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

/* 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_SEC;

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