1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * OMFS (as used by RIO Karma) file operations.
4 * Copyright (C) 2005 Bob Copeland <me@bobcopeland.com>
5 */
6
7#include <linux/module.h>
8#include <linux/fs.h>
9#include <linux/buffer_head.h>
10#include <linux/mpage.h>
11#include "omfs.h"
12
13static u32 omfs_max_extents(struct omfs_sb_info *sbi, int offset)
14{
15	return (sbi->s_sys_blocksize - offset -
16		sizeof(struct omfs_extent)) /
17		sizeof(struct omfs_extent_entry);
18}
19
20void omfs_make_empty_table(struct buffer_head *bh, int offset)
21{
22	struct omfs_extent *oe = (struct omfs_extent *) &bh->b_data[offset];
23
24	oe->e_next = ~cpu_to_be64(0ULL);
25	oe->e_extent_count = cpu_to_be32(1),
26	oe->e_fill = cpu_to_be32(0x22),
27	oe->e_entry[0].e_cluster = ~cpu_to_be64(0ULL);
28	oe->e_entry[0].e_blocks = ~cpu_to_be64(0ULL);
29}
30
31int omfs_shrink_inode(struct inode *inode)
32{
33	struct omfs_sb_info *sbi = OMFS_SB(inode->i_sb);
34	struct omfs_extent *oe;
35	struct omfs_extent_entry *entry;
36	struct buffer_head *bh;
37	u64 next, last;
38	u32 extent_count;
39	u32 max_extents;
40	int ret;
41
42	/* traverse extent table, freeing each entry that is greater
43	 * than inode->i_size;
44	 */
45	next = inode->i_ino;
46
47	/* only support truncate -> 0 for now */
48	ret = -EIO;
49	if (inode->i_size != 0)
50		goto out;
51
52	bh = omfs_bread(inode->i_sb, next);
53	if (!bh)
54		goto out;
55
56	oe = (struct omfs_extent *)(&bh->b_data[OMFS_EXTENT_START]);
57	max_extents = omfs_max_extents(sbi, OMFS_EXTENT_START);
58
59	for (;;) {
60
61		if (omfs_is_bad(sbi, (struct omfs_header *) bh->b_data, next))
62			goto out_brelse;
63
64		extent_count = be32_to_cpu(oe->e_extent_count);
65
66		if (extent_count > max_extents)
67			goto out_brelse;
68
69		last = next;
70		next = be64_to_cpu(oe->e_next);
71		entry = oe->e_entry;
72
73		/* ignore last entry as it is the terminator */
74		for (; extent_count > 1; extent_count--) {
75			u64 start, count;
76			start = be64_to_cpu(entry->e_cluster);
77			count = be64_to_cpu(entry->e_blocks);
78
79			omfs_clear_range(inode->i_sb, start, (int) count);
80			entry++;
81		}
82		omfs_make_empty_table(bh, (char *) oe - bh->b_data);
83		mark_buffer_dirty(bh);
84		brelse(bh);
85
86		if (last != inode->i_ino)
87			omfs_clear_range(inode->i_sb, last, sbi->s_mirrors);
88
89		if (next == ~0)
90			break;
91
92		bh = omfs_bread(inode->i_sb, next);
93		if (!bh)
94			goto out;
95		oe = (struct omfs_extent *) (&bh->b_data[OMFS_EXTENT_CONT]);
96		max_extents = omfs_max_extents(sbi, OMFS_EXTENT_CONT);
97	}
98	ret = 0;
99out:
100	return ret;
101out_brelse:
102	brelse(bh);
103	return ret;
104}
105
106static void omfs_truncate(struct inode *inode)
107{
108	omfs_shrink_inode(inode);
109	mark_inode_dirty(inode);
110}
111
112/*
113 * Add new blocks to the current extent, or create new entries/continuations
114 * as necessary.
115 */
116static int omfs_grow_extent(struct inode *inode, struct omfs_extent *oe,
117			u64 *ret_block)
118{
119	struct omfs_extent_entry *terminator;
120	struct omfs_extent_entry *entry = oe->e_entry;
121	struct omfs_sb_info *sbi = OMFS_SB(inode->i_sb);
122	u32 extent_count = be32_to_cpu(oe->e_extent_count);
123	u64 new_block = 0;
124	u32 max_count;
125	int new_count;
126	int ret = 0;
127
128	/* reached the end of the extent table with no blocks mapped.
129	 * there are three possibilities for adding: grow last extent,
130	 * add a new extent to the current extent table, and add a
131	 * continuation inode.  in last two cases need an allocator for
132	 * sbi->s_cluster_size
133	 */
134
135	/* TODO: handle holes */
136
137	/* should always have a terminator */
138	if (extent_count < 1)
139		return -EIO;
140
141	/* trivially grow current extent, if next block is not taken */
142	terminator = entry + extent_count - 1;
143	if (extent_count > 1) {
144		entry = terminator-1;
145		new_block = be64_to_cpu(entry->e_cluster) +
146			be64_to_cpu(entry->e_blocks);
147
148		if (omfs_allocate_block(inode->i_sb, new_block)) {
149			be64_add_cpu(&entry->e_blocks, 1);
150			terminator->e_blocks = ~(cpu_to_be64(
151				be64_to_cpu(~terminator->e_blocks) + 1));
152			goto out;
153		}
154	}
155	max_count = omfs_max_extents(sbi, OMFS_EXTENT_START);
156
157	/* TODO: add a continuation block here */
158	if (be32_to_cpu(oe->e_extent_count) > max_count-1)
159		return -EIO;
160
161	/* try to allocate a new cluster */
162	ret = omfs_allocate_range(inode->i_sb, 1, sbi->s_clustersize,
163		&new_block, &new_count);
164	if (ret)
165		goto out_fail;
166
167	/* copy terminator down an entry */
168	entry = terminator;
169	terminator++;
170	memcpy(terminator, entry, sizeof(struct omfs_extent_entry));
171
172	entry->e_cluster = cpu_to_be64(new_block);
173	entry->e_blocks = cpu_to_be64((u64) new_count);
174
175	terminator->e_blocks = ~(cpu_to_be64(
176		be64_to_cpu(~terminator->e_blocks) + (u64) new_count));
177
178	/* write in new entry */
179	be32_add_cpu(&oe->e_extent_count, 1);
180
181out:
182	*ret_block = new_block;
183out_fail:
184	return ret;
185}
186
187/*
188 * Scans across the directory table for a given file block number.
189 * If block not found, return 0.
190 */
191static sector_t find_block(struct inode *inode, struct omfs_extent_entry *ent,
192			sector_t block, int count, int *left)
193{
194	/* count > 1 because of terminator */
195	sector_t searched = 0;
196	for (; count > 1; count--) {
197		int numblocks = clus_to_blk(OMFS_SB(inode->i_sb),
198			be64_to_cpu(ent->e_blocks));
199
200		if (block >= searched  &&
201		    block < searched + numblocks) {
202			/*
203			 * found it at cluster + (block - searched)
204			 * numblocks - (block - searched) is remainder
205			 */
206			*left = numblocks - (block - searched);
207			return clus_to_blk(OMFS_SB(inode->i_sb),
208				be64_to_cpu(ent->e_cluster)) +
209				block - searched;
210		}
211		searched += numblocks;
212		ent++;
213	}
214	return 0;
215}
216
217static int omfs_get_block(struct inode *inode, sector_t block,
218			  struct buffer_head *bh_result, int create)
219{
220	struct buffer_head *bh;
221	sector_t next, offset;
222	int ret;
223	u64 new_block;
224	u32 max_extents;
225	int extent_count;
226	struct omfs_extent *oe;
227	struct omfs_extent_entry *entry;
228	struct omfs_sb_info *sbi = OMFS_SB(inode->i_sb);
229	int max_blocks = bh_result->b_size >> inode->i_blkbits;
230	int remain;
231
232	ret = -EIO;
233	bh = omfs_bread(inode->i_sb, inode->i_ino);
234	if (!bh)
235		goto out;
236
237	oe = (struct omfs_extent *)(&bh->b_data[OMFS_EXTENT_START]);
238	max_extents = omfs_max_extents(sbi, OMFS_EXTENT_START);
239	next = inode->i_ino;
240
241	for (;;) {
242
243		if (omfs_is_bad(sbi, (struct omfs_header *) bh->b_data, next))
244			goto out_brelse;
245
246		extent_count = be32_to_cpu(oe->e_extent_count);
247		next = be64_to_cpu(oe->e_next);
248		entry = oe->e_entry;
249
250		if (extent_count > max_extents)
251			goto out_brelse;
252
253		offset = find_block(inode, entry, block, extent_count, &remain);
254		if (offset > 0) {
255			ret = 0;
256			map_bh(bh_result, inode->i_sb, offset);
257			if (remain > max_blocks)
258				remain = max_blocks;
259			bh_result->b_size = (remain << inode->i_blkbits);
260			goto out_brelse;
261		}
262		if (next == ~0)
263			break;
264
265		brelse(bh);
266		bh = omfs_bread(inode->i_sb, next);
267		if (!bh)
268			goto out;
269		oe = (struct omfs_extent *) (&bh->b_data[OMFS_EXTENT_CONT]);
270		max_extents = omfs_max_extents(sbi, OMFS_EXTENT_CONT);
271	}
272	if (create) {
273		ret = omfs_grow_extent(inode, oe, &new_block);
274		if (ret == 0) {
275			mark_buffer_dirty(bh);
276			mark_inode_dirty(inode);
277			map_bh(bh_result, inode->i_sb,
278					clus_to_blk(sbi, new_block));
279		}
280	}
281out_brelse:
282	brelse(bh);
283out:
284	return ret;
285}
286
287static int omfs_read_folio(struct file *file, struct folio *folio)
288{
289	return block_read_full_folio(folio, omfs_get_block);
290}
291
292static void omfs_readahead(struct readahead_control *rac)
293{
294	mpage_readahead(rac, omfs_get_block);
295}
296
297static int
298omfs_writepages(struct address_space *mapping, struct writeback_control *wbc)
299{
300	return mpage_writepages(mapping, wbc, omfs_get_block);
301}
302
303static void omfs_write_failed(struct address_space *mapping, loff_t to)
304{
305	struct inode *inode = mapping->host;
306
307	if (to > inode->i_size) {
308		truncate_pagecache(inode, inode->i_size);
309		omfs_truncate(inode);
310	}
311}
312
313static int omfs_write_begin(struct file *file, struct address_space *mapping,
314			loff_t pos, unsigned len,
315			struct page **pagep, void **fsdata)
316{
317	int ret;
318
319	ret = block_write_begin(mapping, pos, len, pagep, omfs_get_block);
320	if (unlikely(ret))
321		omfs_write_failed(mapping, pos + len);
322
323	return ret;
324}
325
326static sector_t omfs_bmap(struct address_space *mapping, sector_t block)
327{
328	return generic_block_bmap(mapping, block, omfs_get_block);
329}
330
331const struct file_operations omfs_file_operations = {
332	.llseek = generic_file_llseek,
333	.read_iter = generic_file_read_iter,
334	.write_iter = generic_file_write_iter,
335	.mmap = generic_file_mmap,
336	.fsync = generic_file_fsync,
337	.splice_read = filemap_splice_read,
338};
339
340static int omfs_setattr(struct mnt_idmap *idmap,
341			struct dentry *dentry, struct iattr *attr)
342{
343	struct inode *inode = d_inode(dentry);
344	int error;
345
346	error = setattr_prepare(&nop_mnt_idmap, dentry, attr);
347	if (error)
348		return error;
349
350	if ((attr->ia_valid & ATTR_SIZE) &&
351	    attr->ia_size != i_size_read(inode)) {
352		error = inode_newsize_ok(inode, attr->ia_size);
353		if (error)
354			return error;
355		truncate_setsize(inode, attr->ia_size);
356		omfs_truncate(inode);
357	}
358
359	setattr_copy(&nop_mnt_idmap, inode, attr);
360	mark_inode_dirty(inode);
361	return 0;
362}
363
364const struct inode_operations omfs_file_inops = {
365	.setattr = omfs_setattr,
366};
367
368const struct address_space_operations omfs_aops = {
369	.dirty_folio = block_dirty_folio,
370	.invalidate_folio = block_invalidate_folio,
371	.read_folio = omfs_read_folio,
372	.readahead = omfs_readahead,
373	.writepages = omfs_writepages,
374	.write_begin = omfs_write_begin,
375	.write_end = generic_write_end,
376	.bmap = omfs_bmap,
377	.migrate_folio = buffer_migrate_folio,
378};
379
380