Home Home > GIT Browse
summaryrefslogtreecommitdiff
blob: d640b9388238592762bd890268f01a549c521b2e (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
// SPDX-License-Identifier: GPL-2.0-only
/*
 * OMFS (as used by RIO Karma) file operations.
 * Copyright (C) 2005 Bob Copeland <me@bobcopeland.com>
 */

#include <linux/module.h>
#include <linux/fs.h>
#include <linux/buffer_head.h>
#include <linux/mpage.h>
#include "omfs.h"

static u32 omfs_max_extents(struct omfs_sb_info *sbi, int offset)
{
	return (sbi->s_sys_blocksize - offset -
		sizeof(struct omfs_extent)) /
		sizeof(struct omfs_extent_entry) + 1;
}

void omfs_make_empty_table(struct buffer_head *bh, int offset)
{
	struct omfs_extent *oe = (struct omfs_extent *) &bh->b_data[offset];

	oe->e_next = ~cpu_to_be64(0ULL);
	oe->e_extent_count = cpu_to_be32(1),
	oe->e_fill = cpu_to_be32(0x22),
	oe->e_entry.e_cluster = ~cpu_to_be64(0ULL);
	oe->e_entry.e_blocks = ~cpu_to_be64(0ULL);
}

int omfs_shrink_inode(struct inode *inode)
{
	struct omfs_sb_info *sbi = OMFS_SB(inode->i_sb);
	struct omfs_extent *oe;
	struct omfs_extent_entry *entry;
	struct buffer_head *bh;
	u64 next, last;
	u32 extent_count;
	u32 max_extents;
	int ret;

	/* traverse extent table, freeing each entry that is greater
	 * than inode->i_size;
	 */
	next = inode->i_ino;

	/* only support truncate -> 0 for now */
	ret = -EIO;
	if (inode->i_size != 0)
		goto out;

	bh = omfs_bread(inode->i_sb, next);
	if (!bh)
		goto out;

	oe = (struct omfs_extent *)(&bh->b_data[OMFS_EXTENT_START]);
	max_extents = omfs_max_extents(sbi, OMFS_EXTENT_START);

	for (;;) {

		if (omfs_is_bad(sbi, (struct omfs_header *) bh->b_data, next))
			goto out_brelse;

		extent_count = be32_to_cpu(oe->e_extent_count);

		if (extent_count > max_extents)
			goto out_brelse;

		last = next;
		next = be64_to_cpu(oe->e_next);
		entry = &oe->e_entry;

		/* ignore last entry as it is the terminator */
		for (; extent_count > 1; extent_count--) {
			u64 start, count;
			start = be64_to_cpu(entry->e_cluster);
			count = be64_to_cpu(entry->e_blocks);

			omfs_clear_range(inode->i_sb, start, (int) count);
			entry++;
		}
		omfs_make_empty_table(bh, (char *) oe - bh->b_data);
		mark_buffer_dirty(bh);
		brelse(bh);

		if (last != inode->i_ino)
			omfs_clear_range(inode->i_sb, last, sbi->s_mirrors);

		if (next == ~0)
			break;

		bh = omfs_bread(inode->i_sb, next);
		if (!bh)
			goto out;
		oe = (struct omfs_extent *) (&bh->b_data[OMFS_EXTENT_CONT]);
		max_extents = omfs_max_extents(sbi, OMFS_EXTENT_CONT);
	}
	ret = 0;
out:
	return ret;
out_brelse:
	brelse(bh);
	return ret;
}

static void omfs_truncate(struct inode *inode)
{
	omfs_shrink_inode(inode);
	mark_inode_dirty(inode);
}

/*
 * Add new blocks to the current extent, or create new entries/continuations
 * as necessary.
 */
static int omfs_grow_extent(struct inode *inode, struct omfs_extent *oe,
			u64 *ret_block)
{
	struct omfs_extent_entry *terminator;
	struct omfs_extent_entry *entry = &oe->e_entry;
	struct omfs_sb_info *sbi = OMFS_SB(inode->i_sb);
	u32 extent_count = be32_to_cpu(oe->e_extent_count);
	u64 new_block = 0;
	u32 max_count;
	int new_count;
	int ret = 0;

	/* reached the end of the extent table with no blocks mapped.
	 * there are three possibilities for adding: grow last extent,
	 * add a new extent to the current extent table, and add a
	 * continuation inode.  in last two cases need an allocator for
	 * sbi->s_cluster_size
	 */

	/* TODO: handle holes */

	/* should always have a terminator */
	if (extent_count < 1)
		return -EIO;

	/* trivially grow current extent, if next block is not taken */
	terminator = entry + extent_count - 1;
	if (extent_count > 1) {
		entry = terminator-1;
		new_block = be64_to_cpu(entry->e_cluster) +
			be64_to_cpu(entry->e_blocks);

		if (omfs_allocate_block(inode->i_sb, new_block)) {
			be64_add_cpu(&entry->e_blocks, 1);
			terminator->e_blocks = ~(cpu_to_be64(
				be64_to_cpu(~terminator->e_blocks) + 1));
			goto out;
		}
	}
	max_count = omfs_max_extents(sbi, OMFS_EXTENT_START);

	/* TODO: add a continuation block here */
	if (be32_to_cpu(oe->e_extent_count) > max_count-1)
		return -EIO;

	/* try to allocate a new cluster */
	ret = omfs_allocate_range(inode->i_sb, 1, sbi->s_clustersize,
		&new_block, &new_count);
	if (ret)
		goto out_fail;

	/* copy terminator down an entry */
	entry = terminator;
	terminator++;
	memcpy(terminator, entry, sizeof(struct omfs_extent_entry));

	entry->e_cluster = cpu_to_be64(new_block);
	entry->e_blocks = cpu_to_be64((u64) new_count);

	terminator->e_blocks = ~(cpu_to_be64(
		be64_to_cpu(~terminator->e_blocks) + (u64) new_count));

	/* write in new entry */
	be32_add_cpu(&oe->e_extent_count, 1);

out:
	*ret_block = new_block;
out_fail:
	return ret;
}

/*
 * Scans across the directory table for a given file block number.
 * If block not found, return 0.
 */
static sector_t find_block(struct inode *inode, struct omfs_extent_entry *ent,
			sector_t block, int count, int *left)
{
	/* count > 1 because of terminator */
	sector_t searched = 0;
	for (; count > 1; count--) {
		int numblocks = clus_to_blk(OMFS_SB(inode->i_sb),
			be64_to_cpu(ent->e_blocks));

		if (block >= searched  &&
		    block < searched + numblocks) {
			/*
			 * found it at cluster + (block - searched)
			 * numblocks - (block - searched) is remainder
			 */
			*left = numblocks - (block - searched);
			return clus_to_blk(OMFS_SB(inode->i_sb),
				be64_to_cpu(ent->e_cluster)) +
				block - searched;
		}
		searched += numblocks;
		ent++;
	}
	return 0;
}

static int omfs_get_block(struct inode *inode, sector_t block,
			  struct buffer_head *bh_result, int create)
{
	struct buffer_head *bh;
	sector_t next, offset;
	int ret;
	u64 uninitialized_var(new_block);
	u32 max_extents;
	int extent_count;
	struct omfs_extent *oe;
	struct omfs_extent_entry *entry;
	struct omfs_sb_info *sbi = OMFS_SB(inode->i_sb);
	int max_blocks = bh_result->b_size >> inode->i_blkbits;
	int remain;

	ret = -EIO;
	bh = omfs_bread(inode->i_sb, inode->i_ino);
	if (!bh)
		goto out;

	oe = (struct omfs_extent *)(&bh->b_data[OMFS_EXTENT_START]);
	max_extents = omfs_max_extents(sbi, OMFS_EXTENT_START);
	next = inode->i_ino;

	for (;;) {

		if (omfs_is_bad(sbi, (struct omfs_header *) bh->b_data, next))
			goto out_brelse;

		extent_count = be32_to_cpu(oe->e_extent_count);
		next = be64_to_cpu(oe->e_next);
		entry = &oe->e_entry;

		if (extent_count > max_extents)
			goto out_brelse;

		offset = find_block(inode, entry, block, extent_count, &remain);
		if (offset > 0) {
			ret = 0;
			map_bh(bh_result, inode->i_sb, offset);
			if (remain > max_blocks)
				remain = max_blocks;
			bh_result->b_size = (remain << inode->i_blkbits);
			goto out_brelse;
		}
		if (next == ~0)
			break;

		brelse(bh);
		bh = omfs_bread(inode->i_sb, next);
		if (!bh)
			goto out;
		oe = (struct omfs_extent *) (&bh->b_data[OMFS_EXTENT_CONT]);
		max_extents = omfs_max_extents(sbi, OMFS_EXTENT_CONT);
	}
	if (create) {
		ret = omfs_grow_extent(inode, oe, &new_block);
		if (ret == 0) {
			mark_buffer_dirty(bh);
			mark_inode_dirty(inode);
			map_bh(bh_result, inode->i_sb,
					clus_to_blk(sbi, new_block));
		}
	}
out_brelse:
	brelse(bh);
out:
	return ret;
}

static int omfs_readpage(struct file *file, struct page *page)
{
	return block_read_full_page(page, omfs_get_block);
}

static int omfs_readpages(struct file *file, struct address_space *mapping,
		struct list_head *pages, unsigned nr_pages)
{
	return mpage_readpages(mapping, pages, nr_pages, omfs_get_block);
}

static int omfs_writepage(struct page *page, struct writeback_control *wbc)
{
	return block_write_full_page(page, omfs_get_block, wbc);
}

static int
omfs_writepages(struct address_space *mapping, struct writeback_control *wbc)
{
	return mpage_writepages(mapping, wbc, omfs_get_block);
}

static void omfs_write_failed(struct address_space *mapping, loff_t to)
{
	struct inode *inode = mapping->host;

	if (to > inode->i_size) {
		truncate_pagecache(inode, inode->i_size);
		omfs_truncate(inode);
	}
}

static int omfs_write_begin(struct file *file, struct address_space *mapping,
			loff_t pos, unsigned len, unsigned flags,
			struct page **pagep, void **fsdata)
{
	int ret;

	ret = block_write_begin(mapping, pos, len, flags, pagep,
				omfs_get_block);
	if (unlikely(ret))
		omfs_write_failed(mapping, pos + len);

	return ret;
}

static sector_t omfs_bmap(struct address_space *mapping, sector_t block)
{
	return generic_block_bmap(mapping, block, omfs_get_block);
}

const struct file_operations omfs_file_operations = {
	.llseek = generic_file_llseek,
	.read_iter = generic_file_read_iter,
	.write_iter = generic_file_write_iter,
	.mmap = generic_file_mmap,
	.fsync = generic_file_fsync,
	.splice_read = generic_file_splice_read,
};

static int omfs_setattr(struct dentry *dentry, struct iattr *attr)
{
	struct inode *inode = d_inode(dentry);
	int error;

	error = setattr_prepare(dentry, attr);
	if (error)
		return error;

	if ((attr->ia_valid & ATTR_SIZE) &&
	    attr->ia_size != i_size_read(inode)) {
		error = inode_newsize_ok(inode, attr->ia_size);
		if (error)
			return error;
		truncate_setsize(inode, attr->ia_size);
		omfs_truncate(inode);
	}

	setattr_copy(inode, attr);
	mark_inode_dirty(inode);
	return 0;
}

const struct inode_operations omfs_file_inops = {
	.setattr = omfs_setattr,
};

const struct address_space_operations omfs_aops = {
	.readpage = omfs_readpage,
	.readpages = omfs_readpages,
	.writepage = omfs_writepage,
	.writepages = omfs_writepages,
	.write_begin = omfs_write_begin,
	.write_end = generic_write_end,
	.bmap = omfs_bmap,
};