Commit | Line | Data |
---|---|---|
ac27a0ec | 1 | /* |
617ba13b | 2 | * linux/fs/ext4/balloc.c |
ac27a0ec DK |
3 | * |
4 | * Copyright (C) 1992, 1993, 1994, 1995 | |
5 | * Remy Card (card@masi.ibp.fr) | |
6 | * Laboratoire MASI - Institut Blaise Pascal | |
7 | * Universite Pierre et Marie Curie (Paris VI) | |
8 | * | |
9 | * Enhanced block allocation by Stephen Tweedie (sct@redhat.com), 1993 | |
10 | * Big-endian to little-endian byte-swapping/bitmaps by | |
11 | * David S. Miller (davem@caip.rutgers.edu), 1995 | |
12 | */ | |
13 | ||
14 | #include <linux/time.h> | |
15 | #include <linux/capability.h> | |
16 | #include <linux/fs.h> | |
ac27a0ec DK |
17 | #include <linux/quotaops.h> |
18 | #include <linux/buffer_head.h> | |
3dcf5451 CH |
19 | #include "ext4.h" |
20 | #include "ext4_jbd2.h" | |
e21675d4 | 21 | #include "mballoc.h" |
3dcf5451 | 22 | |
0562e0ba JZ |
23 | #include <trace/events/ext4.h> |
24 | ||
5f163cc7 ES |
25 | static unsigned ext4_num_base_meta_clusters(struct super_block *sb, |
26 | ext4_group_t block_group); | |
ac27a0ec DK |
27 | /* |
28 | * balloc.c contains the blocks allocation and deallocation routines | |
29 | */ | |
30 | ||
bd86298e LC |
31 | /* |
32 | * Calculate block group number for a given block number | |
33 | */ | |
34 | ext4_group_t ext4_get_group_number(struct super_block *sb, | |
35 | ext4_fsblk_t block) | |
36 | { | |
37 | ext4_group_t group; | |
38 | ||
39 | if (test_opt2(sb, STD_GROUP_SIZE)) | |
960fd856 TT |
40 | group = (block - |
41 | le32_to_cpu(EXT4_SB(sb)->s_es->s_first_data_block)) >> | |
bd86298e LC |
42 | (EXT4_BLOCK_SIZE_BITS(sb) + EXT4_CLUSTER_BITS(sb) + 3); |
43 | else | |
44 | ext4_get_group_no_and_offset(sb, block, &group, NULL); | |
45 | return group; | |
46 | } | |
47 | ||
72b64b59 | 48 | /* |
3212a80a TT |
49 | * Calculate the block group number and offset into the block/cluster |
50 | * allocation bitmap, given a block number | |
72b64b59 AM |
51 | */ |
52 | void ext4_get_group_no_and_offset(struct super_block *sb, ext4_fsblk_t blocknr, | |
fd2d4291 | 53 | ext4_group_t *blockgrpp, ext4_grpblk_t *offsetp) |
72b64b59 | 54 | { |
8c55e204 | 55 | struct ext4_super_block *es = EXT4_SB(sb)->s_es; |
72b64b59 AM |
56 | ext4_grpblk_t offset; |
57 | ||
8c55e204 | 58 | blocknr = blocknr - le32_to_cpu(es->s_first_data_block); |
3212a80a TT |
59 | offset = do_div(blocknr, EXT4_BLOCKS_PER_GROUP(sb)) >> |
60 | EXT4_SB(sb)->s_cluster_bits; | |
72b64b59 AM |
61 | if (offsetp) |
62 | *offsetp = offset; | |
63 | if (blockgrpp) | |
8c55e204 | 64 | *blockgrpp = blocknr; |
72b64b59 AM |
65 | |
66 | } | |
67 | ||
68911009 LC |
68 | /* |
69 | * Check whether the 'block' lives within the 'block_group'. Returns 1 if so | |
70 | * and 0 otherwise. | |
71 | */ | |
72 | static inline int ext4_block_in_group(struct super_block *sb, | |
73 | ext4_fsblk_t block, | |
74 | ext4_group_t block_group) | |
0bf7e837 JS |
75 | { |
76 | ext4_group_t actual_group; | |
68911009 | 77 | |
bd86298e | 78 | actual_group = ext4_get_group_number(sb, block); |
68911009 | 79 | return (actual_group == block_group) ? 1 : 0; |
0bf7e837 JS |
80 | } |
81 | ||
d5b8f310 TT |
82 | /* Return the number of clusters used for file system metadata; this |
83 | * represents the overhead needed by the file system. | |
84 | */ | |
c197855e SH |
85 | static unsigned ext4_num_overhead_clusters(struct super_block *sb, |
86 | ext4_group_t block_group, | |
87 | struct ext4_group_desc *gdp) | |
0bf7e837 | 88 | { |
d5b8f310 TT |
89 | unsigned num_clusters; |
90 | int block_cluster = -1, inode_cluster = -1, itbl_cluster = -1, i, c; | |
91 | ext4_fsblk_t start = ext4_group_first_block_no(sb, block_group); | |
92 | ext4_fsblk_t itbl_blk; | |
0bf7e837 | 93 | struct ext4_sb_info *sbi = EXT4_SB(sb); |
0bf7e837 | 94 | |
d5b8f310 TT |
95 | /* This is the number of clusters used by the superblock, |
96 | * block group descriptors, and reserved block group | |
97 | * descriptor blocks */ | |
98 | num_clusters = ext4_num_base_meta_clusters(sb, block_group); | |
99 | ||
100 | /* | |
101 | * For the allocation bitmaps and inode table, we first need | |
102 | * to check to see if the block is in the block group. If it | |
103 | * is, then check to see if the cluster is already accounted | |
104 | * for in the clusters used for the base metadata cluster, or | |
105 | * if we can increment the base metadata cluster to include | |
106 | * that block. Otherwise, we will have to track the cluster | |
107 | * used for the allocation bitmap or inode table explicitly. | |
108 | * Normally all of these blocks are contiguous, so the special | |
109 | * case handling shouldn't be necessary except for *very* | |
110 | * unusual file system layouts. | |
111 | */ | |
112 | if (ext4_block_in_group(sb, ext4_block_bitmap(sb, gdp), block_group)) { | |
b0dd6b70 TT |
113 | block_cluster = EXT4_B2C(sbi, |
114 | ext4_block_bitmap(sb, gdp) - start); | |
d5b8f310 TT |
115 | if (block_cluster < num_clusters) |
116 | block_cluster = -1; | |
117 | else if (block_cluster == num_clusters) { | |
118 | num_clusters++; | |
119 | block_cluster = -1; | |
120 | } | |
121 | } | |
122 | ||
123 | if (ext4_block_in_group(sb, ext4_inode_bitmap(sb, gdp), block_group)) { | |
124 | inode_cluster = EXT4_B2C(sbi, | |
b0dd6b70 | 125 | ext4_inode_bitmap(sb, gdp) - start); |
d5b8f310 TT |
126 | if (inode_cluster < num_clusters) |
127 | inode_cluster = -1; | |
128 | else if (inode_cluster == num_clusters) { | |
129 | num_clusters++; | |
130 | inode_cluster = -1; | |
131 | } | |
132 | } | |
133 | ||
134 | itbl_blk = ext4_inode_table(sb, gdp); | |
135 | for (i = 0; i < sbi->s_itb_per_group; i++) { | |
136 | if (ext4_block_in_group(sb, itbl_blk + i, block_group)) { | |
b0dd6b70 | 137 | c = EXT4_B2C(sbi, itbl_blk + i - start); |
d5b8f310 TT |
138 | if ((c < num_clusters) || (c == inode_cluster) || |
139 | (c == block_cluster) || (c == itbl_cluster)) | |
140 | continue; | |
141 | if (c == num_clusters) { | |
142 | num_clusters++; | |
143 | continue; | |
144 | } | |
145 | num_clusters++; | |
146 | itbl_cluster = c; | |
0bf7e837 JS |
147 | } |
148 | } | |
d5b8f310 TT |
149 | |
150 | if (block_cluster != -1) | |
151 | num_clusters++; | |
152 | if (inode_cluster != -1) | |
153 | num_clusters++; | |
154 | ||
155 | return num_clusters; | |
0bf7e837 | 156 | } |
c2ea3fde | 157 | |
d5b8f310 TT |
158 | static unsigned int num_clusters_in_group(struct super_block *sb, |
159 | ext4_group_t block_group) | |
49f7f9af | 160 | { |
d5b8f310 TT |
161 | unsigned int blocks; |
162 | ||
49f7f9af TT |
163 | if (block_group == ext4_get_groups_count(sb) - 1) { |
164 | /* | |
165 | * Even though mke2fs always initializes the first and | |
166 | * last group, just in case some other tool was used, | |
167 | * we need to make sure we calculate the right free | |
168 | * blocks. | |
169 | */ | |
d5b8f310 | 170 | blocks = ext4_blocks_count(EXT4_SB(sb)->s_es) - |
49f7f9af TT |
171 | ext4_group_first_block_no(sb, block_group); |
172 | } else | |
d5b8f310 TT |
173 | blocks = EXT4_BLOCKS_PER_GROUP(sb); |
174 | return EXT4_NUM_B2C(EXT4_SB(sb), blocks); | |
49f7f9af TT |
175 | } |
176 | ||
fd034a84 | 177 | /* Initializes an uninitialized block bitmap */ |
aef4885a | 178 | static int ext4_init_block_bitmap(struct super_block *sb, |
c197855e SH |
179 | struct buffer_head *bh, |
180 | ext4_group_t block_group, | |
181 | struct ext4_group_desc *gdp) | |
717d50e4 | 182 | { |
d5b8f310 | 183 | unsigned int bit, bit_max; |
717d50e4 | 184 | struct ext4_sb_info *sbi = EXT4_SB(sb); |
fd034a84 TT |
185 | ext4_fsblk_t start, tmp; |
186 | int flex_bg = 0; | |
bdfb6ff4 | 187 | struct ext4_group_info *grp; |
fd034a84 TT |
188 | |
189 | J_ASSERT_BH(bh, buffer_locked(bh)); | |
190 | ||
191 | /* If checksum is bad mark all blocks used to prevent allocation | |
192 | * essentially implementing a per-group read-only flag. */ | |
feb0ab32 | 193 | if (!ext4_group_desc_csum_verify(sb, block_group, gdp)) { |
bdfb6ff4 | 194 | grp = ext4_get_group_info(sb, block_group); |
e43bb4e6 NJ |
195 | if (!EXT4_MB_GRP_BBITMAP_CORRUPT(grp)) |
196 | percpu_counter_sub(&sbi->s_freeclusters_counter, | |
197 | grp->bb_free); | |
bdfb6ff4 | 198 | set_bit(EXT4_GROUP_INFO_BBITMAP_CORRUPT_BIT, &grp->bb_state); |
e43bb4e6 NJ |
199 | if (!EXT4_MB_GRP_IBITMAP_CORRUPT(grp)) { |
200 | int count; | |
201 | count = ext4_free_inodes_count(sb, gdp); | |
202 | percpu_counter_sub(&sbi->s_freeinodes_counter, | |
203 | count); | |
204 | } | |
bdfb6ff4 | 205 | set_bit(EXT4_GROUP_INFO_IBITMAP_CORRUPT_BIT, &grp->bb_state); |
6a797d27 | 206 | return -EFSBADCRC; |
717d50e4 | 207 | } |
fd034a84 | 208 | memset(bh->b_data, 0, sb->s_blocksize); |
717d50e4 | 209 | |
d5b8f310 | 210 | bit_max = ext4_num_base_meta_clusters(sb, block_group); |
fd034a84 TT |
211 | for (bit = 0; bit < bit_max; bit++) |
212 | ext4_set_bit(bit, bh->b_data); | |
d00a6d7b | 213 | |
fd034a84 | 214 | start = ext4_group_first_block_no(sb, block_group); |
717d50e4 | 215 | |
e2b911c5 | 216 | if (ext4_has_feature_flex_bg(sb)) |
fd034a84 | 217 | flex_bg = 1; |
717d50e4 | 218 | |
fd034a84 TT |
219 | /* Set bits for block and inode bitmaps, and inode table */ |
220 | tmp = ext4_block_bitmap(sb, gdp); | |
221 | if (!flex_bg || ext4_block_in_group(sb, tmp, block_group)) | |
d5b8f310 | 222 | ext4_set_bit(EXT4_B2C(sbi, tmp - start), bh->b_data); |
717d50e4 | 223 | |
fd034a84 TT |
224 | tmp = ext4_inode_bitmap(sb, gdp); |
225 | if (!flex_bg || ext4_block_in_group(sb, tmp, block_group)) | |
d5b8f310 | 226 | ext4_set_bit(EXT4_B2C(sbi, tmp - start), bh->b_data); |
0bf7e837 | 227 | |
fd034a84 TT |
228 | tmp = ext4_inode_table(sb, gdp); |
229 | for (; tmp < ext4_inode_table(sb, gdp) + | |
230 | sbi->s_itb_per_group; tmp++) { | |
0bf7e837 | 231 | if (!flex_bg || ext4_block_in_group(sb, tmp, block_group)) |
d5b8f310 | 232 | ext4_set_bit(EXT4_B2C(sbi, tmp - start), bh->b_data); |
717d50e4 | 233 | } |
d5b8f310 | 234 | |
fd034a84 TT |
235 | /* |
236 | * Also if the number of blocks within the group is less than | |
237 | * the blocksize * 8 ( which is the size of bitmap ), set rest | |
238 | * of the block bitmap to 1 | |
239 | */ | |
d5b8f310 | 240 | ext4_mark_bitmap_end(num_clusters_in_group(sb, block_group), |
fd034a84 | 241 | sb->s_blocksize * 8, bh->b_data); |
79f1ba49 | 242 | ext4_block_bitmap_csum_set(sb, block_group, gdp, bh); |
feb0ab32 | 243 | ext4_group_desc_csum_set(sb, block_group, gdp); |
aef4885a | 244 | return 0; |
717d50e4 AD |
245 | } |
246 | ||
fd034a84 TT |
247 | /* Return the number of free blocks in a block group. It is used when |
248 | * the block bitmap is uninitialized, so we can't just count the bits | |
249 | * in the bitmap. */ | |
cff1dfd7 TT |
250 | unsigned ext4_free_clusters_after_init(struct super_block *sb, |
251 | ext4_group_t block_group, | |
252 | struct ext4_group_desc *gdp) | |
fd034a84 | 253 | { |
d5b8f310 TT |
254 | return num_clusters_in_group(sb, block_group) - |
255 | ext4_num_overhead_clusters(sb, block_group, gdp); | |
fd034a84 | 256 | } |
717d50e4 | 257 | |
ac27a0ec DK |
258 | /* |
259 | * The free blocks are managed by bitmaps. A file system contains several | |
260 | * blocks groups. Each group contains 1 bitmap block for blocks, 1 bitmap | |
261 | * block for inodes, N blocks for the inode table and data blocks. | |
262 | * | |
263 | * The file system contains group descriptors which are located after the | |
264 | * super block. Each descriptor contains the number of the bitmap block and | |
265 | * the free blocks count in the block. The descriptors are loaded in memory | |
e627432c | 266 | * when a file system is mounted (see ext4_fill_super). |
ac27a0ec DK |
267 | */ |
268 | ||
ac27a0ec | 269 | /** |
617ba13b | 270 | * ext4_get_group_desc() -- load group descriptor from disk |
ac27a0ec DK |
271 | * @sb: super block |
272 | * @block_group: given block group | |
273 | * @bh: pointer to the buffer head to store the block | |
274 | * group descriptor | |
275 | */ | |
af5bc92d | 276 | struct ext4_group_desc * ext4_get_group_desc(struct super_block *sb, |
fd2d4291 | 277 | ext4_group_t block_group, |
af5bc92d | 278 | struct buffer_head **bh) |
ac27a0ec | 279 | { |
498e5f24 TT |
280 | unsigned int group_desc; |
281 | unsigned int offset; | |
8df9675f | 282 | ext4_group_t ngroups = ext4_get_groups_count(sb); |
af5bc92d | 283 | struct ext4_group_desc *desc; |
617ba13b | 284 | struct ext4_sb_info *sbi = EXT4_SB(sb); |
ac27a0ec | 285 | |
8df9675f | 286 | if (block_group >= ngroups) { |
12062ddd ES |
287 | ext4_error(sb, "block_group >= groups_count - block_group = %u," |
288 | " groups_count = %u", block_group, ngroups); | |
ac27a0ec DK |
289 | |
290 | return NULL; | |
291 | } | |
ac27a0ec | 292 | |
617ba13b MC |
293 | group_desc = block_group >> EXT4_DESC_PER_BLOCK_BITS(sb); |
294 | offset = block_group & (EXT4_DESC_PER_BLOCK(sb) - 1); | |
ac27a0ec | 295 | if (!sbi->s_group_desc[group_desc]) { |
12062ddd | 296 | ext4_error(sb, "Group descriptor not loaded - " |
498e5f24 | 297 | "block_group = %u, group_desc = %u, desc = %u", |
af5bc92d | 298 | block_group, group_desc, offset); |
ac27a0ec DK |
299 | return NULL; |
300 | } | |
301 | ||
0d1ee42f AR |
302 | desc = (struct ext4_group_desc *)( |
303 | (__u8 *)sbi->s_group_desc[group_desc]->b_data + | |
304 | offset * EXT4_DESC_SIZE(sb)); | |
ac27a0ec DK |
305 | if (bh) |
306 | *bh = sbi->s_group_desc[group_desc]; | |
0d1ee42f | 307 | return desc; |
ac27a0ec DK |
308 | } |
309 | ||
7a4c5de2 TT |
310 | /* |
311 | * Return the block number which was discovered to be invalid, or 0 if | |
312 | * the block bitmap is valid. | |
313 | */ | |
314 | static ext4_fsblk_t ext4_valid_block_bitmap(struct super_block *sb, | |
315 | struct ext4_group_desc *desc, | |
dbde0abe | 316 | ext4_group_t block_group, |
7a4c5de2 | 317 | struct buffer_head *bh) |
abcb2947 | 318 | { |
e674e5cb | 319 | struct ext4_sb_info *sbi = EXT4_SB(sb); |
abcb2947 AK |
320 | ext4_grpblk_t offset; |
321 | ext4_grpblk_t next_zero_bit; | |
7a4c5de2 | 322 | ext4_fsblk_t blk; |
abcb2947 AK |
323 | ext4_fsblk_t group_first_block; |
324 | ||
e2b911c5 | 325 | if (ext4_has_feature_flex_bg(sb)) { |
abcb2947 AK |
326 | /* with FLEX_BG, the inode/block bitmaps and itable |
327 | * blocks may not be in the group at all | |
328 | * so the bitmap validation will be skipped for those groups | |
329 | * or it has to also read the block group where the bitmaps | |
330 | * are located to verify they are set. | |
331 | */ | |
7a4c5de2 | 332 | return 0; |
abcb2947 AK |
333 | } |
334 | group_first_block = ext4_group_first_block_no(sb, block_group); | |
335 | ||
336 | /* check whether block bitmap block number is set */ | |
7a4c5de2 TT |
337 | blk = ext4_block_bitmap(sb, desc); |
338 | offset = blk - group_first_block; | |
e674e5cb | 339 | if (!ext4_test_bit(EXT4_B2C(sbi, offset), bh->b_data)) |
abcb2947 | 340 | /* bad block bitmap */ |
7a4c5de2 | 341 | return blk; |
abcb2947 AK |
342 | |
343 | /* check whether the inode bitmap block number is set */ | |
7a4c5de2 TT |
344 | blk = ext4_inode_bitmap(sb, desc); |
345 | offset = blk - group_first_block; | |
e674e5cb | 346 | if (!ext4_test_bit(EXT4_B2C(sbi, offset), bh->b_data)) |
abcb2947 | 347 | /* bad block bitmap */ |
7a4c5de2 | 348 | return blk; |
abcb2947 AK |
349 | |
350 | /* check whether the inode table block number is set */ | |
7a4c5de2 TT |
351 | blk = ext4_inode_table(sb, desc); |
352 | offset = blk - group_first_block; | |
abcb2947 | 353 | next_zero_bit = ext4_find_next_zero_bit(bh->b_data, |
e674e5cb DW |
354 | EXT4_B2C(sbi, offset + EXT4_SB(sb)->s_itb_per_group), |
355 | EXT4_B2C(sbi, offset)); | |
356 | if (next_zero_bit < | |
357 | EXT4_B2C(sbi, offset + EXT4_SB(sb)->s_itb_per_group)) | |
7a4c5de2 TT |
358 | /* bad bitmap for inode tables */ |
359 | return blk; | |
abcb2947 AK |
360 | return 0; |
361 | } | |
fa77dcfa | 362 | |
9008a58e DW |
363 | static int ext4_validate_block_bitmap(struct super_block *sb, |
364 | struct ext4_group_desc *desc, | |
365 | ext4_group_t block_group, | |
366 | struct buffer_head *bh) | |
fa77dcfa | 367 | { |
7a4c5de2 | 368 | ext4_fsblk_t blk; |
163a203d | 369 | struct ext4_group_info *grp = ext4_get_group_info(sb, block_group); |
e43bb4e6 | 370 | struct ext4_sb_info *sbi = EXT4_SB(sb); |
7a4c5de2 | 371 | |
9008a58e DW |
372 | if (buffer_verified(bh)) |
373 | return 0; | |
374 | if (EXT4_MB_GRP_BBITMAP_CORRUPT(grp)) | |
375 | return -EFSCORRUPTED; | |
fa77dcfa DW |
376 | |
377 | ext4_lock_group(sb, block_group); | |
9008a58e DW |
378 | if (unlikely(!ext4_block_bitmap_csum_verify(sb, block_group, |
379 | desc, bh))) { | |
7a4c5de2 | 380 | ext4_unlock_group(sb, block_group); |
9008a58e | 381 | ext4_error(sb, "bg %u: bad block bitmap checksum", block_group); |
e43bb4e6 NJ |
382 | if (!EXT4_MB_GRP_BBITMAP_CORRUPT(grp)) |
383 | percpu_counter_sub(&sbi->s_freeclusters_counter, | |
384 | grp->bb_free); | |
163a203d | 385 | set_bit(EXT4_GROUP_INFO_BBITMAP_CORRUPT_BIT, &grp->bb_state); |
9008a58e | 386 | return -EFSBADCRC; |
7a4c5de2 | 387 | } |
9008a58e DW |
388 | blk = ext4_valid_block_bitmap(sb, desc, block_group, bh); |
389 | if (unlikely(blk != 0)) { | |
7a4c5de2 | 390 | ext4_unlock_group(sb, block_group); |
9008a58e DW |
391 | ext4_error(sb, "bg %u: block %llu: invalid block bitmap", |
392 | block_group, blk); | |
e43bb4e6 NJ |
393 | if (!EXT4_MB_GRP_BBITMAP_CORRUPT(grp)) |
394 | percpu_counter_sub(&sbi->s_freeclusters_counter, | |
395 | grp->bb_free); | |
163a203d | 396 | set_bit(EXT4_GROUP_INFO_BBITMAP_CORRUPT_BIT, &grp->bb_state); |
9008a58e | 397 | return -EFSCORRUPTED; |
7a4c5de2 TT |
398 | } |
399 | set_buffer_verified(bh); | |
fa77dcfa | 400 | ext4_unlock_group(sb, block_group); |
9008a58e | 401 | return 0; |
fa77dcfa DW |
402 | } |
403 | ||
ac27a0ec | 404 | /** |
15b49132 | 405 | * ext4_read_block_bitmap_nowait() |
ac27a0ec DK |
406 | * @sb: super block |
407 | * @block_group: given block group | |
408 | * | |
abcb2947 AK |
409 | * Read the bitmap for a given block_group,and validate the |
410 | * bits for block/inode/inode tables are set in the bitmaps | |
ac27a0ec DK |
411 | * |
412 | * Return buffer_head on success or NULL in case of failure. | |
413 | */ | |
717d50e4 | 414 | struct buffer_head * |
813e5727 | 415 | ext4_read_block_bitmap_nowait(struct super_block *sb, ext4_group_t block_group) |
ac27a0ec | 416 | { |
af5bc92d | 417 | struct ext4_group_desc *desc; |
813e5727 | 418 | struct buffer_head *bh; |
7c9e69fa | 419 | ext4_fsblk_t bitmap_blk; |
9008a58e | 420 | int err; |
ac27a0ec | 421 | |
717d50e4 | 422 | desc = ext4_get_group_desc(sb, block_group, NULL); |
ac27a0ec | 423 | if (!desc) |
9008a58e | 424 | return ERR_PTR(-EFSCORRUPTED); |
7c9e69fa | 425 | bitmap_blk = ext4_block_bitmap(sb, desc); |
abcb2947 AK |
426 | bh = sb_getblk(sb, bitmap_blk); |
427 | if (unlikely(!bh)) { | |
813e5727 TT |
428 | ext4_error(sb, "Cannot get buffer for block bitmap - " |
429 | "block_group = %u, block_bitmap = %llu", | |
430 | block_group, bitmap_blk); | |
9008a58e | 431 | return ERR_PTR(-ENOMEM); |
abcb2947 | 432 | } |
2ccb5fb9 AK |
433 | |
434 | if (bitmap_uptodate(bh)) | |
fa77dcfa | 435 | goto verify; |
abcb2947 | 436 | |
c806e68f | 437 | lock_buffer(bh); |
2ccb5fb9 AK |
438 | if (bitmap_uptodate(bh)) { |
439 | unlock_buffer(bh); | |
fa77dcfa | 440 | goto verify; |
2ccb5fb9 | 441 | } |
955ce5f5 | 442 | ext4_lock_group(sb, block_group); |
717d50e4 | 443 | if (desc->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT)) { |
aef4885a | 444 | err = ext4_init_block_bitmap(sb, bh, block_group, desc); |
2ccb5fb9 | 445 | set_bitmap_uptodate(bh); |
abcb2947 | 446 | set_buffer_uptodate(bh); |
955ce5f5 | 447 | ext4_unlock_group(sb, block_group); |
3300beda | 448 | unlock_buffer(bh); |
05145bd7 JK |
449 | if (err) { |
450 | ext4_error(sb, "Failed to init block bitmap for group " | |
451 | "%u: %d", block_group, err); | |
9008a58e | 452 | goto out; |
05145bd7 | 453 | } |
41e5b7ed | 454 | goto verify; |
717d50e4 | 455 | } |
955ce5f5 | 456 | ext4_unlock_group(sb, block_group); |
2ccb5fb9 AK |
457 | if (buffer_uptodate(bh)) { |
458 | /* | |
459 | * if not uninit if bh is uptodate, | |
460 | * bitmap is also uptodate | |
461 | */ | |
462 | set_bitmap_uptodate(bh); | |
463 | unlock_buffer(bh); | |
fa77dcfa | 464 | goto verify; |
2ccb5fb9 AK |
465 | } |
466 | /* | |
813e5727 | 467 | * submit the buffer_head for reading |
2ccb5fb9 | 468 | */ |
813e5727 | 469 | set_buffer_new(bh); |
0562e0ba | 470 | trace_ext4_read_block_bitmap_load(sb, block_group); |
813e5727 TT |
471 | bh->b_end_io = ext4_end_bitmap_read; |
472 | get_bh(bh); | |
9f203507 | 473 | submit_bh(READ | REQ_META | REQ_PRIO, bh); |
813e5727 | 474 | return bh; |
fa77dcfa | 475 | verify: |
9008a58e DW |
476 | err = ext4_validate_block_bitmap(sb, desc, block_group, bh); |
477 | if (err) | |
478 | goto out; | |
479 | return bh; | |
480 | out: | |
48d9eb97 | 481 | put_bh(bh); |
9008a58e | 482 | return ERR_PTR(err); |
813e5727 TT |
483 | } |
484 | ||
485 | /* Returns 0 on success, 1 on error */ | |
486 | int ext4_wait_block_bitmap(struct super_block *sb, ext4_group_t block_group, | |
487 | struct buffer_head *bh) | |
488 | { | |
489 | struct ext4_group_desc *desc; | |
490 | ||
491 | if (!buffer_new(bh)) | |
492 | return 0; | |
493 | desc = ext4_get_group_desc(sb, block_group, NULL); | |
494 | if (!desc) | |
9008a58e | 495 | return -EFSCORRUPTED; |
813e5727 TT |
496 | wait_on_buffer(bh); |
497 | if (!buffer_uptodate(bh)) { | |
12062ddd | 498 | ext4_error(sb, "Cannot read block bitmap - " |
813e5727 | 499 | "block_group = %u, block_bitmap = %llu", |
d4dc462f | 500 | block_group, (unsigned long long) bh->b_blocknr); |
9008a58e | 501 | return -EIO; |
abcb2947 | 502 | } |
813e5727 TT |
503 | clear_buffer_new(bh); |
504 | /* Panic or remount fs read-only if block bitmap is invalid */ | |
9008a58e | 505 | return ext4_validate_block_bitmap(sb, desc, block_group, bh); |
813e5727 TT |
506 | } |
507 | ||
508 | struct buffer_head * | |
509 | ext4_read_block_bitmap(struct super_block *sb, ext4_group_t block_group) | |
510 | { | |
511 | struct buffer_head *bh; | |
9008a58e | 512 | int err; |
813e5727 TT |
513 | |
514 | bh = ext4_read_block_bitmap_nowait(sb, block_group); | |
9008a58e DW |
515 | if (IS_ERR(bh)) |
516 | return bh; | |
517 | err = ext4_wait_block_bitmap(sb, block_group, bh); | |
518 | if (err) { | |
813e5727 | 519 | put_bh(bh); |
9008a58e | 520 | return ERR_PTR(err); |
813e5727 | 521 | } |
ac27a0ec DK |
522 | return bh; |
523 | } | |
ac27a0ec | 524 | |
8c3bf8a0 | 525 | /** |
df55c99d | 526 | * ext4_has_free_clusters() |
8c3bf8a0 | 527 | * @sbi: in-core super block structure. |
df55c99d TT |
528 | * @nclusters: number of needed blocks |
529 | * @flags: flags from ext4_mb_new_blocks() | |
8c3bf8a0 | 530 | * |
df55c99d | 531 | * Check if filesystem has nclusters free & available for allocation. |
8c3bf8a0 ES |
532 | * On success return 1, return 0 on failure. |
533 | */ | |
df55c99d TT |
534 | static int ext4_has_free_clusters(struct ext4_sb_info *sbi, |
535 | s64 nclusters, unsigned int flags) | |
a30d542a | 536 | { |
27dd4385 | 537 | s64 free_clusters, dirty_clusters, rsv, resv_clusters; |
57042651 | 538 | struct percpu_counter *fcc = &sbi->s_freeclusters_counter; |
df55c99d | 539 | struct percpu_counter *dcc = &sbi->s_dirtyclusters_counter; |
a30d542a | 540 | |
df55c99d TT |
541 | free_clusters = percpu_counter_read_positive(fcc); |
542 | dirty_clusters = percpu_counter_read_positive(dcc); | |
27dd4385 | 543 | resv_clusters = atomic64_read(&sbi->s_resv_clusters); |
304e220f LC |
544 | |
545 | /* | |
546 | * r_blocks_count should always be multiple of the cluster ratio so | |
547 | * we are safe to do a plane bit shift only. | |
548 | */ | |
27dd4385 LC |
549 | rsv = (ext4_r_blocks_count(sbi->s_es) >> sbi->s_cluster_bits) + |
550 | resv_clusters; | |
a30d542a | 551 | |
27dd4385 | 552 | if (free_clusters - (nclusters + rsv + dirty_clusters) < |
df55c99d | 553 | EXT4_FREECLUSTERS_WATERMARK) { |
304e220f | 554 | free_clusters = percpu_counter_sum_positive(fcc); |
df55c99d | 555 | dirty_clusters = percpu_counter_sum_positive(dcc); |
6bc6e63f | 556 | } |
df55c99d TT |
557 | /* Check whether we have space after accounting for current |
558 | * dirty clusters & root reserved clusters. | |
6bc6e63f | 559 | */ |
27dd4385 | 560 | if (free_clusters >= (rsv + nclusters + dirty_clusters)) |
a996031c | 561 | return 1; |
a30d542a | 562 | |
df55c99d | 563 | /* Hm, nope. Are (enough) root reserved clusters available? */ |
08cefc7a EB |
564 | if (uid_eq(sbi->s_resuid, current_fsuid()) || |
565 | (!gid_eq(sbi->s_resgid, GLOBAL_ROOT_GID) && in_group_p(sbi->s_resgid)) || | |
55f020db | 566 | capable(CAP_SYS_RESOURCE) || |
27dd4385 | 567 | (flags & EXT4_MB_USE_ROOT_BLOCKS)) { |
55f020db | 568 | |
27dd4385 LC |
569 | if (free_clusters >= (nclusters + dirty_clusters + |
570 | resv_clusters)) | |
571 | return 1; | |
572 | } | |
573 | /* No free blocks. Let's see if we can dip into reserved pool */ | |
574 | if (flags & EXT4_MB_USE_RESERVED) { | |
df55c99d | 575 | if (free_clusters >= (nclusters + dirty_clusters)) |
a996031c ES |
576 | return 1; |
577 | } | |
578 | ||
579 | return 0; | |
a30d542a AK |
580 | } |
581 | ||
e7d5f315 TT |
582 | int ext4_claim_free_clusters(struct ext4_sb_info *sbi, |
583 | s64 nclusters, unsigned int flags) | |
ac27a0ec | 584 | { |
df55c99d | 585 | if (ext4_has_free_clusters(sbi, nclusters, flags)) { |
e7d5f315 | 586 | percpu_counter_add(&sbi->s_dirtyclusters_counter, nclusters); |
16eb7295 | 587 | return 0; |
8c3bf8a0 ES |
588 | } else |
589 | return -ENOSPC; | |
a30d542a | 590 | } |
07031431 | 591 | |
ac27a0ec | 592 | /** |
617ba13b | 593 | * ext4_should_retry_alloc() |
ac27a0ec DK |
594 | * @sb: super block |
595 | * @retries number of attemps has been made | |
596 | * | |
617ba13b | 597 | * ext4_should_retry_alloc() is called when ENOSPC is returned, and if |
ac27a0ec | 598 | * it is profitable to retry the operation, this function will wait |
25985edc | 599 | * for the current or committing transaction to complete, and then |
ac27a0ec DK |
600 | * return TRUE. |
601 | * | |
602 | * if the total number of retries exceed three times, return FALSE. | |
603 | */ | |
617ba13b | 604 | int ext4_should_retry_alloc(struct super_block *sb, int *retries) |
ac27a0ec | 605 | { |
df55c99d | 606 | if (!ext4_has_free_clusters(EXT4_SB(sb), 1, 0) || |
8f64b32e ES |
607 | (*retries)++ > 3 || |
608 | !EXT4_SB(sb)->s_journal) | |
ac27a0ec DK |
609 | return 0; |
610 | ||
611 | jbd_debug(1, "%s: retrying operation after ENOSPC\n", sb->s_id); | |
612 | ||
dab291af | 613 | return jbd2_journal_force_commit_nested(EXT4_SB(sb)->s_journal); |
ac27a0ec DK |
614 | } |
615 | ||
654b4908 | 616 | /* |
d2a17637 | 617 | * ext4_new_meta_blocks() -- allocate block for meta data (indexing) blocks |
654b4908 AK |
618 | * |
619 | * @handle: handle to this transaction | |
620 | * @inode: file inode | |
621 | * @goal: given target block(filesystem wide) | |
7b415bf6 | 622 | * @count: pointer to total number of clusters needed |
654b4908 AK |
623 | * @errp: error code |
624 | * | |
97df5d15 | 625 | * Return 1st allocated block number on success, *count stores total account |
d2a17637 | 626 | * error stores in errp pointer |
654b4908 | 627 | */ |
d2a17637 | 628 | ext4_fsblk_t ext4_new_meta_blocks(handle_t *handle, struct inode *inode, |
55f020db AH |
629 | ext4_fsblk_t goal, unsigned int flags, |
630 | unsigned long *count, int *errp) | |
654b4908 | 631 | { |
97df5d15 | 632 | struct ext4_allocation_request ar; |
d2a17637 | 633 | ext4_fsblk_t ret; |
97df5d15 TT |
634 | |
635 | memset(&ar, 0, sizeof(ar)); | |
636 | /* Fill with neighbour allocated blocks */ | |
637 | ar.inode = inode; | |
638 | ar.goal = goal; | |
639 | ar.len = count ? *count : 1; | |
55f020db | 640 | ar.flags = flags; |
97df5d15 TT |
641 | |
642 | ret = ext4_mb_new_blocks(handle, &ar, errp); | |
643 | if (count) | |
644 | *count = ar.len; | |
d2a17637 | 645 | /* |
72b8ab9d ES |
646 | * Account for the allocated meta blocks. We will never |
647 | * fail EDQUOT for metdata, but we do account for it. | |
d2a17637 | 648 | */ |
e3cf5d5d | 649 | if (!(*errp) && (flags & EXT4_MB_DELALLOC_RESERVED)) { |
7b415bf6 AK |
650 | dquot_alloc_block_nofail(inode, |
651 | EXT4_C2B(EXT4_SB(inode->i_sb), ar.len)); | |
d2a17637 MC |
652 | } |
653 | return ret; | |
654b4908 AK |
654 | } |
655 | ||
ac27a0ec | 656 | /** |
5dee5437 | 657 | * ext4_count_free_clusters() -- count filesystem free clusters |
ac27a0ec DK |
658 | * @sb: superblock |
659 | * | |
5dee5437 | 660 | * Adds up the number of free clusters from each block group. |
ac27a0ec | 661 | */ |
5dee5437 | 662 | ext4_fsblk_t ext4_count_free_clusters(struct super_block *sb) |
ac27a0ec | 663 | { |
617ba13b MC |
664 | ext4_fsblk_t desc_count; |
665 | struct ext4_group_desc *gdp; | |
fd2d4291 | 666 | ext4_group_t i; |
8df9675f | 667 | ext4_group_t ngroups = ext4_get_groups_count(sb); |
2746f7a1 | 668 | struct ext4_group_info *grp; |
617ba13b MC |
669 | #ifdef EXT4FS_DEBUG |
670 | struct ext4_super_block *es; | |
671 | ext4_fsblk_t bitmap_count; | |
498e5f24 | 672 | unsigned int x; |
ac27a0ec DK |
673 | struct buffer_head *bitmap_bh = NULL; |
674 | ||
617ba13b | 675 | es = EXT4_SB(sb)->s_es; |
ac27a0ec DK |
676 | desc_count = 0; |
677 | bitmap_count = 0; | |
678 | gdp = NULL; | |
679 | ||
ac27a0ec | 680 | for (i = 0; i < ngroups; i++) { |
617ba13b | 681 | gdp = ext4_get_group_desc(sb, i, NULL); |
ac27a0ec DK |
682 | if (!gdp) |
683 | continue; | |
2746f7a1 DW |
684 | grp = NULL; |
685 | if (EXT4_SB(sb)->s_group_info) | |
686 | grp = ext4_get_group_info(sb, i); | |
687 | if (!grp || !EXT4_MB_GRP_BBITMAP_CORRUPT(grp)) | |
688 | desc_count += ext4_free_group_clusters(sb, gdp); | |
ac27a0ec | 689 | brelse(bitmap_bh); |
574ca174 | 690 | bitmap_bh = ext4_read_block_bitmap(sb, i); |
9008a58e DW |
691 | if (IS_ERR(bitmap_bh)) { |
692 | bitmap_bh = NULL; | |
ac27a0ec | 693 | continue; |
9008a58e | 694 | } |
ac27a0ec | 695 | |
f6fb99ca | 696 | x = ext4_count_free(bitmap_bh->b_data, |
036acea2 | 697 | EXT4_CLUSTERS_PER_GROUP(sb) / 8); |
9fd9784c | 698 | printk(KERN_DEBUG "group %u: stored = %d, counted = %u\n", |
021b65bb | 699 | i, ext4_free_group_clusters(sb, gdp), x); |
ac27a0ec DK |
700 | bitmap_count += x; |
701 | } | |
702 | brelse(bitmap_bh); | |
5dee5437 TT |
703 | printk(KERN_DEBUG "ext4_count_free_clusters: stored = %llu" |
704 | ", computed = %llu, %llu\n", | |
810da240 | 705 | EXT4_NUM_B2C(EXT4_SB(sb), ext4_free_blocks_count(es)), |
4776004f | 706 | desc_count, bitmap_count); |
ac27a0ec DK |
707 | return bitmap_count; |
708 | #else | |
709 | desc_count = 0; | |
ac27a0ec | 710 | for (i = 0; i < ngroups; i++) { |
617ba13b | 711 | gdp = ext4_get_group_desc(sb, i, NULL); |
ac27a0ec DK |
712 | if (!gdp) |
713 | continue; | |
2746f7a1 DW |
714 | grp = NULL; |
715 | if (EXT4_SB(sb)->s_group_info) | |
716 | grp = ext4_get_group_info(sb, i); | |
717 | if (!grp || !EXT4_MB_GRP_BBITMAP_CORRUPT(grp)) | |
718 | desc_count += ext4_free_group_clusters(sb, gdp); | |
ac27a0ec DK |
719 | } |
720 | ||
721 | return desc_count; | |
722 | #endif | |
723 | } | |
724 | ||
fd2d4291 | 725 | static inline int test_root(ext4_group_t a, int b) |
ac27a0ec | 726 | { |
f4afb4f4 TT |
727 | while (1) { |
728 | if (a < b) | |
729 | return 0; | |
730 | if (a == b) | |
731 | return 1; | |
732 | if ((a % b) != 0) | |
733 | return 0; | |
734 | a = a / b; | |
735 | } | |
ac27a0ec DK |
736 | } |
737 | ||
ac27a0ec | 738 | /** |
617ba13b | 739 | * ext4_bg_has_super - number of blocks used by the superblock in group |
ac27a0ec DK |
740 | * @sb: superblock for filesystem |
741 | * @group: group number to check | |
742 | * | |
743 | * Return the number of blocks used by the superblock (primary or backup) | |
744 | * in this group. Currently this will be only 0 or 1. | |
745 | */ | |
fd2d4291 | 746 | int ext4_bg_has_super(struct super_block *sb, ext4_group_t group) |
ac27a0ec | 747 | { |
1beeef1b DW |
748 | struct ext4_super_block *es = EXT4_SB(sb)->s_es; |
749 | ||
750 | if (group == 0) | |
751 | return 1; | |
e2b911c5 | 752 | if (ext4_has_feature_sparse_super2(sb)) { |
1beeef1b DW |
753 | if (group == le32_to_cpu(es->s_backup_bgs[0]) || |
754 | group == le32_to_cpu(es->s_backup_bgs[1])) | |
755 | return 1; | |
756 | return 0; | |
757 | } | |
e2b911c5 | 758 | if ((group <= 1) || !ext4_has_feature_sparse_super(sb)) |
1beeef1b DW |
759 | return 1; |
760 | if (!(group & 1)) | |
ac27a0ec | 761 | return 0; |
1beeef1b DW |
762 | if (test_root(group, 3) || (test_root(group, 5)) || |
763 | test_root(group, 7)) | |
764 | return 1; | |
765 | ||
766 | return 0; | |
ac27a0ec DK |
767 | } |
768 | ||
fd2d4291 AM |
769 | static unsigned long ext4_bg_num_gdb_meta(struct super_block *sb, |
770 | ext4_group_t group) | |
ac27a0ec | 771 | { |
617ba13b | 772 | unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb); |
fd2d4291 AM |
773 | ext4_group_t first = metagroup * EXT4_DESC_PER_BLOCK(sb); |
774 | ext4_group_t last = first + EXT4_DESC_PER_BLOCK(sb) - 1; | |
ac27a0ec DK |
775 | |
776 | if (group == first || group == first + 1 || group == last) | |
777 | return 1; | |
778 | return 0; | |
779 | } | |
780 | ||
fd2d4291 AM |
781 | static unsigned long ext4_bg_num_gdb_nometa(struct super_block *sb, |
782 | ext4_group_t group) | |
ac27a0ec | 783 | { |
8dadb198 TT |
784 | if (!ext4_bg_has_super(sb, group)) |
785 | return 0; | |
786 | ||
e2b911c5 | 787 | if (ext4_has_feature_meta_bg(sb)) |
8dadb198 TT |
788 | return le32_to_cpu(EXT4_SB(sb)->s_es->s_first_meta_bg); |
789 | else | |
790 | return EXT4_SB(sb)->s_gdb_count; | |
ac27a0ec DK |
791 | } |
792 | ||
793 | /** | |
617ba13b | 794 | * ext4_bg_num_gdb - number of blocks used by the group table in group |
ac27a0ec DK |
795 | * @sb: superblock for filesystem |
796 | * @group: group number to check | |
797 | * | |
798 | * Return the number of blocks used by the group descriptor table | |
799 | * (primary or backup) in this group. In the future there may be a | |
800 | * different number of descriptor blocks in each group. | |
801 | */ | |
fd2d4291 | 802 | unsigned long ext4_bg_num_gdb(struct super_block *sb, ext4_group_t group) |
ac27a0ec DK |
803 | { |
804 | unsigned long first_meta_bg = | |
617ba13b MC |
805 | le32_to_cpu(EXT4_SB(sb)->s_es->s_first_meta_bg); |
806 | unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb); | |
ac27a0ec | 807 | |
e2b911c5 | 808 | if (!ext4_has_feature_meta_bg(sb) || metagroup < first_meta_bg) |
af5bc92d | 809 | return ext4_bg_num_gdb_nometa(sb, group); |
ac27a0ec | 810 | |
617ba13b | 811 | return ext4_bg_num_gdb_meta(sb,group); |
ac27a0ec DK |
812 | |
813 | } | |
c2ea3fde | 814 | |
49f7f9af | 815 | /* |
d5b8f310 | 816 | * This function returns the number of file system metadata clusters at |
49f7f9af TT |
817 | * the beginning of a block group, including the reserved gdt blocks. |
818 | */ | |
5f163cc7 | 819 | static unsigned ext4_num_base_meta_clusters(struct super_block *sb, |
d5b8f310 | 820 | ext4_group_t block_group) |
49f7f9af TT |
821 | { |
822 | struct ext4_sb_info *sbi = EXT4_SB(sb); | |
d5b8f310 | 823 | unsigned num; |
49f7f9af TT |
824 | |
825 | /* Check for superblock and gdt backups in this group */ | |
826 | num = ext4_bg_has_super(sb, block_group); | |
827 | ||
e2b911c5 | 828 | if (!ext4_has_feature_meta_bg(sb) || |
49f7f9af TT |
829 | block_group < le32_to_cpu(sbi->s_es->s_first_meta_bg) * |
830 | sbi->s_desc_per_block) { | |
831 | if (num) { | |
832 | num += ext4_bg_num_gdb(sb, block_group); | |
833 | num += le16_to_cpu(sbi->s_es->s_reserved_gdt_blocks); | |
834 | } | |
835 | } else { /* For META_BG_BLOCK_GROUPS */ | |
836 | num += ext4_bg_num_gdb(sb, block_group); | |
837 | } | |
d5b8f310 | 838 | return EXT4_NUM_B2C(sbi, num); |
49f7f9af | 839 | } |
f86186b4 ES |
840 | /** |
841 | * ext4_inode_to_goal_block - return a hint for block allocation | |
842 | * @inode: inode for block allocation | |
843 | * | |
844 | * Return the ideal location to start allocating blocks for a | |
845 | * newly created inode. | |
846 | */ | |
847 | ext4_fsblk_t ext4_inode_to_goal_block(struct inode *inode) | |
848 | { | |
849 | struct ext4_inode_info *ei = EXT4_I(inode); | |
850 | ext4_group_t block_group; | |
851 | ext4_grpblk_t colour; | |
852 | int flex_size = ext4_flex_bg_size(EXT4_SB(inode->i_sb)); | |
853 | ext4_fsblk_t bg_start; | |
854 | ext4_fsblk_t last_block; | |
855 | ||
856 | block_group = ei->i_block_group; | |
857 | if (flex_size >= EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME) { | |
858 | /* | |
859 | * If there are at least EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME | |
860 | * block groups per flexgroup, reserve the first block | |
861 | * group for directories and special files. Regular | |
862 | * files will start at the second block group. This | |
863 | * tends to speed up directory access and improves | |
864 | * fsck times. | |
865 | */ | |
866 | block_group &= ~(flex_size-1); | |
867 | if (S_ISREG(inode->i_mode)) | |
868 | block_group++; | |
869 | } | |
870 | bg_start = ext4_group_first_block_no(inode->i_sb, block_group); | |
871 | last_block = ext4_blocks_count(EXT4_SB(inode->i_sb)->s_es) - 1; | |
872 | ||
873 | /* | |
874 | * If we are doing delayed allocation, we don't need take | |
875 | * colour into account. | |
876 | */ | |
877 | if (test_opt(inode->i_sb, DELALLOC)) | |
878 | return bg_start; | |
879 | ||
880 | if (bg_start + EXT4_BLOCKS_PER_GROUP(inode->i_sb) <= last_block) | |
881 | colour = (current->pid % 16) * | |
882 | (EXT4_BLOCKS_PER_GROUP(inode->i_sb) / 16); | |
883 | else | |
884 | colour = (current->pid % 16) * ((last_block - bg_start) / 16); | |
885 | return bg_start + colour; | |
886 | } | |
887 |