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1/*
2 * OMFS (as used by RIO Karma) file operations.
3 * Copyright (C) 2005 Bob Copeland <me@bobcopeland.com>
4 * Released under GPL v2.
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) + 1;
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.e_cluster = ~cpu_to_be64(0ULL);
28 oe->e_entry.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 entry->e_blocks =
150 cpu_to_be64(be64_to_cpu(entry->e_blocks) + 1);
151 terminator->e_blocks = ~(cpu_to_be64(
152 be64_to_cpu(~terminator->e_blocks) + 1));
153 goto out;
154 }
155 }
156 max_count = omfs_max_extents(sbi, OMFS_EXTENT_START);
157
158 /* TODO: add a continuation block here */
159 if (be32_to_cpu(oe->e_extent_count) > max_count-1)
160 return -EIO;
161
162 /* try to allocate a new cluster */
163 ret = omfs_allocate_range(inode->i_sb, 1, sbi->s_clustersize,
164 &new_block, &new_count);
165 if (ret)
166 goto out_fail;
167
168 /* copy terminator down an entry */
169 entry = terminator;
170 terminator++;
171 memcpy(terminator, entry, sizeof(struct omfs_extent_entry));
172
173 entry->e_cluster = cpu_to_be64(new_block);
174 entry->e_blocks = cpu_to_be64((u64) new_count);
175
176 terminator->e_blocks = ~(cpu_to_be64(
177 be64_to_cpu(~terminator->e_blocks) + (u64) new_count));
178
179 /* write in new entry */
180 oe->e_extent_count = cpu_to_be32(1 + be32_to_cpu(oe->e_extent_count));
181
182out:
183 *ret_block = new_block;
184out_fail:
185 return ret;
186}
187
188/*
189 * Scans across the directory table for a given file block number.
190 * If block not found, return 0.
191 */
192static sector_t find_block(struct inode *inode, struct omfs_extent_entry *ent,
193 sector_t block, int count, int *left)
194{
195 /* count > 1 because of terminator */
196 sector_t searched = 0;
197 for (; count > 1; count--) {
198 int numblocks = clus_to_blk(OMFS_SB(inode->i_sb),
199 be64_to_cpu(ent->e_blocks));
200
201 if (block >= searched &&
202 block < searched + numblocks) {
203 /*
204 * found it at cluster + (block - searched)
205 * numblocks - (block - searched) is remainder
206 */
207 *left = numblocks - (block - searched);
208 return clus_to_blk(OMFS_SB(inode->i_sb),
209 be64_to_cpu(ent->e_cluster)) +
210 block - searched;
211 }
212 searched += numblocks;
213 ent++;
214 }
215 return 0;
216}
217
218static int omfs_get_block(struct inode *inode, sector_t block,
219 struct buffer_head *bh_result, int create)
220{
221 struct buffer_head *bh;
222 sector_t next, offset;
223 int ret;
224 u64 uninitialized_var(new_block);
225 u32 max_extents;
226 int extent_count;
227 struct omfs_extent *oe;
228 struct omfs_extent_entry *entry;
229 struct omfs_sb_info *sbi = OMFS_SB(inode->i_sb);
230 int max_blocks = bh_result->b_size >> inode->i_blkbits;
231 int remain;
232
233 ret = -EIO;
234 bh = omfs_bread(inode->i_sb, inode->i_ino);
235 if (!bh)
236 goto out;
237
238 oe = (struct omfs_extent *)(&bh->b_data[OMFS_EXTENT_START]);
239 max_extents = omfs_max_extents(sbi, OMFS_EXTENT_START);
240 next = inode->i_ino;
241
242 for (;;) {
243
244 if (omfs_is_bad(sbi, (struct omfs_header *) bh->b_data, next))
245 goto out_brelse;
246
247 extent_count = be32_to_cpu(oe->e_extent_count);
248 next = be64_to_cpu(oe->e_next);
249 entry = &oe->e_entry;
250
251 if (extent_count > max_extents)
252 goto out_brelse;
253
254 offset = find_block(inode, entry, block, extent_count, &remain);
255 if (offset > 0) {
256 ret = 0;
257 map_bh(bh_result, inode->i_sb, offset);
258 if (remain > max_blocks)
259 remain = max_blocks;
260 bh_result->b_size = (remain << inode->i_blkbits);
261 goto out_brelse;
262 }
263 if (next == ~0)
264 break;
265
266 brelse(bh);
267 bh = omfs_bread(inode->i_sb, next);
268 if (!bh)
269 goto out;
270 oe = (struct omfs_extent *) (&bh->b_data[OMFS_EXTENT_CONT]);
271 max_extents = omfs_max_extents(sbi, OMFS_EXTENT_CONT);
272 }
273 if (create) {
274 ret = omfs_grow_extent(inode, oe, &new_block);
275 if (ret == 0) {
276 mark_buffer_dirty(bh);
277 mark_inode_dirty(inode);
278 map_bh(bh_result, inode->i_sb,
279 clus_to_blk(sbi, new_block));
280 }
281 }
282out_brelse:
283 brelse(bh);
284out:
285 return ret;
286}
287
288static int omfs_readpage(struct file *file, struct page *page)
289{
290 return block_read_full_page(page, omfs_get_block);
291}
292
293static int omfs_readpages(struct file *file, struct address_space *mapping,
294 struct list_head *pages, unsigned nr_pages)
295{
296 return mpage_readpages(mapping, pages, nr_pages, omfs_get_block);
297}
298
299static int omfs_writepage(struct page *page, struct writeback_control *wbc)
300{
301 return block_write_full_page(page, omfs_get_block, wbc);
302}
303
304static int
305omfs_writepages(struct address_space *mapping, struct writeback_control *wbc)
306{
307 return mpage_writepages(mapping, wbc, omfs_get_block);
308}
309
310static int omfs_write_begin(struct file *file, struct address_space *mapping,
311 loff_t pos, unsigned len, unsigned flags,
312 struct page **pagep, void **fsdata)
313{
314 int ret;
315
316 ret = block_write_begin(mapping, pos, len, flags, pagep,
317 omfs_get_block);
318 if (unlikely(ret)) {
319 loff_t isize = mapping->host->i_size;
320 if (pos + len > isize)
321 vmtruncate(mapping->host, isize);
322 }
323
324 return ret;
325}
326
327static sector_t omfs_bmap(struct address_space *mapping, sector_t block)
328{
329 return generic_block_bmap(mapping, block, omfs_get_block);
330}
331
332const struct file_operations omfs_file_operations = {
333 .llseek = generic_file_llseek,
334 .read = do_sync_read,
335 .write = do_sync_write,
336 .aio_read = generic_file_aio_read,
337 .aio_write = generic_file_aio_write,
338 .mmap = generic_file_mmap,
339 .fsync = generic_file_fsync,
340 .splice_read = generic_file_splice_read,
341};
342
343static int omfs_setattr(struct dentry *dentry, struct iattr *attr)
344{
345 struct inode *inode = dentry->d_inode;
346 int error;
347
348 error = inode_change_ok(inode, attr);
349 if (error)
350 return error;
351
352 if ((attr->ia_valid & ATTR_SIZE) &&
353 attr->ia_size != i_size_read(inode)) {
354 error = vmtruncate(inode, attr->ia_size);
355 if (error)
356 return error;
357 }
358
359 setattr_copy(inode, attr);
360 mark_inode_dirty(inode);
361 return 0;
362}
363
364const struct inode_operations omfs_file_inops = {
365 .setattr = omfs_setattr,
366 .truncate = omfs_truncate
367};
368
369const struct address_space_operations omfs_aops = {
370 .readpage = omfs_readpage,
371 .readpages = omfs_readpages,
372 .writepage = omfs_writepage,
373 .writepages = omfs_writepages,
374 .write_begin = omfs_write_begin,
375 .write_end = generic_write_end,
376 .bmap = omfs_bmap,
377};
378