[linux.git] / fs / minix / itree_common.c

// SPDX-License-Identifier: GPL-2.0
/* Generic part */

typedef struct {
	block_t	*p;
	block_t	key;
	struct buffer_head *bh;
} Indirect;

static DEFINE_RWLOCK(pointers_lock);

static inline void add_chain(Indirect *p, struct buffer_head *bh, block_t *v)
{
	p->key = *(p->p = v);
	p->bh = bh;
}

static inline int verify_chain(Indirect *from, Indirect *to)
{
	while (from <= to && from->key == *from->p)
		from++;
	return (from > to);
}

static inline block_t *block_end(struct buffer_head *bh)
{
	return (block_t *)((char*)bh->b_data + bh->b_size);
}

static inline Indirect *get_branch(struct inode *inode,
					int depth,
					int *offsets,
					Indirect chain[DEPTH],
					int *err)
{
	struct super_block *sb = inode->i_sb;
	Indirect *p = chain;
	struct buffer_head *bh;

	*err = 0;
	/* i_data is not going away, no lock needed */
	add_chain (chain, NULL, i_data(inode) + *offsets);
	if (!p->key)
		goto no_block;
	while (--depth) {
		bh = sb_bread(sb, block_to_cpu(p->key));
		if (!bh)
			goto failure;
		read_lock(&pointers_lock);
		if (!verify_chain(chain, p))
			goto changed;
		add_chain(++p, bh, (block_t *)bh->b_data + *++offsets);
		read_unlock(&pointers_lock);
		if (!p->key)
			goto no_block;
	}
	return NULL;

changed:
	read_unlock(&pointers_lock);
	brelse(bh);
	*err = -EAGAIN;
	goto no_block;
failure:
	*err = -EIO;
no_block:
	return p;
}

static int alloc_branch(struct inode *inode,
			     int num,
			     int *offsets,
			     Indirect *branch)
{
	int n = 0;
	int i;
	int parent = minix_new_block(inode);

	branch[0].key = cpu_to_block(parent);
	if (parent) for (n = 1; n < num; n++) {
		struct buffer_head *bh;
		/* Allocate the next block */
		int nr = minix_new_block(inode);
		if (!nr)
			break;
		branch[n].key = cpu_to_block(nr);
		bh = sb_getblk(inode->i_sb, parent);
		lock_buffer(bh);
		memset(bh->b_data, 0, bh->b_size);
		branch[n].bh = bh;
		branch[n].p = (block_t*) bh->b_data + offsets[n];
		*branch[n].p = branch[n].key;
		set_buffer_uptodate(bh);
		unlock_buffer(bh);
		mark_buffer_dirty_inode(bh, inode);
		parent = nr;
	}
	if (n == num)
		return 0;

	/* Allocation failed, free what we already allocated */
	for (i = 1; i < n; i++)
		bforget(branch[i].bh);
	for (i = 0; i < n; i++)
		minix_free_block(inode, block_to_cpu(branch[i].key));
	return -ENOSPC;
}

static inline int splice_branch(struct inode *inode,
				     Indirect chain[DEPTH],
				     Indirect *where,
				     int num)
{
	int i;

	write_lock(&pointers_lock);

	/* Verify that place we are splicing to is still there and vacant */
	if (!verify_chain(chain, where-1) || *where->p)
		goto changed;

	*where->p = where->key;

	write_unlock(&pointers_lock);

	/* We are done with atomic stuff, now do the rest of housekeeping */

	inode->i_ctime = current_time(inode);

	/* had we spliced it onto indirect block? */
	if (where->bh)
		mark_buffer_dirty_inode(where->bh, inode);

	mark_inode_dirty(inode);
	return 0;

changed:
	write_unlock(&pointers_lock);
	for (i = 1; i < num; i++)
		bforget(where[i].bh);
	for (i = 0; i < num; i++)
		minix_free_block(inode, block_to_cpu(where[i].key));
	return -EAGAIN;
}

static int get_block(struct inode * inode, sector_t block,
			struct buffer_head *bh, int create)
{
	int err = -EIO;
	int offsets[DEPTH];
	Indirect chain[DEPTH];
	Indirect *partial;
	int left;
	int depth = block_to_path(inode, block, offsets);

	if (depth == 0)
		goto out;

reread:
	partial = get_branch(inode, depth, offsets, chain, &err);

	/* Simplest case - block found, no allocation needed */
	if (!partial) {
got_it:
		map_bh(bh, inode->i_sb, block_to_cpu(chain[depth-1].key));
		/* Clean up and exit */
		partial = chain+depth-1; /* the whole chain */
		goto cleanup;
	}

	/* Next simple case - plain lookup or failed read of indirect block */
	if (!create || err == -EIO) {
cleanup:
		while (partial > chain) {
			brelse(partial->bh);
			partial--;
		}
out:
		return err;
	}

	/*
	 * Indirect block might be removed by truncate while we were
	 * reading it. Handling of that case (forget what we've got and
	 * reread) is taken out of the main path.
	 */
	if (err == -EAGAIN)
		goto changed;

	left = (chain + depth) - partial;
	err = alloc_branch(inode, left, offsets+(partial-chain), partial);
	if (err)
		goto cleanup;

	if (splice_branch(inode, chain, partial, left) < 0)
		goto changed;

	set_buffer_new(bh);
	goto got_it;

changed:
	while (partial > chain) {
		brelse(partial->bh);
		partial--;
	}
	goto reread;
}

static inline int all_zeroes(block_t *p, block_t *q)
{
	while (p < q)
		if (*p++)
			return 0;
	return 1;
}

static Indirect *find_shared(struct inode *inode,
				int depth,
				int offsets[DEPTH],
				Indirect chain[DEPTH],
				block_t *top)
{
	Indirect *partial, *p;
	int k, err;

	*top = 0;
	for (k = depth; k > 1 && !offsets[k-1]; k--)
		;
	partial = get_branch(inode, k, offsets, chain, &err);

	write_lock(&pointers_lock);
	if (!partial)
		partial = chain + k-1;
	if (!partial->key && *partial->p) {
		write_unlock(&pointers_lock);
		goto no_top;
	}
	for (p=partial;p>chain && all_zeroes((block_t*)p->bh->b_data,p->p);p--)
		;
	if (p == chain + k - 1 && p > chain) {
		p->p--;
	} else {
		*top = *p->p;
		*p->p = 0;
	}
	write_unlock(&pointers_lock);

	while(partial > p)
	{
		brelse(partial->bh);
		partial--;
	}
no_top:
	return partial;
}

static inline void free_data(struct inode *inode, block_t *p, block_t *q)
{
	unsigned long nr;

	for ( ; p < q ; p++) {
		nr = block_to_cpu(*p);
		if (nr) {
			*p = 0;
			minix_free_block(inode, nr);
		}
	}
}

static void free_branches(struct inode *inode, block_t *p, block_t *q, int depth)
{
	struct buffer_head * bh;
	unsigned long nr;

	if (depth--) {
		for ( ; p < q ; p++) {
			nr = block_to_cpu(*p);
			if (!nr)
				continue;
			*p = 0;
			bh = sb_bread(inode->i_sb, nr);
			if (!bh)
				continue;
			free_branches(inode, (block_t*)bh->b_data,
				      block_end(bh), depth);
			bforget(bh);
			minix_free_block(inode, nr);
			mark_inode_dirty(inode);
		}
	} else
		free_data(inode, p, q);
}

static inline void truncate (struct inode * inode)
{
	struct super_block *sb = inode->i_sb;
	block_t *idata = i_data(inode);
	int offsets[DEPTH];
	Indirect chain[DEPTH];
	Indirect *partial;
	block_t nr = 0;
	int n;
	int first_whole;
	long iblock;

	iblock = (inode->i_size + sb->s_blocksize -1) >> sb->s_blocksize_bits;
	block_truncate_page(inode->i_mapping, inode->i_size, get_block);

	n = block_to_path(inode, iblock, offsets);
	if (!n)
		return;

	if (n == 1) {
		free_data(inode, idata+offsets[0], idata + DIRECT);
		first_whole = 0;
		goto do_indirects;
	}

	first_whole = offsets[0] + 1 - DIRECT;
	partial = find_shared(inode, n, offsets, chain, &nr);
	if (nr) {
		if (partial == chain)
			mark_inode_dirty(inode);
		else
			mark_buffer_dirty_inode(partial->bh, inode);
		free_branches(inode, &nr, &nr+1, (chain+n-1) - partial);
	}
	/* Clear the ends of indirect blocks on the shared branch */
	while (partial > chain) {
		free_branches(inode, partial->p + 1, block_end(partial->bh),
				(chain+n-1) - partial);
		mark_buffer_dirty_inode(partial->bh, inode);
		brelse (partial->bh);
		partial--;
	}
do_indirects:
	/* Kill the remaining (whole) subtrees */
	while (first_whole < DEPTH-1) {
		nr = idata[DIRECT+first_whole];
		if (nr) {
			idata[DIRECT+first_whole] = 0;
			mark_inode_dirty(inode);
			free_branches(inode, &nr, &nr+1, first_whole+1);
		}
		first_whole++;
	}
	inode->i_mtime = inode->i_ctime = current_time(inode);
	mark_inode_dirty(inode);
}

static inline unsigned nblocks(loff_t size, struct super_block *sb)
{
	int k = sb->s_blocksize_bits - 10;
	unsigned blocks, res, direct = DIRECT, i = DEPTH;
	blocks = (size + sb->s_blocksize - 1) >> (BLOCK_SIZE_BITS + k);
	res = blocks;
	while (--i && blocks > direct) {
		blocks -= direct;
		blocks += sb->s_blocksize/sizeof(block_t) - 1;
		blocks /= sb->s_blocksize/sizeof(block_t);
		res += blocks;
		direct = 1;
	}
	return res;
}
Commit	Line	Data
b2441318	1	// SPDX-License-Identifier: GPL-2.0
1da177e4 LT	2	/* Generic part */
	3
	4	typedef struct {
	5	block_t *p;
	6	block_t key;
	7	struct buffer_head *bh;
	8	} Indirect;
	9
	10	static DEFINE_RWLOCK(pointers_lock);
	11
	12	static inline void add_chain(Indirect p, struct buffer_head bh, block_t *v)
	13	{
	14	p->key = *(p->p = v);
	15	p->bh = bh;
	16	}
	17
	18	static inline int verify_chain(Indirect from, Indirect to)
	19	{
	20	while (from <= to && from->key == *from->p)
	21	from++;
	22	return (from > to);
	23	}
	24
	25	static inline block_t block_end(struct buffer_head bh)
	26	{
939b00df	27	return (block_t )((char)bh->b_data + bh->b_size);
1da177e4 LT	28	}
	29
	30	static inline Indirect get_branch(struct inode inode,
	31	int depth,
	32	int *offsets,
	33	Indirect chain[DEPTH],
	34	int *err)
	35	{
	36	struct super_block *sb = inode->i_sb;
	37	Indirect *p = chain;
	38	struct buffer_head *bh;
	39
	40	*err = 0;
	41	/* i_data is not going away, no lock needed */
	42	add_chain (chain, NULL, i_data(inode) + *offsets);
	43	if (!p->key)
	44	goto no_block;
	45	while (--depth) {
	46	bh = sb_bread(sb, block_to_cpu(p->key));
	47	if (!bh)
	48	goto failure;
	49	read_lock(&pointers_lock);
	50	if (!verify_chain(chain, p))
	51	goto changed;
	52	add_chain(++p, bh, (block_t )bh->b_data + ++offsets);
	53	read_unlock(&pointers_lock);
	54	if (!p->key)
	55	goto no_block;
	56	}
	57	return NULL;
	58
	59	changed:
	60	read_unlock(&pointers_lock);
	61	brelse(bh);
	62	*err = -EAGAIN;
	63	goto no_block;
	64	failure:
	65	*err = -EIO;
	66	no_block:
	67	return p;
	68	}
	69
	70	static int alloc_branch(struct inode *inode,
	71	int num,
	72	int *offsets,
	73	Indirect *branch)
	74	{
	75	int n = 0;
	76	int i;
	77	int parent = minix_new_block(inode);
	78
	79	branch[0].key = cpu_to_block(parent);
	80	if (parent) for (n = 1; n < num; n++) {
	81	struct buffer_head *bh;
	82	/* Allocate the next block */
	83	int nr = minix_new_block(inode);
	84	if (!nr)
	85	break;
	86	branch[n].key = cpu_to_block(nr);
	87	bh = sb_getblk(inode->i_sb, parent);
	88	lock_buffer(bh);
939b00df	89	memset(bh->b_data, 0, bh->b_size);
1da177e4 LT	90	branch[n].bh = bh;
	91	branch[n].p = (block_t*) bh->b_data + offsets[n];
	92	*branch[n].p = branch[n].key;
	93	set_buffer_uptodate(bh);
	94	unlock_buffer(bh);
	95	mark_buffer_dirty_inode(bh, inode);
	96	parent = nr;
	97	}
	98	if (n == num)
	99	return 0;
	100
	101	/* Allocation failed, free what we already allocated */
	102	for (i = 1; i < n; i++)
	103	bforget(branch[i].bh);
	104	for (i = 0; i < n; i++)
	105	minix_free_block(inode, block_to_cpu(branch[i].key));
	106	return -ENOSPC;
	107	}
	108
	109	static inline int splice_branch(struct inode *inode,
	110	Indirect chain[DEPTH],
	111	Indirect *where,
	112	int num)
	113	{
	114	int i;
	115
	116	write_lock(&pointers_lock);
	117
	118	/* Verify that place we are splicing to is still there and vacant */
	119	if (!verify_chain(chain, where-1) \|\| *where->p)
	120	goto changed;
	121
	122	*where->p = where->key;
	123
	124	write_unlock(&pointers_lock);
	125
	126	/* We are done with atomic stuff, now do the rest of housekeeping */
	127
02027d42	128	inode->i_ctime = current_time(inode);
1da177e4 LT	129
	130	/* had we spliced it onto indirect block? */
	131	if (where->bh)
	132	mark_buffer_dirty_inode(where->bh, inode);
	133
	134	mark_inode_dirty(inode);
	135	return 0;
	136
	137	changed:
	138	write_unlock(&pointers_lock);
	139	for (i = 1; i < num; i++)
	140	bforget(where[i].bh);
	141	for (i = 0; i < num; i++)
	142	minix_free_block(inode, block_to_cpu(where[i].key));
	143	return -EAGAIN;
	144	}
	145
4f2ed694	146	static int get_block(struct inode * inode, sector_t block,
1da177e4 LT	147	struct buffer_head *bh, int create)
	148	{
	149	int err = -EIO;
	150	int offsets[DEPTH];
	151	Indirect chain[DEPTH];
	152	Indirect *partial;
	153	int left;
	154	int depth = block_to_path(inode, block, offsets);
	155
	156	if (depth == 0)
	157	goto out;
	158
	159	reread:
	160	partial = get_branch(inode, depth, offsets, chain, &err);
	161
	162	/* Simplest case - block found, no allocation needed */
	163	if (!partial) {
	164	got_it:
	165	map_bh(bh, inode->i_sb, block_to_cpu(chain[depth-1].key));
	166	/* Clean up and exit */
	167	partial = chain+depth-1; /* the whole chain */
	168	goto cleanup;
	169	}
	170
	171	/* Next simple case - plain lookup or failed read of indirect block */
	172	if (!create \|\| err == -EIO) {
	173	cleanup:
	174	while (partial > chain) {
	175	brelse(partial->bh);
	176	partial--;
	177	}
	178	out:
	179	return err;
	180	}
	181
	182	/*
	183	* Indirect block might be removed by truncate while we were
	184	* reading it. Handling of that case (forget what we've got and
	185	* reread) is taken out of the main path.
	186	*/
	187	if (err == -EAGAIN)
	188	goto changed;
	189
	190	left = (chain + depth) - partial;
	191	err = alloc_branch(inode, left, offsets+(partial-chain), partial);
	192	if (err)
	193	goto cleanup;
	194
	195	if (splice_branch(inode, chain, partial, left) < 0)
	196	goto changed;
	197
	198	set_buffer_new(bh);
	199	goto got_it;
	200
	201	changed:
	202	while (partial > chain) {
	203	brelse(partial->bh);
	204	partial--;
	205	}
	206	goto reread;
	207	}
	208
	209	static inline int all_zeroes(block_t p, block_t q)
	210	{
211	while (p < q)
212	if (*p++)
213	return 0;
214	return 1;
215	}
216
217	static Indirect find_shared(struct inode inode,
218	int depth,
219	int offsets[DEPTH],
220	Indirect chain[DEPTH],
221	block_t *top)
222	{
223	Indirect partial, p;
224	int k, err;
225
226	*top = 0;
227	for (k = depth; k > 1 && !offsets[k-1]; k--)
228	;
229	partial = get_branch(inode, k, offsets, chain, &err);
230
231	write_lock(&pointers_lock);
232	if (!partial)
233	partial = chain + k-1;
234	if (!partial->key && *partial->p) {
235	write_unlock(&pointers_lock);
236	goto no_top;
237	}
238	for (p=partial;p>chain && all_zeroes((block_t*)p->bh->b_data,p->p);p--)
239	;
240	if (p == chain + k - 1 && p > chain) {
241	p->p--;
242	} else {
243	top = p->p;
244	*p->p = 0;
245	}
246	write_unlock(&pointers_lock);
247
248	while(partial > p)
249	{
250	brelse(partial->bh);
251	partial--;
252	}
253	no_top:
254	return partial;
255	}
256
257	static inline void free_data(struct inode inode, block_t p, block_t *q)
258	{
259	unsigned long nr;
260
261	for ( ; p < q ; p++) {
262	nr = block_to_cpu(*p);
263	if (nr) {
264	*p = 0;
265	minix_free_block(inode, nr);
266	}
267	}
268	}
269
270	static void free_branches(struct inode inode, block_t p, block_t *q, int depth)
271	{
272	struct buffer_head * bh;
273	unsigned long nr;
274
275	if (depth--) {
276	for ( ; p < q ; p++) {
277	nr = block_to_cpu(*p);
278	if (!nr)
279	continue;
280	*p = 0;
281	bh = sb_bread(inode->i_sb, nr);
282	if (!bh)
283	continue;
284	free_branches(inode, (block_t*)bh->b_data,
285	block_end(bh), depth);
286	bforget(bh);
287	minix_free_block(inode, nr);
288	mark_inode_dirty(inode);
289	}
290	} else
291	free_data(inode, p, q);
292	}
293
294	static inline void truncate (struct inode * inode)
295	{
939b00df	296	struct super_block *sb = inode->i_sb;
1da177e4 LT	297	block_t *idata = i_data(inode);
	298	int offsets[DEPTH];
	299	Indirect chain[DEPTH];
	300	Indirect *partial;
	301	block_t nr = 0;
	302	int n;
	303	int first_whole;
	304	long iblock;
	305
939b00df	306	iblock = (inode->i_size + sb->s_blocksize -1) >> sb->s_blocksize_bits;
1da177e4 LT	307	block_truncate_page(inode->i_mapping, inode->i_size, get_block);
	308
	309	n = block_to_path(inode, iblock, offsets);
	310	if (!n)
	311	return;
	312
	313	if (n == 1) {
	314	free_data(inode, idata+offsets[0], idata + DIRECT);
	315	first_whole = 0;
	316	goto do_indirects;
	317	}
	318
	319	first_whole = offsets[0] + 1 - DIRECT;
	320	partial = find_shared(inode, n, offsets, chain, &nr);
	321	if (nr) {
	322	if (partial == chain)
	323	mark_inode_dirty(inode);
	324	else
	325	mark_buffer_dirty_inode(partial->bh, inode);
	326	free_branches(inode, &nr, &nr+1, (chain+n-1) - partial);
	327	}
	328	/* Clear the ends of indirect blocks on the shared branch */
	329	while (partial > chain) {
	330	free_branches(inode, partial->p + 1, block_end(partial->bh),
	331	(chain+n-1) - partial);
	332	mark_buffer_dirty_inode(partial->bh, inode);
	333	brelse (partial->bh);
	334	partial--;
	335	}
	336	do_indirects:
	337	/* Kill the remaining (whole) subtrees */
	338	while (first_whole < DEPTH-1) {
	339	nr = idata[DIRECT+first_whole];
	340	if (nr) {
	341	idata[DIRECT+first_whole] = 0;
	342	mark_inode_dirty(inode);
	343	free_branches(inode, &nr, &nr+1, first_whole+1);
	344	}
	345	first_whole++;
	346	}
02027d42	347	inode->i_mtime = inode->i_ctime = current_time(inode);
1da177e4 LT	348	mark_inode_dirty(inode);
	349	}
	350
939b00df	351	static inline unsigned nblocks(loff_t size, struct super_block *sb)
1da177e4	352	{
939b00df	353	int k = sb->s_blocksize_bits - 10;
1da177e4	354	unsigned blocks, res, direct = DIRECT, i = DEPTH;
939b00df	355	blocks = (size + sb->s_blocksize - 1) >> (BLOCK_SIZE_BITS + k);
1da177e4 LT	356	res = blocks;
	357	while (--i && blocks > direct) {
	358	blocks -= direct;
939b00df AB	359	blocks += sb->s_blocksize/sizeof(block_t) - 1;
939b00df AB	360	blocks /= sb->s_blocksize/sizeof(block_t);
1da177e4 LT	361	res += blocks;
	362	direct = 1;
	363	}
	364	return res;
	365	}