh = bh;
	89	sbi->s_last_bmap = bmap;
	90	}
	91
	92	mask = 1 << (bit & 31);
	93	data = (__be32 *)bh->b_data + bit / 32 + 1;
	94
	95	/* mark block free */
	96	tmp = be32_to_cpu(*data);
	97	if (tmp & mask)
	98	goto err_free;
	99	*data = cpu_to_be32(tmp \| mask);
	100
	101	/* fix checksum */
	102	tmp = be32_to_cpu((__be32 )bh->b_data);
	103	(__be32 )bh->b_data = cpu_to_be32(tmp - mask);
	104
	105	mark_buffer_dirty(bh);
	106	sb->s_dirt = 1;
	107	bm->bm_free++;
	108
7d135a5d	109	mutex_unlock(&sbi->s_bmlock);
1da177e4 LT	110	return;
	111
	112	err_free:
	113	affs_warning(sb,"affs_free_block","Trying to free block %u which is already free", block);
7d135a5d	114	mutex_unlock(&sbi->s_bmlock);
1da177e4 LT	115	return;
	116
	117	err_bh_read:
	118	affs_error(sb,"affs_free_block","Cannot read bitmap block %u", bm->bm_key);
	119	sbi->s_bmap_bh = NULL;
	120	sbi->s_last_bmap = ~0;
7d135a5d	121	mutex_unlock(&sbi->s_bmlock);
1da177e4 LT	122	return;
	123
	124	err_range:
	125	affs_error(sb, "affs_free_block","Block %u outside partition", block);
	126	return;
	127	}
	128
	129	/*
	130	* Allocate a block in the given allocation zone.
	131	* Since we have to byte-swap the bitmap on little-endian
3ad2f3fb	132	* machines, this is rather expensive. Therefore we will
1da177e4 LT	133	* preallocate up to 16 blocks from the same word, if
	134	* possible. We are not doing preallocations in the
	135	* header zone, though.
	136	*/
	137
	138	u32
	139	affs_alloc_block(struct inode *inode, u32 goal)
	140	{
	141	struct super_block *sb;
	142	struct affs_sb_info *sbi;
	143	struct affs_bm_info *bm;
	144	struct buffer_head *bh;
	145	__be32 data, enddata;
	146	u32 blk, bmap, bit, mask, mask2, tmp;
	147	int i;
	148
	149	sb = inode->i_sb;
	150	sbi = AFFS_SB(sb);
	151
	152	pr_debug("AFFS: balloc(inode=%lu,goal=%u): ", inode->i_ino, goal);
	153
	154	if (AFFS_I(inode)->i_pa_cnt) {
	155	pr_debug("%d\n", AFFS_I(inode)->i_lastalloc+1);
	156	AFFS_I(inode)->i_pa_cnt--;
	157	return ++AFFS_I(inode)->i_lastalloc;
	158	}
	159
	160	if (!goal \|\| goal > sbi->s_partition_size) {
	161	if (goal)
	162	affs_warning(sb, "affs_balloc", "invalid goal %d", goal);
	163	//if (!AFFS_I(inode)->i_last_block)
	164	// affs_warning(sb, "affs_balloc", "no last alloc block");
	165	goal = sbi->s_reserved;
	166	}
	167
	168	blk = goal - sbi->s_reserved;
	169	bmap = blk / sbi->s_bmap_bits;
	170	bm = &sbi->s_bitmap[bmap];
	171
7d135a5d	172	mutex_lock(&sbi->s_bmlock);
1da177e4 LT	173
	174	if (bm->bm_free)
	175	goto find_bmap_bit;
	176
	177	find_bmap:
	178	/* search for the next bmap buffer with free bits */
	179	i = sbi->s_bmap_count;
	180	do {
	181	if (--i < 0)
	182	goto err_full;
	183	bmap++;
	184	bm++;
	185	if (bmap < sbi->s_bmap_count)
	186	continue;
	187	/* restart search at zero */
	188	bmap = 0;
	189	bm = sbi->s_bitmap;
	190	} while (!bm->bm_free);
	191	blk = bmap * sbi->s_bmap_bits;
	192
	193	find_bmap_bit:
	194
	195	bh = sbi->s_bmap_bh;
	196	if (sbi->s_last_bmap != bmap) {
	197	affs_brelse(bh);
	198	bh = affs_bread(sb, bm->bm_key);
	199	if (!bh)
	200	goto err_bh_read;
	201	sbi->s_bmap_bh = bh;
	202	sbi->s_last_bmap = bmap;
	203	}
	204
	205	/* find an unused block in this bitmap block */
	206	bit = blk % sbi->s_bmap_bits;
	207	data = (__be32 *)bh->b_data + bit / 32 + 1;
	208	enddata = (__be32 )((u8 )bh->b_data + sb->s_blocksize);
	209	mask = ~0UL << (bit & 31);
	210	blk &= ~31UL;
	211
	212	tmp = be32_to_cpu(*data);
	213	if (tmp & mask)
	214	goto find_bit;
	215
	216	/* scan the rest of the buffer */
	217	do {
	218	blk += 32;
	219	if (++data >= enddata)
	220	/* didn't find something, can only happen
	221	* if scan didn't start at 0, try next bmap
	222	*/
	223	goto find_bmap;
	224	} while (!*data);
	225	tmp = be32_to_cpu(*data);
	226	mask = ~0;
	227
	228	find_bit:
	229	/* finally look for a free bit in the word */
	230	bit = ffs(tmp & mask) - 1;
	231	blk += bit + sbi->s_reserved;
	232	mask2 = mask = 1 << (bit & 31);
	233	AFFS_I(inode)->i_lastalloc = blk;
	234
	235	/* prealloc as much as possible within this word */
	236	while ((mask2 <<= 1)) {
237	if (!(tmp & mask2))
238	break;
239	AFFS_I(inode)->i_pa_cnt++;
240	mask \|= mask2;
241	}
242	bm->bm_free -= AFFS_I(inode)->i_pa_cnt + 1;
243
244	*data = cpu_to_be32(tmp & ~mask);
245
246	/* fix checksum */
247	tmp = be32_to_cpu((__be32 )bh->b_data);
248	(__be32 )bh->b_data = cpu_to_be32(tmp + mask);
249
250	mark_buffer_dirty(bh);
251	sb->s_dirt = 1;
252
7d135a5d	253	mutex_unlock(&sbi->s_bmlock);
1da177e4 LT	254
	255	pr_debug("%d\n", blk);
	256	return blk;
	257
	258	err_bh_read:
	259	affs_error(sb,"affs_read_block","Cannot read bitmap block %u", bm->bm_key);
	260	sbi->s_bmap_bh = NULL;
	261	sbi->s_last_bmap = ~0;
	262	err_full:
7d135a5d	263	mutex_unlock(&sbi->s_bmlock);
1da177e4 LT	264	pr_debug("failed\n");
	265	return 0;
	266	}
	267
	268	int affs_init_bitmap(struct super_block sb, int flags)
	269	{
	270	struct affs_bm_info *bm;
	271	struct buffer_head bmap_bh = NULL, bh = NULL;
	272	__be32 *bmap_blk;
	273	u32 size, blk, end, offset, mask;
	274	int i, res = 0;
	275	struct affs_sb_info *sbi = AFFS_SB(sb);
	276
	277	if (*flags & MS_RDONLY)
	278	return 0;
	279
	280	if (!AFFS_ROOT_TAIL(sb, sbi->s_root_bh)->bm_flag) {
	281	printk(KERN_NOTICE "AFFS: Bitmap invalid - mounting %s read only\n",
	282	sb->s_id);
	283	*flags \|= MS_RDONLY;
	284	return 0;
	285	}
	286
	287	sbi->s_last_bmap = ~0;
	288	sbi->s_bmap_bh = NULL;
	289	sbi->s_bmap_bits = sb->s_blocksize * 8 - 32;
	290	sbi->s_bmap_count = (sbi->s_partition_size - sbi->s_reserved +
	291	sbi->s_bmap_bits - 1) / sbi->s_bmap_bits;
	292	size = sbi->s_bmap_count * sizeof(*bm);
b593e48d	293	bm = sbi->s_bitmap = kzalloc(size, GFP_KERNEL);
1da177e4 LT	294	if (!sbi->s_bitmap) {
	295	printk(KERN_ERR "AFFS: Bitmap allocation failed\n");
	296	return -ENOMEM;
	297	}
1da177e4 LT	298
	299	bmap_blk = (__be32 *)sbi->s_root_bh->b_data;
	300	blk = sb->s_blocksize / 4 - 49;
	301	end = blk + 25;
	302
	303	for (i = sbi->s_bmap_count; i > 0; bm++, i--) {
	304	affs_brelse(bh);
	305
	306	bm->bm_key = be32_to_cpu(bmap_blk[blk]);
	307	bh = affs_bread(sb, bm->bm_key);
	308	if (!bh) {
	309	printk(KERN_ERR "AFFS: Cannot read bitmap\n");
	310	res = -EIO;
	311	goto out;
	312	}
	313	if (affs_checksum_block(sb, bh)) {
	314	printk(KERN_WARNING "AFFS: Bitmap %u invalid - mounting %s read only.\n",
	315	bm->bm_key, sb->s_id);
	316	*flags \|= MS_RDONLY;
	317	goto out;
	318	}
	319	pr_debug("AFFS: read bitmap block %d: %d\n", blk, bm->bm_key);
	320	bm->bm_free = affs_count_free_bits(sb->s_blocksize - 4, bh->b_data + 4);
	321
	322	/* Don't try read the extension if this is the last block,
	323	* but we also need the right bm pointer below
	324	*/
	325	if (++blk < end \|\| i == 1)
	326	continue;
	327	if (bmap_bh)
	328	affs_brelse(bmap_bh);
	329	bmap_bh = affs_bread(sb, be32_to_cpu(bmap_blk[blk]));
	330	if (!bmap_bh) {
	331	printk(KERN_ERR "AFFS: Cannot read bitmap extension\n");
	332	res = -EIO;
	333	goto out;
	334	}
	335	bmap_blk = (__be32 *)bmap_bh->b_data;
	336	blk = 0;
	337	end = sb->s_blocksize / 4 - 1;
	338	}
	339
	340	offset = (sbi->s_partition_size - sbi->s_reserved) % sbi->s_bmap_bits;
	341	mask = ~(0xFFFFFFFFU << (offset & 31));
	342	pr_debug("last word: %d %d %d\n", offset, offset / 32 + 1, mask);
	343	offset = offset / 32 + 1;
	344
	345	if (mask) {
	346	u32 old, new;
	347
	348	/* Mark unused bits in the last word as allocated */
	349	old = be32_to_cpu(((__be32 *)bh->b_data)[offset]);
	350	new = old & mask;
	351	//if (old != new) {
	352	((__be32 *)bh->b_data)[offset] = cpu_to_be32(new);
	353	/* fix checksum */
	354	//new -= old;
	355	//old = be32_to_cpu((__be32 )bh->b_data);
	356	//(__be32 )bh->b_data = cpu_to_be32(old - new);
	357	//mark_buffer_dirty(bh);
	358	//}
	359	/* correct offset for the bitmap count below */
	360	//offset++;
	361	}
362	while (++offset < sb->s_blocksize / 4)
363	((__be32 *)bh->b_data)[offset] = 0;
364	((__be32 *)bh->b_data)[0] = 0;
365	((__be32 *)bh->b_data)[0] = cpu_to_be32(-affs_checksum_block(sb, bh));
366	mark_buffer_dirty(bh);
367
368	/* recalculate bitmap count for last block */
369	bm--;
370	bm->bm_free = affs_count_free_bits(sb->s_blocksize - 4, bh->b_data + 4);
371
372	out:
373	affs_brelse(bh);
374	affs_brelse(bmap_bh);
375	return res;
376	}
377
378	void affs_free_bitmap(struct super_block *sb)
379	{
380	struct affs_sb_info *sbi = AFFS_SB(sb);
381
382	if (!sbi->s_bitmap)
383	return;
384
385	affs_brelse(sbi->s_bmap_bh);
386	sbi->s_bmap_bh = NULL;
387	sbi->s_last_bmap = ~0;
388	kfree(sbi->s_bitmap);
389	sbi->s_bitmap = NULL;
390	}