1 | // SPDX-License-Identifier: GPL-2.0 |
2 | /* |
3 | * linux/fs/affs/bitmap.c |
4 | * |
5 | * (c) 1996 Hans-Joachim Widmaier |
6 | * |
7 | * bitmap.c contains the code that handles all bitmap related stuff - |
8 | * block allocation, deallocation, calculation of free space. |
9 | */ |
10 | |
11 | #include <linux/slab.h> |
12 | #include "affs.h" |
13 | |
14 | u32 |
15 | affs_count_free_blocks(struct super_block *sb) |
16 | { |
17 | struct affs_bm_info *bm; |
18 | u32 free; |
19 | int i; |
20 | |
21 | pr_debug("%s()\n" , __func__); |
22 | |
23 | if (sb_rdonly(sb)) |
24 | return 0; |
25 | |
26 | mutex_lock(&AFFS_SB(sb)->s_bmlock); |
27 | |
28 | bm = AFFS_SB(sb)->s_bitmap; |
29 | free = 0; |
30 | for (i = AFFS_SB(sb)->s_bmap_count; i > 0; bm++, i--) |
31 | free += bm->bm_free; |
32 | |
33 | mutex_unlock(lock: &AFFS_SB(sb)->s_bmlock); |
34 | |
35 | return free; |
36 | } |
37 | |
38 | void |
39 | affs_free_block(struct super_block *sb, u32 block) |
40 | { |
41 | struct affs_sb_info *sbi = AFFS_SB(sb); |
42 | struct affs_bm_info *bm; |
43 | struct buffer_head *bh; |
44 | u32 blk, bmap, bit, mask, tmp; |
45 | __be32 *data; |
46 | |
47 | pr_debug("%s(%u)\n" , __func__, block); |
48 | |
49 | if (block > sbi->s_partition_size) |
50 | goto err_range; |
51 | |
52 | blk = block - sbi->s_reserved; |
53 | bmap = blk / sbi->s_bmap_bits; |
54 | bit = blk % sbi->s_bmap_bits; |
55 | bm = &sbi->s_bitmap[bmap]; |
56 | |
57 | mutex_lock(&sbi->s_bmlock); |
58 | |
59 | bh = sbi->s_bmap_bh; |
60 | if (sbi->s_last_bmap != bmap) { |
61 | affs_brelse(bh); |
62 | bh = affs_bread(sb, block: bm->bm_key); |
63 | if (!bh) |
64 | goto err_bh_read; |
65 | sbi->s_bmap_bh = bh; |
66 | sbi->s_last_bmap = bmap; |
67 | } |
68 | |
69 | mask = 1 << (bit & 31); |
70 | data = (__be32 *)bh->b_data + bit / 32 + 1; |
71 | |
72 | /* mark block free */ |
73 | tmp = be32_to_cpu(*data); |
74 | if (tmp & mask) |
75 | goto err_free; |
76 | *data = cpu_to_be32(tmp | mask); |
77 | |
78 | /* fix checksum */ |
79 | tmp = be32_to_cpu(*(__be32 *)bh->b_data); |
80 | *(__be32 *)bh->b_data = cpu_to_be32(tmp - mask); |
81 | |
82 | mark_buffer_dirty(bh); |
83 | affs_mark_sb_dirty(sb); |
84 | bm->bm_free++; |
85 | |
86 | mutex_unlock(lock: &sbi->s_bmlock); |
87 | return; |
88 | |
89 | err_free: |
90 | affs_warning(sb,function: "affs_free_block" ,fmt: "Trying to free block %u which is already free" , block); |
91 | mutex_unlock(lock: &sbi->s_bmlock); |
92 | return; |
93 | |
94 | err_bh_read: |
95 | affs_error(sb,function: "affs_free_block" ,fmt: "Cannot read bitmap block %u" , bm->bm_key); |
96 | sbi->s_bmap_bh = NULL; |
97 | sbi->s_last_bmap = ~0; |
98 | mutex_unlock(lock: &sbi->s_bmlock); |
99 | return; |
100 | |
101 | err_range: |
102 | affs_error(sb, function: "affs_free_block" ,fmt: "Block %u outside partition" , block); |
103 | } |
104 | |
105 | /* |
106 | * Allocate a block in the given allocation zone. |
107 | * Since we have to byte-swap the bitmap on little-endian |
108 | * machines, this is rather expensive. Therefore we will |
109 | * preallocate up to 16 blocks from the same word, if |
110 | * possible. We are not doing preallocations in the |
111 | * header zone, though. |
112 | */ |
113 | |
114 | u32 |
115 | affs_alloc_block(struct inode *inode, u32 goal) |
116 | { |
117 | struct super_block *sb; |
118 | struct affs_sb_info *sbi; |
119 | struct affs_bm_info *bm; |
120 | struct buffer_head *bh; |
121 | __be32 *data, *enddata; |
122 | u32 blk, bmap, bit, mask, mask2, tmp; |
123 | int i; |
124 | |
125 | sb = inode->i_sb; |
126 | sbi = AFFS_SB(sb); |
127 | |
128 | pr_debug("balloc(inode=%lu,goal=%u): " , inode->i_ino, goal); |
129 | |
130 | if (AFFS_I(inode)->i_pa_cnt) { |
131 | pr_debug("%d\n" , AFFS_I(inode)->i_lastalloc+1); |
132 | AFFS_I(inode)->i_pa_cnt--; |
133 | return ++AFFS_I(inode)->i_lastalloc; |
134 | } |
135 | |
136 | if (!goal || goal > sbi->s_partition_size) { |
137 | if (goal) |
138 | affs_warning(sb, function: "affs_balloc" , fmt: "invalid goal %d" , goal); |
139 | //if (!AFFS_I(inode)->i_last_block) |
140 | // affs_warning(sb, "affs_balloc", "no last alloc block"); |
141 | goal = sbi->s_reserved; |
142 | } |
143 | |
144 | blk = goal - sbi->s_reserved; |
145 | bmap = blk / sbi->s_bmap_bits; |
146 | bm = &sbi->s_bitmap[bmap]; |
147 | |
148 | mutex_lock(&sbi->s_bmlock); |
149 | |
150 | if (bm->bm_free) |
151 | goto find_bmap_bit; |
152 | |
153 | find_bmap: |
154 | /* search for the next bmap buffer with free bits */ |
155 | i = sbi->s_bmap_count; |
156 | do { |
157 | if (--i < 0) |
158 | goto err_full; |
159 | bmap++; |
160 | bm++; |
161 | if (bmap < sbi->s_bmap_count) |
162 | continue; |
163 | /* restart search at zero */ |
164 | bmap = 0; |
165 | bm = sbi->s_bitmap; |
166 | } while (!bm->bm_free); |
167 | blk = bmap * sbi->s_bmap_bits; |
168 | |
169 | find_bmap_bit: |
170 | |
171 | bh = sbi->s_bmap_bh; |
172 | if (sbi->s_last_bmap != bmap) { |
173 | affs_brelse(bh); |
174 | bh = affs_bread(sb, block: bm->bm_key); |
175 | if (!bh) |
176 | goto err_bh_read; |
177 | sbi->s_bmap_bh = bh; |
178 | sbi->s_last_bmap = bmap; |
179 | } |
180 | |
181 | /* find an unused block in this bitmap block */ |
182 | bit = blk % sbi->s_bmap_bits; |
183 | data = (__be32 *)bh->b_data + bit / 32 + 1; |
184 | enddata = (__be32 *)((u8 *)bh->b_data + sb->s_blocksize); |
185 | mask = ~0UL << (bit & 31); |
186 | blk &= ~31UL; |
187 | |
188 | tmp = be32_to_cpu(*data); |
189 | if (tmp & mask) |
190 | goto find_bit; |
191 | |
192 | /* scan the rest of the buffer */ |
193 | do { |
194 | blk += 32; |
195 | if (++data >= enddata) |
196 | /* didn't find something, can only happen |
197 | * if scan didn't start at 0, try next bmap |
198 | */ |
199 | goto find_bmap; |
200 | } while (!*data); |
201 | tmp = be32_to_cpu(*data); |
202 | mask = ~0; |
203 | |
204 | find_bit: |
205 | /* finally look for a free bit in the word */ |
206 | bit = ffs(tmp & mask) - 1; |
207 | blk += bit + sbi->s_reserved; |
208 | mask2 = mask = 1 << (bit & 31); |
209 | AFFS_I(inode)->i_lastalloc = blk; |
210 | |
211 | /* prealloc as much as possible within this word */ |
212 | while ((mask2 <<= 1)) { |
213 | if (!(tmp & mask2)) |
214 | break; |
215 | AFFS_I(inode)->i_pa_cnt++; |
216 | mask |= mask2; |
217 | } |
218 | bm->bm_free -= AFFS_I(inode)->i_pa_cnt + 1; |
219 | |
220 | *data = cpu_to_be32(tmp & ~mask); |
221 | |
222 | /* fix checksum */ |
223 | tmp = be32_to_cpu(*(__be32 *)bh->b_data); |
224 | *(__be32 *)bh->b_data = cpu_to_be32(tmp + mask); |
225 | |
226 | mark_buffer_dirty(bh); |
227 | affs_mark_sb_dirty(sb); |
228 | |
229 | mutex_unlock(lock: &sbi->s_bmlock); |
230 | |
231 | pr_debug("%d\n" , blk); |
232 | return blk; |
233 | |
234 | err_bh_read: |
235 | affs_error(sb,function: "affs_read_block" ,fmt: "Cannot read bitmap block %u" , bm->bm_key); |
236 | sbi->s_bmap_bh = NULL; |
237 | sbi->s_last_bmap = ~0; |
238 | err_full: |
239 | mutex_unlock(lock: &sbi->s_bmlock); |
240 | pr_debug("failed\n" ); |
241 | return 0; |
242 | } |
243 | |
244 | int affs_init_bitmap(struct super_block *sb, int *flags) |
245 | { |
246 | struct affs_bm_info *bm; |
247 | struct buffer_head *bmap_bh = NULL, *bh = NULL; |
248 | __be32 *bmap_blk; |
249 | u32 size, blk, end, offset, mask; |
250 | int i, res = 0; |
251 | struct affs_sb_info *sbi = AFFS_SB(sb); |
252 | |
253 | if (*flags & SB_RDONLY) |
254 | return 0; |
255 | |
256 | if (!AFFS_ROOT_TAIL(sb, sbi->s_root_bh)->bm_flag) { |
257 | pr_notice("Bitmap invalid - mounting %s read only\n" , sb->s_id); |
258 | *flags |= SB_RDONLY; |
259 | return 0; |
260 | } |
261 | |
262 | sbi->s_last_bmap = ~0; |
263 | sbi->s_bmap_bh = NULL; |
264 | sbi->s_bmap_bits = sb->s_blocksize * 8 - 32; |
265 | sbi->s_bmap_count = (sbi->s_partition_size - sbi->s_reserved + |
266 | sbi->s_bmap_bits - 1) / sbi->s_bmap_bits; |
267 | size = sbi->s_bmap_count * sizeof(*bm); |
268 | bm = sbi->s_bitmap = kzalloc(size, GFP_KERNEL); |
269 | if (!sbi->s_bitmap) { |
270 | pr_err("Bitmap allocation failed\n" ); |
271 | return -ENOMEM; |
272 | } |
273 | |
274 | bmap_blk = (__be32 *)sbi->s_root_bh->b_data; |
275 | blk = sb->s_blocksize / 4 - 49; |
276 | end = blk + 25; |
277 | |
278 | for (i = sbi->s_bmap_count; i > 0; bm++, i--) { |
279 | affs_brelse(bh); |
280 | |
281 | bm->bm_key = be32_to_cpu(bmap_blk[blk]); |
282 | bh = affs_bread(sb, block: bm->bm_key); |
283 | if (!bh) { |
284 | pr_err("Cannot read bitmap\n" ); |
285 | res = -EIO; |
286 | goto out; |
287 | } |
288 | if (affs_checksum_block(sb, bh)) { |
289 | pr_warn("Bitmap %u invalid - mounting %s read only.\n" , |
290 | bm->bm_key, sb->s_id); |
291 | *flags |= SB_RDONLY; |
292 | goto out; |
293 | } |
294 | pr_debug("read bitmap block %d: %d\n" , blk, bm->bm_key); |
295 | bm->bm_free = memweight(ptr: bh->b_data + 4, bytes: sb->s_blocksize - 4); |
296 | |
297 | /* Don't try read the extension if this is the last block, |
298 | * but we also need the right bm pointer below |
299 | */ |
300 | if (++blk < end || i == 1) |
301 | continue; |
302 | if (bmap_bh) |
303 | affs_brelse(bh: bmap_bh); |
304 | bmap_bh = affs_bread(sb, be32_to_cpu(bmap_blk[blk])); |
305 | if (!bmap_bh) { |
306 | pr_err("Cannot read bitmap extension\n" ); |
307 | res = -EIO; |
308 | goto out; |
309 | } |
310 | bmap_blk = (__be32 *)bmap_bh->b_data; |
311 | blk = 0; |
312 | end = sb->s_blocksize / 4 - 1; |
313 | } |
314 | |
315 | offset = (sbi->s_partition_size - sbi->s_reserved) % sbi->s_bmap_bits; |
316 | mask = ~(0xFFFFFFFFU << (offset & 31)); |
317 | pr_debug("last word: %d %d %d\n" , offset, offset / 32 + 1, mask); |
318 | offset = offset / 32 + 1; |
319 | |
320 | if (mask) { |
321 | u32 old, new; |
322 | |
323 | /* Mark unused bits in the last word as allocated */ |
324 | old = be32_to_cpu(((__be32 *)bh->b_data)[offset]); |
325 | new = old & mask; |
326 | //if (old != new) { |
327 | ((__be32 *)bh->b_data)[offset] = cpu_to_be32(new); |
328 | /* fix checksum */ |
329 | //new -= old; |
330 | //old = be32_to_cpu(*(__be32 *)bh->b_data); |
331 | //*(__be32 *)bh->b_data = cpu_to_be32(old - new); |
332 | //mark_buffer_dirty(bh); |
333 | //} |
334 | /* correct offset for the bitmap count below */ |
335 | //offset++; |
336 | } |
337 | while (++offset < sb->s_blocksize / 4) |
338 | ((__be32 *)bh->b_data)[offset] = 0; |
339 | ((__be32 *)bh->b_data)[0] = 0; |
340 | ((__be32 *)bh->b_data)[0] = cpu_to_be32(-affs_checksum_block(sb, bh)); |
341 | mark_buffer_dirty(bh); |
342 | |
343 | /* recalculate bitmap count for last block */ |
344 | bm--; |
345 | bm->bm_free = memweight(ptr: bh->b_data + 4, bytes: sb->s_blocksize - 4); |
346 | |
347 | out: |
348 | affs_brelse(bh); |
349 | affs_brelse(bh: bmap_bh); |
350 | return res; |
351 | } |
352 | |
353 | void affs_free_bitmap(struct super_block *sb) |
354 | { |
355 | struct affs_sb_info *sbi = AFFS_SB(sb); |
356 | |
357 | if (!sbi->s_bitmap) |
358 | return; |
359 | |
360 | affs_brelse(bh: sbi->s_bmap_bh); |
361 | sbi->s_bmap_bh = NULL; |
362 | sbi->s_last_bmap = ~0; |
363 | kfree(objp: sbi->s_bitmap); |
364 | sbi->s_bitmap = NULL; |
365 | } |
366 | |