[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);
	int err = -ENOSPC;

	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);
		if (!bh) {
			minix_free_block(inode, nr);
			err = -ENOMEM;
			break;
		}
		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 err;
}

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_set_ctime_current(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_set_mtime_to_ts(inode, inode_set_ctime_current(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);
da27e0a0	78	int err = -ENOSPC;
1da177e4 LT	79
	80	branch[0].key = cpu_to_block(parent);
	81	if (parent) for (n = 1; n < num; n++) {
	82	struct buffer_head *bh;
	83	/* Allocate the next block */
	84	int nr = minix_new_block(inode);
	85	if (!nr)
	86	break;
	87	branch[n].key = cpu_to_block(nr);
	88	bh = sb_getblk(inode->i_sb, parent);
da27e0a0 EB	89	if (!bh) {
	90	minix_free_block(inode, nr);
	91	err = -ENOMEM;
	92	break;
	93	}
1da177e4	94	lock_buffer(bh);
939b00df	95	memset(bh->b_data, 0, bh->b_size);
1da177e4 LT	96	branch[n].bh = bh;
	97	branch[n].p = (block_t*) bh->b_data + offsets[n];
	98	*branch[n].p = branch[n].key;
	99	set_buffer_uptodate(bh);
	100	unlock_buffer(bh);
	101	mark_buffer_dirty_inode(bh, inode);
	102	parent = nr;
	103	}
	104	if (n == num)
	105	return 0;
	106
	107	/* Allocation failed, free what we already allocated */
	108	for (i = 1; i < n; i++)
	109	bforget(branch[i].bh);
	110	for (i = 0; i < n; i++)
	111	minix_free_block(inode, block_to_cpu(branch[i].key));
da27e0a0	112	return err;
1da177e4 LT	113	}
	114
	115	static inline int splice_branch(struct inode *inode,
	116	Indirect chain[DEPTH],
	117	Indirect *where,
	118	int num)
	119	{
	120	int i;
	121
	122	write_lock(&pointers_lock);
	123
	124	/* Verify that place we are splicing to is still there and vacant */
	125	if (!verify_chain(chain, where-1) \|\| *where->p)
	126	goto changed;
	127
	128	*where->p = where->key;
	129
	130	write_unlock(&pointers_lock);
	131
	132	/* We are done with atomic stuff, now do the rest of housekeeping */
	133
f7f43858	134	inode_set_ctime_current(inode);
1da177e4 LT	135
	136	/* had we spliced it onto indirect block? */
	137	if (where->bh)
	138	mark_buffer_dirty_inode(where->bh, inode);
	139
	140	mark_inode_dirty(inode);
	141	return 0;
	142
	143	changed:
	144	write_unlock(&pointers_lock);
	145	for (i = 1; i < num; i++)
	146	bforget(where[i].bh);
	147	for (i = 0; i < num; i++)
	148	minix_free_block(inode, block_to_cpu(where[i].key));
	149	return -EAGAIN;
	150	}
	151
4f2ed694	152	static int get_block(struct inode * inode, sector_t block,
1da177e4 LT	153	struct buffer_head *bh, int create)
	154	{
	155	int err = -EIO;
	156	int offsets[DEPTH];
	157	Indirect chain[DEPTH];
	158	Indirect *partial;
	159	int left;
	160	int depth = block_to_path(inode, block, offsets);
	161
	162	if (depth == 0)
	163	goto out;
	164
	165	reread:
	166	partial = get_branch(inode, depth, offsets, chain, &err);
	167
	168	/* Simplest case - block found, no allocation needed */
	169	if (!partial) {
	170	got_it:
	171	map_bh(bh, inode->i_sb, block_to_cpu(chain[depth-1].key));
	172	/* Clean up and exit */
	173	partial = chain+depth-1; /* the whole chain */
	174	goto cleanup;
	175	}
	176
	177	/* Next simple case - plain lookup or failed read of indirect block */
	178	if (!create \|\| err == -EIO) {
	179	cleanup:
	180	while (partial > chain) {
	181	brelse(partial->bh);
	182	partial--;
	183	}
	184	out:
	185	return err;
	186	}
	187
	188	/*
	189	* Indirect block might be removed by truncate while we were
	190	* reading it. Handling of that case (forget what we've got and
	191	* reread) is taken out of the main path.
	192	*/
	193	if (err == -EAGAIN)
	194	goto changed;
	195
	196	left = (chain + depth) - partial;
	197	err = alloc_branch(inode, left, offsets+(partial-chain), partial);
	198	if (err)
	199	goto cleanup;
	200
	201	if (splice_branch(inode, chain, partial, left) < 0)
	202	goto changed;
	203
	204	set_buffer_new(bh);
	205	goto got_it;
	206
	207	changed:
	208	while (partial > chain) {
	209	brelse(partial->bh);
	210	partial--;
	211	}
	212	goto reread;
	213	}
	214
	215	static inline int all_zeroes(block_t p, block_t q)
	216	{
217	while (p < q)
218	if (*p++)
219	return 0;
220	return 1;
221	}
222
223	static Indirect find_shared(struct inode inode,
224	int depth,
225	int offsets[DEPTH],
226	Indirect chain[DEPTH],
227	block_t *top)
228	{
229	Indirect partial, p;
230	int k, err;
231
232	*top = 0;
233	for (k = depth; k > 1 && !offsets[k-1]; k--)
234	;
235	partial = get_branch(inode, k, offsets, chain, &err);
236
237	write_lock(&pointers_lock);
238	if (!partial)
239	partial = chain + k-1;
240	if (!partial->key && *partial->p) {
241	write_unlock(&pointers_lock);
242	goto no_top;
243	}
244	for (p=partial;p>chain && all_zeroes((block_t*)p->bh->b_data,p->p);p--)
245	;
246	if (p == chain + k - 1 && p > chain) {
247	p->p--;
248	} else {
249	top = p->p;
250	*p->p = 0;
251	}
252	write_unlock(&pointers_lock);
253
254	while(partial > p)
255	{
256	brelse(partial->bh);
257	partial--;
258	}
259	no_top:
260	return partial;
261	}
262
263	static inline void free_data(struct inode inode, block_t p, block_t *q)
264	{
265	unsigned long nr;
266
267	for ( ; p < q ; p++) {
268	nr = block_to_cpu(*p);
269	if (nr) {
270	*p = 0;
271	minix_free_block(inode, nr);
272	}
273	}
274	}
275
276	static void free_branches(struct inode inode, block_t p, block_t *q, int depth)
277	{
278	struct buffer_head * bh;
279	unsigned long nr;
280
281	if (depth--) {
282	for ( ; p < q ; p++) {
283	nr = block_to_cpu(*p);
284	if (!nr)
285	continue;
286	*p = 0;
287	bh = sb_bread(inode->i_sb, nr);
288	if (!bh)
289	continue;
290	free_branches(inode, (block_t*)bh->b_data,
291	block_end(bh), depth);
292	bforget(bh);
293	minix_free_block(inode, nr);
294	mark_inode_dirty(inode);
295	}
296	} else
297	free_data(inode, p, q);
298	}
299
300	static inline void truncate (struct inode * inode)
301	{
939b00df	302	struct super_block *sb = inode->i_sb;
1da177e4 LT	303	block_t *idata = i_data(inode);
	304	int offsets[DEPTH];
	305	Indirect chain[DEPTH];
	306	Indirect *partial;
	307	block_t nr = 0;
	308	int n;
	309	int first_whole;
	310	long iblock;
	311
939b00df	312	iblock = (inode->i_size + sb->s_blocksize -1) >> sb->s_blocksize_bits;
1da177e4 LT	313	block_truncate_page(inode->i_mapping, inode->i_size, get_block);
	314
	315	n = block_to_path(inode, iblock, offsets);
	316	if (!n)
	317	return;
	318
	319	if (n == 1) {
	320	free_data(inode, idata+offsets[0], idata + DIRECT);
	321	first_whole = 0;
	322	goto do_indirects;
	323	}
	324
	325	first_whole = offsets[0] + 1 - DIRECT;
	326	partial = find_shared(inode, n, offsets, chain, &nr);
	327	if (nr) {
	328	if (partial == chain)
	329	mark_inode_dirty(inode);
	330	else
	331	mark_buffer_dirty_inode(partial->bh, inode);
	332	free_branches(inode, &nr, &nr+1, (chain+n-1) - partial);
	333	}
	334	/* Clear the ends of indirect blocks on the shared branch */
	335	while (partial > chain) {
	336	free_branches(inode, partial->p + 1, block_end(partial->bh),
	337	(chain+n-1) - partial);
	338	mark_buffer_dirty_inode(partial->bh, inode);
	339	brelse (partial->bh);
	340	partial--;
	341	}
	342	do_indirects:
	343	/* Kill the remaining (whole) subtrees */
	344	while (first_whole < DEPTH-1) {
	345	nr = idata[DIRECT+first_whole];
	346	if (nr) {
	347	idata[DIRECT+first_whole] = 0;
	348	mark_inode_dirty(inode);
	349	free_branches(inode, &nr, &nr+1, first_whole+1);
	350	}
	351	first_whole++;
	352	}
06475f4b	353	inode_set_mtime_to_ts(inode, inode_set_ctime_current(inode));
1da177e4 LT	354	mark_inode_dirty(inode);
	355	}
	356
939b00df	357	static inline unsigned nblocks(loff_t size, struct super_block *sb)
1da177e4	358	{
939b00df	359	int k = sb->s_blocksize_bits - 10;
1da177e4	360	unsigned blocks, res, direct = DIRECT, i = DEPTH;
939b00df	361	blocks = (size + sb->s_blocksize - 1) >> (BLOCK_SIZE_BITS + k);
1da177e4 LT	362	res = blocks;
	363	while (--i && blocks > direct) {
	364	blocks -= direct;
939b00df AB	365	blocks += sb->s_blocksize/sizeof(block_t) - 1;
939b00df AB	366	blocks /= sb->s_blocksize/sizeof(block_t);
1da177e4 LT	367	res += blocks;
	368	direct = 1;
	369	}
	370	return res;
	371	}