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
13 static 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
20 void 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
31 int 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;
99 out:
100 return ret;
101 out_brelse:
102 brelse(bh);
103 return ret;
104 }
105
106 static 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 */
116 static 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
181 out:
182 *ret_block = new_block;
183 out_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 */
191 static 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
217 static 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 }
281 out_brelse:
282 brelse(bh);
283 out:
284 return ret;
285 }
286
287 static int omfs_read_folio(struct file *file, struct folio *folio)
288 {
289 return block_read_full_folio(folio, omfs_get_block);
290 }
291
292 static void omfs_readahead(struct readahead_control *rac)
293 {
294 mpage_readahead(rac, omfs_get_block);
295 }
296
297 static int
298 omfs_writepages(struct address_space *mapping, struct writeback_control *wbc)
299 {
300 return mpage_writepages(mapping, wbc, omfs_get_block);
301 }
302
303 static 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
313 static 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
326 static sector_t omfs_bmap(struct address_space *mapping, sector_t block)
327 {
328 return generic_block_bmap(mapping, block, omfs_get_block);
329 }
330
331 const 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
340 static 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
364 const struct inode_operations omfs_file_inops = {
365 .setattr = omfs_setattr,
366 };
367
368 const 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
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